This is chicken.info, produced by makeinfo version 4.7 from
chicken.texi.

Copyright (C) 2000-2006, Felix L. Winkelmann All rights reserved.

Redistribution and use in source and binary forms, with or without
modification, are permitted provided that the following conditions are
met:

   * Redistributions of source code must retain the above copyright
     notice, this list of conditions and the following disclaimer.

   * Redistributions in binary form must reproduce the above copyright
     notice, this list of conditions and the following disclaimer in the
     documentation and/or other materials provided with the
     distribution.

   * Neither the name of the author nor the names of its contributors
     may be used to endorse or promote products derived from this
     software without specific prior written permission.

THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS "AS
IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED
TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A
PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT
HOLDERS OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL,
SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT
LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES LOSS OF USE,
DATA, OR PROFITS OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY
THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
(INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE
OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.

INFO-DIR-SECTION The Algorithmic Language Scheme
START-INFO-DIR-ENTRY
* CHICKEN: (chicken).          A pratical and portable Scheme system (Version 2, Build 41).
END-INFO-DIR-ENTRY

Copyright (C) 2000-2006, Felix L. Winkelmann All rights reserved.

Redistribution and use in source and binary forms, with or without
modification, are permitted provided that the following conditions are
met:

   * Redistributions of source code must retain the above copyright
     notice, this list of conditions and the following disclaimer.

   * Redistributions in binary form must reproduce the above copyright
     notice, this list of conditions and the following disclaimer in the
     documentation and/or other materials provided with the
     distribution.

   * Neither the name of the author nor the names of its contributors
     may be used to endorse or promote products derived from this
     software without specific prior written permission.

THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS "AS
IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED
TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A
PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT
HOLDERS OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL,
SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT
LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES LOSS OF USE,
DATA, OR PROFITS OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY
THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
(INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE
OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.


File: chicken.info,  Node: Top,  Next: Introduction,  Up: (dir)

CHICKEN
*******

CHICKEN - A practical and portable Scheme system User's manual (Version
2, Build 41)

   (c) 2000-2006, Felix L. Winkelmann All rights reserved. Translated
to LaTeX by Peter Keller. Translated to texinfo by Linh Dang.

* Menu:

* Introduction::
* Basic mode of operation::
* Using the compiler::
* Using the interpreter::
* Supported language::
* Interface to external functions and variables::
* chicken-setup::
* Additional files::
* Data Representation::
* Bugs and limitations::
* FAQ::
* Acknowledgements::
* Bibliography::
* Index::

 --- The Detailed Node Listing ---

Using the compiler

* Compiler command line format::
* Runtime options::
* An example::
* Extending the compiler::
* Distributing compiled C files::

Using the interpreter

* Interpreter  command line format::
* Writing Scheme scripts::
* Toplevel commands::
* Macros and procedures implemented in the interpreter::

Supported language

* Deviations from the standard::
* Extensions to the standard::
* Non standard read syntax::
* Non-standard macros and special forms::
* Pattern Matching::
* Declarations::
* Parameters::
* Unit library::
* Unit eval::
* Unit extras::
* Unit srfi-1::
* Unit srfi-4::
* Unit srfi-13::
* Unit srfi-14::
* Unit match::
* Unit regex::
* Unit srfi-18::
* Unit posix::
* Unit utils::
* Unit tcp::
* Unit lolevel::
* Unit tinyclos::

Non-standard macros and special forms

* Binding forms for optional arguments::
* Other binding forms::
* Substitution forms and macros::
* Conditional forms::
* Record structures::
* Other forms::

Unit library

* Arithmetic::
* File Input/Output::
* Files::
* String ports::
* Feature identifiers::
* Keywords::
* Exceptions::
* Environment information and system interface::
* Execution time::
* Interrupts and error-handling::
* Garbage collection::
* Other control structures::
* String utilities::
* Generating uninterned symbols::
* Standard Input/Output::
* User-defined named characters::
* Vectors::
* The unspecified value::
* Continuations::
* Setters::

Unit eval

* Loading code::
* Read-eval-print loop::
* Macros::
* Loading extension libraries::
* Reader extensions::
* Eval::

Unit extras

* Lists::
* String-port extensions::
* Formatted output::
* Hash tables::
* Queues::
* Sorting::
* Random numbers::
* Input/Output extensions::
* Strings::
* Combinators::
* Binary searching::

Unit posix

* Directories::
* Pipes::
* Fifos::
* File descriptors and low-level I/O::
* Retrieving file attributes::
* Changing file attributes::
* Processes::
* Hard and symbolic links::
* Permissions::
* Record locking::
* Signal handling::
* Environment access::
* Memory mapped I/O::
* Date and time routines::
* Raw exit::
* ERRNO values::
* Finding files::
* Getting the hostname and system information::
* Setting the file buffering mode::
* Terminal ports::
* How Scheme procedures relate to UNIX C functions::
* Windows specific notes::

Unit utils

* Pathname operations::
* Temporary files::
* Deleting a file without signalling an error::
* Iterating over input lines and files::
* Executing shell commands with formatstring and error checking::

Unit lolevel

* Foreign pointers::
* Tagged pointers::
* Extending procedures with data::
* Bytevectors::
* Data in unmanaged memory::
* Locatives::
* Accessing toplevel variables::
* Low-level data access::
* Procedure-call- and variable reference hooks::
* Magic::

Unit tinyclos

* Defining forms::
* Base language::
* Introspection::
* Intercessory protocol::
* Additional protocol::
* Utility procedures::
* Builtin classes::

Interface to external functions and variables

* Accessing external objects::
* Foreign type specifiers::
* Embedding::
* Callbacks::
* Locations::
* Other support procedures::
* The Easy Foreign Function Interface::
* C interface::

The _Easy_ Foreign Function Interface

* #> ... <# Syntax::
* General operation::
* Pseudo declarations::
* Grammar::
* C notes::
* C++ notes::

chicken-setup

* Extension libraries::
* Installing extensions::
* Creating extensions::
* Procedures and macros available in setup scripts::

Additional files

* chicken-more-macros.scm::
* chicken-ffi-macros.scm::


File: chicken.info,  Node: Introduction,  Next: Basic mode of operation,  Prev: Top,  Up: Top

1 Introduction
**************

CHICKEN is a compiler that translates Scheme source files into C, which
in turn can be fed to a C-compiler to generate a standalone executable.
This principle, which is used by several existing compilers, achieves
high portability because C is implemented on nearly all available
platforms.

   This package is distributed under the BSD license and as such is free
to use and modify. An interpreter is also available and can be used as
a scripting environment or for testing programs before compilation.

   The method of compilation and the design of the runtime-system follow
closely Henry Baker's `CONS Should Not CONS Its Arguments, Part II:
Cheney on the M.T.A.' paper and expose a number of interesting
properties: consing (creation of data on the heap) is relatively
inexpensive, because a generational garbage collection scheme is used,
in which short-lived data structures are reclaimed extremely quickly.
Moreover, `call-with-current-continuation' is practically for free and
CHICKEN does not suffer under any performance penalties if first-class
continuations are used in complex ways.  The generated C code is fully
tail-recursive.

   Some of the features supported by CHICKEN:
   * SRFIs 0, 1, 2, 4, 6, 7, 8, 9, 10, 13, 14, 16, 17, 18, 23, 28, 30,
     31, 39, 55, 61 and 62.

   * Lightweight threads based on first-class continuations

   * Pattern matching with Andrew Wright's `match' package

   * Record structures

   * An object system with multiple inheritance, multimethods and a
                meta-object protocol

   * Extended comment- and string-literal syntaxes

   * Libraries for regular expressions, string handling UNIX system
     calls and extended data structures

   * Create interpreted or compiled shell scripts written in Scheme
                for UNIX or Windows

   * Compiled C files can be easily distributed

   * Allows the creation of fully self-contained statically linked
     executables

   * On systems that support it, compiled code can be loaded dynamically

   This manual is merely a reference for the CHICKEN system and assumes
a working knowledge of Scheme.


File: chicken.info,  Node: Basic mode of operation,  Next: Using the compiler,  Prev: Introduction,  Up: Top

2 Basic mode of operation
*************************

The compiler translates Scheme source code into fairly portable C that
can be compiled and linked with most available C compilers. CHICKEN
supports the generation of executables and libraries, linked either
statically or dynamically. Compiled Scheme code can be loaded
dynamically, or can be embedded in applications written in other
languages. Separate compilation of modules is fully supported.

   The most portable way of creating separately linkable entities is
supported by so-called _unit_s.  A unit is a single compiled object
module that contains a number of toplevel expressions that are executed
either when the unit is the _main_ unit or if the unit is _used_.  To
use a unit, the unit has to be _declare_ed as used, like this:


(declare (uses UNITNAME))

   The toplevel expressions of used units are executed in the order in
which the units appear in the `uses' declaration. Units may be used
multiple times and `uses' declarations may be circular (the unit is
initialized at most once).  To compile a file as a unit, add a `unit'
declaration:


(declare (unit UNITNAME))

   When compiling different object modules, make sure to have one main
unit. This unit is called initially and initializes all used units
before executing its toplevel expressions. The main-unit has no `unit'
declaration.

   Another method of using definitions in separate source files is to
_include_ them. This simply inserts the code in a given file into the
current file:


(include "FILENAME")

   Macro definitions are only available when processed by `include'.
Macro definitions in separate units are not available, since they are
defined at compile time, i.e the time when that other unit was compiled
(macros can optionally be available at runtime, see `define-macro' in
*Note Substitution forms and macros::).

   On platforms that support dynamic loading of compiled code (like
Windows and most ELF based systems like Linux or BSD) code can be
compiled into a shared object (`.so') and loaded dynamically into a
running application.


File: chicken.info,  Node: Using the compiler,  Next: Using the interpreter,  Prev: Basic mode of operation,  Up: Top

3 Using the compiler
********************

The interface to `chicken' is intentionally simple.  System dependent
makefiles, shell-scripts or batch-files should perform any necessary
steps before and after invocation of `chicken'.  A program named `csc'
provides a much simpler interface to the Scheme- and C-compilers and
linker. Enter


csc -help

   on the command line for more information.

* Menu:

* Compiler command line format::
* Runtime options::
* An example::
* Extending the compiler::
* Distributing compiled C files::


File: chicken.info,  Node: Compiler command line format,  Next: Runtime options,  Up: Using the compiler

3.1 Command line format
=======================

`chicken FILENAME {OPTION}'

   `FILENAME' is the complete pathname of the source file that is to be
translated into C. A filename argument of "`-'" specifies that the
source text should be read from standard input. Note that the filename
has to be the first argument to `chicken'.  Possible options are:

`-analyze-only'
     Stop compilation after first analysis pass.

`-benchmark-mode'
     Equivalent to `-no-trace -no-lambda-info -optimize-level 3'
     `-fixnum-arithmetic -disable-interrupts -block -lambda-lift'.

`-block'
     Enable block-compilation. When this option is specified, the
     compiler assumes that global variables are not modified outside
     this compilation-unit.  Specifically, toplevel bindings are not
     seen by `eval' and unused toplevel bindings are removed.

`-case-insensitive'
     Enables the reader to read symbols case insensitive. The default
     is to read case sensitive (in violation of R5RS).  This option
     registers the `case-insensitive' feature identifier.

`-check-imports'
     Search for references to undefined global variables. For each
     library unit accessed via `(declare (uses ...))', the compiler
     will search a file named `UNITNAME.exports' in the current include
     path and load its contents into the "import-table" (if found).
     Also, export-information for extensions (accessed through
     `(require-extension ...)') will be searched and stored in the
     import-table. If a required extensions does not provide explicit
     exports-innformation and `.exports' file is searched (as with used
     units). After the analysis phase of the compiler, referenced
     toplevel variables for which no assignment was found will generate
     a warning. Also, re-assignments of imported variables will trigger
     a warning.

`-check-syntax'
     Aborts compilation process after macro-expansion and syntax checks.

`-compress-literals THRESHOLD'
     Compiles quoted literals that exceed the size `THRESHOLD' as
     strings and parse the strings at run-time. This reduces the size
     of the code and speeds up compile-times of the host C compiler,
     but has a small run-time performance penalty. The size of a
     literal is computed by counting recursively the objects in the
     literal, so a vector counts as 1 plus the count of the elements, a
     pair counts as the counts of the car and the cdr, respectively.
     All other objects count 1.

`-debug MODES'
     Enables one or more compiler debugging modes. `MODES' is a string
     of characters that select debugging information about the compiler
     that will be printed to standard output.

    `t'
          show time needed for compilation

    `b'
          show breakdown of time needed for each compiler pass

    `o'
          show performed optimizations

    `r'
          show invocation parameters

    `s'
          show program-size information and other statistics

    `a'
          show node-matching during simplification

    `p'
          show execution of compiler sub-passes

    `l'
          show lambda-lifting information

    `m'
          show GC statistics during compilation

    `n'
          print the line-number database

    `c'
          print every expression before macro-expansion

    `u'
          lists all unassigned global variable references

    `x'
          display information about experimental features

    `D'
          when printing nodes, use node-tree output

    `N'
          show the real-name mapping table

    `U'
          show expressions after the secondary user pass

    `0'
          show database before lambda-lifting pass

    `L'
          show expressions after lambda-lifting

    `F'
          show output of "easy" FFI parser

    `M'
          show unit-information and syntax-/runtime-requirements

    `1'
          show source expressions

    `2'
          show canonicalized expressions

    `3'
          show expressions converted into CPS

    `4'
          show database after each analysis pass

    `5'
          show expressions after each optimization pass

    `6'
          show expressions after each inlining pass

    `7'
          show expressions after complete optimization

    `8'
          show database after final analysis

    `9'
          show expressions after closure conversion

`-debug-level LEVEL'
     Selects amount of debug-information. `LEVEL' should be an integer.

        * `-debug-level 0' is equivalent to `-no-trace -no-lambda-info'

        * `-debug-level 1' is equivalent to `-no-trace'

        * `-debug-level 2' does nothing (the default)

`-disable-c-syntax-checks'
     Disable basic syntax checking of embedded C code fragments.

`-disable-interrupts'
     Equivalent to the `(disable-interrupts)' declaration. No
     interrupt-checks are generated for compiled programs.

`-disable-stack-overflow-checks'
     Disables detection of stack overflows. This is equivalent to
     running the compiled executable with the `-:o' runtime option.

`-disable-warning CLASS'
     Disables specific class of warnings, may be given multiple times.
     The following classes are defined:

        * `usage' warnings related to command-line arguments

        * `type' warnings related to type-conversion

        * `ext' warnings related to extension libraries

        * `var' warnings related to variable- and syntax-definitions
          and use

        * `const' warnings related to constant-definitions

        * `syntax' syntax-related warnings

        * `redef' warnings about redefinitions of standard- or
          extended-bindings

        * `call' warnings related to known procedure calls

        * `ffi' warnings related to the foreign function interface

`-dynamic'
     This option should be used when compiling files intended to be
     loaded dynamically into a running Scheme program.

`-epilogue FILENAME'
     Includes the file named `FILENAME' at the end of the compiled
     source file. The include-path is not searched. This option may be
     given multiple times.

`-emit-exports FILENAME'
     Write exported toplevel variables to `FILENAME'.

`-emit-external-prototypes-first'
     Emit prototypes for callbacks defined with `define-external'
     before any other foreign declarations. This is sometimes useful,
     when C/C++ code embedded into the a Scheme program has to access
     the callbacks. By default the prototypes are emitted after foreign
     declarations.

`-explicit-use'
     Disables automatic use of the units `library, eval' and `extras'.
     Use this option if compiling a library unit instead of an
     application unit.

`-extend FILENAME'
     Loads a Scheme source file or compiled Scheme program (on systems
     that support it) before compilation commences. This feature can be
     used to extend the compiler.  This option may be given multiple
     times.  The file is also searched in the current include path and
     in the extension-repository.

`-extension'
     Mostly equivalent to `-prelude '(define-extension <NAME>)'', where
     `<NAME>' is the basename of the currently compiled file.  Note
     that if you want to compile a file as a normal (dynamically
     loadable) extension library, you should also pass the `-shared'
     option.

`-feature SYMBOL'
     Registers `SYMBOL' to be a valid feature identifier for
     `cond-expand'.

`-ffi'
     Parse C/C++ code and generate Scheme bindings. This is effectively
     equivalent to wrapping the code in `#>! ... <#'.

`-ffi-parse'
     Parse C/C++ code and embed as if wrapped inside `#>? ... <#'.

`-ffi-define SYMBOL'
     Defines a macro that will be accessible in `foreign-parse'
     declarations.

`-ffi-include-path PATH'
     Set include path for "easy" FFI parser.

`-ffi-no-include'
     Don't parse include files when encountered by the FFI parser.

`-fixnum-arithmetic'
     Equivalent to `(fixnum-arithmetic)' declaration. Assume all
     mathematical operations use small integer arguments.

`-heap-size NUMBER'
     Sets a fixed heap size of the generated executable to `NUMBER'
     bytes. The parameter may be followed by a `M' (`m') or `K' (`k')
     suffix which stand for mega- and kilobytes, respectively.  The
     default heap size is 5 kilobytes. Note that only half of it is in
     use at every given time.

`-heap-initial-size NUMBER'
     Sets the size that the heap of the compiled application should
     have at startup time.

`-heap-growth PERCENTAGE'
     Sets the heap-growth rate for the compiled program at compile time
     (see: `-:hg').

`-heap-shrinkage PERCENTAGE'
     Sets the heap-shrinkage rate for the compiled program at compile
     time (see: `-:hs').

`-help'
     Print a summary of available options and the format of the command
     line parameters and exit the compiler.

`-import FILENAME'
     Read exports from linked or loaded libraries from given file. See
     also `-check-imports'. This is equivalent to declaring


     (declare (import FILENAME))

     Implies `-check-imports'.

`-include-path PATHNAME'
     Specifies an additional search path for files included via the
     `include' special form. This option may be given multiple times. If
     the environment variable `CHICKEN_INCLUDE_PATH' is set, it should
     contain a list of alternative include pathnames separated by
     "`;'". The environment variable `CHICKEN_HOME' is also considered
     as a search path.

`-inline'
     Enable procedure inlining for known procedures of a size below the
     threshold (which can be set through the `-inline-limit' option).

`-inline-limit THRESHOLD'
     Sets the maximum size of a potentially inlinable procedure. This
     option is only effective when inlining has been enabled with the
     `-inline' option.  The default threshold is `10'.

`-keyword-style STYLE'
     Enables alternative keyword syntax, where `STYLE' may be either
     `prefix' (as in Common Lisp), `suffix' (as in DSSSL) or `none'.
     Any other value is ignored. The default is `suffix'.

`-lambda-lift'
     Enable the optimization known as lambda-lifting.

`-no-lambda-info'
     Don't emit additional information for each `lambda' expression
     (currently the argument-list, after alpha-conversion/renaming).

`-no-trace'
     Disable generation of tracing information. If a compiled
     executable should halt due to a runtime error, then a list of the
     name and the line-number (if available) of the last procedure
     calls is printed, unless `-no-trace' is specified. With this
     option the generated code is slightly faster.

`-no-warnings'
     Disable generation of compiler warnings.

`-nursery NUMBER'

`-stack-size NUMBER'
     Sets the size of the first heap-generation of the generated
     executable to `NUMBER' bytes. The parameter may be followed by a
     `M' (`m') or `K' (`k') suffix.  The default stack-size depends on
     the target platform.

`-optimize-leaf-routines'
     Enable leaf routine optimization.

`-optimize-level LEVEL'
     Enables certain sets of optimization options. `LEVEL' should be an
     integer.

        * `-optimize-level 0' does nothing.

        * `-optimize-level 1' is equivalent to
          `-optimize-leaf-routines'

        * `-optimize-level 2' is currently the same as `-optimize-level
          1'

        * `-optimize-level 3' is equivalent to
          `-optimize-leaf-routines -unsafe'

`-output-file FILENAME'
     Specifies the pathname of the generated C file. Default is
     `FILENAME.c'.

`-postlude EXPRESSIONS'
     Add `EXPRESSIONS' after all other toplevel expressions in the
     compiled file.  This option may be given multiple times.
     Processing of this option takes place after processing of
     `-epilogue'.

`-prelude EXPRESSIONS'
     Add `EXPRESSIONS' before all other toplevel expressions in the
     compiled file.  This option may be given multiple times.
     Processing of this option takes place before processing of
     `-prologue'.

`-profile'

`-accumulate-profile'
     Instruments the source code to count procedure calls and execution
     times. After the program terminates (either via an explicit `exit'
     or implicitly), profiling statistics are written to a file named
     `PROFILE'. Each line of the generated file contains a list with
     the procedure name, the number of calls and the time spent
     executing it. Use the `chicken-profile' program to display the
     profiling information in a more user-friendly form. Enter
     `chicken-profile' with no arguments at the command line to get a
     list of available options.

     The `-accumulate-profile' option is similar to `-profile', but the
     resulting profile information will be appended to any existing
     `PROFILE' file. `chicken-profile' will merge and sum up the
     accumulated timing information, if several entries for the same
     procedure calls exist.

`-profile-name FILENAME'
     Specifies name of the generated profile information (which
     defaults to `PROFILE'. Implies `-profile'.

`-prologue FILENAME'
     Includes the file named `FILENAME' at the start of the compiled
     source file.  The include-path is not searched. This option may be
     given multiple times.

`-quiet'
     Disables output of compile information.

`-raw'
     Disables the generation of any implicit code that uses the Scheme
     libraries (that is all runtime system files besides `runtime.c'
     and `chicken.h').

`-require-extension NAME'
     Loads the extension `NAME' before the compilation process
     commences. This is identical to adding `(require-extension NAME)'
     at the start of the compiled program.

`-run-time-macros'
     Makes macros also available at run-time. By default macros are not
     available at run-time.

`-to-stdout'
     Write compiled code to standard output instead of creating a `.c'
     file.

`-unit NAME'
     Compile this file as a library unit. Equivalent to


     -prelude "(declare (unit NAME))"

`-unsafe'
     Disable runtime safety checks.

`-unsafe-libraries'
     Marks the generated file for being linked with the unsafe runtime
     system. This should be used when generating shared object files
     that are to be loaded dynamically. If the marker is present, any
     attempt to load code compiled with this option will signal an
     error.

`-uses NAME'
     Use definitions from the library unit `NAME'. This is equivalent to


     -prelude "(declare (uses NAME))"

`-no-usual-integrations'
     Specifies that standard procedures and certain internal procedures
     may be redefined, and can not be inlined. This is equivalent to
     declaring `(not usual-integrations)'.

`-version'
     Prints the version and some copyright information and exit the
     compiler.

`-verbose'
     Prints progress information to standard output during compilation.


   The environment variable `CHICKEN_OPTIONS' can be set to a string
with default command-line options for the compiler.


File: chicken.info,  Node: Runtime options,  Next: An example,  Prev: Compiler command line format,  Up: Using the compiler

3.2 Runtime options
===================

After successful compilation a C source file is generated and can be
compiled with a C compiler. Executables generated with CHICKEN (and the
compiler itself) accept a small set of runtime options:

`-:?'
     Shows a list of the available runtime options and exits the
     program.

`-:b'
     Enter a read-eval-print-loop when an error is encountered.

`-:c'
     Forces console mode. Currently this is only used in the interpreter
     (`csi') to force output of the #;N> prompt even if stdin is not a
     terminal (for example if running in an `emacs' buffer under
     Windows).

`-:d'
     Prints some debug-information at runtime.

`-:D'
     Prints some more debug-information at runtime.

`-:hNUMBER'
     Specifies fixed heap size

`-:hiNUMBER'
     Specifies the initial heap size

`-:hgPERCENTAGE'
     Sets the growth rate of the heap in percent. If the heap is
     exhausted, then it will grow by `PERCENTAGE'.  The default is 200.

`-:hmNUMBER'
     Specifies a maximal heap size. The default is (2GB - 15).

`-:hsPERCENTAGE'
     Sets the shrink rate of the heap in percent. If no more than a
     quarter of `PERCENTAGE' of the heap is used, then it will shrink to
     `PERCENTAGE'. The default is 50.  Note: If you want to make sure
     that the heap never shrinks, specify a value of `0'.  (this can be
     useful in situations where an optimal heap-size is known in
     advance).

`-:o'
     Disables detection of stack overflows at run-time.

`-:sNUMBER'
     Specifies stack size.

`-:tNUMBER'
     Specifies symbol table size.

`-:fNUMBER'
     Specifies the maximal number of currently pending finalizers before
     finalization is forced.

`-:aNUMBER'
     Specifies the length of the buffer for recording a trace of the
     last invoked procedures. Defaults to 16.

`-:w'
     Enables garbage collection of unused symbols. By default unused and
     unbound symbols are not garbage collected.

`-:r'
     Writes trace output to stderr. This option has no effect with in
     files compiled with the `-no-trace' options.

`-:x'
     Raises uncaught exceptions of separately spawned threads in
     primordial thread.  By default uncaught exceptions in separate
     threads are not handled, unless the primordial one explicitly
     joins them. When warnings are enabled (the default) and `-:x' is
     not given, a warning will be shown, though.

`-:B'
     Sounds a bell (ASCII 7) on every major garbage collection.


   The argument values may be given in bytes, in kilobytes (suffixed
with `K' or `k'), in megabytes (suffixed with `M' or `m'), or in
gigabytes (suffixed with `G' or `g'). Runtime options may be combined,
like `-:dc', but everything following a `NUMBER' argument is ignored. So
`-:wh64m' is OK, but `-:h64mw' will not enable GC of unused symbols.


File: chicken.info,  Node: An example,  Next: Extending the compiler,  Prev: Runtime options,  Up: Using the compiler

3.3 An example
==============

To compile a Scheme program (assuming a UNIX-like environment) perform
the following steps:

   * Consider this Scheme source file, named `foo.scm'
       ;;; foo.scm

       (define (fac n)
         (if (zero? n)
             1
             (* n (fac (- n 1))) ) )

       (write (fac 10))
       (newline)

   * Compile the file `foo.scm'
     % csc foo.scm

   * Start the compiled program
     % foo

     3628800


   If multiple bodies of Scheme code are to be combined into a single
executable, then we have to compile each file and link the resulting
object files together with the runtime system:

   * Consider these two Scheme source files, named `foo.scm' and
     `bar.scm'


       ;;; foo.scm

       (declare (uses bar))

       (write (fac 10)) (newline)


       ;;; bar.scm

       (declare (unit bar))

       (define (fac n)
         (if (zero? n)
             1
             (* n (fac (- n 1))) ) )

   * Compile and link the files `foo.scm' and `bar.scm'
     % csc -c bar.scm
     % csc foo.scm bar.o -o foo

   * Start the compiled program
     % foo
     3628800


   The declarations specify which of the compiled files is the main
module, and which is the library module. An executable can only have
one main module, since a program has only a single entry-point. In this
case `foo.scm' is the main module, because it doesn't have a `unit'
declaration.


File: chicken.info,  Node: Extending the compiler,  Next: Distributing compiled C files,  Prev: An example,  Up: Using the compiler

3.4 Extending the compiler
==========================

The compiler supplies a couple of hooks to add user-level passes to the
compilation process. Before compilation commences any Scheme source
files or compiled code specified using the `-extend' option are loaded
and evaluated.  The parameters `user-options-pass, user-read-pass,
user-preprocessor-pass, user-pass, user-pass-2' and
`user-post-analysis-pass' can be set to procedures that are called to
perform certain compilation passes instead of the usual processing (for
more information about parameters see: *Note Parameters::.

 -- parameter: user-options-pass
     Holds a procedure that will be called with a list of command-line
     arguments and should return two values: the source filename and
     the actual list of options, where compiler switches have their
     leading `-' (hyphen) removed and are converted to symbols.  Note
     that this parameter is invoked before processing of the `-extend'
     option, and so can only be changed in compiled user passes.

 -- parameter: user-read-pass
     Holds a procedure of three arguments. The first argument is a list
     of strings with the code passed to the compiler via `-prelude'
     options. The second argument is a list of source files including
     any files specified by `-prologue' and `-epilogue'. The third
     argument is a list of strings specified using `-postlude' options.
     The procedure should return a list of toplevel Scheme expressions.

 -- parameter: user-preprocessor-pass
     Holds a procedure of one argument. This procedure is applied to
     each toplevel expression in the source file before
     macro-expansion. The result is macro-expanded and compiled in
     place of the original expression.

 -- parameter: user-pass
     Holds a procedure of one argument. This procedure is applied to
     each toplevel expression after macro-expansion.  The result of the
     procedure is then compiled in place of the original expression.

 -- parameter: user-pass-2
     Holds a procedure of three arguments, which is called with the
     canonicalized node-graph as its sole argument. The result is
     ignored, so this pass has to mutate the node-structure to cause
     any effect.

 -- parameter: user-post-analysis-pass
     Holds a procedure that will be called after the last performed
     program analysis. The procedure (when defined) will be called with
     three arguments: the program database, a getter and a
     setter-procedure which can be used to access and manipulate the
     program database, which holds various information about the
     compiled program. The getter procedure should be called with two
     arguments: a symbol representing the binding for which information
     should be retrieved, and a symbol that specifies the
     database-entry. The current value of the database entry will be
     returned or `#f', if no such entry is available. The setter
     procedure is called with three arguments: the symbol and key and
     the new value.

     For information about the contents of the program database contact
     the author.

   Loaded code (via the `-extend' option) has access to the library
units `extras, srfi-1, srfi-4, utils, regex' and the pattern matching
macros.  Multithreading is not available.

   Note that the macroexpansion/canonicalization phase of the compiler
adds certain forms to the source program.  These extra expressions are
not seen by `user-preprocessor-pass' but by `user-pass'.


File: chicken.info,  Node: Distributing compiled C files,  Prev: Extending the compiler,  Up: Using the compiler

3.5 Distributing compiled C files
=================================

It is relatively easy to create distributions of Scheme projects that
have been compiled to C.  The runtime system of CHICKEN consists of only
two handcoded C files (`runtime.c' and `chicken.h'), plus the file
`chicken-config.h', which is generated by the build process. All other
modules of the runtime system and the extension libraries are just
compiled Scheme code. The following example shows a minimal
application, which should run without changes on the most frequent
operating systems, like Windows, Linux or FreeBSD:

   Let's take a simple "Hello, world!":


; hello.scm

(print "Hello, world!")

   Compiled to C, we get `hello.c'. We need the files `chicken.h' and
`runtime.c', which contain the basic runtime system, plus the three
basic library files `library.c', `eval.c' and `extras.c' which contain
the same functionality as the library linked into a plain
CHICKEN-compiled application, or which is available by default in the
interpreter, `csi':


% csc hello.scm -O2 -d1

   A simple makefile is needed as well:


# Makefile for UNIX systems

hello: hello.o runtime.o library.o eval.o extras.o
       $(CC) -o hello hello.o runtime.o library.o eval.o extras.o -lm

hello.o: chicken.h
runtime.o: chicken.h
library.o: chicken.h
eval.o: chicken.h
extras.o: chicken.h

   Now we have all files together, and can create an tarball containing
all the files:


% tar cf hello.tar Makefile hello.c runtime.c library.c eval.c extras.c chicken.h
% gzip hello.tar

   This is of naturally rather simplistic. Things like enabling dynamic
loading, estimating the optimal stack-size and selecting supported
features of the host system would need more configuration- and
build-time support. All this can be addressed using more elaborate
build-scripts, makefiles or by using autoconf/automake/libtool.

   Note also that the size of the application can still be reduced by
removing `extras' and `eval' and compiling `hello.scm' with the
`-explicit-use' option.

   For more information, study the CHICKEN source code and/or get in
contact with the author.


File: chicken.info,  Node: Using the interpreter,  Next: Supported language,  Prev: Using the compiler,  Up: Top

4 Using the interpreter
***********************

CHICKEN provides an interpreter named `csi' for evaluating Scheme
programs and expressions interactively.

* Menu:

* Interpreter  command line format::
* Writing Scheme scripts::
* Toplevel commands::
* Macros and procedures implemented in the interpreter::


File: chicken.info,  Node: Interpreter command line format,  Next: Writing Scheme scripts,  Up: Using the interpreter

4.1 Command line format
=======================


  csi {FILENAME|OPTION}

where `FILENAME' specifies a file with Scheme source-code.  If the
extension of the source file is `.scm', it may be omitted. The runtime
options described in *Note Compiler command line format:: are also
available for the interpreter.  If the environment variable
`CSI_OPTIONS' is set to a list of options, then these options are
additionally passed to every direct or indirect invocation of `csi'.
Please note that runtime options (like `-:...') can not be passed using
this method.  The options recognized by the interpreter are:

`--'
     Ignore everything on the command-line following this marker.
     Runtime options ("`-:...'") are still recognized.

`-i  -case-insensitive'
     Enables the reader to read symbols case insensitive. The default
     is to read case sensitive (in violation of R5RS).  This option
     registers the `case-insensitive' feature identifier.

`-b  -batch'
     Quit the interpreter after processing all command line options.

`-e  -eval EXPRESSIONS'
     Evaluate `EXPRESSIONS'. This option implies `-batch' and `-quiet',
     so no startup message will be printed and the interpreter exits
     after processing all `-eval' options and/or loading files given on
     the command-line.

`-D  -feature SYMBOL'
     Registers `SYMBOL' to be a valid feature identifier for
     `cond-expand'.

`-h  -help'
     Write a summary of the available command line options to standard
     output and exit.

`-I  -include-path PATHNAME'
     Specifies an alternative search-path for files included via the
     `include' special form. This option may be given multiple times. If
     the environment variable `CHICKEN_INCLUDE_PATH' is set, it should
     contain a list of alternative include pathnames separated by ";".
     The environment variable `CHICKEN_HOME' is also considered as a
     search path.

`-k  -keyword-style STYLE'
     Enables alternative keyword syntax, where `STYLE' may be either
     `prefix' (as in Common Lisp) or `suffix' (as in DSSSL).  Any other
     value is ignored.

`-n  -no-init'
     Do not load initialization-file. If this option is not given and
     the file `./.csirc' or `$(HOME)/.csirc' exists, then it is loaded
     before the read-eval-print loop commences.

`-w  -no-warnings'
     Disables any warnings that might be issued by the reader or
     evaluated code.

`-q  -quiet'
     Do not print a startup message.

`-s  -script PATHNAME'
     This is equivalent to `-batch -quiet -no-init PATHNAME'. Arguments
     following `PATHNAME' are available by using
     `command-line-arguments' and are not processed as interpreter
     options. Extra options in the environment variable `CSI_OPTIONS'
     are ignored.

`-R  -require-extension NAME'
     Equivalent to evaluating `(require-extension NAME)'.

`-v  -version'
     Write the banner with version information to standard output and
     exit.



File: chicken.info,  Node: Writing Scheme scripts,  Next: Toplevel commands,  Prev: Interpreter command line format,  Up: Using the interpreter

4.2 Writing Scheme scripts
==========================

   * Since UNIX shells use the `#!' notation for starting scripts,
     anything following the characters `#!' is ignored, with the
     exception of the special symbols `#!optional, #!key, #!rest' and
     `#!eof'.

     The easiest way is to use the `-script' option like this:


     % cat foo
     #! /usr/local/bin/csi -script
     (print (eval (with-input-from-string
                     (car (command-line-arguments))
                      read)))

     % chmod +x foo
     % foo "(+ 3 4)"
     7

     The parameter `command-line-arguments' is set to a list of the
     parameters that were passed to the Scheme script.  Scripts can be
     compiled to standalone executables (don't forget to declare used
     library units).

   * Windows:

     CHICKEN supports writing shell scripts in Scheme for these
     platforms as well, using a slightly different approach. The first
     example would look like this on Windows:


     C:>type foo.bat
     @;csibatch %0 %1 %2 %3 %4 %5 %6 %7 %8 %9
     (print (eval (with-input-from-string
                     (car (command-line-arguments))
                     read)))

     C:>foo "(+ 3 4)"
     7

     Like UNIX scripts, batch files can be compiled. Windows batch
     scripts do not accept more than 8 arguments.



File: chicken.info,  Node: Toplevel commands,  Next: Macros and procedures implemented in the interpreter,  Prev: Writing Scheme scripts,  Up: Using the interpreter

4.3 Toplevel commands
=====================

The toplevel loop understands a number of special commands:

`,?'
     Show summary of available toplevel commands.

`,l FILENAME ...'
     Load files with given `FILENAME's

`,ln FILENAME ...'
     Load files and print result(s) of each top-level expression.

`,p EXP'
     Pretty-print evaluated expression `EXP'.

`,d EXP'
     Describe result of evaluated expression `EXP'.

`,du EXP'
     Dump contents of the result of evaluated expression `EXP'.

`,dur EXP N'
     Dump `N' bytes of the result of evaluated expression `EXP'.

`,exn'
     Describes the last exception that occurred and adds it to the
     result history (it can be accessed using the `#' notation).

`,q'
     Quit the interpreter.

`,r'
     Show system information.

`,s TEXT ...'
     Execute shell-command.

`,t EXP'
     Evaluate form and print elapsed time.

`,x EXP'
     Pretty-print macroexpanded expression `EXP' (the expression is not
     evaluated).

`,tr SYMBOL ...'
     Enables tracing of the toplevel procedures with the given names.


     #;1> (fac 10)                       ==> 3628800
     #;2> ,tr fac
     #;3> (fac 3)
     |(fac 3)
     | (fac 2)
     |  (fac 1)
     |   (fac 0)
     |   fac -> 1
     |  fac -> 1
     | fac -> 2
     |fac -> 6                          ==> 6
     #;4> ,utr fac
     #;5> (fac 3)                        ==> 6

`,utr SYMBOL ...'
     Disables tracing of the given toplevel procedures.

`,br SYMBOL ...'
     Sets a breakpoint at the procedures named `SYMBOL ...'.

     Breakpoint can also be trigged using the `breakpoint' procedure.

`,ubr SYMBOL ...'
     Removes breakpoints.

`,c'
     Continues execution from the last invoked breakpoint.

`,breakall'
     Enable breakpoints for all threads (this is the default).

`,breakonly THREAD'
     Enable breakpoints only for the thread returned by the expression
     `THREAD'.

`,info'
     Lists traced procedures and breakpoints.

`,step EXPR'
     Evaluates `EXPR' in single-stepping mode. On each procedure call
     you will be presented with a menu that allows stepping to the next
     call, leaving single-stepping mode or triggering a breakpoint.
     Note that you will see some internal calls, and unsafe or heavily
     optimized compiled code might not be stepped at all.
     Single-stepping mode is also possible by invoking the `singlestep'
     procedure.


   You can define your own toplevel commands using the
`toplevel-command' procedure:

 -- procedure: toplevel-command
          (toplevel-command SYMBOL PROC [HELPSTRING])
     Defines or defines a toplevel interpreter command the can be
     invoked by entering `,SYMBOL'. `PROC' will be invoked when the
     command is entered and may read any required argument via `read'
     (or `read-line'). If the optional argument `HELPSTRING' is given,
     it will be listed by the `,?' command.


File: chicken.info,  Node: Macros and procedures implemented in the interpreter,  Prev: Toplevel commands,  Up: Using the interpreter

4.4 Macros and procedures implemented in the interpreter
========================================================

Additional macros and procedures available in the interpreter are:

 -- read syntax: #[INDEX]
          #
          #INDEX
     Returns the result of entry number `INDEX' in the history list. If
     the expression for that entry resulted in multiple values, the
     first result (or an unspecified value for no values) is returned.
     If no `INDEX' is given (and if a whitespace or closing paranthesis
     character follows the `#', then the result of the last expression
     is returned.  Note that this facility is a reader macro and is
     implicitly quoted.

 -- procedure: set-describer!
          (set-describer! TAG PROC)
     Sets a custom description handler that invokes `PROC' when the
     `,d' command is invoked with a record-type object that has the
     type `TAG' (a symbol). `PROC' is called with two arguments: the
     object to be described an an output-port and should write a
     possibly useful textual description of the object to the passed
     output-port. For example:


     #;1> (define-record point x y)
     #;2> (set-describer! 'point (lambda (pt o) (print "a point with x=" (point-x pt) "and y=" (point-y pt))))
     #;3> ,d (make-point 1 2)
     a point with x=1 and y=2


File: chicken.info,  Node: Supported language,  Next: Interface to external functions and variables,  Prev: Using the interpreter,  Up: Top

5 Supported language
********************

* Menu:

* Deviations from the standard::
* Extensions to the standard::
* Non standard read syntax::
* Non-standard macros and special forms::
* Pattern Matching::
* Declarations::
* Parameters::
* Unit library::
* Unit eval::
* Unit extras::
* Unit srfi-1::
* Unit srfi-4::
* Unit srfi-13::
* Unit srfi-14::
* Unit match::
* Unit regex::
* Unit srfi-18::
* Unit posix::
* Unit utils::
* Unit tcp::
* Unit lolevel::
* Unit tinyclos::


File: chicken.info,  Node: Deviations from the standard,  Next: Extensions to the standard,  Up: Supported language

5.1 Deviations from the standard
================================

[2] Identifiers are by default case-sensitive.

   [4.1.3] The maximal number of arguments that may be passed to a
compiled procedure or macro is 120.  A macro-definition that has a
single rest-parameter can have any number of arguments.

   If the `libffi' library is available on this platform, and if it is
installed, then CHICKEN can take advantage of this. See the `README'
file for more details.

   [4.3] `syntax-rules' macros are not provided but available
separately.

   [6.2.4]  The runtime system uses the numerical string-conversion
routines of the underlying C library and so does only understand
standard (C-library) syntax for floating-point constants.

   [6.2.5] There is no built-in support for rationals, complex numbers
or extended-precision integers (bignums).  The routines `complex?',
`real?' and `rational?' are identical to the standard procedure
`number?'. The procedures `numerator', `denominator', `rationalize',
`make-rectangular' and `make-polar' are not implemented.

   Support for extended numbers is available as a separate package,
provided the GNU multiprecision library is installed.

   [6.2.6] The procedure `string->number' does not obey read/write
invariance on inexact numbers.

   [6.4] The maximum number of values that can be passed to
continuations captured using `call-with-current-continuation' is 120.

   [6.5] Code evaluated in `scheme-report-environment' or
`null-environment' still sees non-standard syntax.

   [6.6.2] The procedure `char-ready?' always returns `#t' for terminal
ports.  The procedure `read' does not obey read/write invariance on
inexact numbers.

   [6.6.3] The procedures `write' and `display' do not obey read/write
invariance to inexact numbers.

   [6.6.4] The `transcript-on' and `transcript-off' procedures are not
implemented.


File: chicken.info,  Node: Extensions to the standard,  Next: Non standard read syntax,  Prev: Deviations from the standard,  Up: Supported language

5.2 Extensions to the standard
==============================

[2.1] Identifiers may contain special characters if delimited with `|
... |'.

   [2.3] The brackets `[ ... ]' are provided as an alternative syntax
for `( ... )'.  A number of reader extensions is provided. See *Note
Non standard read syntax::.

   [4] Numerous non-standard macros are provided. See *Note
Non-standard macros and special forms:: for more information.

   [4.1.4] Extended DSSSL style lambda lists are supported. DSSSL
formal argument lists are defined by the following grammar:


<formal-argument-list> ==> <required-formal-argument>*
                           [(#!optional <optional-formal-argument>*)]
                           [(#!rest <rest-formal-argument>)]
                           [(#!key <key-formal-argument>*)]
<required-formal-argument> ==> <ident>
<optional-formal-argument> ==> <ident>
                             | (<ident> <initializer>)
<rest-formal-argument> ==> <ident>
<key-formal-argument> ==> <ident>
                          | (<ident> <initializer>)
<initializer> ==> <expr>

   When a procedure is applied to a list of actual arguments, the
formal and actual arguments are processed from left to right as follows:

   Variables in required-formal-arguments are bound to successive
actual arguments starting with the first actual argument.  It shall be
an error if there are fewer actual arguments than
required-formal-arguments.

   Next, variables in optional-formal-arguments are bound to any
remaining actual arguments.  If there are fewer remaining actual
arguments than optional-formal-arguments, then variables are bound to
the result of the evaluation of initializer, if one was specified or
otherwise to `#f'. The initializer is evaluated in an environment in
which all previous formal arguments have been bound.

   If there is a rest-formal-argument, then it is bound to a list of
all remaining actual arguments.  The remaining actual arguments are
also eligible to be bound to keyword-formal-arguments.  If there is no
rest-formal-argument and there are no keywordas, then it shall be an
error if there are any remaining actual arguments.

   If `#!key' was specified in the formal-argument-list, there shall be
an even number of remaining actual arguments.  These are interpreted as
a series of pairs, where the first member of each pair is a keyword
specifying the argument name, and thorresplue. It shall be an error if
the first member of a pair is not a keyword.  It shall be an error if
the argument name is not the same as a variable in a
keyword-formal-argument, unless there is a rest-formal-argument. If the
same argument name occurs more than once in the list of actual
arguments, then the first value is used. If there is no actual argument
for a particular keyword-formal-argument, then the variable is bound to
the result of evaluating initializer if one was specified or `#f'. The
initializer is evaluated in an environment in which all previous formal
arguments have been bound.

   It shall be an error for an `<ident>' to appear more than once in a
formal-argument-list.

   Example:


((lambda x x) 3 4 5 6)       => (3 4 5 6)
((lambda (x y #!rest z) z)
 3 4 5 6)                    => (5 6)
((lambda (x y #!optional z #!rest r #!key i (j 1))
    (list x y z i: i j: j))
 3 4 5 i: 6 i: 7)            => (3 4 5 i: 6 j: 1)

   [4.1.6] `set!' for unbound toplevel variables is allowed. `set!
(PROCEDURE ...) ...)' is supported, as CHICKEN implements SRFI-17
(http://srfi.schemers.org/srfi-17/srfi-17.html).  [4.2.1] The `cond'
form supports SRFI-61 (http://srfi.schemers.org/srfi-61).

   [4.2.2] It is allowed for initialization values of bindings in a
`letrec' construct to refer to previous variables in the same set of
bindings, so


(letrec ([foo 123]
         [bar foo] )
  bar)

   is allowed and returns `123'.

   [4.2.3] `(begin)' is allowed in non-toplevel contexts and evaluates
to an unspecified value.

   [4.2.5] Delayed expressions may return multiple values.

   [5.2.2] CHICKEN extends standard semantics by allowing internal
definitions everywhere, and not only at the beginning of a body. A set
of internal definitions is equivalent to a `letrec' form enclosing all
following expressions in the body:


(let ([foo 123])
  (bar)
  (define foo 456)
  (baz foo) )

   expands into


(let ([foo 123])
  (bar)
  (letrec ([foo 456])
    (baz foo) ) )

   [5.2] `define' with a single argument is allowed and initializes the
toplevel or local binding to an unspecified value. CHICKEN supports
"curried" definitions, where the the variable name may also be a list
specifying a name and a nested lambda list. So

     (define ((make-adder x) y) (+ x y))

   is equivalent to

     (define (make-adder x) (lambda (y) (+ x y)))

   [6] CHICKEN provides numerous non-standard procedures. See the manual
sections on library units for more information.

   [6.2.4] The special IEEE floating-point numbers "+nan", "+inf" and
"-inf" are supported, as is negative zero.

   [6.3.4] User defined character names are supported. See `char-name'
in *Note User-defined named characters::. Characters can be given in
hexadecimal notation using the "#\xXX" syntax where "XX" specifies the
character code. Character codes above 255 are supported and can be read
(and are written) using the "#\uXXXX" and "#\UXXXXXXXX" notations.

   Non-standard characters names supported are `#\tab', `#\linefeed',
`#\return', `#\alarm', `#\vtab', `#\nul', `#\page', `#\esc', `#\delete'
and `#\backspace'.

   [6.3.5]  CHICKEN supports special characters preceded with a
backslash "\" in quoted string constants. "\n" denotes the
newline-character, "\r" carriage return, "\b" backspace, "\t" TAB, "\v"
vertical TAB, "\a" alarm, "\f" formfeed, "\xXX" a character with the
code `XX' in hex and "\uXXXX" (and "\UXXXXXXXX") a unicode character
with the code `XXXX'.  The latter is encoded in UTF-8 format.

   The third argument to `substring' is optional and defaults to the
length of the string.

   [6.4] `force' called with an argument that is not a promise returns
that object unchanged.  Captured continuations can be safely invoked
inside before- and after-thunks of a `dynamic-wind' form and execute in
the outer dynamic context of the `dynamic-wind' form.

   Implicit non-multival continuations accept multiple values by
discarding all but the first result. Zero values result in the
continuation receiving an unspecified value. Note that this slight
relaxation of the behaviour of returning mulitple values to
non-multival continuations does not apply to explicit continuations
(created with `call-with-current-continuation').

   [6.5] The second argument to `eval' is optional and defaults to the
value of `(interaction-environment)'.  `scheme-report-environment' and
`null-environment' accept an optional 2nd parameter: if not `#f' (which
is the default), toplevel bindings to standard procedures are mutable
and new toplevel bindings may be introduced.

   [6.6] The "tilde" character (`~') is automatically expanded in
pathnames.  Additionally, if a pathname starts with `$VARIABLE...',
then the prefix is replaced by the value of the given environment
variable.

   [6.6.1] if the procedures `current-input-port' and
`current-output-port' are called with an argument (which should be a
port), then that argument is selected as the new current input- and
output-port, respectively.  The procedures `open-input-file',
`open-output-file', `with-input-from-file', `with-output-to-file',
`call-with-input-file' and `call-with-output-file' accept an optional
second (or third) argument which should be one or more keywords, if
supplied. These arguments specify the mode in which the file is opened.
Possible values are the keywords `#:text', `#:binary' or `#:append'.


File: chicken.info,  Node: Non standard read syntax,  Next: Non-standard macros and special forms,  Prev: Extensions to the standard,  Up: Supported language

5.3 Non standard read syntax
============================

 -- read syntax: #| ... |#
     A multiline "block" comment. May be nested. Implements SRFI-30
     (http://srfi.schemers.org/srfi-30/srfi-30.html))

 -- read syntax: #;EXPRESSION
     Treats `EXPRESSION' as a comment.

 -- read syntax: #,(CONSTRUCTORNAME DATUM ...)
     Allows user-defined extension of external representations.  (For
     more information see the documentation for SRFI-10
     (http://srfi.schemers.org/srfi-10/srfi-10.html))

 -- read syntax: #'EXPRESSION
     An abbreviation for `(syntax EXPRESSION)'.

 -- read syntax: #$EXPRESSION
     An abbreviation for `(location EXPRESSION)'.

 -- read syntax: #:SYMBOL
     Syntax for keywords. Keywords are symbols that evaluate to
     themselves, and as such don't have to be quoted.

 -- read syntax: #<<TAG
     Specifies a multiline string constant. Anything up to a line equal
     to `TAG' (or end of file) will be returned as a single string:


     (define msg #<<END
     "Hello, world!", she said.
     END
     )

     is equivalent to


     (define msg "\"Hello, world!\", she said.")

 -- read syntax: #<#TAG
     Similar to `#<<', but allows substitution of embedded Scheme
     expressions prefixed with `#' and optionally enclosed in `{ ...
     }'.  Two consecutive `#'s are translated to a single `#':


     (define three 3)
     (display #<#EOF
     This is a simple string with an embedded `##' character
     and substituted expressions: (+ three 99) ==> #(+ three 99)
     (three is "#{three}")
     EOF
     )

     prints


     This is a simple string with an embedded `#' character
     and substituted expressions: (+ three 99) ==> 102
     (three is "3")

 -- read syntax: #> ... <#
     Abbreviation for `foreign-declare " ... ")'.

 -- read syntax: #>? ... <#
     Abbreviation for `(foreign-parse " ... ")'.

 -- read syntax: #>! ... <#
     Abbreviation for `(foreign-parse(declare " ... ")'.

 -- read syntax: #%...
     Reads like a normal symbol.

 -- read syntax: #!...
     Treated as a commment and ignores everything up the end of the
     current line.  The keywords `#!optional, #!rest' and `#!key' are
     handled separately and returned as normal symbols.  The special
     (self-evaluating) symbol `#!eof' is read as the end-of-file object.
     Note that if this constant appears at top-level in a loaded file,
     it is indistiguishable from normal end-of-file.

 -- read syntax: #cs...
     Read the next expression in case-sensitive mode (regardless of the
     current global setting).

 -- read syntax: #ci...
     Read the next expression in case-insensitive mode (regardless of
     the current global setting).

 -- read syntax: #+FEATURE EXPR
     Equivalent to

          (cond-expand (FEATURE EXPR) (else))


File: chicken.info,  Node: Non-standard macros and special forms,  Next: Pattern Matching,  Prev: Non standard read syntax,  Up: Supported language

5.4 Non-standard macros and special forms
=========================================

* Menu:

* Making extra libraries and extensions available::
* Binding forms for optional arguments::
* Other binding forms::
* Substitution forms and macros::
* Conditional forms::
* Record structures::
* Other forms::


File: chicken.info,  Node: Making extra libraries and extensions available,  Next: Binding forms for optional arguments,  Up: Non-standard macros and special forms

5.4.1 Making extra libraries and extensions available
-----------------------------------------------------

 -- syntax: require-extension
 -- syntax: use
          (require-extension ID ...)
          (use ID ...)
     This form does all necessary steps to make the libraries or
     extensions given in `ID ...' available. It loads syntactic
     extension, if needed and generates code for loading/linking with
     core library modules or separately installed extensions. `use' is
     just a shorter alias for `require-extension'.  This implementation
     of `require-extension' is compliant to SRFI-55 (see SRFI-55
     (http://srfi.schemers.org/srfi-16/srfi-16.html) for more
     information).

     During interpretation/evaluation `require-extension' performs one
     of the following:

        * If `ID' names a built in features `chicken srfi-23 srfi-30
          srfi-39 srfi-8 srfi-6 srfi-2 srfi-0 srfi-10 srfi-9 srfi-17
          srfi-55', then nothing is done.

        * If `ID' names one of syntactic extensions
          `chicken-more-macros chicken-ffi-macros', then this extension
          will be loaded.

        * If `ID' names one of the core library units shipped with
          CHICKEN, then a `(load-library 'ID)' will be performed.

        * If `ID' names an installed extension with the `syntax' or
          `require-at-runtime' attribute, then the equivalent of
          `(require-for-syntax 'ID)' is performed.

        * Otherwise `(require-extension ID)' is equivalent to `(require
          'ID)'.

     During compilation one of the following happens instead:

        * If `ID' names a built in features `chicken srfi-23 srfi-30
          srfi-39 srfi-8 srfi-6 srfi-2 srfi-0 srfi-10  srfi-9 srfi-17
          srfi-55', then nothing is done.

        * If `ID' names one of syntactic extensions
          `chicken-more-macros chicken-ffi-macros', then this extension
          will be loaded  at compile-time, making the syntactic
          extensions available in compiled code.

        * If `ID' names one of the core library units shipped with
          CHICKEN, then a `(declare (uses ID))' is generated.

        * If `ID' names an installed extension with the `syntax' or
          `require-at-runtime' attribute, then  the equivalent of
          `(require-for-syntax 'ID)' is performed.

        * Otherwise `(require-extension ID)' is equivalent to `(require
          'ID)'.

     To make long matters short - just use `require-extension' and it
     will normally figure everything out for dynamically loadable
     extensions and core library units.

     `ID' should be a pure extension name and should not contain any
     path prefixes (for example `dir/lib...') is illegal).

     `ID' may also be a list that designates an extension-specifier.
     Currently the following extension specifiers are defined:

        * `(srfi NUMBER ...)' is required for SRFI-55 compatibility and
          is fully implemented

        * `(version ID NUMBER)' is equivalent to `ID', but checks at
          compile-time whether the extension named `ID' is installed
          and whether its version is equal or higher than `NUMBER'.
          `NUMBER' may be a string or a number, the comparison is done
          lexicographically (using `string>=?').

     See also: `set-extension-specifier!'


 -- syntax: define-extension
          (define-extension NAME CLAUSE ...)
     This macro simplifies the task of writing extensions that can be
     linked both statically and dynamically.  If encountered in
     interpreted code or code that is compiled into a shared object
     (specifically if compiled with the feature
     `chicken-compile-shared', done automatically by `csc' when
     compiling with the `-shared' or `-dynamic' option) then the code
     given by clauses if the form


     (dynamic EXPRESSION ...)

     is inserted into the output as a `begin' form.

     If compiled statically (specifically if the feature
     `chicken-compiled-shared' has not been given), then this form
     expands into the following:


     (declare (unit NAME))
     (provide 'NAME)

     and all clauses of the form


     (static EXPRESSION ...)

     all additionally inserted into the expansion.

     As a convenience, the clause


     (export IDENTIFIER ...)

     is also allowed and is identical to `(declare (export IDENTIFIER
     ...))' (unless the `define-extension' form occurs in interpreted
     code, in with it is simply ignored).

     Note that the compiler option `-extension NAME' is equivalent to
     prefixing the compiled file with

          (define-extension NAME)


File: chicken.info,  Node: Binding forms for optional arguments,  Next: Other binding forms,  Prev: Making extra libraries and extensions available,  Up: Non-standard macros and special forms

5.4.2 Binding forms for optional arguments
------------------------------------------

 -- syntax: :optional
          (:optional ARGS DEFAULT)
     Use this form for procedures that take a single optional argument.
     If `ARGS' is the empty list `DEFAULT' is evaluated and returned,
     otherwise the first element of the list `ARGS'. It is an error if
     `ARGS' contains more than one value.


     (define (incr x . i) (+ x (:optional i 1)))
     (incr 10)                                   ==> 11
     (incr 12 5)                                 ==> 17


 -- syntax: case-lambda
          (case-lambda (LAMBDA-LIST1 EXP1 ...) ...)
     SRFI-16. Expands into a lambda that invokes the body following the
     first matching lambda-list.


     (define plus
       (case-lambda
         (() 0)
         ((x) x)
         ((x y) (+ x y))
         ((x y z) (+ (+ x y) z))
         (args (apply + args))))

     (plus)                      ==> 9
     (plus 1)                    ==> 1
     (plus 1 2 3)                ==> 6

     For more information see the documentation for SRFI-16
     (http://srfi.schemers.org/srfi-16/srfi-16.html)


 -- syntax: let-optionals
 -- syntax: let-optionals*
          (let-optionals ARGS ((VAR1 DEFAULT1) ...) BODY ...)
          (let-optionals* ARGS ((VAR1 DEFAULT1) ... [RESTVAR]) BODY ...)
     Binding constructs for optional procedure arguments. `ARGS' should
     be a rest-parameter taken from a lambda-list. `let-optionals'
     binds `VAR1 ...' to available arguments in parallel, or to
     `DEFAULT1 ...' if not enough arguments were provided.
     `let-optionals*' binds `VAR1 ...' sequentially, so every variable
     sees the previous ones. If a single variable `RESTVAR' is given,
     then it is bound to any remaining arguments, otherwise it is an
     error if any excess arguments are provided.


     (let-optionals '(one two) ((a 1) (b 2) (c 3))
       (list a b c) )                               ==> (one two 3)
     (let-optionals* '(one two) ((a 1) (b 2) (c a))
       (list a b c) )                               ==> (one two one)


File: chicken.info,  Node: Other binding forms,  Next: Substitution forms and macros,  Prev: Binding forms for optional arguments,  Up: Non-standard macros and special forms

5.4.3 Other binding forms
-------------------------

 -- syntax: and-let*
          (and-let* (BINDING ...) EXP1 EXP2 ...)
     SRFI-2. Bind sequentially and execute body. `BINDING' can be a
     list of a variable and an expression, a list with a single
     expression, or a single variable. If the value of an expression
     bound to a variable is `#f', the `and-let*' form evaluates to `#f'
     (and the subsequent bindings and the body are not executed).
     Otherwise the next binding is performed. If all
     bindings/expressions evaluate to a true result, the body is
     executed normally and the result of the last expression is the
     result of the `and-let*' form. See also the documentation for
     SRFI-2 (http://srfi.schemers.org/srfi-2/srfi-2.html).


 -- syntax: rec
          (rec NAME EXPRESSION)
          (rec (NAME VARIABLE ...) BODY ...)
     Allows simple definition of recursive definitions. `(rec NAME
     EXPRESSION)' is equivalent to `(letrec ((NAME EXPRESSION)) NAME)'
     and `(rec (NAME VARIABLE ...) BODY ...)' is the same as `(letrec
     ((NAME (lambda (VARIABLE ...) BODY ...))) NAME)'.

 -- syntax: cut
 -- syntax: cute
          (cut SLOT ...)
          (cute SLOT ...)
     Syntactic sugar for specializing parameters.
     (http://srfi.schemers.org/srfi-26/srfi-26.html)


 -- syntax: define-values
          (define-values (NAME ...) EXP)
     Defines several variables at once, with the result values of
     expression `EXP'.


 -- syntax: fluid-let
          (fluid-let ((VAR1 X1) ...) BODY ...)
     Binds the variables `VAR1 ...' dynamically to the values `X1 ...'
     during execution of `BODY ...'.


 -- syntax: let-values
          (let-values (((NAME ...) EXP) ...) BODY ...)
     Binds multiple variables to the result values of `EXP ...'.  All
     variables are bound simultaneously.


 -- syntax: let*-values
          (let*-values (((NAME ...) EXP) ...) BODY ...)
     Binds multiple variables to the result values of `EXP ...'.  The
     variables are bound sequentially.
     (let*-values (((a b) (values 2 3))
                   ((p) (+ a b)) )
       p)                               ==> 5


 -- syntax: letrec-values
          (letrec-values (((NAME ...) EXP) ...) BODY ...)
     Binds the result values of `EXP ...' to multiple variables at once.
     All variables are mutually recursive.
     (letrec-values (((odd even)
                        (values
                          (lambda (n) (if (zero? n) #f (even (sub1 n))))
                          (lambda (n) (if (zero? n) #t (odd (sub1 n)))) ) ) )
       (odd 17) )                           ==> #t


 -- syntax: parameterize
          (parameterize ((PARAMETER1 X1) ...) BODY ...)
     Binds the parameters `PARAMETER1 ...' dynamically to the values
     `X1 ...' during execution of `BODY ...'.  (see also:
     `make-parameter' in *Note Parameters::). Note that `PARAMETER' may
     be any expression that evaluates to a parameter procedure.


 -- syntax: receive
          (receive (NAME1 ... [. NAMEn]) VALUEEXP BODY ...)
          (receive VALUEEXP)
     SRFI-8. Syntactic sugar for `call-with-values'. Binds variables to
     the result values of `VALUEEXP' and evaluates `BODY ...'.

     The syntax


     (receive VALUEEXP)

     is equivalent to


     (receive _ VALUEEXP _)


 -- syntax: set!-values
          (set!-values (NAME ...) EXP)
     Assigns the result values of expression `EXP' to multiple
     variables.


File: chicken.info,  Node: Substitution forms and macros,  Next: Conditional forms,  Prev: Other binding forms,  Up: Non-standard macros and special forms

5.4.4 Substitution forms and macros
-----------------------------------

 -- syntax: define-constant
          (define-constant NAME CONST)
     Define a variable with a constant value, evaluated at compile-time.
     Any reference to such a constant should appear textually after its
     definition. This construct is equivalent to `define' when
     evaluated or interpreted.  Constant definitions should only appear
     at toplevel. Note that constants are local to the current
     compilation unit and are not available outside of the source file
     in which they are defined. Names of constants still exist in the
     Scheme namespace and can be lexically shadowed.  If the value is
     mutable, then the compiler is careful to preserve its identity.
     `CONST' may be any constant expression, and may also refer to
     constants defined via `define-constant' previously.  This for
     should only be used at top-level.


 -- syntax: define-inline
          (define-inline (NAME VAR ... [. VAR]) BODY ...)
          (define-inline NAME EXP)
     Defines an inline procedure. Any occurrence of `NAME' will be
     replaced by `EXP' or `(lambda (VAR ... [. VAR]) BODY ...)'.  This
     is similar to a macro, but variable-names and -scope will be
     correctly handled.  Inline substitutions take place after
     macro-expansion.  `EXP' should be a lambda-expression. Any
     reference to `NAME' should appear textually after its definition.
     Note that inline procedures are local to the current compilation
     unit and are not available outside of the source file in which
     they are defined. Names of inline procedures still exist in the
     Scheme namespace and can be lexically shadowed.  This construct is
     equivalent to `define' when evaluated or interpreted. Inline
     definitions should only appear at toplevel.


 -- syntax: define-macro
          (define-macro (NAME VAR ... [. VAR]) EXP1 ...)
          (define-macro NAME (lambda (VAR ... [. VAR]) EXP1 ...))
          (define-macro NAME1 NAME2)
     Define a globally visible macro special form. The macro is
     available as soon as it is defined, i.e. it is registered at
     compile-time. If the file containing this definition invokes
     `eval' and the declaration `run-time-macros' (or the command line
     option `-run-time-macros') has been used, then the macro is
     visible in evaluated expressions during runtime. The second
     possible syntax for `define-macro' is allowed for portability
     purposes only. In this case the second argument must be a
     lambda-expression or a macro name.  Only global macros can be
     defined using this form.  `(define-macro NAME1 NAME2)' simply
     copies the macro definition from `NAME2' to `NAME1', creating an
     alias.

     Extended lambda list syntax (`#!optional', etc.) can be used but
     note that arguments are source expressions and thus default values
     for optional or keyword arguments should take this into
     consideration.


 -- syntax: define-for-syntax
          (define-for-syntax (NAME VAR ... [. VAR]) EXP1 ...)
          (define-for-syntax NAME [VALUE])
     Defines the toplevel variable `NAME' at macro-expansion time. This
     can be helpful when you want to define support procedures for use
     in macro-transformers, for example.


File: chicken.info,  Node: Conditional forms,  Next: Record structures,  Prev: Substitution forms and macros,  Up: Non-standard macros and special forms

5.4.5 Conditional forms
-----------------------

 -- syntax: switch
          (switch EXP (KEY EXP1 ...) ... [(else EXPn ...)])
     This is similar to `case', but a) only a single key is allowed,
     and b) the key is evaluated.


 -- syntax: unless
          (unless TEST EXP1 EXP2 ...)
     Equivalent to:
     (if (not TEST) (begin EXP1 EXP2 ...))


 -- syntax: when
          (when TEST EXP1 EXP2 ...)
     Equivalent to:
     (if TEST (begin EXP1 EXP2 ...))


File: chicken.info,  Node: Record structures,  Next: Other forms,  Prev: Conditional forms,  Up: Non-standard macros and special forms

5.4.6 Record structures
-----------------------

 -- syntax: define-record
          (define-record NAME SLOTNAME ...)
     Defines a record type. Call `make-NAME' to create an instance of
     the structure (with one initialization-argument for each slot).
     `(NAME? STRUCT)' tests any object for being an instance of this
     structure.  Slots are accessed via `(NAME-SLOTNAME STRUCT)' and
     updated using `(NAME-SLOTNAME-set!' `STRUCT' `VALUE)'.


     (define-record point x y)
     (define p1 (make-point 123 456))
     (point? p1)                      ==> #t
     (point-x p1)                     ==> 123
     (point-y-set! p1 99)
     (point-y p1)                     ==> 99


 -- syntax: define-record-printer
          (define-record-printer (NAME RECORDVAR PORTVAR) BODY ...)
          (define-record-printer NAME PROCEDURE)
     Defines a printing method for record of the type `NAME' by
     associating a procedure with the record type. When a record of this
     type is written using `display, write' or `print', then the
     procedure is called with two arguments: the record to be printed
     and an output-port.


     (define-record foo x y z)
     (define f (make-foo 1 2 3))
     (define-record-printer (foo x out)
       (fprintf out "#,(foo ~S ~S ~S)"
                (foo-x x) (foo-y x) (foo-z x)) )
     (define-reader-ctor 'foo make-foo)
     (define s (with-output-to-string
                   (lambda () (write f))))
     s                                   ==> "#,(foo 1 2 3)"
     (equal? f (with-input-from-string
                   s read)))             ==> #t

     `define-record-printer' works also with SRFI-9 record types.


 -- syntax: define-record-type
          (define-record-type NAME (CONSTRUCTOR TAG ...) PREDICATE
                              (FIELD ACCESSOR [MODIFIER]) ...)
     SRFI-9 record types. For more information see the documentation for
     SRFI-9 (http://srfi.schemers.org/srfi-9/srfi-9.html).


File: chicken.info,  Node: Other forms,  Prev: Record structures,  Up: Non-standard macros and special forms

5.4.7 Other forms
-----------------

 -- syntax: assert
          (assert EXP [STRING ARG ...])
     Signals an error if `EXP' evaluates to false. An optional message
     `STRING' and arguments `ARG ...' may be supplied to give a more
     informative error-message.  If compiled in _unsafe_ mode (either
     by specifying the `-unsafe' compiler option or by declaring
     `(unsafe)'), then this expression expands to an unspecified value.
     The result is the value of `EXP'.


 -- syntax: cond-expand
          (cond-expand FEATURE-CLAUSE ...)
     SRFI-0. Expands by selecting feature clauses. Predefined
     feature-identifiers are `srfi-0', `srfi-2', `srfi-6', `srfi-8',
     `srfi-9', `srfi-10',  and `chicken'. If the source file containing
     this form is currently compiled, the feature `compiling' is
     defined.  For further information, see the documentation for
     SRFI-0 (http://srfi.schemers.org/srfi-0/srfi-0.html) This form is
     allowed to appear in non-toplevel expressions.


 -- syntax: ensure
          (ensure PREDICATE EXP [ARGUMENTS ...])
     Evaluates the expression `EXP' and applies the one-argument
     procedure `PREDICATE' to the result. If the predicate returns `#f'
     an error is signaled, otherwise the result of `EXP' is returned.
     If compiled in _unsafe_ mode (either by specifying the `-unsafe'
     compiler option or by declaring `(unsafe)'), then this expression
     expands to an unspecified value.  If specified, the optional
     `ARGUMENTS' are used as arguments to the invocation of the
     error-signalling code, as in `(error ARGUMENTS ...)'. If no
     `ARGUMENTS' are given, a generic error message is displayed with
     the offending value and `PREDICATE' expression.


 -- syntax: eval-when
          (eval-when (SITUATION ...) EXP ...)
     Controls evaluation/compilation of subforms. `SITUATION' should be
     one of the symbols `eval', `compile' or `load'.  When encountered
     in the evaluator, and the situation specifier `eval' is not given,
     then this form is not evaluated and an unspecified value is
     returned.  When encountered while compiling code, and the
     situation specifier `compile' is given, then this form is
     evaluated at compile-time.  When encountered while compiling code,
     and the situation specifier `load' is not given, then this form is
     ignored and an expression resulting into an unspecified value is
     compiled instead.

     The following table should make this clearer:

               in compiled code           In interpreted code
     `eval'    ignore                     evaluate
     `compile' evaluate at compile time   ignore
     `load'    compile as normal          ignore

     The situation specifiers `compile-time' and `run-time' are also
     defined and have the same meaning as `compile' and `load',
     respectively.


 -- syntax: include
          (include STRING)
     Include toplevel-expressions from the given source file in the
     currently compiled/interpreted program.  If the included file has
     the extension `.scm', then it may be omitted.  The file is
     searched in the current directory and, if not found, in all
     directories specified in the `-include-path' option.


 -- syntax: nth-value
          (nth-value N EXP)
     Returns the `N'th value (counting from zero) of the values returned
     by expression `EXP'.


 -- syntax: time
          (time EXP1 ...)
     Evaluates `EXP1 ...' and prints elapsed time and some values about
     GC use, like time spent in major GCs, number of minor and major
     GCs.


File: chicken.info,  Node: Pattern Matching,  Next: Declarations,  Prev: Non-standard macros and special forms,  Up: Supported language

5.5 Pattern Matching
====================

(This description has been taken mostly from Andrew Wright's postscript
document)

   Pattern matching allows complicated control decisions based on data
structure to be expressed in a concise manner.  Pattern matching is
found in several modern languages, notably Standard ML, Haskell and
Miranda. These syntactic extensions internally use the `match' library
unit.

   The basic form of pattern matching expression is:
     (match exp [pat body] ...)

   where `exp' is an expression, `pat' is a pattern, and `body' is one
or more expressions (like the body of a lambda-expression).  The
`match' form matches its first subexpression against a sequence of
patterns, and branches to the `body' corresponding to the first pattern
successfully matched.  For example, the following code defines the
usual `map' function:

     (define map
       (lambda (f l)
         (match l
           [() ()]
           [(x . y) (cons (f x) (map f y))])))

   The first pattern `()' matches the empty list.  The second pattern
`(x . y)' matches a pair, binding `x' to the first component of the
pair and `y' to the second component of the pair.

5.5.1 Pattern Matching Expressions
----------------------------------

The complete syntax of the pattern matching expressions follows:


exp ::= (match exp clause ...)
     |  (match-lambda clause ...)
     |  (match-lambda* clause ...)
     |  (match-let ([pat exp] ...) body)
     |  (match-let* ([pat exp] ...) body)
     |  (match-letrec ([pat exp] ...) body)
     |  (match-let var ([pat exp] ...) body)
     |  (match-define pat exp)

clause ::= [pat body]
        |  [pat (=> identifier) body]

pat ::= identifier           matches anything, and binds identifier as a variable
     |  _                    anything
     |  ()                   itself (the empty list)
     |  #t                   itself
     |  #f                   itself
     |  string               an `equal?' string
     |  number               an `equal?' number
     |  character            an `equal?' character
     |  's-expression        an `equal?' s-expression
     |  (pat-1 ... pat-n)    a proper list of n elements
     |  (pat-1 ... pat-n . pat-n+1)
                             a list of n or more elements
     |  (pat-1 ... pat-n pat-n+1 ..k)
                             a proper list of n+k or more elements [1]
     |  #(pat-1 ... pat-n)   a vector of n elements
     |  #(pat-1 ... pat-n pat-n+1 ..k)
                             a vector of n+k or more elements
     |  ($ struct pat-1 ... pat-n)
                             a structure
     |  (= field pat)        a field of a structure
     |  (and pat-1 ... pat-n)
                             if all of pat-1 through pat-n match
     |  (or pat-1 ... pat-n)
                             if any of pat-1 through pat-n match
     |  (not pat-1 ... pat-n)
                             if none of pat-1 through pat-n match
     |  (? predicate pat-1 ... pat-n)
                             if predicate true and pat-1 through pat-n all match
     |  (set! identifier)    anything, and binds identifier as a setter
     |  (get! identifier)    anything, and binds identifier as a getter
     |  `qp                  a quasipattern

qp ::= ()                    itself (the empty list)
    |  #t                    itself
    |  #f                    itself
    |  string                an `equal?' string
    |  number                an `equal?' number
    |  character             an `equal?' character
    |  symbol                an `equal?' symbol
    |  (qp-1 ... qp-n)       a proper list of n elements
    |  (qp-1 ... qp-n . qp-n+1)
                             a list of n or more elements
    |  (qp-1 ... qp-n qp-n+1 ..k)
                             a proper list of n+k or more elements
    |  #(qp-1 ... qp-n)      a vector of n elements
    |  #(qp-1 ... qp-n qp-n+1 ..k)
                             a vector of n+k or more elements
    |  ,pat                  a pattern
    |  ,@pat                 a pattern, spliced

   The notation `..k' denotes a keyword consisting of three consecutive
dots (ie., "`...'"), or two dots and an non-negative integer (eg.,
"`..1'", "`..2'"), or three consecutive underscores (ie., "`___'"), or
two underscores and a non-negative integer.  The keywords "`..k'" and
"`__ k'" are equivalent.  The keywords "`...'", "`___'", "`..0'", and
"`__0'" are equivalent.

   The next subsection describes the various patterns.

   The `match-lambda' and `match-lambda*' forms are convenient
combinations of `match' and `lambda', and can be explained as follows:

     (match-lambda [pat body] ...)   =  (lambda (x) (match x [pat body] ...))
     (match-lambda* [pat body] ...)  =  (lambda x (match x [pat body] ...))

   where `x' is a unique variable.  The `match-lambda' form is
convenient when defining a single argument function that immediately
destructures its argument.  The `match-lambda*' form constructs a
function that accepts any number of arguments; the patterns of
`match-lambda*' should be lists.

   The `match-let', `match-let*', `match-letrec', and `match-define'
forms generalize Scheme's `let', `let*', `letrec', and `define'
expressions to allow patterns in the binding position rather than just
variables.  For example, the following expression:

     (match-let ([(x y z) (list 1 2 3)]) body ...)

   binds `x' to 1, `y' to 2, and `z' to 3 in `body ...'.  These forms
are convenient for destructuring the result of a function that returns
multiple values as a list or vector.  As usual for `letrec' and
`define', pattern variables bound by `match-letrec' and `match-define'
should not be used in computing the bound value.

   The `match', `match-lambda', and `match-lambda*' forms allow the
optional syntax `(=> identifier)' between the pattern and the body of a
clause.  When the pattern match for such a clause succeeds, the
`identifier' is bound to a `failure procedure' of zero arguments within
the `body'.  If this procedure is invoked, it jumps back to the pattern
matching expression, and resumes the matching process as if the pattern
had failed to match.  The `body' must not mutate the object being
matched, otherwise unpredictable behavior may result.

5.5.2 Patterns
--------------

`identifier': (excluding the reserved names `?', `,', `=', `_', `and',
`or', `not', `set!', `get!', `...', and `..k' for non-negative integers
`k') matches anything, and binds a variable of this name to the
matching value in the `body'.

   `_': matches anything, without binding any variables.

   `()', `#t', `#f', `string', `number', `character', '`s-expression':
These constant patterns match themselves, i.e., the corresponding value
must be `equal?' to the pattern.

   `(pat-1 ... pat-n)': matches a proper list of `n' elements that
match `pat-1' through `pat-n'.

   `(pat-1 ... pat-n . pat-n+1)': matches a (possibly improper) list of
at least `n' elements that ends in something matching `pat-n+1'.

   `(pat-1 ... pat-n pat-n+1 ...)': matches a proper list of `n' or
more elements, where each element of the tail matches `pat-n+1'.  Each
pattern variable in `pat-n+1' is bound to a list of the matching
values.  For example, the expression:

     (match '(let ([x 1][y 2]) z)
       [('let ((binding values) ...) exp)  body])

   binds `binding' to the list `'(x y)', `values' to the list \`'(1 2)',
and `exp' to `'z' in the body of the `match'-expression.  For the
special case where `pat-n+1' is a pattern variable, the list bound to
that variable may share with the matched value.

   `(pat-1 ... pat-n pat-n+1 ___)': This pattern means the same thing
as the previous pattern.

   `(pat-1 ... pat-n pat-n+1 ..k)': This pattern is similar to the
previous pattern, but the tail must be at least `k' elements long.  The
pattern keywords `..0' and `...' are equivalent.

   `(pat-1 ... pat-n ~ pat-n+1 __k)': This pattern means the same thing
as the previous pattern.

   `#(pat-1 ... pat-n)': matches a vector of length `n', whose elements
match `pat-1' through `pat-n'.

   `#(pat-1 ... pat-n pat-n+1 ...)': matches a vector of length `n' or
more, where each element beyond `n' matches `pat-n+1'.

   `#(pat-1 ... pat-n pat-n+1 ..k)': matches a vector of length `n+k'
or more, where each element beyond `n' matches `pat-n+1'.

   `($ struct pat-1 ... pat-n)': matches a structure declared with
`define-record' or `define-record-type'.

   `(= field pat)': is intended for selecting a field from a structure.
"field" may be any expression; it is applied to the value being
matched, and the result of this application is matched against `pat'.

   `(and pat-1 ... pat-n)': matches if all of the subpatterns match.
At least one subpattern must be present.  This pattern is often used as
`(and x pat)' to bind `x' to to the entire value that matches `pat'
(cf. "as-patterns" in ML or Haskell).

   `(or pat-1 ... pat-n)': matches if any of the subpatterns match.  At
least one subpattern must be present.  All subpatterns must bind the
same set of pattern variables.

   `(not pat-1 ... pat-n)': matches if none of the subpatterns match.
At least one subpattern must be present.  The subpatterns may not bind
any pattern variables.

   `(? predicate pat-1 ... pat-n)': In this pattern, `predicate' must
be an expression evaluating to a single argument function.  This
pattern matches if `predicate' applied to the corresponding value is
true, and the subpatterns `pat-1 ... pat-n' all match.  The `predicate'
should not have side effects, as the code generated by the pattern
matcher may invoke predicates repeatedly in any order.  The `predicate'
expression is bound in the same scope as the match expression, i.e.,
free variables in `predicate' are not bound by pattern variables.

   `(set! identifier)': matches anything, and binds `identifier' to a
procedure of one argument that mutates the corresponding field of the
matching value.  This pattern must be nested within a pair, vector,
box, or structure pattern. For example, the expression:

     (define x (list 1 (list 2 3)))
     (match x [(_ (_ (set! setit)))  (setit 4)])

   mutates the `cadadr' of `x' to 4, so that `x' is `'(1 (2 4))'.

   `(get! identifier)': matches anything, and binds `identifier' to a
procedure of zero arguments that accesses the corresponding field of
the matching value.  This pattern is the complement to `set!'.  As with
`set!', this pattern must be nested within a pair, vector, box, or
structure pattern.

   _Quasipatterns_: Quasiquote introduces a quasipattern, in which
identifiers are considered to be symbolic constants.  Like Scheme's
quasiquote for data, `unquote' (,) and `unquote-splicing' (,@) escape
back to normal patterns.

5.5.3 Match Failure
-------------------

If no clause matches the value, the default action is to invoke the
procedure `##sys#match-error' with the value that did not match.  The
default definition of `##sys#match-error' calls `error' with an
appropriate message:


#;1> (match 1 (2 2))

Failed match:
Error: no matching clause for : 1

   For most situations, this behavior is adequate, but it can be changed
by altering the value of the parameter `match-error-control':

 -- procedure: match-error-control
          (match-error-control [MODE])
     Selects a mode that specifies how `match...' macro forms are to be
     expanded.  With no argument this procedure returns the current
     mode. A single argument specifies the new mode that decides what
     should happen if no match-clause applies.  The following modes are
     supported:

    `#:error'
          Signal an error. This is the default.

    `#:match'
          Signal an error and output the offending form.

    `#:fail'
          Omits `pair?' tests when the consequence is to fail in `car'
          or `cdr' rather than to signal an error.

    `#:unspecified'
          Non-matching expressions will either fail in `car' or `cdr'
          or return an unspecified value.  This mode applies to files
          compiled with the `unsafe' option or declaration.


     When an error is signalled, the raised exception will be of kind
     `(exn match)'.


   Note: the `$' pattern handles native record structures and SRFI-9
records transparently.  Currently it is required that SRFI-9 record
predicates are named exactly like the record type name, followed by a
`?' (question mark) character.

5.5.4 Code Generation
---------------------

Pattern matching macros are compiled into `if'-expressions that
decompose the value being matched with standard Scheme procedures, and
test the components with standard predicates.  Rebinding or lexically
shadowing the names of any of these procedures will change the
semantics of the `match' macros.  The names that should not be rebound
or shadowed are:

     null? pair? number? string? symbol? boolean? char? procedure? vector? list?
     equal?
     car cdr cadr cdddr ...
     vector-length vector-ref
     reverse length call/cc

   Additionally, the code generated to match a structure pattern like
`($ Foo pat-1 ... pat-n)' refers to the name `Foo?'.  This name also
should not be shadowed.


File: chicken.info,  Node: Declarations,  Next: Parameters,  Prev: Pattern Matching,  Up: Supported language

5.6 Declarations
================

 -- syntax: declare
          (declare DECLSPEC ...)
     Process declaration specifiers. Declarations always override any
     command-line settings.  Declarations are valid for the whole
     compilation-unit (source file), the position of the declaration in
     the source file can be arbitrary. Declarations are ignored in the
     interpreter but not in code evaluated at compile-time (by
     `eval-when' or in syntax extensions loaded via `require-extension'
     or `require-for-syntax'.  `DECLSPEC' may be any of the following:

      -- declaration specifier: always-bound
               (always-bound SYMBOL ...)
          Declares that the given variables are always bound and
          accesses to those have not to be checked.

      -- declaration specifier: block
               (block)
          Assume global variables are never redefined. This is the same
          as specifying the `-block' option.

      -- declaration specifier: block-global
      -- declaration specifier: hide
               (block-global SYMBOL ...)
               (hide SYMBOL ...)
          Declares that the toplevel bindings for `SYMBOL ...' should
          not be accessible from code in other compilation units or by
          `eval'. Access to toplevel bindings declared as block global
          is also more efficient.

      -- declaration specifier: bound-to-procedure
               (bound-to-procedure SYMBOL ...)
          Declares that the given identifiers are always bound to
          procedure values.

      -- declaration specifier: c-options
               (c-options STRING ...)
          Declares additional C/C++ compiler options that are to be
          passed to the subsequent compilation pass that translates C
          to machine code. This declaration will only work if the
          source file is compiled with the `csc' compiler driver.

      -- declaration specifier: check-c-syntax
               (check-c-syntax)
               (not check-c-syntax)
          Enables or disables syntax-checking of embedded C/C++ code
          fragments. Checking C syntax is the default.

      -- declaration specifier: compress-literals
               (compress-literals [THRESHOLD [INITIALIZER]])
          The same as the `-compress-literals' compiler option.  The
          threshold argument defaults to 50. If the optional argument
          `INITIALIZER' is given, then the literals will not be created
          at module startup, but when the procedure with this name will
          be called.

      -- declaration specifier: constant
               (constant SYMBOL ...)
          Declares the procedures with the names `SYMMBOL ...' as
          constant, that is, as not having any side effects. This can
          help the compiler to remove non-side-effecting expressions.

      -- declaration specifier: export
               (export SYMBOL ...)
          The opposite of `hide'. All given identifiers will be
          exported and all toplevel variables not listed will be hidden
          and not be accessible outside of this compilation unit.

      -- declaration-specifier: emit-exports
               (emit-exports STRING)
          Write exported toplevel variables to file with name `STRING'.

      -- declaration specifier: emit-external-prototypes-first
               (emit-external-prototypes-first)
          Emit prototypes for callbacks defined with `define-external'
          before any other foreign declarations. Equivalent to giving
          the `-emit-external-prototypes-first' option to the compiler.

      -- declaration specifier: disable-interrupts
               (disable-interrupts)
               (not interrupts-enabled)
          Disable timer-interrupts checks in the compiled program.
          Threads can not be preempted in main- or library-units that
          contain this declaration.

      -- declaration specifier: disable-warning
               (disable-warning CLASS ...)
          Disable warnings of type `CLASS ...' (equivalent to the
          `-disable-warning CLASS' compiler option).

      -- declaration specifier: import
               (import SYMBOL-OR-STRING ...)
          Adds new imports to the list of externally available toplevel
          variables. Arguments to this declaration may be either
          strings (designating `.exports' files, without the
          file-extension) or symbols which directly designate imported
          variables.

      -- declaration specifier: inline
               (inline)
               (not inline)
               (inline IDENTIFIER ...)
               (not inline IDENTIFIER ...)
          If given without an identifier-list, inlining of known
          procedures is enabled (this is equivalent to the `-inline'
          compiler option). When an identifier-list is given, then
          inlining is enabled only for the specified global procedures.
          The negated forms `(not inline)' and `(not inline
          IDENTIFIER)' disable global inlining, or inlining for the
          given global procedures only, respectively.

      -- declaration specifier: inline-limit
               (inline-limit THRESHOLD)
          Sets the maximum size of procedures which may potentially be
          inlined. The default threshold is `10'.

      -- declaration specifier: interrupts-enabled
               (interrupts-enabled)
          Enable timer-interrupts checks in the compiled program (the
          default).

      -- declaration specifier: keep-shadowed-macros
               (keep-shadowed-macros)
          Normally, when a toplevel variable is assigned or defined
          that has the same name as a macro, the macro-definition will
          be removed (in addition to showing a warning). This
          declaration will disable the removal of the macro.

      -- declaration specifier: lambda-lift
               (lambda-lift)
          Enables lambda-lifting (equivalent to the `-lambda-lift'
          option).

      -- declaration specifier: link-options
               (link-options STRING ...)
          Declares additional linker compiler options that are to be
          passed to the subsequent compilation pass that links the
          generated code into an executable or library.  This
          declaration will only work if the source file is compiled
          with the `csc' compiler driver.

      -- declaration specifier: no-argc-checks
               (no-argc-checks)
          Disables argument count checking.

      -- declaration specifier: no-bound-checks
               (no-bound-checks)
          Disables the bound-checking of toplevel bindings.

      -- declaration specifier: no-procedure-checks
               (no-procedure-checks)
          Disables checking of values in operator position for being of
          procedure type.

      -- declaration specifier: post-process
               (post-process STRING ...)
          Arranges for the shell commands `STRING ...' to be invoked
          after the current file has been translated to C. Any
          occurrences of the substring `$@' in the strings given for
          this declaration will be replaced by the pathname of the
          currently compiled file, without the file-extension.  This
          declaration will only work if the source file is compiled
          with the `csc' compiler driver.

      -- declaration specifier: TYPE
      -- declaration specifier: fixnum-arithmetic
               ([number-type] TYPE)
               (fixnum-arithmetic)
          Declares that only numbers of the given type are used. `TYPE'
          may be `fixnum' or `generic' (which is the default).

      -- declaration specifier: run-time-macros
               (run-time-macros)
          Equivalent to the compiler option of the same name - macros
          defined in the compiled code are also made available at
          runtime.

      -- declaration specifier: standard-bindings
               (standard-bindings SYMBOL ...)
               (not standard-bindings SYMBOL ...)
          Declares that all given standard procedures (or all if no
          symbols are specified) are never globally redefined.  If
          `not' is specified, then all but the given standard bindings
          are assumed to be never redefined.

      -- declaration specifier: extended-bindings
               (extended-bindings SYMBOL ...)
               (not extended-bindings SYMBOL ...)
          Declares that all given non-standard and CHICKEN-specific
          procedures (or all if no symbols are specified) are never
          globally redefined.  If `not' is specified, then all but the
          given extended bindings are assumed to be never redefined.

      -- declaration specifier: usual-integrations
               (usual-integrations SYMBOL ...)
               (not usual-integrations SYMBOL ...)
          Declares that all given standard and extended bindings (or
          all if no symbols are specified) are never globally
          redefined.  If `not' is specified, then all but the given
          standard and extended bindings are assumed to be never
          redefined. Note that this is the default behaviour, unless
          the `-no-usual-integrations' option has been given.

      -- declaration specifier: unit
               (unit SYMBOL)
          Specify compilation unit-name (if this is a library)

      -- declaration specifier: unsafe
               (unsafe)
               (not safe)
          Do not generate safety-checks. This is the same as specifying
          the `-unsafe' option.  Also implies


          (declare (no-bound-checks) (no-procedure-checks) (no-argc-checks))

      -- declaration specifier: uses
               (uses SYMBOL ...)
          Gives a list of used library-units. Before the
          toplevel-expressions of the main-module are executed, all
          used units evaluate their toplevel-expressions in the order
          in which they appear in this declaration. If a library unit A
          uses another unit B, then B's toplevel expressions are
          evaluated before A's.  Furthermore, the used symbols are
          registered as features during compile-time, so `cond-expand'
          knows about them.



File: chicken.info,  Node: Parameters,  Next: Unit library,  Prev: Declarations,  Up: Supported language

5.7 Parameters
==============

Certain behavior of the interpreter and compiled programs can be
customized via 'parameters', where a parameter is a procedure of zero
or one arguments. To retrieve the value of a parameter call the
parameter-procedure with zero arguments. To change the setting of the
parameter, call the parameter-procedure with the new value as argument:


(define foo (make-parameter 123))
(foo)                             ==> 123
(foo 99)
(foo)                             ==> 99

   Parameters are fully thread-local, each thread of execution owns a
local copy of a parameters' value.

   CHICKEN implements SRFI-39
(http://srfi.schemers.org/srfi-39/srfi-39.html)

 -- procedure: make-parameter
          (make-parameter VALUE [GUARD])
     Returns a procedure that accepts zero or one argument. Invoking the
     procedure with zero arguments returns `VALUE'. Invoking the
     procedure with one argument changes its value to the value of that
     argument (subsequent invocations with zero parameters return the
     new value). `GUARD' should be a procedure of a single argument. Any
     new values of the parameter (even the initial value) are passed to
     this procedure. The guard procedure should check the value and/or
     convert it to an appropriate form.


 -- parameter: case-sensitive
     If true, then `read' reads symbols and identifiers in
     case-sensitive mode and uppercase characters in symbols are printed
     escaped. Defaults to `#t'.


 -- parameter: dynamic-load-libraries
     A list of strings containing shared libraries that should be
     checked for explicitly loaded library units (this facility is not
     available on all platforms). See `load-library'.


 -- parameter: command-line-arguments
     Contains the list of arguments passed to this program, with the
     name of the program and any runtime options (all options starting
     with `-:') removed.


 -- parameter: current-read-table
     A read-table object that holds read-procedures for special
     non-standard read-syntax (see `set-read-syntax!' for more
     information).

 -- parameter: exit-handler
     A procedure of a single optional argument. When `exit' is called,
     then this procedure will be invoked with the exit-code as
     argument. The default behavior is to terminate the program.


 -- parameter: eval-handler
     A procedure of one or two arguments. When `eval' is invoked, it
     calls the value of this parameter with the same arguments. The
     default behavior is to evaluate the argument expression and to
     ignore the second parameter.


 -- parameter: force-finalizers
     If true, force and execute all pending finalizers before exiting
     the program (either explicitly by `exit' or implicitly when the
     last toplevel expression has been executed). Default is `#t'.


 -- parameter: implicit-exit-handler
     A procedure of no arguments. When the last toplevel expression of
     the program has executed, then the value of this parameter is
     called. The default behaviour is to invoke all pending finalizers.


 -- parameter: keyword-style
     Enables alternative keyword syntax, where `STYLE' may be either
     `#:prefix' (as in Common Lisp) or `#:suffix' (as in DSSSL).  Any
     other value disables the alternative syntaxes.


 -- parameter: load-verbose
     A boolean indicating whether loading of source files, compiled code
     (if available) and compiled libraries should display a message.


 -- parameter: repl-prompt
     A procedure that should evaluate to a string that will be printed
     before reading interactive input from the user in a
     read-eval-print loop. Defaults to `(lambda () "#;N> ")'.


 -- parameter: reset-handler
     A procedure of zero arguments that is called via `reset'. The
     default behavior in compiled code is to invoke the value of
     `(exit-handler)'. The default behavior in the interpreter is to
     abort the current computation and to restart the read-eval-print
     loop.



File: chicken.info,  Node: Unit library,  Next: Unit eval,  Prev: Parameters,  Up: Supported language

5.8 Unit library
================

This unit contains basic Scheme definitions. This unit is used by
default, unless the program is compiled with the `-explicit-use' option.

* Menu:

* Arithmetic::
* File Input/Output::
* Files::
* String ports::
* Feature identifiers::
* Keywords::
* Exceptions::
* Environment information and system interface::
* Execution time::
* Interrupts and error-handling::
* Garbage collection::
* Other control structures::
* String utilities::
* Generating uninterned symbols::
* Standard Input/Output::
* User-defined named characters::
* Vectors::
* The unspecified value::
* Continuations::
* Setters::


File: chicken.info,  Node: Arithmetic,  Next: File Input/Output,  Up: Unit library

5.8.1 Arithmetic
----------------

 -- procedure: add1
 -- procedure: sub1
          (add1 N)
          (sub1 N)
     Adds/subtracts 1 from `N'.


 -- procedure: bitwise-and
 -- procedure: bitwise-ior
 -- procedure: bitwise-xor
 -- procedure: bitwise-not
 -- procedure: arithmetic-shift
          (bitwise-and N1 ...)
          (bitwise-ior N1 ...)
          (bitwise-xor N1 ...)
          (bitwise-not N)
          (arithmetic-shift N1 N2)
     Binary integer operations. `arithmetic-shift' shifts the argument
     `N1' by `N2' bits to the left. If `N2' is negative, than `N1' is
     shifted to the right.  These operations only accept exact integers
     or inexact integers in word range (32 bit signed on 32-bit
     platforms, or 64 bit signed on 64-bit platforms).


 -- procedure: fixnum?
          (fixnum? X)
     Returns `#t' if `X' is a fixnum, or `#f' otherwise.


 -- procedure: fx+
 -- procedure: fx-
 -- procedure: fx*
 -- procedure: fx/
 -- procedure: fxmod
 -- procedure: fxneg
 -- procedure: fxmin
 -- procedure: fxmax
 -- procedure: fx=
 -- procedure: fx>
 -- procedure: fx<
 -- procedure: fx>=
 -- procedure: fx<=
 -- procedure: fxand
 -- procedure: fxior
 -- procedure: fxxor
 -- procedure: fxnot
 -- procedure: fxshl
 -- procedure: fxshr
          (fx+ N1 N2)
          (fx- N1 N2)
          (fx* N1 N2)
          (fx/ N1 N2)
          (fxmod N1 N2)
          (fxneg N)
          (fxmin N1 N2)
          (fxmax N1 N2)
          (fx= N1 N2)
          (fx> N1 N2)
          (fx< N1 N2)
          (fx>= N1 N2)
          (fx<= N1 N2)
          (fxand N1 N2)
          (fxior N1 N2)
          (fxxor N1 N2)
          (fxnot N)
          (fxshl N1 N2)
          (fxshr N1 N2)
     Arithmetic fixnum operations. These procedures do not check their
     arguments, so non-fixnum parameters will result in incorrect
     results. `fxneg' negates its argument.

     On division by zero, `fx/' and `fxmod' signal a condition of kind
     `(exn arithmetic)'.

     `fxshl' and `fxshr' perform arithmetic shift left and right,
     respectively.


 -- procedure: fp+
 -- procedure: fp-
 -- procedure: fp*
 -- procedure: fp/
 -- procedure: fpneg
 -- procedure: fpmin
 -- procedure: fpmax
 -- procedure: fp=
 -- procedure: fp>
 -- procedure: fp<
 -- procedure: fp>=
 -- procedure: fp<=
          (fp+ N1 N2)
          (fp- N1 N2)
          (fp* N1 N2)
          (fp/ N1 N2)
          (fpneg N)
          (fpmin N1 N2)
          (fpmax N1 N2)
          (fp= N1 N2)
          (fp> N1 N2)
          (fp< N1 N2)
          (fp>= N1 N2)
          (fp<= N1 N2)
     Arithmetic floating-point operations. These procedures do not
     check their arguments, so non-flonum parameters will result in
     incorrect results.  On division by zero, `fp/' signals a condition
     of kind `(exn arithmetic)'.


 -- procedure: signum
          (signum N)
     Returns `1' if `N' is positive, `-1' if `N' is negative or `0' if
     `N' is zero. `signum' is exactness preserving.


File: chicken.info,  Node: File Input/Output,  Next: Files,  Prev: Arithmetic,  Up: Unit library

5.8.2 File Input/Output
-----------------------

 -- procedure: current-error-port
          (current-error-port [PORT])
     Returns default error output port. If `PORT' is given, then that
     port is selected as the new current error output port.

 -- procedure: flush-output
          (flush-output [PORT])
     Write buffered output to the given output-port. `PORT' defaults to
     the value of `(current-output-port)'.


 -- procedure: port-name
          (port-name PORT)
     Fetch filename from `PORT'. This returns the filename that was
     used to open this file.  Returns a special tag string, enclosed
     into parentheses for non-file ports.


 -- procedure: port-position
          (port-position PORT)
     Returns the current position of `PORT' as two values: row and
     column number.  If the port does not support such an operation an
     error is signaled. This procedure is currently only available for
     input ports.


 -- procedure: set-port-name!
          (set-port-name! PORT STRING)
     Sets the name of `PORT' to `STRING'.


File: chicken.info,  Node: Files,  Next: String ports,  Prev: File Input/Output,  Up: Unit library

5.8.3 Files
-----------

 -- procedure: delete-file
          (delete-file STRING)
     Deletes the file with the pathname `STRING'. If the file does not
     exist, an error is signaled.


 -- procedure: file-exists?
          (file-exists? STRING)
     Returns `STRING' if a file with the given pathname exists, or `#f'
     otherwise.


 -- procedure: rename-file
          (rename-file OLD NEW)
     Renames the file or directory with the pathname `OLD' to `NEW'. If
     the operation does not succeed, an error is signaled.


File: chicken.info,  Node: String ports,  Next: Feature identifiers,  Prev: Files,  Up: Unit library

5.8.4 String ports
------------------

 -- procedure: get-output-string
          (get-output-string PORT)
     Returns accumulated output of a port created with
     `(open-output-string)'.


 -- procedure: open-input-string
          (open-input-string STRING)
     Returns a port for reading from `STRING'.


 -- procedure: open-output-string
          (open-output-string)
     Returns a port for accumulating output in a string.


File: chicken.info,  Node: Feature identifiers,  Next: Keywords,  Prev: String ports,  Up: Unit library

5.8.5 Feature identifiers
-------------------------

CHICKEN maintains a global list of "features" naming functionality
available int the current system. Additionally the `cond-expand' form
accesses this feature list to infer what features are provided.
Predefined features are `chicken', and the SRFIs (Scheme Request For
Implementation) provided by the base system: `srfi-23, srfi-30,
srfi-39'. If the `eval' unit is used (the default), the features
`srfi-0, srfi-2, srfi-6, srfi-8, srfi-9' and `srfi-10' are defined.
When compiling code (during compile-time) the feature `compiling' is
registered. When evaluating code in the interpreter (csi), the feature
`csi' is registered.

 -- procedure: features
          (features)
     Returns a list of all registered features that will be accepted as
     valid feature-identifiers by `cond-expand'.

 -- procedure: feature?
          (feature? ID ...)
     Returns `#t' if all features with the given feature-identifiers
     `ID ...' are registered.


 -- procedure: register-feature!
          (register-feature! FEATURE ...)
     Register one or more features that will be accepted as valid
     feature-identifiers by `cond-expand'. `FEATURE ...' may be a
     keyword, string or symbol.


 -- procedure: unregister-feature!
          (unregister-feature! FEATURE ...)
     Unregisters the specified feature-identifiers. `FEATURE ...' may
     be a keyword, string or symbol.


File: chicken.info,  Node: Keywords,  Next: Exceptions,  Prev: Feature identifiers,  Up: Unit library

5.8.6 Keywords
--------------

Keywords are special symbols prefixed with `#:' that evaluate to
themselves.  Procedures can use keywords to accept optional named
parameters in addition to normal required parameters.  Assignment to
and bindings of keyword symbols is not allowed.  The parameter
`keyword-style' and the compiler/interpreter option `-keyword-style'
can be used to allow an additional keyword syntax, either compatible to
Common LISP, or to DSSSL.

 -- procedure: get-keyword
          (get-keyword KEYWORD ARGLIST [THUNK])
     Returns the argument from `ARGLIST' specified under the keyword
     `KEYWORD'.  If the keyword is not found, then the zero-argument
     procedure `THUNK' is invoked and the result value is returned. If
     `THUNK' is not given, `#f' is returned.


     (define (increase x . args)
       (+ x (get-keyword #:amount args (lambda () 1))) )
     (increase 123)                                      ==> 124
     (increase 123 #:amount 10)                          ==> 133

     Note: the `KEYWORD' may actually be any kind of object.


 -- procedure: keyword?
          (keyword? X)
     Returns `#t' if `X' is a keyword symbol, or `#f' otherwise.


 -- procedure: keyword->string
          (keyword->string KEYWORD)
     Transforms `KEYWORD' into a string.


 -- procedure: string->keyword
          (string->keyword STRING)
     Returns a keyword with the name `STRING'.


File: chicken.info,  Node: Exceptions,  Next: Environment information and system interface,  Prev: Keywords,  Up: Unit library

5.8.7 Exceptions
----------------

CHICKEN implements the (currently withdrawn) SRFI-12 exception system.
For more information, see the SRFI-12 document
(http://srfi.schemers.org/srfi-12/srfi-12.html)

 -- syntax: condition-case
          (condition-case EXPRESSION CLAUSE ...)
     Evaluates `EXPRESSION' and handles any exceptions that are covered
     by `CLAUSE ...', where `CLAUSE' should be of the following form:


     CLAUSE = ([VARIABLE] (KIND ...) BODY ...)

     If provided, `VARIABLE' will be bound to the signalled exception
     object. `BODY ...' is executed when the exception is a property-
     or composite condition with the kinds given `KIND ...'
     (unevaluated).  If no clause applies, the exception is
     re-signalled in the same dynamic context as the `condition-case'
     form.


     (define (check thunk)
       (condition-case (thunk)
         [(exn file) (print "file error")]
         [(exn) (print "other error")]
         [var () (print "something else")] ) )

     (check (lambda () (open-input-file "")))   ; -> "file error"
     (check (lambda () some-unbound-variable))  ; -> "othererror"
     (check (lambda () (signal 99)))            ; -> "something else"

     (condition-case some-unbound-variable
       [(exn file) (print "ignored)] )      ; -> signals error

 -- procedure: breakpoint
          (breakpoint [NAME])
     Programmatically triggers a breakpoint (similar to the `,br'
     top-level csi command).

   All error-conditions signalled by the system are of kind `exn'.  The
following composite conditions are additionally defined:

`(exn arity)'
     Signalled when a procedure is called with the wrong number of
     arguments.

`(exn type)'
     Signalled on type-mismatch errors, for example when an argument of
     the wrong type is passed to a builtin procedure.

`(exn arithmetic)'
     Signalled on arithmetic errors, like division by zero.

`(exn i/o)'
     Signalled on input/output errors.

`(exn i/o file)'
     Signalled on file-related errors.

`(exn i/o net)'
     Signalled on network errors.

`(exn bounds)'
     Signalled on errors caused by accessing non-existent elements of a
     collection.

`(exn runtime)'
     Signalled on low-level runtime-system error-situations.

`(exn runtime limit)'
     Signalled when an internal limit is exceeded (like running out of
     memory).

`(exn match)'
     Signalled on errors raised by failed matches (see the section on
     `match').

`(exn syntax)'
     Signalled on syntax errors.

`(exn breakpoint)'
     Signalled when a breakpoint is reached.


   Notes:
   * All error-exceptions (of the kind `exn') are non-continuable.

   * Error-exceptions of the `exn' kind have additional `arguments' and
     `location' properties that contain the arguments passed to the
     exception-handler and the name of the procedure where the error
     occurred (if available).

   * When the `posix' unit is available and used, then a user-interrupt
     (`signal/int') signals an exception of the kind `user-interrupt'.

   * the procedure `condition-property-accessor' accepts an optional
     third argument. If the condition does not have a value for the
     desired property and if the optional argument is given, no error
     is signalled and the accessor returns the third argument.

   * In composite conditionss all properties are currently collected in
     a single property-list, so in the case that to conditions have the
     same named property, only one will be visible.



File: chicken.info,  Node: Environment information and system interface,  Next: Execution time,  Prev: Exceptions,  Up: Unit library

5.8.8 Environment information and system interface
--------------------------------------------------

 -- procedure: argv
          (argv)
     Return a list of all supplied command-line arguments. The first
     item in the list is a string containing the name of the executing
     program. The other items are the arguments passed to the
     application. This list is freshly created on every invocation of
     `(argv)'.  It depends on the host-shell whether arguments are
     expanded ('globbed') or not.


 -- procedure: exit
          (exit [CODE])
     Exit the running process and return exit-code, which defaults to 0
     (Invokes `exit-handler').


 -- procedure: build-platform
          (build-platform)
     Returns a symbol specifying the toolset which has been used for
     building the executing system, which is one of the following:


     cygwin
     msvc
     mingw32
     gnu
     metrowerks
     intel
     watcom
     unknown


 -- procedure: chicken-version
          (chicken-version [FULL])
     Returns a string containing the version number of the CHICKEN
     runtime system. If the optional argument `FULL' is given and true,
     then a full version string is returned.


 -- procedure: errno
          (errno)
     Returns the error code of the last system call.


 -- procedure: getenv
          (getenv STRING)
     Returns the value of the environment variable `STRING' or `#f' if
     that variable is not defined.


 -- procedure: machine-byte-order
          (machine-byte-order)
     Returns the symbol `little-endian' or `big-endian', depending on
     the machine's byte-order.

 -- procedure: machine-type
          (machine-type)
     Returns a symbol specifying the processor on which this process is
     currently running, which is one of the following:


     alpha
     mips
     hppa
     ultrasparc
     sparc
     ppc
     ia64
     x86
     x86-64
     unknown


 -- procedure: software-type
          (software-type)
     Returns a symbol specifying the operating system on which this
     process is currently running, which is one of the following:


     windows
     unix
     macos
     ecos
     unknown


 -- procedure: software-version
          (software-version)
     Returns a symbol specifying the operating system version on which
     this process is currently running, which is one of the following:


     linux
     freebsd
     netbsd
     openbsd
     macosx
     hpux
     solaris
     sunos
     unknown


 -- procedure: c-runtime
          (c-runtime)
     Returns a symbol that designates what kind of C runtime library
     has been linked with this version of the Chicken libraries.
     Possible return values are `static', `dynamic' or `unknown'. On
     systems not compiled with the Microsoft C compiler, `c-runtime'
     always returns `unknown'.

 -- procedure: chicken-home
          (chicken-home)
     Returns a string given the installation directory (usually
     `/usr/local/share/chicken' on UNIX-like systems).  If the
     environment variable `CHICKEN_HOME' is set, then its value will be
     returned. As a last option, if the environment variable
     `CHICKEN_PREFIX' is set, then `chicken-home' will return
     `$CHICKEN_PREFIX/share'.

 -- procedure: system
          (system STRING)
     Execute shell command. The functionality offered by this procedure
     depends on the capabilities of the host shell.


File: chicken.info,  Node: Execution time,  Next: Interrupts and error-handling,  Prev: Environment information and system interface,  Up: Unit library

5.8.9 Execution time
--------------------

 -- procedure: cpu-time
          (cpu-time)
     Returns the used CPU time of the current process in milliseconds as
     two values: the time spent in user code, and the time spent in
     system code. On platforms where user and system time can not be
     differentiated, system time will be always be 0.


 -- procedure: current-milliseconds
          (current-milliseconds)
     Returns the number of milliseconds since process- or machine
     startup.


 -- procedure: current-seconds
          (current-seconds)
     Returns the number of seconds since midnight, Jan. 1, 1970.

 -- procedure: current-gc-milliseconds
          (current-gc-milliseconds)
     Returns the number of milliseconds spent in major garbage
     collections since the last call of `current-gc-milliseconds' and
     returns an exact integer.


File: chicken.info,  Node: Interrupts and error-handling,  Next: Garbage collection,  Prev: Execution time,  Up: Unit library

5.8.10 Interrupts and error-handling
------------------------------------

 -- procedure: enable-warnings
          (enable-warnings [BOOL])
     Enables or disables warnings, depending on wether `BOOL' is true
     or false.  If called with no arguments, this procedure returns
     `#t' if warnings are currently enabled, or `#f' otherwise. Note
     that this is not a parameter.  The current state (wether warnings
     are enabled or disabled) is global and not thread-local.


 -- procedure: error
          (error [LOCATION] STRING EXP ...)
     Prints error message, writes all extra arguments to the value of
     `(current-error-port)' and invokes the current exception-handler.
     This conforms to SRFI-23
     (http://srfi.schemers.org/srfi-23/srfi-23.html).  If `LOCATION' is
     given and a symbol, it specifies the "location" (the name of the
     procedure) where the error occurred.


 -- procedure: get-call-chain
          (get-call-chain [START [THREAD]])
     Returns a list with the call history. Backtrace information is
     only generated in code compiled without `-no-trace' and evaluated
     code.  If the optional argument `START' is given, the backtrace
     starts at this offset, i.e. when `START' is 1, the next to last
     trace-entry is printed, and so on. If the optional argument
     `THREAD' is given, then the call-chain will only be constructed
     for calls performed by this thread.


 -- procedure: print-call-chain
          (print-call-chain [PORT [START [THREAD]]])
     Prints a backtrace of the procedure call history to `PORT', which
     defaults to `(current-output-port)'.


 -- procedure: print-error-message
          (print-error-message EXN [PORT [STRING]])
     Prints an appropriate error message to `PORT' (which defaults to
     the value of `(current-output-port)' for the object `EXN'.  `EXN'
     may be a condition, a string or any other object.  If the optional
     argument `STRING' is given, it is printed before the
     error-message. `STRING' defaults to `"Error:"'.


 -- procedure: procedure-information
          (procedure-information PROC)
     Returns an s-expression with debug information for the procedure
     `PROC', or `#f', if `PROC' has no associated debug information.

 -- procedure: reset
          (reset)
     Reset program (Invokes `reset-handler').

 -- procedure: warning
          (warning STRING EXP ...)
     Displays a warning message (if warnings are enabled with
     `enable-warnings') and continues execution.

 -- procedure: singlestep
          (singlestep THUNK)
     Executes the code in the zero-procedure `THUNK' in single-stepping
     mode.


File: chicken.info,  Node: Garbage collection,  Next: Other control structures,  Prev: Interrupts and error-handling,  Up: Unit library

5.8.11 Garbage collection
-------------------------

 -- procedure: gc
          (gc [FLAG])
     Invokes a garbage-collection and returns the number of free bytes
     in the heap. The flag specifies whether a minor (`#f') or major
     (`#t') GC is to be triggered. If no argument is given, `#t' is
     assumed. When the argument is `#t', all pending finalizers are
     executed. 

 -- procedure: memory-statistics
          (memory-statistics)
     Performs a major garbage collection and returns a three element
     vector containing the total heap size in bytes, the number of
     bytes currently used and the size of the nursery (the first heap
     generation). Note that the actual heap is actually twice the size
     given in the heap size, because CHICKEN uses a copying semi-space
     collector.

 -- procedure: set-finalizer!
          (set-finalizer! X PROC)
     Registers a procedure of one argument `PROC', that will be called
     as soon as the non-immediate data object `X' is about to be
     garbage-collected (with that object as its argument).  Note that
     the finalizer will not be called when interrupts are disabled.
     This procedure returns `X'.


 -- procedure: set-gc-report!
          (set-gc-report! FLAG)
     Print statistics after every GC, depending on `FLAG'. A value of
     `#t' shows statistics after every major GC. A true value different
     from `#t' shows statistics after every minor GC. `#f' switches
     statistics off.


File: chicken.info,  Node: Other control structures,  Next: String utilities,  Prev: Garbage collection,  Up: Unit library

5.8.12 Other control structures
-------------------------------

 -- procedure: andmap
          (andmap PROC LIST1 ...)
     Repeatedly calls `PROC' with arguments taken from `LIST1 ...'.  If
     any invocation should return `#f', the result of `andmap' is `#f'.
     If all invocations return a true result, then the result of
     `andmap' is `#t'.


 -- procedure: ormap
          (ormap PROC LIST1 ...)
     Repeatedly calls `PROC' with arguments taken from `LIST1 ...'.  If
     any invocation should return a value different from `#f', then
     this value is returned as the  result of `ormap'. If all
     invocations return #f, then the result of `ormap' is `#f'.

 -- procedure: promise?
          (promise? X)
     Returns `#t' if `X' is a promise returned by `delay', or `#f'
     otherwise.


File: chicken.info,  Node: String utilities,  Next: Generating uninterned symbols,  Prev: Other control structures,  Up: Unit library

5.8.13 String utilities
-----------------------

 -- procedure: reverse-list->string
          (reverse-list->string LIST)
     Returns a string with the characters in `LIST' in reverse order.
     This is equivalent to `(list->string (reverse LIST))', but much
     more efficient.


File: chicken.info,  Node: Generating uninterned symbols,  Next: Standard Input/Output,  Prev: String utilities,  Up: Unit library

5.8.14 Generating uninterned symbols
------------------------------------

 -- procedure: gensym
          (gensym [STRING-OR-SYMBOL])
     Returns a newly created uninterned symbol. If an argument is
     provided, the new symbol is prefixed with that argument.


 -- procedure: string->uninterned-symbol
          (string->uninterned-symbol STRING)
     Returns a newly created, unique symbol with the name `STRING'.


File: chicken.info,  Node: Standard Input/Output,  Next: User-defined named characters,  Prev: Generating uninterned symbols,  Up: Unit library

5.8.15 Standard Input/Output
----------------------------

 -- procedure: port?
          (port? X)
     Returns `#t' if `X' is a port object or `#f' otherwise.


 -- procedure: print
          (print EXP1 EXP2 ...)
     Outputs the arguments `EXP1 EXP2 ...' using `display' and writes a
     newline character to the port that is the value of
     `(current-output-port)'. Returns its first argument.


 -- procedure: print*
          (print* EXP1 ...)
     Similar to `print', but does not output a terminating newline
     character and performes a `flush-outout' after writing its
     arguments.


File: chicken.info,  Node: User-defined named characters,  Next: Vectors,  Prev: Standard Input/Output,  Up: Unit library

5.8.16 User-defined named characters
------------------------------------

 -- procedure: char-name
          (char-name SYMBOL-OR-CHAR [CHAR])
     This procedure can be used to inquire about character names or to
     define new ones. With a single argument the behavior is as follows:
     If `SYMBOL-OR-CHAR' is a symbol, then `char-name' returns the
     character with this name, or `#f' if no character is defined under
     this name.  If `SYMBOL-OR-CHAR' is a character, then the name of
     the character is returned as a symbol, or `#f' if the character
     has no associated name.

     If the optional argument `CHAR' is provided, then `SYMBOL-OR-CHAR'
     should be a symbol that will be the new name of the given
     character.  If multiple names designate the same character, then
     the `write' will use the character name that was defined last.


     (char-name 'space)                  ==> #\space
     (char-name #\space)                 ==> space
     (char-name 'bell)                   ==> #f
     (char-name (integer->char 7))       ==> #f
     (char-name 'bell (integer->char 7))
     (char-name 'bell)                   ==> #\bell
     (char->integer (char-name 'bell))   ==> 7


File: chicken.info,  Node: Vectors,  Next: The unspecified value,  Prev: User-defined named characters,  Up: Unit library

5.8.17 Vectors
--------------

 -- procedure: vector-copy!
          (vector-copy! VECTOR1 VECTOR2 [COUNT])
     Copies contents of `VECTOR1' into `VECTOR2'. If the argument
     `COUNT' is given, it specifies the maximal number of elements to
     be copied. If not given, the minimum of the lengths of the
     argument vectors is copied.

     Exceptions: `(exn bounds)'


 -- procedure: vector-resize
          (vector-resize VECTOR N [INIT])
     Creates and returns a new vector with the contents of `VECTOR' and
     length `N'.  If `N' is greater than the original length of
     `VECTOR', then all additional items are initialized to `INIT'. If
     `INIT' is not specified, the contents are initialized to some
     unspecified value.


File: chicken.info,  Node: The unspecified value,  Next: Continuations,  Prev: Vectors,  Up: Unit library

5.8.18 The _unspecified_ value
------------------------------

 -- procedure: void
          (void)
     Returns an unspecified value.


File: chicken.info,  Node: Continuations,  Next: Setters,  Prev: The unspecified value,  Up: Unit library

5.8.19 Continuations
--------------------

 -- procedure: call/cc
          (call/cc PROCEDURE)
     An alias for `call-with-current-continuation'.

 -- procedure: continuation-capture
          (continuation-capture PROCEDURE)
     Creates a continuation object representing the current
     continuation and tail-calls `PROCEDURE' with this continuation as
     the single argument.

     More information about this continuation API can be found in the
     paper
     `http://repository.readscheme.org/ftp/papers/sw2001/feeley.pdf' "A
     Better API for first class Continuations" by Marc Feeley.

 -- procedure: continuation?
          (continuation? X)
     Returns `#t' if `X' is a continuation object, or `#f' otherwise.

 -- procedure: continuation-graft
          (continuation-graft CONT THUNK)
     Calls the procedure `THUNK' with no arguments and the implicit
     continuation `CONT'.

 -- procedure: continuation-return
          (continuation-return CONT VALUE ...)
     Returns the value(s) to the continuation `CONT'.
     `continuation-result' could be implemented like this:

          (define (continuation-return k . vals)
            (continuation-graft
              k
              (lambda () (apply values vals)) ) )


File: chicken.info,  Node: Setters,  Prev: Continuations,  Up: Unit library

5.8.20 Setters
--------------

SRFI-17 is fully implemented. For more information see: SRFI-17
(http://srfi.schemers.org/srfi-17/srfi-17.html)

 -- procedure: setter
          (setter PROCEDURE)
     Returns the setter-procedure of `PROCEDURE', or signals an error
     if `PROCEDURE' has no associated setter-procedure.

     Note that `(set! (setter PROC) ...)' for a procedure that has no
     associated setter procedure yet is a very slow operation (the old
     procedure is replaced by a modified copy, which involves a garbage
     collection).

 -- procedure: getter-with-setter
          (getter-with-setter GETTER SETTER)
     Returns a copy of the procedure `GETTER' with the associated
     setter procedure `SETTER'.  Contrary to the SRFI specification,
     the setter of the returned procedure may be changed.


File: chicken.info,  Node: Unit eval,  Next: Unit extras,  Prev: Unit library,  Up: Supported language

5.9 Unit eval
=============

This unit has support for evaluation and macro-handling. This unit is
used by default, unless the program is compiled with the `-explicit-use'
option.

* Menu:

* Loading code::
* Read-eval-print loop::
* Macros::
* Loading extension libraries::
* Reader extensions::
* Eval::


File: chicken.info,  Node: Loading code,  Next: Read-eval-print loop,  Up: Unit eval

5.9.1 Loading code
------------------

 -- procedure: load
          (load FILE [EVALPROC])
     Loads and evaluates expressions from the given source file, which
     may be either a string or an input port.  Each expression read is
     passed to `EVALPROC' (which defaults to `eval').  On platforms that
     support it (currently native Windows, Linux ELF and Solaris),
     `load' can be used to load compiled programs:


     % cat x.scm
     (define (hello) (print "Hello!"))
     % csc -s x.scm
     % csi -q
     #;1> (load "x.so")
     ; loading x.so ...
     #;2> (hello)
     Hello!
     #;3>

     The second argument to `load' is ignored when loading compiled
     code.  If source code is loaded from a port, then that port is
     closed after all expressions have been read.

     Compiled code can be re-loaded, but care has to be taken, if code
     from the replaced dynamically loaded module is still executing
     (i.e.  if an active continuation refers to compiled code in the
     old module).

     Support for realoding compiled code dynamically is still
     experimental.


 -- procedure: load-relative
          (load-relative FILE [EVALPROC])
     Similar to `load', but loads `FILE' relative to the path of the
     currently loaded file.

 -- procedure: load-noisily
          (load-noisily FILE #!key EVALUATOR TIME PRINTER)
     As `load' but the result(s) of each evaluated toplevel-expression
     is written to standard output. If `EVALUATOR' is given and not
     `#f', then each expression is evaluated by calling this argument
     with the read expression as argument. If `TIME' is given and not
     false, then the execution time of each expression is shown (as
     with the `time' macro).  If `PRINTER' is given and not false, then
     each expression is printed before evaluation by applying the
     expression to the value of this argument, which should be a
     one-argument procedure.

 -- procedure: load-library
          (load-library UNIT [LIBRARYFILE])
     On platforms that support dynamic loading, `load-library' loads
     the compiled library unit `UNIT' (which should be a symbol). If the
     string `LIBRARYFILE' is given, then the given shared library will
     be loaded and the toplevel code of the contained unit will be
     executed.  If no `LIBRARYFILE' argument is given, then the
     following libraries are checked for the required unit:

        * a file named "`<UNIT>.so'"

        * the files given in the parameter `dynamic-load-libraries'


     If the unit is not found, an error is signaled.  When the library
     unit can be successfully loaded, a feature-identifier named `UNIT'
     is registered. If the feature is already registered before loading,
     the `load-library' does nothing.


 -- procedure: set-dynamic-load-mode!
          (set-dynamic-load-mode! MODELIST)
     On systems that support dynamic loading of compiled code via the
     `dlopen(3)' interface (for example Linux and Solaris), some
     options can be specified to fine-tune the behaviour of the dynamic
     linker. `MODE' should be a list of symbols (or a single symbol)
     taken from the following set:

        * `local' If `local' is given, then any C/C++ symbols defined
          in the dynamically loaded file are not available for
          subsequently loaded files and libraries. Use this if you have
          linked foreign code into your dynamically loadable file and
          if you don't want to export them (for example because you
          want to load another file that defines the same symbols).

        * `global' The default is `global', which means all C/C++
          symbols are available to code loaded at a later stage.

        * `now' If `now' is specified, all symbols are resolved
          immediately.

        * `lazy' Unresolved symbols are resolved as code from the file
          is executed.  This is the default.

     Note that this procedure does not control the way Scheme variables
     are handled - this facility is mainly of interest when accessing
     foreign code.



File: chicken.info,  Node: Read-eval-print loop,  Next: Macros,  Prev: Loading code,  Up: Unit eval

5.9.2 Read-eval-print loop
--------------------------

 -- procedure: repl
          (repl)
     Start a new read-eval-print loop. Sets the `reset-handler' so that
     any invocation of `reset' restarts the read-eval-print loop. Also
     changes the current exception-handler to display a message, write
     any arguments to the value of `(current-error-port)' and reset.


File: chicken.info,  Node: Macros,  Next: Loading extension libraries,  Prev: Read-eval-print loop,  Up: Unit eval

5.9.3 Macros
------------

 -- procedure: get-line-number
          (get-line-number EXPR)
     If `EXPR' is a pair with the car being a symbol, and line-number
     information is available for this expression, then this procedure
     returns the associated line number. If line-number information is
     not available, then `#f' is returned.  Note that line-number
     information for expressions is only available in the compiler.


 -- procedure: macro?
          (macro? SYMBOL)
     Returns `#t' if there exists a macro-definition for `SYMBOL'.


 -- procedure: macroexpand
          (macroexpand X)
     If `X' is a macro-form, expand the macro (and repeat expansion
     until expression is a non-macro form).  Returns the resulting
     expression.


 -- procedure: macroexpand-1
          (macroexpand-1 X)
     If `X' is a macro-form, expand the macro.  Returns the resulting
     expression.


 -- procedure: undefine-macro!
          (undefine-macro! SYMBOL)
     Remove the current macro-definition of the macro named `SYMBOL'.

 -- procedure: syntax-error
          (syntax-error [LOCATION] MESSAGE ARGUMENT ...)
     Signals an exception of the kind `(exn syntax)'. Otherwise
     identical to `error'.


File: chicken.info,  Node: Loading extension libraries,  Next: Reader extensions,  Prev: Macros,  Up: Unit eval

5.9.4 Loading extension libraries
---------------------------------

This functionality is only available on platforms that support dynamic
loading of compiled code. Currently Linux, BSD, Solaris, Windows (with
Cygwin) and HP/UX are supported.

 -- parameter: repository-path
     Contains a string naming the path to the extension repository,
     which defaults to either the value of the environment variable
     `CHICKEN_REPOSITORY', the value of the environment variable
     `CHICKEN_HOME' or the default library path (usually
     `/usr/local/lib/chicken' on UNIX systems).

 -- procedure: extension-information
          (extension-information ID)
     If an extension with the name `ID' is installed and if it has a
     setup-information list registered in the extension repository,
     then the info-list is returned. Otherwise `extension-information'
     returns `#f'.

 -- procedure: provide
          (provide ID ...)
     Registers the extension IDs `ID ...' as loaded. This is mainly
     intended to provide aliases for certain extension identifiers.


 -- procedure: provided?
          (provided? ID ...)
     Returns `#t' if the extension with the IDs `ID ...' are currently
     loaded, or `#f' otherwise.  Works also for feature-ids.


 -- procedure: require
 -- procedure: require-for-syntax
          (require ID ...)
          (require-for-syntax ID ...)
     If the extension library `ID' is not already loaded into the
     system, then `require' will lookup the location of the shared
     extension library and load it. If `ID' names a library-unit of the
     base system, then it is loaded via `load-library'.  If no
     extension library is available for the given ID, then an attempt is
     made to load the file `ID.so' or `ID.scm' (in that order) from one
     of the following locations:

       1. the current include path, which defaults to the pathnames
          given in `CHICKEN_INCLUDE_PATH' and `CHICKEN_HOME'.

       2. the current directory


     `ID' should be a string or a symbol. The difference between
     `require' and `require-for-syntax' is the the latter loads the
     extension library at compile-time (the argument is still
     evaluated), while the former loads it at run-time.


 -- procedure: set-extension-specifier!
          (set-extension-specifier! SYMBOL PROC)
     Registers the handler-procedure `PROC' as a extension-specifier
     with the name `SYMBOL'. This facility allows extending the set of
     valid extension specifiers to be used with `require-extension'.
     When `register-extension' is called with an extension specifier of
     the form `(SPEC ...)' and `SPEC' has been registered with
     `set-extension-specifier!', then `PROC' will be called with two
     arguments: the specifier and the previously installed handler (or
     `#f' if no such handler was defined). The handler should return a
     new specifier that will be processed recursively. If the handler
     returns a vector, then each element of the vector will be
     processed recursively.  Alternatively the handler may return a
     string which specifies a file to be loaded:

          (eval-when (compile eval)
            (set-extension-specifier!
              'my-package
              (lambda (spec old)
                (make-pathname my-package-directory (->string (cadr spec))) ) ) )

          (require-extension (my-package stuff))     ; --> expands into '(load "my-package-dir/stuff")

     Note that the handler has to be registered at compile time, if it
     is to be visible in compiled code.


File: chicken.info,  Node: Reader extensions,  Next: Eval,  Prev: Loading extension libraries,  Up: Unit eval

5.9.5 Reader extensions
-----------------------

 -- procedure: define-reader-ctor
          (define-reader-ctor SYMBOL PROC)
     Define new read-time constructor for `#,' read syntax. For further
     information, see the documentation for SRFI-10
     (http://srfi.schemers.org/srfi-10/srfi-10.html).

 -- procedure: set-read-syntax!
          (set-read-syntax! CHAR PROC)
     When the reader is encounting the non-whitespace character `CHAR'
     while reading an expression from a given port, then the procedure
     `PROC' will be called with that port as its argument. The
     procedure should return a value that will be returned to the
     reader:

          ; A simple RGB color syntax:

          (set-read-syntax! #\%
            (lambda (port)
              (apply vector
                (map (cut string->number <> 16)
                     (string-chop (read-string 6 port) 2) ) ) ) )

          (with-input-from-string "(1 2 %f0f0f0 3)" read)
          ; ==> (1 2 #(240 240 240) 3)

     You can undo special handling of read-syntax by passing `#f' as
     the second argument (if the syntax was previously defined via
     `set-read-syntax!').

     Note that all of CHICKEN's special non-standard read-syntax is
     handled directly by the reader to disable built-in read-syntax,
     define a handler that triggers an error (for example).

 -- procedure: set-sharp-read-syntax!
          (set-sharp-read-syntax! CHAR PROC)
     Similar to `set-read-syntax!', but allows defining new `#<CHAR>
     ...' reader syntax.

 -- procedure: copy-read-table
          (copy-read-table READ-TABLE)
     Returns a copy of the given read-table. You can access the
     currently active read-table with `(current-read-table)'.


File: chicken.info,  Node: Eval,  Prev: Reader extensions,  Up: Unit eval

5.9.6 Eval
----------

 -- procedure: eval
          (eval EXP [ENVIRONMENT])
     Evaluates `EXP' and returns the result of the evaluation. The
     second argument is optional and defaults to the value of
     `(interaction-environment)'.


File: chicken.info,  Node: Unit extras,  Next: Unit srfi-1,  Prev: Unit eval,  Up: Supported language

5.10 Unit extras
================

This unit contains a collection of useful utility definitions.  This
unit is used by default, unless the program is compiled with the
`-explicit-use' option.

* Menu:

* Lists::
* String-port extensions::
* Formatted output::
* Hash tables::
* Queues::
* Sorting::
* Random numbers::
* Input/Output extensions::
* Strings::
* Combinators::
* Binary searching::


File: chicken.info,  Node: Lists,  Next: String-port extensions,  Up: Unit extras

5.10.1 Lists
------------

 -- procedure: alist-ref
          (alist-ref KEY ALIST [TEST [DEFAULT]])
     Looks up `KEY' in `ALIST' using `TEST' as the comparison function
     (or `eqv?' if no test was given) and returns the cdr of the found
     pair, or `DEFAULT' (which defaults to `#f').

 -- procedure: alist-update!
          (alist-update! KEY VALUE ALIST [TEST])
     If the list `ALIST' contains a pair of the form `(KEY . X)', then
     this procedure replaces `X' with `VALUE' and returns `ALIST'. If
     `ALIST' contains no such item, then `alist-update!' returns `((KEY
     . VALUE) . ALIST)'. The optional argument `TEST' specifies the
     comparison procedure to search a matching pair in `ALIST' and
     defaults to `eqv?'.

 -- procedure: atom?
          (atom? X)
     Returns `#t' if `X' is a not list (`X' is not a pair nor the empty
     list).

 -- procedure: rassoc
          (rassoc KEY LIST [TEST])
     Similar to `assoc', but compares `KEY' with the `cdr' of each pair
     in `LIST' using `TEST' as the comparison procedures (which
     defaults to `eqv?'.


 -- procedure: butlast
          (butlast LIST)
     Returns a fresh list with all elements but the last of `LIST'.


 -- procedure: chop
          (chop LIST N)
     Returns a new list of sublists, where each sublist contains `N'
     elements of `LIST'. If `LIST' has a length that is not a multiple
     of `N', then the last sublist contains the remaining elements.


     (chop '(1 2 3 4 5 6) 2) ==> ((1 2) (3 4) (5 6))
     (chop '(a b c d) 3)     ==> ((a b c) (d))


 -- procedure: compress
          (compress BLIST LIST)
     Returns a new list with elements taken from `LIST' with
     corresponding true values in the list `BLIST'.


     (define nums '(99 100 110 401 1234))
     (compress (map odd? nums) nums)      ==> (99 401)


 -- procedure: flatten
          (flatten LIST1 ...)
     Returns `LIST1 ...' concatenated together, with nested lists
     removed (flattened).


 -- procedure: intersperse
          (intersperse LIST X)
     Returns a new list with `X' placed between each element.


 -- procedure: join
          (join LISTOFLISTS [LIST])
     Concatenates the lists in `LISTOFLISTS' with `LIST' placed between
     each sublist. `LIST' defaults to the empty list.


     (join '((a b) (c d) (e)) '(x y)) ==> (a b x y c d x y e)
     (join '((p q) () (r (s) t)) '(-))  ==> (p q - - r (s) t)

     `join' could be implemented as follows:


     (define (join lstoflsts #!optional (lst '()))
       (apply append (intersperse lstoflists lst)) )


 -- procedure: shuffle
          (shuffle LIST)
     Returns `LIST' with its elements sorted in a random order.


 -- procedure: tail?
          (tail? X LIST)
     Returns true if `X' is one of the tails (cdr's) of `LIST'.


File: chicken.info,  Node: String-port extensions,  Next: Formatted output,  Prev: Lists,  Up: Unit extras

5.10.2 String-port extensions
-----------------------------

 -- procedure: call-with-input-string
          (call-with-input-string STRING PROC)
     Calls the procedure `PROC' with a single argument that is a
     string-input-port with the contents of `STRING'.


 -- procedure: call-with-output-string
          (call-with-output-string PROC)
     Calls the procedure `PROC' with a single argument that is a
     string-output-port.  Returns the accumulated output-string.


 -- procedure: with-input-from-string
          (with-input-from-string STRING THUNK)
     Call procedure `THUNK' with the current input-port temporarily
     bound to an input-string-port with the contents of `STRING'.


 -- procedure: with-output-to-string
          (with-output-to-string THUNK)
     Call procedure `THUNK' with the current output-port temporarily
     bound to a string-output-port and return the accumulated output
     string.


File: chicken.info,  Node: Formatted output,  Next: Hash tables,  Prev: String-port extensions,  Up: Unit extras

5.10.3 Formatted output
-----------------------

 -- procedure: fprintf
 -- procedure: printf
 -- procedure: sprintf
 -- procedure: format
          (fprintf PORT FORMATSTRING ARG ...)
          (printf FORMATSTRING ARG)
          (sprintf FORMATSTRING ARG ...)
          (format FORMATSTRING ARG ...)
     Simple formatted output to a given port (`fprintf'), the value of
     `(current-output-port) ' (`printf') or a string
     (`sprintf'/`format').  The `FORMATSTRING' can contain any sequence
     of characters. The character `~' prefixes special formatting
     directives:

    `~%'
          write newline character

    `~N'
          the same as `~%'

    `~S'
          write the next argument

    `~A'
          display the next argument

    `~\n'
          skip all whitespace in the format-string until the next
          non-whitespace character

    `~B'
          write the next argument as a binary number

    `~O'
          write the next argument as an octal number

    `~X'
          write the next argument as a hexadecimal number

    `~C'
          write the next argument as a character

    `~~'
          display `~'

    `~!'
          flush all pending output

    `~?'
          invoke formatted output routine recursively with the next two
          arguments as format-string and list of parameters



File: chicken.info,  Node: Hash tables,  Next: Queues,  Prev: Formatted output,  Up: Unit extras

5.10.4 Hash tables
------------------

CHICKEN implements SRFI-69. For more information, see SRFI-69
(http://srfi.schemers.org/srfi-69/srfi-69.html).

   A setter for `hash-table-ref' is defined, so


(set! (hash-table-ref HT KEY) VAL)

   is equivalent to


(hash-table-set! HT KEY VAL)


File: chicken.info,  Node: Queues,  Next: Sorting,  Prev: Hash tables,  Up: Unit extras

5.10.5 Queues
-------------

 -- procedure: list->queue
          (list->queue LIST)
     Returns `LIST' converted into a queue, where the first element of
     the list is the same as the first element of the queue. The
     resulting queue may share memory with the list and the list should
     not be modified after this operation.


 -- procedure: make-queue
          (make-queue)
     Returns a newly created queue.


 -- procedure: queue?
          (queue? X)
     Returns `#t' if `X' is a queue, or `#f' otherwise.


 -- procedure: queue->list
          (queue->list QUEUE)
     Returns `QUEUE' converted into a list, where the first element of
     the list is the same as the first element of the queue. The
     resulting list may share memory with the queue object and should
     not be modified.


 -- procedure: queue-add!
          (queue-add! QUEUE X)
     Adds `X' to the rear of `QUEUE'.


 -- procedure: queue-empty?
          (queue-empty? QUEUE)
     Returns `#t' if `QUEUE' is empty, or `#f' otherwise.


 -- procedure: queue-first
          (queue-first QUEUE)
     Returns the first element of `QUEUE'. If `QUEUE' is empty an error
     is signaled


 -- procedure: queue-last
          (queue-last QUEUE)
     Returns the last element of `QUEUE'. If `QUEUE' is empty an error
     is signaled


 -- procedure: queue-remove!
          (queue-remove! QUEUE)
     Removes and returns the first element of `QUEUE'. If `QUEUE' is
     empty an error is signaled

 -- procedure: queue-push-back!
          (queue-push-back! QUEUE ITEM)
     Pushes an item into the first position of a queue, i.e. the next
     `queue-remove!' will return `ITEM'.

 -- procedure: queue-push-back-list!
          (queue-push-back-list! QUEUE LIST)
     Pushes the items in item-list back onto the queue, so that `(car
     LIST)' becomes the next removable item.


File: chicken.info,  Node: Sorting,  Next: Random numbers,  Prev: Queues,  Up: Unit extras

5.10.6 Sorting
--------------

 -- procedure: merge
 -- procedure: merge!
          (merge LIST1 LIST2 LESS?)
          (merge! LIST1 LIST2 LESS?)
     Joins two lists in sorted order. `merge!' is the destructive
     version of merge. `LESS?  ' should be a procedure of two arguments,
     that returns true if the first argument is to be ordered before the
     second argument.


 -- procedure: sort
 -- procedure: sort!
          (sort SEQUENCE LESS?)
          (sort! SEQUENCE LESS?)
     Sort `SEQUENCE', which should be a list or a vector. `sort!' is
     the destructive version of sort.


 -- procedure: sorted?
          (sorted? SEQUENCE LESS?)
     Returns true if the list or vector `SEQUENCE' is already sorted.


File: chicken.info,  Node: Random numbers,  Next: Input/Output extensions,  Prev: Sorting,  Up: Unit extras

5.10.7 Random numbers
---------------------

 -- procedure: random
          (random N)
     Returns an exact random integer from 0 to `N'-1.


 -- procedure: randomize
          (randomize [X])
     Set random-number seed. If `X' is not supplied, the current time
     is used.  On startup (when the `extras' unit is initialized), the
     random number generator is initialized with the current time.


File: chicken.info,  Node: Input/Output extensions,  Next: Strings,  Prev: Random numbers,  Up: Unit extras

5.10.8 Input/Output extensions
------------------------------

 -- procedure: make-input-port
          (make-input-port READ READY? CLOSE [PEEK])
     Returns a custom input port. Common operations on this port are
     handled by the given parameters, which should be procedures of no
     arguments. `READ' is called when the next character is to be read
     and should return a character or `#!eof'. `READY?' is called when
     `char-ready?' is called on this port and should return `#t' or
     `#f'.  `CLOSE' is called when the port is closed. `PEEK' is called
     when `peek-char' is called on this port and should return a
     character or `#!eof'.  if the argument `PEEK' is not given, then
     `READ' is used instead and the created port object handles peeking
     automatically (by calling `READ' and buffering the character).


 -- procedure: make-output-port
          (make-output-port WRITE CLOSE [FLUSH])
     Returns a custom output port. Common operations on this port are
     handled by the given parameters, which should be procedures.
     `WRITE' is called when output is sent to the port and receives a
     single argument, a string.  `CLOSE' is called when the port is
     closed and should be a procedure of no arguments. `FLUSH' (if
     provided) is called for flushing the output port.


 -- procedure: pretty-print
 -- procedure: pp
          (pretty-print EXP [PORT])
          (pp EXP [PORT])
     Print expression nicely formatted. `PORT' defaults to the value of
     `(current-output-port)'.


 -- parameter: pretty-print-width
     Specifies the maximal line-width for pretty printing, after which
     line wrap will occur.


 -- procedure: read-file
          (read-file [FILE-OR-PORT [READER [MAXCOUNT]]])
     Returns a list containing all toplevel expressions read from the
     file or port `FILE-OR-PORT'. If no argument is given, input is
     read from the port that is the current value of
     `(current-input-port)'.  After all expressions are read, and if
     the argument is a port, then the port will not be closed. The
     `READER' argument specifies the procedure used to read expressions
     from the given file or port and defaults to `read'. The reader
     procedure will be called with a single argument (an input port).
     If `MAXCOUNT' is given then only up to `MAXCOUNT' expressions will
     be read in.


 -- procedure: read-line
 -- procedure: write-line
          (read-line [PORT [LIMIT]])
          (write-line STRING [PORT])
     Line-input and -output. `PORT' defaults to the value of
     `(current-input-port)' and `(current-output-port)', respectively.
     if the optional argument `LIMIT' is given and not `#f', then
     `read-line' reads at most `LIMIT' characters per line.


 -- procedure: read-lines
          (read-lines [PORT [MAX]])
     Read `MAX' or fewer lines from `PORT'. `PORT' defaults to the
     value of `(current-input-port)'. `PORT' may optionally be a string
     naming a file.


 -- procedure: read-string
 -- procedure: write-string
          (read-string [NUM [PORT]])
          (write-string STRING [NUM [PORT]]
     Read or write `NUM' characters from/to `PORT', which defaults to
     the value of `(current-input-port)' or `(current-output-port)',
     respectively.  If `NUM' is `#f' or not given, then all data up to
     the end-of-file is read, or, in the case of `write-string' the
     whole string is written. If no more input is available,
     `read-string' returns the empty string.

 -- procedure: read-token
          (read-token PREDICATE [PORT])
     Reads characters from `PORT' (which defaults to the value of
     `(current-input-port)') and calls the procedure `PREDICATE' with
     each character until `PREDICATE' returns false. Returns a string
     with the accumulated characters.

 -- procedure: with-error-output-to-port
          (with-error-output-to-port PORT THUNK)
     Call procedure `THUNK' with the current error output-port
     temporarily bound to `PORT'.


 -- procedure: with-input-from-port
          (with-input-from-port PORT THUNK)
     Call procedure `THUNK' with the current input-port temporarily
     bound to `PORT'.


 -- procedure: with-output-to-port
          (with-output-to-port PORT THUNK)
     Call procedure `THUNK' with the current output-port temporarily
     bound to `PORT'.


File: chicken.info,  Node: Strings,  Next: Combinators,  Prev: Input/Output extensions,  Up: Unit extras

5.10.9 Strings
--------------

 -- procedure: conc
          (conc X ...)
     Returns a string with the string-represenation of all arguments
     concatenated together. `conc' could be implemented as


     (define (conc . args)
       (apply string-append (map ->string args)) )

 -- procedure: ->string
          (->string X)
     Returns a string-representation of `X'.


 -- procedure: string-chop
          (string-chop STRING LENGTH)
     Returns a list of substrings taken by "chopping" `STRING' every
     `LENGTH' characters:


     (string-chop "one two three" 4)  ==>  ("one " "two " "thre" "e")


 -- procedure: string-chomp
          (string-chomp STRING [SUFFIX])
     If `STRING' ends with `SUFFIX', then this procedure returns a copy
     of its first argument with the suffix removed, otherwise returns
     `STRING' unchanged. `SUFFIX' defaults to `"\n"'.

 -- procedure: string-compare3
          (string-compare3 STRING1 STRING2)

 -- procedure: string-compare3-ci
          (string-compare3-ci STRING1 STRING2)
     Perform a three-way comparison between the `STRING1' and `STRING2',
     returning either `-1' if `STRING1' is lexicographically less than
     `STRING2', `0' if it is equal, or `1' if it s greater.
     `string-compare3-ci' performs a case-insensitive comparison.

 -- procedure: string-intersperse
          (string-intersperse LIST [STRING])
     Returns a string that contains all strings in `LIST' concatenated
     together.  `STRING' is placed between each concatenated string and
     defaults to `" "'.


     (string-intersperse '("one" "two") "three")

     is equivalent to


     (apply string-append (intersperse '("one" "two") "three"))


 -- procedure: string-split
          (string-split STRING [DELIMITER-STRING [KEEPEMPTY]])
     Split string into substrings separated by the given delimiters. If
     no delimiters are specified, a string comprising the tab, newline
     and space characters is assumed. If the parameter `KEEPEMPTY' is
     given and not `#f', then empty substrings are retained:


     (string-split "one  two  three") ==> ("one" "two" "three")
     (string-split "foo:bar::baz:" ":" #t) ==> ("foo" "bar" "" "baz" "")


 -- procedure: string-translate
          (string-translate STRING FROM [TO])
     Returns a fresh copy of `STRING' with characters matching `FROM'
     translated to `TO'.  If `TO' is omitted, then matching characters
     are removed. `FROM' and `TO' may be a character, a string or a
     list. If both `FROM' and `TO' are strings, then the character at
     the same position in `TO' as the matching character in `FROM' is
     substituted.


 -- procedure: string-translate*
          (string-translate* STRING SMAP)
     Substitutes elements of `STRING' according to `SMAP'.  `SMAP'
     should be an association-list where each element of the list is a
     pair of the form `(MATCH \. REPLACEMENT)'. Every occurrence of the
     string `MATCH' in `STRING' will be replaced by the string
     `REPLACEMENT':


     (string-translate*
       "<h1>this is a \"string\"</h1>"
       '(("<" . "&lt:") (">" . "&gt;") ("\"" . "&quot;")) )

     ==>  "&lt;h1&gt;this is a &quot;string&quot;&lt;/ht&gt;"


 -- procedure: substring=?
 -- procedure: substring-ci=?
          (substring=? STRING1 STRING2 [START1 [START2 [LENGTH]]])
          (substring-ci=? STRING1 STRING2 [START1 [START2 [LENGTH]]])
     Returns `#t' if the strings `STRING1' and `STRING2' are equal, or
     `#f' otherwise.  The comparison starts at the positions `START1'
     and `START2' (which default to 0), comparing `LENGTH' characters
     (which defaults to the minimum of the remaining length of both
     strings).


 -- procedure: substring-index
 -- procedure: substring-index-ci
          (substring-index WHICH WHERE [START])
          (substring-index-ci WHICH WHERE [START])
     Searches for first index in string `WHERE' where string `WHICH'
     occurs.  If the optional argument `START' is given, then the
     search starts at that index.  `substring-index-ci' is a
     case-insensitive version of `substring-index'.


File: chicken.info,  Node: Combinators,  Next: Binary searching,  Prev: Strings,  Up: Unit extras

5.10.10 Combinators
-------------------

 -- procedure: constantly
          (constantly X ...)
     Returns a procedure that always returns the values `X ...'
     regardless of the number and value of its arguments.


     (constantly X) <=> (lambda args X)


 -- procedure: complement
          (complement PROC)
     Returns a procedure that returns the boolean inverse of `PROC'.
     (complement PROC) <=> (lambda (x) (not (PROC x)))


 -- procedure: compose
          (compose PROC1 PROC2 ...)
     Returns a procedure that represents the composition of the
     argument-procedures `PROC1 PROC2 ...'.


     (compose F G) <=> (lambda args
                           (call-with-values
                              (lambda () (apply G args))
                              F))


 -- procedure: conjoin
          (conjoin PRED ...)
     Returns a procedure that returns `#t' if its argument satisfies the
     predicates `PRED ...'.
     ((conjoin odd? positive?) 33)   ==>  #t
     ((conjoin odd? positive?) -33)  ==>  #f


 -- procedure: disjoin
          (disjoin PRED ...)
     Returns a procedure that returns `#t' if its argument satisfies any
     predicate `PRED ...'.
     ((disjoin odd? positive?) 32)    ==>  #t
     ((disjoin odd? positive?) -32)   ==>  #f


 -- procedure: each
          (each PROC ...)
     Returns a procedure that applies `PROC ...' to its arguments, and
     returns the result(s) of the last procedure application. For
     example
          (each pp eval)
     is equivalent to
          (lambda args
            (apply pp args)
            (apply eval args) )
     `(each PROC)' is equivalent to `PROC' and `(each)' is equivalent to
     `noop'.

 -- procedure: flip
          (flip PROC)
     Returns a two-argument procedure that calls `PROC' with its
     arguments swapped:
     (flip PROC) <=> (lambda (x y) (PROC y x))


 -- procedure: identity
          (identity X)
     Returns its sole argument `X'.


 -- procedure: project
          (project N)
     Returns a procedure that returns its `N'th argument (starting from
     0).


 -- procedure: list-of
          (list-of PRED)
     Returns a procedure of one argument that returns `#t' when applied
     to a list of elements that all satisfy the predicate procedure
     `PRED', or `#f' otherwise.


     ((list-of even?) '(1 2 3))   ==> #f
     ((list-of number?) '(1 2 3)) ==> #t

 -- procedure: noop
          (noop X ...)
     Ignores it's arguments, does nothing and returns an unspecified
     value.


File: chicken.info,  Node: Binary searching,  Prev: Combinators,  Up: Unit extras

5.10.11 Binary searching
------------------------

 -- procedure: binary-search
          (binary-search SEQUENCE PROC)
     Performs a binary search in `SEQUENCE', which should be a sorted
     list or vector.  `PROC' is called to compare items in the sequence,
     should accept a single argument and return an exact integer: zero
     if the searched value is equal to the current item, negative if
     the searched value is "less" than the current item, and positive
     otherwise.


File: chicken.info,  Node: Unit srfi-1,  Next: Unit srfi-4,  Prev: Unit extras,  Up: Supported language

5.11 Unit srfi-1
================

List library, see the documentation for SRFI-1
(http://srfi.schemers.org/srfi-1/srfi-1.html)


File: chicken.info,  Node: Unit srfi-4,  Next: Unit srfi-13,  Prev: Unit srfi-1,  Up: Supported language

5.12 Unit srfi-4
================

Homogeneous numeric vectors, see the documentation for SRFI-4
(http://srfi.schemers.org/srfi-4/srfi-4.html).  64-bit integer vectors
(`u64vector' and `s64vector' are not supported.

   The basic constructor procedures for number vectors are extended to
allow allocating the storage in non garbage collected memory:

 -- procedure: make-XXXvector
          (make-XXXvector SIZE [INIT NONGC FINALIZE])
     Creates a SRFI-4 homogenous number vector of length `SIZE'. If
     `INIT' is given, it specifies the initial value for each slot in
     the vector. The optional arguments `NONGC' and `FINALIZE' define
     whether the vector should be allocated in a memory area not
     subject to garbage collection and whether the associated storage
     should be automatically freed (using finalization) when there are
     no references from Scheme variables and data.  `NONGC' defaults to
     `#f' (the vector will be located in normal garbage collected
     memory) and `FINALIZE' defaults to  `#t'. Note that the `FINALIZE'
     argument is only used when `NONGC' is true.

   Additionally, the following procedures are provided:

 -- procedure: u8vector->byte-vector
 -- procedure: s8vector->byte-vector
 -- procedure: u16vector->byte-vector
 -- procedure: s16vector->byte-vector
 -- procedure: u32vector->byte-vector
 -- procedure: s32vector->byte-vector
 -- procedure: f32vector->byte-vector
 -- procedure: f64vector->byte-vector
          (u8vector->byte-vector U8VECTOR)
          (s8vector->byte-vector S8VECTOR)
          (u16vector->byte-vector U16VECTOR)
          (s16vector->byte-vector S16VECTOR)
          (u32vector->byte-vector U32VECTOR)
          (s32vector->byte-vector S32VECTOR)
          (f32vector->byte-vector F32VECTOR)
          (f64vector->byte-vector F64VECTOR)
     Each of these procedures return the contents of the given vector
     as a 'packed' byte-vector. The byte order in that vector is
     platform-dependent (for example little-endian on an Intel
     processor). The returned byte-vector shares memory with the
     contents of the vector.

 -- procedure: byte-vector->u8vector
 -- procedure: byte-vector->s8vector
 -- procedure: byte-vector->u16vector
 -- procedure: byte-vector->s16vector
 -- procedure: byte-vector->u32vector
 -- procedure: byte-vector->s32vector
 -- procedure: byte-vector->f32vector
 -- procedure: byte-vector->f64vector
          (byte-vector->u8vector BYTE-VECTOR)
          (byte-vector->s8vector BYTE-VECTOR)
          (byte-vector->u16vector BYTE-VECTOR)
          (byte-vector->s16vector BYTE-VECTOR)
          (byte-vector->u32vector BYTE-VECTOR)
          (byte-vector->s32vector BYTE-VECTOR)
          (byte-vector->f32vector BYTE-VECTOR)
          (byte-vector->f64vector BYTE-VECTOR)
     Each of these procedures return a vector where the argument
     `BYTE-VECTOR' is taken as a 'packed' representation of the contents
     of the vector. The argument-byte-vector shares memory with the
     contents of the vector.


 -- procedure: subu8vector
 -- procedure: subu16vector
 -- procedure: subu32vector
 -- procedure: subs8vector
 -- procedure: subs16vector
 -- procedure: subs32vector
 -- procedure: subf32vector
 -- procedure: subf64vector
          (subu8vector U8VECTOR FROM TO)
          (subu16vector U16VECTOR FROM TO)
          (subu32vector U32VECTOR FROM TO)
          (subs8vector S8VECTOR FROM TO)
          (subs16vector S16VECTOR FROM TO)
          (subs32vector S32VECTOR FROM TO)
          (subf32vector F32VECTOR FROM TO)
          (subf64vector F64VECTOR FROM TO)
     Creates a number vector of the same type as the argument vector
     with the elements at the positions `FROM' up to but not including
     `TO'.

     SRFI-17 Setters for `XXXvector-ref' are defined.


File: chicken.info,  Node: Unit srfi-13,  Next: Unit srfi-14,  Prev: Unit srfi-4,  Up: Supported language

5.13 Unit srfi-13
=================

String library, see the documentation for SRFI-13
(http://srfi.schemers.org/srfi-13/srfi-13.html)

   On systems that support dynamic loading, the `srfi-13' unit can be
made available in the interpreter (`csi') by entering


(require-extension srfi-13)


File: chicken.info,  Node: Unit srfi-14,  Next: Unit match,  Prev: Unit srfi-13,  Up: Supported language

5.14 Unit srfi-14
=================

Character set library, see the documentation for SRFI-14
(http://srfi.schemers.org/srfi-14/srfi-14.html)

   On systems that support dynamic loading, the `srfi-14' unit can be
made available in the interpreter (`csi') by entering


(require-extension srfi-14)

   * This library provides only the Latin-1 character set.


File: chicken.info,  Node: Unit match,  Next: Unit regex,  Prev: Unit srfi-14,  Up: Supported language

5.15 Unit match
===============

The runtime-support code for the Pattern Matching extensions. Note that
to use the macros in normal compiled code it is not required to declare
this unit as used. Only if forms containing these macros are to be
expanded at runtime, this is needed.


File: chicken.info,  Node: Unit regex,  Next: Unit srfi-18,  Prev: Unit match,  Up: Supported language

5.16 Unit regex
===============

This library unit provides support for regular expressions. The flavor
depends on the particular installation platform:

   * On UNIX systems that have PCRE (the Perl Compatible Regular
     Expression package) installed, PCRE is used.

   * If PCRE is not available, and the C library provides regular
     expressions, these are used instead.

   * on Windows (or of PCRE and libc regexes are not available), Dorai
     Sitaram's portable `pregexp' library is used.

 -- procedure: grep
          (grep REGEX LIST)
     Returns all items of `LIST' that match the regular expression
     `REGEX'.  This procedure could be defined as follows:


     (define (grep regex lst)
       (filter (lambda (x) (string-search regex x)) lst) )


 -- procedure: glob->regexp
          (glob->regexp PATTERN)
     Converts the file-pattern `PATTERN' into a regular expression.


     (glob->regexp "foo.*") ==> "foo\..*"


 -- procedure: regexp
          (regexp STRING [IGNORECASE [IGNORESPACE [UTF8]]])
     Returns a precompiled regular expression object for `string'.  The
     optional arguments `IGNORECASE', `IGNORESPACE' and `UTF8' specify
     whether the regular expression should be matched with case- or
     whitespace-differences ignored, or whether the string should be
     treated as containing UTF-8 encoded characters, respectively.

     Notes:

        * regex doesn't allow (?: ) cloisters (non-capturing groups)
          Currently this means if you use utf8 matching, individual "."
             matching will return extra submatches.

        * pregexp doesn't allow a # comment w/o a trailing newline.


 -- procedure: regexp?
          (regexp? X)
     Returns `#t' if `X' is a precompiled regular expression, or `#f'
     otherwise.


 -- procedure: string-match
 -- procedure: string-match-positions
          (string-match REGEXP STRING [START])
          (string-match-positions REGEXP STRING [START])
     Matches the regular expression in `REGEXP' (a string or a
     precompiled regular expression) with `STRING' and returns either
     `#f' if the match failed, or a list of matching groups, where the
     first element is the complete match. If the optional argument
     `START' is supplied, it specifies the starting position in
     `STRING'.  For each matching group the result-list contains
     either: `#f' for a non-matching but optional group; a list of
     start- and end-position of the match in `STRING' (in the case of
     `string-match-positions'); or the matching substring (in the case
     of `string-match'). Note that the exact string is matched. For
     searching a pattern inside a string, see below.  Note also that
     `string-match' is implemented by calling `string-search' with the
     regular expression wrapped in `^ ... $'.


 -- procedure: string-search
 -- procedure: string-search-positions
          (string-search REGEXP STRING [START [RANGE]])
          (string-search-positions REGEXP STRING [START [RANGE]])
     Searches for the first match of the regular expression in `REGEXP'
     with `STRING'. The search can be limited to `RANGE' characters.


 -- procedure: string-split-fields
          (string-split-fields REGEXP STRING [MODE [START]])
     Splits `STRING' into a list of fields according to `MODE', where
     `MODE' can be the keyword `#:infix' (`REGEXP' matches field
     separator), the keyword `#:suffix' (`REGEXP' matches field
     terminator) or `#t' (`REGEXP' matches field), which is the default.

          (define s "this is a string 1, 2, 3,")

          (string-split-fields "[^ ]+" s)

            => ("this" "is" "a" "string" "1," "2," "3,")

          (string-split-fields " " s #:infix)

            => ("this" "is" "a" "string" "1," "2," "3,")

          (string-split-fields "," s #:suffix))

            => ("this is a string 1" " 2" " 3")


 -- procedure: string-substitute
          (string-substitute REGEXP SUBST STRING [MODE])
     Searches substrings in `STRING' that match `REGEXP' and
     substitutes them with the string `SUBST'. The substitution can
     contain references to subexpressions in `REGEXP' with the `\NUM'
     notation, where `NUM' refers to the NUMth parenthesized
     expression. The optional argument `MODE' defaults to 1 and
     specifies the number of the match to be substituted. Any
     non-numeric index specifies that all matches are to be substituted.


     (string-substitute "([0-9]+) (eggs|chicks)"
                        "\\2 (\\1)" "99 eggs or 99 chicks" 2)
      ==> "99 eggs or chicks (99)"


 -- procedure: string-substitute*
          (string-substitute* STRING SMAP [MODE])
     Substitutes elements of `STRING' with `string-substitute'
     according to `SMAP'.  `SMAP' should be an association-list where
     each element of the list is a pair of the form `(MATCH .
     REPLACEMENT)'. Every occurrence of the regular expression `MATCH'
     in `STRING' will be replaced by the string `REPLACEMENT'


     (string-substitute* "<h1>Hello, world!</h1>"
                         '(("<[/A-Za-z0-9]+>" . ""))))

     ==>  "Hello, world!"

 -- procedure: regexp-escape
          (regexp-escape STRING)
     Escapes all special characters in `STRING' with `\', so that the
     string can be embedded into a regular expression.


     (regexp-escape "^[0-9]+:.*$")   ==>  "\\^\\[0-9\\]\\+:.\n.\\*\\$"

   Platform-specific notes:

   * due to a bug in the `pregexp' library, character classes enclosed
     in `[ ... ]' may not begin with a hyphen (`-'). A workaround is
     either to precede the hyphen with a backslash or use the range
     `---'.


File: chicken.info,  Node: Unit srfi-18,  Next: Unit posix,  Prev: Unit regex,  Up: Supported language

5.17 Unit srfi-18
=================

A simple multithreading package. This threading package follows largely
the specification of SRFI-18. For more information see the documentation
for SRFI-18 (http://srfi.schemers.org/srfi-18/srfi-18.html)

   Notes:

   * `thread-start!' accepts a thunk (a zero argument procedure) as
     argument, which is equivalent to `(thread-start! (make-thread
     THUNK))'.

   * When an uncaught exception (i.e. an error) is signalled in a
     thread other than the primordial thread and warnings are enabled
     (see: `enable-warnings', then a warning message is written to the
     port that is the value of `(current-error-port)'.

   * Blocking I/O will block all threads, except for some socket
     operations (see the section about the `tcp' unit). An exception is
     the read-eval-print loop on UNIX platforms: waiting for input will
     not block other threads, provided the current input port reads
     input from a console.

   * It is generally not a good idea for one thread to call a
     continuation created by another thread, if `dynamic-wind' is
     involved.

   * When more than one thread compete for the current time-slice, the
     thread that was waiting first will become the next runnable thread.

   * The dynamic environment of a thread consists of the following
     state:

        * The current input-, output- and error-port

        * The current exception handler

        * The values of all current parameters (created by
          `make-parameter')

        * Any pending `dynamic-wind' thunks.



   The following procedures are provided, in addition to the procedures
defined in SRFI-18:

 -- procedure: thread-signal!
          (thread-signal! THREAD X)
     This will cause `THREAD' to signal the condition `X' once it is
     scheduled for execution. After signalling the condition, the
     thread continues with its normal execution.


 -- procedure: thread-quantum
          (thread-quantum THREAD)
     Returns the quantum of `THREAD', which is an exact integer
     specifying the approximate time-slice of the thread.


 -- procedure: thread-quantum-set!
          (thread-quantum-set! THREAD QUANTUM)
     Sets the quantum of `THREAD' to `QUANTUM'.


File: chicken.info,  Node: Unit posix,  Next: Unit utils,  Prev: Unit srfi-18,  Up: Supported language

5.18 Unit posix
===============

This unit provides services as used on many UNIX-like systems.  Note
that the following definitions are not all available on non-UNIX
systems like Windows. See below for Windows specific notes.

   This unit uses the `regex', `scheduler', `extras' and `utils' units.

   All errors related to failing file-operations will signal a condition
of kind `(exn i/o file)'.

* Menu:

* Directories::
* Pipes::
* Fifos::
* File descriptors and low-level I/O::
* Retrieving file attributes::
* Changing file attributes::
* Processes::
* Hard and symbolic links::
* Permissions::
* Record locking::
* Signal handling::
* Environment access::
* Memory mapped I/O::
* Date and time routines::
* Raw exit::
* ERRNO values::
* Finding files::
* Getting the hostname and system information::
* Setting the file buffering mode::
* Terminal ports::
* How Scheme procedures relate to UNIX C functions::
* Windows specific notes::


File: chicken.info,  Node: Directories,  Next: Pipes,  Up: Unit posix

5.18.1 Directories
------------------

 -- procedure: change-directory
          (change-directory NAME)
     Changes the current working directory to `NAME'.


 -- procedure: current-directory
          (current-directory [DIR])
     Returns the name of the current working directory. If the optional
     argument `DIR' is given, then `(current-directory DIR)' is
     equivalent to `(change-directory DIR)'.


 -- procedure: create-directory
          (create-directory NAME)
     Creates a directory with the pathname `NAME'.


 -- procedure: delete-directory
          (delete-directory NAME)
     Deletes the directory with the pathname `NAME'. The directory has
     to be empty.


 -- procedure: directory
          (directory [PATHNAME [SHOW-DOTFILES?]])
     Returns a list with all files that are contained in the directory
     with the name `PATHNAME' (which defaults to the value of
     `(current-directory)'). If `SHOW-DOTFILES?' is given and not `#f',
     then files beginning with "." are not included in the directory
     listing.


 -- procedure: directory?
          (directory? NAME)
     Returns `#t' if there exists a file with the name `NAME' and if
     that file is a directory, or `#f' otherwise.


 -- procedure: glob
          (glob PATTERN1 ...)
     Returns a list of the pathnames of all existing files matching
     `PATTERN1 ...', which should be strings containing the usual
     file-patterns (with `*' matching zero or more characters and `?'
     matching zero or one character).

 -- procedure: set-root-directory!
          (set-root-directory! STRING)
     Sets the root directory for the current process to the path given
     in `STRING' (using the `chroot' function).  If the current process
     has no root permissions, the operation will fail.


File: chicken.info,  Node: Pipes,  Next: Fifos,  Prev: Directories,  Up: Unit posix

5.18.2 Pipes
------------

 -- procedure: call-with-input-pipe
 -- procedure: call-with-output-pipe
          (call-with-input-pipe CMDLINE PROC [MODE])
          (call-with-output-pipe CMDLINE PROC [MODE])
     Call `PROC' with a single argument: a input- or output port for a
     pipe connected to the subprocess named in `CMDLINE'. If `PROC'
     returns normally, the pipe is closed and any result values are
     returned.


 -- procedure: close-input-pipe
 -- procedure: close-output-pipe
          (close-input-pipe PORT)
          (close-output-pipe PORT)
     Closes the pipe given in `PORT' and waits until the connected
     subprocess finishes. The exit-status code of the invoked process
     is returned.


 -- procedure: create-pipe
          (create-pipe)
     The fundamental pipe-creation operator. Calls the C function
     `pipe()' and returns 2 values: the file-descriptors of the input-
     and output-ends of the pipe.


 -- procedure: open-input-pipe
          (open-input-pipe CMDLINE [MODE])
     Spawns a subprocess with the command-line string `CMDLINE' and
     returns a port, from which the output of the process can be read.
     If `MODE' is specified, it should be the keyword `#:text' (the
     default) or `#:binary'.


 -- procedure: open-output-pipe
          (open-output-pipe CMDLINE [MODE])
     Spawns a subprocess with the command-line string `CMDLINE' and
     returns a port. Anything written to that port is treated as the
     input for the process.  If `MODE' is specified, it should be the
     keyword `#:text' (the default) or `#:binary'.


 -- limit: pipe/buf
     This variable contains the maximal number of bytes that can be
     written atomically into a pipe or FIFO.


 -- procedure: with-input-from-pipe
 -- procedure: with-output-to-pipe
          (with-input-from-pipe CMDLINE THUNK [MODE])
          (with-output-to-pipe CMDLINE THUNK [MODE])
     Temporarily set the value of
     `current-input-port/current-output-port' to a port for a pipe
     connected to the subprocess named in `CMDLINE' and call the
     procedure `THUNK' with no arguments. After `THUNK' returns
     normally the pipe is closed and the standard input-/output port is
     restored to its previous value and any result values are returned.


     (with-output-to-pipe
       "gs -dNOPAUSE -sDEVICE=jpeg -dBATCH -sOutputFile=signballs.jpg -g600x600 -q -"
       (lambda ()
         (print #<<EOF
     %!IOPSC-1993 %%Creator: HAYAKAWA Takashi<xxxxxxxx@xx.xxxxxx.xx.xx>
     /C/neg/d/mul/R/rlineto/E/exp/H{{cvx def}repeat}def/T/dup/g/gt/r/roll/J/ifelse 8
     H/A/copy(z&v4QX&93r9AxYQOZomQalxS2w!!O&vMYa43d6r93rMYvx2dca!D&cjSnjSnjjS3o!v&6A
     X&55SAxM1CD7AjYxTTd62rmxCnTdSST0g&12wECST!&!J0g&D1!&xM0!J0g!l&544dC2Ac96ra!m&3A
     F&&vGoGSnCT0g&wDmlvGoS8wpn6wpS2wTCpS1Sd7ov7Uk7o4Qkdw!&Mvlx1S7oZES3w!J!J!Q&7185d
     Z&lx1CS9d9nE4!k&X&MY7!&1!J!x&jdnjdS3odS!N&mmx1C2wEc!G&150Nx4!n&2o!j&43r!U&0777d
     ]&2AY2A776ddT4oS3oSnMVC00VV0RRR45E42063rNz&v7UX&UOzF!F!J![&44ETCnVn!a&1CDN!Y&0M
     V1c&j2AYdjmMdjjd!o&1r!M){( )T 0 4 3 r put T(/)g{T(9)g{cvn}{cvi}J}{($)g[]J}J
     cvx}forall/moveto/p/floor/w/div/S/add 29 H[{[{]setgray fill}for Y}for showpage
     EOF
     ) ) )


File: chicken.info,  Node: Fifos,  Next: File descriptors and low-level I/O,  Prev: Pipes,  Up: Unit posix

5.18.3 Fifos
------------

 -- procedure: create-fifo
          (create-fifo FILENAME [MODE])
     Creates a FIFO with the name `FILENAME' and the permission bits
     `MODE', which defaults to


     (+ perm/irwxu perm/irwxg perm/irwxo)


 -- procedure: fifo?
          (fifo? FILENAME)
     Returns `#t' if the file with the name `FILENAME' names a FIFO.


File: chicken.info,  Node: File descriptors and low-level I/O,  Next: Retrieving file attributes,  Prev: Fifos,  Up: Unit posix

5.18.4 File descriptors and low-level I/O
-----------------------------------------

 -- procedure: duplicate-fileno
          (duplicate-fileno OLD [NEW])
     If `NEW' is given, then the file-descriptor `NEW' is opened to
     access the file with the file-descriptor `OLD'. Otherwise a fresh
     file-descriptor accessing the same file as `OLD' is returned.


 -- procedure: file-close
          (file-close FILENO)
     Closes the input/output file with the file-descriptor `FILENO'.


 -- procedure: file-open
          (file-open FILENAME FLAGS [MODE])
     Opens the file specified with the string `FILENAME' and open-flags
     `FLAGS' using the C function `open()'. On success a
     file-descriptor for the opened file is returned.  `FLAGS' should
     be a bitmask containing one or more of the `open/...' values ored
     together using `bitwise-ior' (or simply added together).  The
     optional `MODE' should be a bitmask composed of one or more
     permission values like `perm/irusr' and is only relevant when a
     new file is created. The default mode is `perm/irwxu | perm/irgrp
     | perm/iroth'.


 -- procedure: file-mkstemp
          (file-mkstemp TEMPLATE-FILENAME)
     Create a file based on the given `TEMPLATE-FILENAME', in which the
     six last characters must be "XXXXXX".  These will be replaced with
     a string that makes the filename unique.  The file descriptor of
     the created file and the generated filename is returned.  See the
     `mkstemp(3)' manual page for details on how this function works.
     The template string given is not modified.

     Example usage:
     (let-values (((fd temp-path) (file-mkstemp "/tmp/mytemporary.XXXXXX")))
       (let ((temp-port (open-output-file* fd)))
         (format temp-port "This file is ~A.~%" temp-path)
         (close-output-port temp-port)))


 -- procedure: file-read
          (file-read FILENO SIZE [BUFFER])
     Reads `SIZE' bytes from the file with the file-descriptor
     `FILENO'.  If a string or bytevector is passed in the optional
     argument `BUFFER', then this string will be destructively modified
     to contain the read data. This procedure returns a list with two
     values: the buffer containing the data and the number of bytes
     read.


 -- procedure: file-select
          (file-select READFDLIST WRITEFDLIST [TIMEOUT])
     Waits until any of the file-descriptors given in the lists
     `READFDLIST' and `WRITEFDLIST' is ready for input or output,
     respectively. If the optional argument `TIMEOUT' is given and not
     false, then it should specify the number of seconds after which
     the wait is to be aborted. This procedure returns two values: the
     lists of file-descriptors ready for input and output, respectively.
     `READFDLIST' and WRITEFDLIST may also by file-descriptors instead
     of lists.  In this case the returned values are booleans
     indicating whether input/output is ready by `#t' or `#f'
     otherwise.  You can also pass `#f' as `READFDLIST' or
     `WRITEFDLIST' argument, which is equivalent to `()'.


 -- procedure: file-write
          (file-write FILENO BUFFER [SIZE])
     Writes the contents of the string or bytevector `BUFFER' into the
     file with the file-descriptor `FILENO'. If the optional argument
     `SIZE' is given, then only the specified number of bytes are
     written.

 -- file descriptor: fileno/stdin
 -- file descriptor: fileno/stdout
 -- file descriptor: fileno/stderr
     These variables contain file-descriptors for the standard I/O
     files.

 -- flag: open/rdonly
 -- flag: open/wronly
 -- flag: open/rdwr
 -- flag: open/read
 -- flag: open/write
 -- flag: open/creat
 -- flag: open/append
 -- flag: open/excl
 -- flag: open/noctty
 -- flag: open/nonblock
 -- flag: open/trunc
 -- flag: open/sync
 -- flag: open/fsync
 -- flag: open/binary
 -- flag: open/text
     Flags for use with `file-open'.

 -- procedure: open-input-file*
 -- procedure: open-output-file*
          (open-input-file* FILENO [OPENMODE])
          (open-output-file* FILENO [OPENMODE])
     Opens file for the file-descriptor `FILENO' for input or output
     and returns a port.  `FILENO' should be a positive exact integer.
     `OPENMODE' specifies an additional mode for opening the file
     (currently only the keyword `#:append' is supported, which opens
     an output-file for appending).

 -- procedure: port->fileno
          (port->fileno PORT)
     If `PORT' is a file- or tcp-port, then a file-descriptor is
     returned for this port. Otherwise an error is signaled.


File: chicken.info,  Node: Retrieving file attributes,  Next: Changing file attributes,  Prev: File descriptors and low-level I/O,  Up: Unit posix

5.18.5 Retrieving file attributes
---------------------------------

 -- procedure: file-access-time
 -- procedure: file-change-time
 -- procedure: file-modification-time
          (file-access-time FILE)
          (file-change-time FILE)
          (file-modification-time FILE)
     Returns time (in seconds) of the last acces, modification or
     change of `FILE'. `FILE' may be a filename or a file-descriptor.
     If the file does not exist, an error is signaled.

 -- procedure: file-stat
          (file-stat FILE [LINK])
     Returns a 9-element vector with the following contents:
     inode-number, mode (as with `file-permissions'), number of hard
     links, uid of owner (as with `file-owner'), gid of owner, size (as
     with `file-size') and access-, change- and modification-time (as
     with `file-access-time', `file-change-time' and
     `file-modification-time').  If the optional argument `LINK' is
     given and not `#f', then the file-statistics vector will be
     resolved for symbolic links (otherwise symbolic links are
     resolved).


 -- procedure: file-position
          (file-position FILE)
     Returns the current file position of `FILE', which should be a
     port or a file-descriptor.


 -- procedure: file-size
          (file-size FILENAME)
     Returns the size of the file designated by `FILE'.  `FILE' may be
     a filename or a file-descriptor.  If the file does not exist, an
     error is signaled.

 -- procedure: regular-file?
          (regular-file? FILENAME)
     Returns true, if `FILENAME' names a regular file (not a directory
     or symbolic link).


File: chicken.info,  Node: Changing file attributes,  Next: Processes,  Prev: Retrieving file attributes,  Up: Unit posix

5.18.6 Changing file attributes
-------------------------------

 -- procedure: file-truncate
          (file-truncate FILE OFFSET)
     Truncates the file `FILE' to the length `OFFSET', which should be
     an integer. If the file-size is smaller or equal to `OFFSET' then
     nothing is done.  `FILE' should be a filename or a file-descriptor.


 -- procedure: set-file-position!
          (set-file-position! FILE POSITION [WHENCE])
     Sets the current read/write position of `FILE' to `POSITION',
     which should be an exact integer. `FILE' should be a port or a
     file-descriptor.  `WHENCE' specifies how the position is to
     interpreted and should be one of the values `seek/set, seek/cur'
     and `seek/end'. It defaults to `seek/set'.

     Exceptions: `(exn bounds)', `(exn i/o file)'


File: chicken.info,  Node: Processes,  Next: Hard and symbolic links,  Prev: Changing file attributes,  Up: Unit posix

5.18.7 Processes
----------------

 -- procedure: current-process-id
          (current-process-id)
     Returns the process ID of the current process.


 -- procedure: parent-process-id
          (parent-process-id)
     Returns the process ID of the parent of the current process.


 -- procedure: process-execute
          (process-execute PATHNAME [ARGUMENT-LIST [ENVIRONMENT-LIST]])
     Creates a new child process and replaces the running process with
     it using the C library function `execvp(3)'. If the optional
     argument `ARGUMENT-LIST' is given, then it should contain a list
     of strings which are passed as arguments to the subprocess. If the
     optional argument `ENVIRONMENT-LIST' is supplied, then the library
     function `execve(2)' is used, and the environment passed in
     `ENVIRONMENT-LIST' (which should be of the form `("<NAME>=<VALUE>"
     ...)' is given to the invoked process. Note that `execvp(3)'
     respects the current setting of the `PATH' environment variable
     while `execve(3)' does not.

     On native Windows, `process-execute' ignores the
     `ENVIRONMENT-LIST' arguments.


 -- procedure: process-fork
          (process-fork [THUNK])
     Creates a new child process with the UNIX system call `fork()'.
     Returns either the PID of the child process or 0. If `THUNK' is
     given, then the child process calls it as a procedure with no
     arguments and terminates.


 -- procedure: process-run
          (process-run PATHNAME [LIST])
     Creates a new child process using the UNIX system call `fork()'
     that executes the program given by the string `PATHNAME' using the
     UNIX system call `execv()'.  The PID of the new process is
     returned. If `LIST' is not specified, then `PATHNAME' is passed to
     a program named by the environment variable `SHELL' (or `/bin/sh',
     if the variable is not defined), so usual argument expansion can
     take place.


 -- procedure: process-signal
          (process-signal PID [SIGNAL])
     Sends `SIGNAL' to the process with the id `PID' using the UNIX
     system call `kill()'. `SIGNAL' defaults to the value of the
     variable `signal/term'.


 -- procedure: process-wait
          (process-wait [PID [NOHANG]])
     Suspends the current process until the child process with the id
     `PID' has terminated using the UNIX system call `waitpid()'. If
     `PID' is not given, then this procedure waits for any child
     process. If `NOHANG' is given and not `#f' then the current
     process is not suspended.  This procedure returns three values:

   * `PID' or 0, if `NOHANG' is true and the child process has not
     terminated yet;

   * `#t' if the process exited normally or `#f' otherwise;

   * either the exit status, if the process terminated normally or the
     signal number that terminated/stopped the process.

 -- procedure: process
          (process COMMANDLINE [ARGUMENTLIST [ENVIRONMENT]])
     Passes the string `COMMANDLINE' to the host-system's shell that is
     invoked as a subprocess and returns three values: an input port
     from which data written by the sub-process can be read, an output
     port from which any data written to will be received as input in
     the sub-process and the process-id of the started sub-process.
     Blocking reads and writes to or from the ports returned by
     `process' only block the current thread, not other threads
     executing concurrently.

     If `ARGUMENTLIST' is given, then the invocation of the subprocess
     is not done via the shell, but directly. The arguments are directly
     passed to `process-execute' (as is `ENVIRONMENT').  Not using the
     shell may be preferrable for security reasons.

     On native Windows the `ARGUMENTLIST' and `ENVIRONMENT' arguments
     are ignored.


 -- procedure: sleep
          (sleep SECONDS)
     Puts the process to sleep for `SECONDS'. Returns either 0 if the
     time has completely elapsed, or the number of remaining seconds,
     if a signal occurred.


File: chicken.info,  Node: Hard and symbolic links,  Next: Permissions,  Prev: Processes,  Up: Unit posix

5.18.8 Hard and symbolic links
------------------------------

 -- procedure: symbolic-link?
          (symbolic-link? FILENAME)
     Returns true, if `FILENAME' names a symbolic link.

 -- procedure: create-symbolic-link
          (create-symbolic-link OLDNAME NEWNAME)
     Creates a symbolic link with the filename `NEWNAME' that points to
     the file named `OLDNAME'.


 -- procedure: read-symbolic-link
          (read-symbolic-link FILENAME)
     Returns the filename to which the symbolic link `FILENAME' points.

 -- procedure: file-link
          (file-link OLDNAME NEWNAME)
     Creates a hard link from `OLDNAME' to `NEWNAME' (both strings).


File: chicken.info,  Node: Permissions,  Next: Record locking,  Prev: Hard and symbolic links,  Up: Unit posix

5.18.9 Permissions, owners, users and groups
--------------------------------------------

 -- procedure: file-owner
          (file-owner FILE)
     Returns the user-id of `FILE'.  `FILE' may be a filename or a
     file-descriptor.


 -- procedure: file-permissions
          (file-permissions FILE)
     Returns the permission bits for `FILE'. You can test this value by
     performing bitwise operations on the result and the `perm/...'
     values.  `FILE' may be a filename or a file-descriptor.


 -- procedure: file-read-access?
 -- procedure: file-write-access?
 -- procedure: file-execute-access?
          (file-read-access? FILENAME)
          (file-write-access? FILENAME)
          (file-execute-access? FILENAME)
     These procedures return `#t' if the current user has read, write
     or execute permissions on the file named `FILENAME'.


 -- procedure: change-file-mode
          (change-file-mode FILENAME MODE)
     Changes the current file mode of the file named `FILENAME' to
     `MODE' using the `chmod()' system call.  The `perm/...' variables
     contain the various permission bits and can be combinded with the
     `bitwise-ior' procedure.


 -- procedure: change-file-owner
          (change-file-owner FILENAME UID GID)
     Changes the owner information of the file named `FILENAME' to the
     user- and group-ids `UID' and `GID' (which should be exact
     integers) using the `chown()' system call.


 -- procedure: current-user-id
 -- procedure: current-group-id
 -- procedure: current-effective-user-id
 -- procedure: current-effective-group-id
          (current-user-id)
          (current-group-id)
          (current-effective-user-id)
          (current-effective-group-id)
     Return the user- and group-ids of the current process.

      -- procedure: process-group-id
               (process-group-id PID)
          Returns the process group ID of the process specified by
          `PID'.


 -- procedure: group-information
          (group-information GROUP)
     If `GROUP' specifies a valid group-name or group-id, then this
     procedure returns a list of four values: the group-name, the
     encrypted group password, the group ID and a list of the names of
     all group members. If no group with the given name or ID exists,
     then `#f' is returned.

 -- procedure: get-groups
          (get-groups)
     Returns a list with the supplementary group IDs of the current
     user.

 -- procedure: set-groups!
          (set-groups! GIDLIST)
     Sets the supplementrary group IDs of the current user to the IDs
     given in the list `GIDLIST'.

     Only the superuser may invoke this procedure.

 -- procedure: initialize-groups
          (initialize-groups USERNAME BASEGID)
     Sets the supplementrary group IDs of the current user to the IDs
     from the user with name `USERNAME' (a string), including `BASEGID'.

     Only the superuser may invoke this procedure.

 -- permission bits: perm/irusr
 -- permission bits: perm/iwusr
 -- permission bits: perm/ixusr
 -- permission bits: perm/irgrp
 -- permission bits: perm/iwgrp
 -- permission bits: perm/ixgrp
 -- permission bits: perm/iroth
 -- permission bits: perm/iwoth
 -- permission bits: perm/ixoth
 -- permission bits: perm/irwxu
 -- permission bits: perm/irwxg
 -- permission bits: perm/irwxo
 -- permission bits: perm/isvtx
 -- permission bits: perm/isuid
 -- permission bits: perm/isgid
     These variables contain permission bits as used in
     `change-file-mode'.

 -- procedure: set-user-id!
          (set-user-id! UID)
     Sets the effective user id of the current process to `UID', which
     should be a positive integer.

 -- procedure: set-group-id!
          (set-group-id! GID)
     Sets the effective group id of the current process to `GID', which
     should be a positive integer.

 -- procedure: set-process-group-id!
          (set-user-id! PID PGID)
     Sets the process group ID of the process specifed by `PID' to
     `PGID'.

 -- procedure: user-information
          (user-information USER)
     If `USER' specifes a valid username (as a string) or user ID, then
     the user database is consulted and a list of 7 values are
     returned: the user-name, the encrypted password, the user ID, the
     group ID, a user-specific string, the home directory and the
     default shell. If no user with this name or ID can be found, then
     `#f' is returned.

 -- procedure: create-session
          (create-session)
     Creates a new session if the calling process is not a process
     group leader and returns the session ID.


File: chicken.info,  Node: Record locking,  Next: Signal handling,  Prev: Permissions,  Up: Unit posix

5.18.10 Record locking
----------------------

 -- procedure: file-lock
          (file-lock PORT [START [LEN]])
     Locks the file associated with `PORT' for reading or writing
     (according to whether `PORT' is an input- or output-port). `START'
     specifies the starting position in the file to be locked and
     defaults to 0. `LEN' specifies the length of the portion to be
     locked and defaults to `#t', which means the complete file.
     `file-lock' returns a "lock"-object.


 -- procedure: file-lock/blocking
          (file-lock/blocking PORT [START [LEN]])
     Similar to `file-lock', but if a lock is held on the file, the
     current process blocks (including all threads) until the lock is
     released.


 -- procedure: file-test-lock
          (file-test-lock PORT [START [LEN]])
     Tests whether the file associated with `PORT' is locked for reading
     or writing (according to whether `PORT' is an input- or
     output-port) and returns either `#f' or the process-id of the
     locking process.


 -- procedure: file-unlock
          (file-unlock LOCK)
     Unlocks the previously locked portion of a file given in `LOCK'.


File: chicken.info,  Node: Signal handling,  Next: Environment access,  Prev: Record locking,  Up: Unit posix

5.18.11 Signal handling
-----------------------

 -- procedure: set-alarm!
          (set-alarm! SECONDS)
     Sets an internal timer to raise the `signal/alrm' after `SECONDS'
     are elapsed.  You can use the `set-signal-handler!' procedure to
     write a handler for this signal.


 -- procedure: set-signal-handler!
          (set-signal-handler! SIGNUM PROC)
     Establishes the procedure of one argument `PROC' as the handler
     for the signal with the code `SIGNAL'. `PROC' is called with the
     signal number as its sole argument. If the argument `PROC' is `#f'
     then this signal will be ignored. Note that is is unspecified in
     which thread of execution the signal handler will be invoked.


 -- procedure: set-signal-mask!
          (set-signal-mask! SIGLIST)
     Sets the signal mask of the current process to block all signals
     given in the list `SIGLIST'.  Signals masked in that way will not
     be delivered to the current process.

 -- signal code: signal/term
 -- signal code: signal/kill
 -- signal code: signal/int
 -- signal code: signal/hup
 -- signal code: signal/fpe
 -- signal code: signal/ill
 -- signal code: signal/segv
 -- signal code: signal/abrt
 -- signal code: signal/trap
 -- signal code: signal/quit
 -- signal code: signal/alrm
 -- signal code: signal/vtalrm
 -- signal code: signal/prof
 -- signal code: signal/io
 -- signal code: signal/urg
 -- signal code: signal/chld
 -- signal code: signal/cont
 -- signal code: signal/stop
 -- signal code: signal/tstp
 -- signal code: signal/pipe
 -- signal code: signal/xcpu
 -- signal code: signal/xfsz
 -- signal code: signal/usr1
 -- signal code: signal/usr2
 -- signal code: signal/winch
     These variables contain signal codes for use with `process-signal'
     or `set-signal-handler!'.


File: chicken.info,  Node: Environment access,  Next: Memory mapped I/O,  Prev: Signal handling,  Up: Unit posix

5.18.12 Environment access
--------------------------

 -- procedure: current-environment
          (current-environment)
     Returns a association list of the environment variables and their
     current values.


 -- procedure: setenv
          (setenv VARIABLE VALUE)
     Sets the environment variable named `VARIABLE' to `VALUE'. Both
     arguments should be strings. If the variable is not defined in the
     environment, a new definition is created.


 -- procedure: unsetenv
          (unsetenv VARIABLE)
     Removes the definition of the environment variable `VARIABLE' from
     the environment of the current process. If the variable is not
     defined, nothing happens.


File: chicken.info,  Node: Memory mapped I/O,  Next: Date and time routines,  Prev: Environment access,  Up: Unit posix

5.18.13 Memory mapped I/O
-------------------------

 -- pocedure: memory-mapped-file?
          (memory-mapped-file? X)
     Returns `#t', if `X' is an object representing a memory mapped
     file, or `#f' otherwise.

 -- procedure: map-file-to-memory
          (map-file-to-memory ADDRESS LEN PROTECTION FLAG FILENO [OFFSET])
     Maps a section of a file to memory using the C function `mmap()'.
     `ADDRESS' should be a foreign pointer object or `#f'; `LEN'
     specifies the size of the section to be mapped; `PROTECTION'
     should be one or more of the flags `prot/read, prot/write,
     prot/exec' or `prot/none' bitwise-iored together; `FLAG' should be
     one or more of the flags `map/fixed, map/shared, map/private,
     map/anonymous' or `map/file'; `FILENO' should be the
     file-descriptor of the mapped file. The optional argument `OFFSET'
     gives the offset of the section of the file to be mapped and
     defaults to 0. This procedure returns an object representing the
     mapped file section.  The procedure `move-memory!' can be used to
     access the mapped memory.


 -- procedure: memory-mapped-file-pointer
          (memory-mapped-file-pointer MMAP)
     Returns a machine pointer to the start of the memory region to
     which the file is mapped.


 -- procedure: unmap-file-from-memory
          (unmap-file-from-memory MMAP [LEN])
     Unmaps the section of a file mapped to memory using the C function
     `munmap()'.  `MMAP' should be a mapped file as returned by the
     procedure `map-file-to-memory'.  The optional argument `LEN'
     specifies the length of the section to be unmapped and defaults to
     the complete length given when the file was mapped.


File: chicken.info,  Node: Date and time routines,  Next: Raw exit,  Prev: Memory mapped I/O,  Up: Unit posix

5.18.14 Date and time routines
------------------------------

 -- procedure: seconds->local-time
          (seconds->local-time SECONDS)
     Breaks down the time value represented in `SECONDS' into a 10
     element vector of the form `#(seconds minutes hours mday month
     year wday yday dstflag timezone)', in the following format:

        * seconds: the number of seconds after the minute (0 - 59)

        * minutes: the number of minutes after the hour (0 - 59)

        * hours: the number of hours past midnight (0 - 23)

        * mday: the day of the month (1 - 31)

        * month: the number of months since january (0 - 11)

        * year: the number of years since 1900

        * wday: the number of days since Sunday (0 - 6)

        * yday: the number of days since January 1 (0 - 365)

        * dstflag: a flag that is true if Daylight Saving Time is in
          effect at the time described.

        * timezone: the difference between UTC and the latest local
          standard time, in seconds west of UTC.


 -- procedure: local-time->seconds
          (local-time->seconds VECTOR)
     Converts the ten-element vector `VECTOR' representing the time
     value relative to the current timezone into the number of seconds
     since the first of January, 1970 UTC.

 -- procedure: local-timezone-abbreviation
          (local-timezone-abbrevtiation)
     Returns the abbreviation for the local timezone as a string.

 -- procedure: seconds->string
          (seconds->string SECONDS)
     Converts the local time represented in `SECONDS' into a string of
     the form `"Tue May 21 13:46:22 1991\n"'.


 -- procedure: seconds->utc-time
          (seconds->utc-time SECONDS)
     Similar to `seconds->local-time', but interpretes `SECONDS' as UTC
     time.


 -- procedure: utc-time->seconds
          (utc-time->seconds VECTOR)
     Converts the ten-element vector `VECTOR' representing the UTC time
     value into the number of seconds since the first of January, 1970
     UTC.

 -- procedure: time->string
          (time->string VECTOR)
     Converts the broken down time represented in the 10 element vector
     `VECTOR' into a string of the form `"Tue May 21 13:46:22 1991\n"'.


File: chicken.info,  Node: Raw exit,  Next: ERRNO values,  Prev: Date and time routines,  Up: Unit posix

5.18.15 _Raw_ exit
------------------

 -- procedure: _exit
          (_exit [CODE])
     Exits the current process without flushing any buffered output
     (using the C function `_exit').  Note that the `exit-handler' is
     not called when this procedure is invoked. The optional return-code
     `CODE' defaults to `0'.


File: chicken.info,  Node: ERRNO values,  Next: Finding files,  Prev: Raw exit,  Up: Unit posix

5.18.16 ERRNO values
--------------------

 -- error code: errno/perm
 -- error code: errno/noent
 -- error code: errno/srch
 -- error code: errno/intr
 -- error code: errno/io
 -- error code: errno/noexec
 -- error code: errno/badf
 -- error code: errno/child
 -- error code: errno/nomem
 -- error code: errno/acces
 -- error code: errno/fault
 -- error code: errno/busy
 -- error code: errno/notdir
 -- error code: errno/isdir
 -- error code: errno/inval
 -- error code: errno/mfile
 -- error code: errno/nospc
 -- error code: errno/spipe
 -- error code: errno/pipe
 -- error code: errno/again
 -- error code: errno/rofs
 -- error code: errno/exist
 -- error code: errno/wouldblock
     These variables contain error codes as returned by `errno'.


File: chicken.info,  Node: Finding files,  Next: Getting the hostname and system information,  Prev: ERRNO values,  Up: Unit posix

5.18.17 Finding files
---------------------

 -- procedure: find-files
          (find-files DIRECTORY PREDICATE [ACTION [IDENTITY [LIMIT]]])
     Recursively traverses the contents of `DIRECTORY' (which should be
     a string) and invokes the procedure `ACTION' for all files for
     which the procedure `PREDICATE' is true.  `PREDICATE' may me a
     procedure of one argument or a regular-expression string.
     `ACTION' should be a procedure of two arguments: the currently
     encountered file and the result of the previous invocation of
     `ACTION', or, if this is the first invocation, the value of
     `IDENTITY'. `ACTION' defaults to `cons', `IDENTITY' defaults to
     `()'.  `LIMIT' should a procedure of one argument that is called
     for each nested directory and which should return true, if that
     directory is to be traversed recursively. `LIMIT' may also be an
     exact integer that gives the maximum recursion depth. A depth of
     `0' means the files in the specified directory are traversed but
     not any nested directories. `LIMIT' may also be `#f' (the default),
     which is equivalent to `(constantly #t)'.

     Note that `ACTION' is called with the full pathname of each file,
     including the directory prefix.


File: chicken.info,  Node: Getting the hostname and system information,  Next: Setting the file buffering mode,  Prev: Finding files,  Up: Unit posix

5.18.18 Getting the hostname and system information
---------------------------------------------------

 -- procedure: get-host-name
          (get-host-name)
     Returns the hostname of the machine that this process is running
     on.


 -- procedure: system-information
          (system-information)
     Invokes the UNIX system call `uname()' and returns a list of 5
     values: system-name, node-name, OS release, OS version and machine.


File: chicken.info,  Node: Setting the file buffering mode,  Next: Terminal ports,  Prev: Getting the hostname and system information,  Up: Unit posix

5.18.19 Setting the file buffering mode
---------------------------------------

 -- procedure: set-buffering-mode!
          (set-buffering-mode! PORT MODE [BUFSIZE])
     Sets the buffering-mode for the file associated with `PORT' to
     `MODE', which should be one of the keywords `#:full, #:line' or
     `#:none'. If `BUFSIZE' is specified it determines the size of the
     buffer to be used (if any).


File: chicken.info,  Node: Terminal ports,  Next: How Scheme procedures relate to UNIX C functions,  Prev: Setting the file buffering mode,  Up: Unit posix

5.18.20 Terminal ports
----------------------

 -- procedure: terminal-name
          (terminal-name PORT)
     Returns the name of the terminal that is connected to `PORT'.


 -- procedure: terminal-port?
          (terminal-port? PORT)
     Returns `#t' if `PORT' is connected to a terminal and `#f'
     otherwise.


File: chicken.info,  Node: How Scheme procedures relate to UNIX C functions,  Next: Windows specific notes,  Prev: Terminal ports,  Up: Unit posix

5.18.21 How Scheme procedures relate to UNIX C functions
--------------------------------------------------------

`change-directory'
     chdir

`change-file-mode'
     chmod

`change-file-owner'
     chown

`create-directory'
     mkdir

`create-fifo'
     mkfifo

`create-pipe'
     pipe

`create-session'
     setsid

`create-symbolic-link'
     link

`current-directory'
     curdir

`current-effective-groupd-id'
     getegid

`current-effective-user-id'
     geteuid

`current-group-id'
     getgid

`current-parent-id'
     getppid

`current-process-id'
     getpid

`current-user-id'
     getuid

`delete-directory'
     rmdir

`duplicate-fileno'
     dup/dup2

`_exit'
     _exit

`file-close'
     close

`file-access-time'
     stat

`file-change-time'
     stat

`file-modification-time'
     stat

`file-execute-access?'
     access

`file-open'
     open

`file-lock'
     fcntl

`file-position'
     ftell/lseek

`file-read'
     read

`file-read-access?'
     access

`file-select'
     select

`file-stat'
     stat

`file-test-lock'
     fcntl

`file-truncate'
     truncate/ftruncate

`file-unlock'
     fcntl

`file-write'
     write

`file-write-access?'
     access

`get-groups'
     getgroups

`get-host-name'
     gethostname

`initialize-groups'
     initgroups

`local-time->seconds'
     mktime

`local-timezone-abbreviation'
     localtime

`map-file-to-memory'
     mmap

`open-input-file*'
     fdopen

`open-output-file*'
     fdopen

`open-input-pipe'
     popen

`open-output-pipe'
     popen

`port->fileno'
     fileno

`process-execute'
     execvp

`process-fork'
     fork

`process-group-id'
     getpgid

`process-signal'
     kill

`process-wait'
     waitpid

`close-input-pipe'
     pclose

`close-output-pipe'
     pclose

`read-symbolic-link'
     readlink

`seconds->local-time'
     localtime

`seconds->string'
     ctime

`seconds->utc-time'
     gmtime

`set-alarm!'
     alarm

`set-buffering-mode!'
     setvbuf

`set-file-position!'
     fseek/seek

`set-groups!'
     setgroups

`set-signal-mask!'
     sigprocmask

`set-group-id!'
     setgid

`set-process-group-id!'
     setpgid

`set-user-id!'
     setuid

`set-root-directory!'
     chroot

`setenv'
     setenv/putenv

`sleep'
     sleep

`system-information'
     uname

`terminal-name'
     ttyname

`terminal-port?'
     isatty

`time->string'
     asctime

`unsetenv'
     putenv

`unmap-file-from-memory'
     munmap

`user-information'
     getpwnam/getpwuid

`utc-time->seconds'
     timegm


File: chicken.info,  Node: Windows specific notes,  Prev: How Scheme procedures relate to UNIX C functions,  Up: Unit posix

5.18.22 Windows specific notes
------------------------------

The following definitions are not supported for native Windows builds
(compiled with the Microsoft tools or with MingW):


open/noctty  open/nonblock  open/fsync  open/sync
perm/isvtx  perm/isuid  perm/isgid
file-select
signal/...
set-signal-handler!  set-signal-mask!
user-information  group-information  get-groups  set-groups!  initialize-groups
errno/wouldblock
change-file-owner
current-user-id  current-group-id  current-effective-user-id  current-effective-groupd-id
set-user-id!  set-group-id!
create-session
process-group-id  set-process-group-id!
create-symbolic-link  read-symbolic-link
file-truncate
file-lock  file-lock/blocking  file-unlock  file-test-lock
create-fifo  fifo?
prot/...
map/...
map-file-to-memory  unmap-file-from-memory  memory-mapped-file-pointer  memory-mapped-file?
set-alarm!
terminal-port?  terminal-name
process-fork  process-signal
parent-process-id
set-root-directory!
utc-time->seconds local-timezone-abbreviation

   Additionally, the following definitions are only available for
Windows:

 -- spawn mode: spawn/overlay
 -- spawn mode: spawn/wait
 -- spawn mode: spawn/nowait
 -- spawn mode: spawn/nowaito
 -- spawn mode: spawn/detach
     These variables contains special flags that specify the exact
     semantics of `process-spawn': `spawn/overlay' replaces the current
     process with the new one.  `spawn/wait' suspends execution of the
     current process until the spawned process returns.  `spawn/nowait'
     does the opposite (`spawn/nowaito' is identical, according to the
     Microsoft documentation) and runs the process asynchronously.
     `spawn/detach' runs the new process in the background, without
     being attached to a console.

 -- procedure: process-spawn
          (process-spawn MODE FILENAME ARGUMENT ...)
     Creates and runs a new process with the given filename and
     command-line arguments. `MODE' specifies how exactly the process
     should be executed and must be one or more of the `spawn/...'
     flags defined above.


File: chicken.info,  Node: Unit utils,  Next: Unit tcp,  Prev: Unit posix,  Up: Supported language

5.19 Unit utils
===============

This unit contains some utility procedures for Shell scripting and for
some file operations.

   This unit uses the `extras' and `regex' units.

* Menu:

* Pathname operations::
* Temporary files::
* Deleting a file without signalling an error::
* Iterating over input lines and files::
* Executing shell commands with formatstring and error checking::
* Reading a file's contents::
* Miscellaneous handy things::


File: chicken.info,  Node: Pathname operations,  Next: Temporary files,  Up: Unit utils

5.19.1 Pathname operations
--------------------------

 -- procedure: absolute-pathname?
          (absolute-pathname? PATHNAME)
     Returns `#t' if the string `PATHNAME' names an absolute pathname,
     and returns `#f' otherwise.


 -- procedure: decompose-pathname
          (decompose-pathname PATHNAME)
     Returns three values: the directory-, filename- and
     extension-components of the file named by the string `PATHNAME'.
     For any component that is not contained in `PATHNAME', `#f' is
     returned.


 -- procedure: make-pathname
 -- procedure: make-absolute-pathname
          (make-pathname DIRECTORY FILENAME [EXTENSION])
          (make-absolute-pathname DIRECTORY FILENAME [EXTENSION])
     Returns a string that names the file with the components
     `DIRECTORY, FILENAME' and (optionally) `EXTENSION'. `DIRECTORY'
     can be `#f' (meaning no directory component), a string or a list
     of strings. `FILENAME' and `EXTENSION' should be strings or `#f'.
     `make-absolute-pathname' returns always an absolute pathname.

 -- procedure: pathname-directory
          (pathname-directory PATHNAME)

 -- procedure: pathname-file
          (pathname-file PATHNAME)

 -- procedure: pathname-extension
          (pathname-extension PATHNAME)
     Accessors for the components of `PATHNAME'. If the pathname does
     not contain the accessed component, then `#f' is returned.


 -- procedure: pathname-replace-directory
          (pathname-replace-directory PATHNAME DIRECTORY)

 -- procedure: pathname-replace-file
          (pathname-replace-file PATHNAME FILENAME)

 -- procedure: pathname-replace-extension
          (pathname-replace-extension PATHNAME EXTENSION)
     Return a new pathname with the specified component of `PATHNAME'
     replaced by a new value.


 -- procedure: pathname-strip-directory
          (pathname-strip-directory PATHNAME)

 -- procedure: pathname-strip-extension
          (pathname-strip-extension PATHNAME)
     Return a new pathname with the specified component of `PATHNAME'
     stripped.


File: chicken.info,  Node: Temporary files,  Next: Deleting a file without signalling an error,  Prev: Pathname operations,  Up: Unit utils

5.19.2 Temporary files
----------------------

 -- procedure: create-temporary-file
          (create-temporary-file [EXTENSION])
     Creates an empty temporary file and returns its pathname. If
     `EXTENSION' is not given, then `.tmp' is used. If the environment
     variable `TMPDIR, TEMP' or `TMP' is set, then the pathname names a
     file in that directory.   


File: chicken.info,  Node: Deleting a file without signalling an error,  Next: Iterating over input lines and files,  Prev: Temporary files,  Up: Unit utils

5.19.3 Deleting a file without signalling an error
--------------------------------------------------

 -- procedure: delete-file*
          (delete-file* FILENAME)
     If the file `FILENAME' exists, it is deleted and `#t' is returned.
     If the file does not exist, nothing happens and `#f' is returned.


File: chicken.info,  Node: Iterating over input lines and files,  Next: Executing shell commands with formatstring and error checking,  Prev: Deleting a file without signalling an error,  Up: Unit utils

5.19.4 Iterating over input lines and files
-------------------------------------------

 -- procedure: for-each-line
          (for-each-line PROCEDURE [PORT])
     Calls `PROCEDURE' for each line read from `PORT' (which defaults
     to the value of `(current-input-port)'. The argument passed to
     `PORCEDURE' is a string with the contents of the line, excluding
     any line-terminators.  When all input has been read from the port,
     `for-each-line' returns some unspecified value.


 -- procedure: for-each-argv-line
          (for-each-argv-line PROCEDURE)
      Opens each file listed on the command line in order, passing one
     line at a time into `PROCEDURE'.  The filename `-' is interpreted
     as `(current-input-port)'.  If no arguments are given on the
     command line it again uses the value of `(current-input-port)'.
     During execution of `PROCEDURE', the current input port will be
     correctly bound to the current input source.

     This code will act as a simple Unix cat(1) command:


     (for-each-argv-line print)

 -- procedure: port-for-each
 -- procedure: port-map
          (port-for-each FN THUNK)
          (port-map FN THUNK)
     Apply `FN' to successive results of calling the zero argument
     procedure `THUNK' until it returns `#!eof'. `port-for-each'
     discards the results, while `port-map' returns a list of the
     collected results.


File: chicken.info,  Node: Executing shell commands with formatstring and error checking,  Next: Reading a file's contents,  Prev: Iterating over input lines and files,  Up: Unit utils

5.19.5 Executing shell commands with formatstring and error checking
--------------------------------------------------------------------

 -- procedure: system*
          (system* FORMATSTRING ARGUMENT1 ...)
     Similar to `(system (sprintf FORMATSTRING ARGUMENT1 ...))', but
     signals an error if the invoked program should return a nonzero
     exit status.


File: chicken.info,  Node: Reading a file's contents,  Next: Miscellaneous handy things,  Prev: Executing shell commands with formatstring and error checking,  Up: Unit utils

5.19.6 Reading a file's contents
--------------------------------

 -- procedure: read-all
          (read-all [FILE-OR-PORT])
     If `FILE-OR-PORT' is a string, then this procedure returns the
     contents of the file as a string. If `FILE-OR-PORT' is a port, all
     remaining input is read and returned as a string. The port is not
     closed. If no argument is provided, input will be read from the
     port that is the current value of `(current-input-port)'.


File: chicken.info,  Node: Miscellaneous handy things,  Prev: Reading a file's contents,  Up: Unit utils

5.19.7 Miscellaneous handy things
---------------------------------

 -- procedure: shift!
          (shift! LIST [DEFAULT])
     Returns the car of `LIST' (or `DEFAULT' if `LIST' is empty) and
     replaces the car of `LIST' with it's cadr and the cdr with the
     cddr. If `DEFAULT' is not given, and the list is empty, `#f' is
     returned. An example might be clearer, here:

          (define lst '(1 2 3))
          (shift! lst)             ==> 1, lst is now (2 3)

     The list must at least contain 2 elements.

 -- procedure: unshift!
          (unshift! X PAIR)
     Sets the car of `PAIR' to `X' and the cdr to its cddr. Returns
     `PAIR':

          (define lst '(2))
          (unshift! 99 lst)      ; lst is now (99 2)


File: chicken.info,  Node: Unit tcp,  Next: Unit lolevel,  Prev: Unit utils,  Up: Supported language

5.20 Unit tcp
=============

This unit provides basic facilities for communicating over TCP sockets.
The socket interface should be mostly compatible to the one found in
PLT Scheme.

   This unit uses the `extras' unit.

   All errors related to failing network operations will raise a
condition of kind `(exn i/o network)'.

 -- procedure: tcp-listen
          (tcp-listen TCPPORT [BACKLOG [HOST]])
     Creates and returns a TCP listener object that listens for
     connections on `TCPPORT', which should be an exact integer.
     `BACKLOG' specifies the number of maximally pending connections
     (and defaults to 4). If the optional argument `HOST' is given and
     not `#f', then only incoming connections for the given host (or
     IP) are accepted.


 -- procedure: tcp-listener?
          (tcp-listener? X)
     Returns `#t' if `X' is a TCP listener object, or `#f' otherwise.


 -- procedure: tcp-close
          (tcp-close LISTENER)
     Reclaims any resources associated with `LISTENER'.


 -- procedure: tcp-accept
          (tcp-accept LISTENER)
     Waits until a connection is established on the port on which
     `LISTENER' is listening and returns two values: an input- and
     output-port that can be used to communicate with the remote
     process.

     Note: this operation and any I/O on the ports returned will not
     block other running threads.


 -- procedure: tcp-accept-ready?
          (tcp-accept-ready? LISTENER)
     Returns `#t' if there are any connections pending on `LISTENER',
     or `#f' otherwise.


 -- procedure: tcp-listener-port
          (tcp-listener-port LISTENER)
     Returns the port number assigned to `LISTENER' (If you pass `0' to
     `tcp-listen', then the system will choose a port-number for you).


 -- procedure: tcp-listener-fileno
          (tcp-listener-port LISTENER)
     Returns the file-descriptor associated with `LISTENER'.


 -- procedure: tcp-connect
          (tcp-connect HOSTNAME [TCPPORT])
     Establishes a client-side TCP connection to the machine with the
     name `HOSTNAME' (a string) at `TCPPORT' (an exact integer) and
     returns two values: an input- and output-port for communicating
     with the remote process.

     Note: any I/O on the ports returned will not block other running
     threads.


 -- procedure: tcp-addresses
          (tcp-addresses PORT)
     Returns two values for the input- or output-port `PORT' (which
     should be a port returned by either `tcp-accept' or
     `tcp-connect'): the IP address of the local and the remote machine
     that are connected over the socket associated with `PORT'. The
     returned addresses are strings in `XXX.XXX.XXX.XXX' notation.


 -- procedure: tcp-port-numbers
          (tcp-port-numbers PORT)
     Returns two values for the input- or output-port `PORT' (which
     should be a port returned by either `tcp-accept' or
     `tcp-connect'): the TCP port numbers of the local and the remote
     machine that are connected over the socket associated with `PORT'.


 -- procedure: tcp-abandon-port
          (tcp-abandon-port PORT)
     Marks the socket port `PORT' as abandoned. This is mainly useful
     to close down a port without breaking the connection.

 -- parameter: tcp-buffer-size
     Sets the size of the output buffer. By default no output-buffering
     for TCP output is done, but to improve performance by minimizing
     the number of TCP packets, buffering may be turned on by setting
     this parameter to an exact integer greater zero. A buffer size of
     zero or `#f' turns buffering off. The setting of this parameter
     takes effect at the time when the I/O ports for a particular
     socket are created, i.e. when `tcp-connect' or `tcp-accept' is
     called.

     Note that since output is not immediately written to the
     associated socket, you may need to call `flush-output', once you
     want the output to be transmitted.  Closing the output port will
     flush automatically.

   A very simple example follows. Say we have the two files `client.scm'
and `server.scm':


; client.scm
(define-values (i o) (tcp-connect "localhost" 4242))
(write-line "Good Bye!" o)
(print (read-line i))


; server.scm
(define l (tcp-listen 4242))
(define-values (i o) (tcp-accept l))
(write-line "Hello!" o)
(print (read-line i))
(close-input-port i)
(close-output-port o)

% csi -script server.scm &
[1] 1409
% csi -script client.scm
Good Bye!
Hello!


File: chicken.info,  Node: Unit lolevel,  Next: Unit tinyclos,  Prev: Unit tcp,  Up: Supported language

5.21 Unit lolevel
=================

This unit provides a number of handy low-level operations. Use at your
own risk.

   This unit uses the `srfi-4' and `extras' units.

* Menu:

* Foreign pointers::
* Tagged pointers::
* Extending procedures with data::
* Bytevectors::
* Data in unmanaged memory::
* Locatives::
* Accessing toplevel variables::
* Low-level data access::
* Procedure-call- and variable reference hooks::
* Magic::


File: chicken.info,  Node: Foreign pointers,  Next: Tagged pointers,  Up: Unit lolevel

5.21.1 Foreign pointers
-----------------------

 -- procedure: address->pointer
          (address->pointer ADDRESS)
     Creates a new foreign pointer object initialized to point to the
     address given in the integer `ADDRESS'.


 -- procedure: allocate
          (allocate BYTES)
     Returns a pointer to a freshly allocated region of static memory.
     This procedure could be defined as follows:


     (define allocate (foreign-lambda c-pointer "malloc" integer))


 -- procedure: free
          (free POINTER)
     Frees the memory pointed to by `POINTER'.  This procedure could be
     defined as follows:


     (define free (foreign-lambda c-pointer "free" integer))


 -- procedure: null-pointer
          (null-pointer)
     Another way to say `(address->pointer 0)'.


 -- procedure: null-pointer?
          (null-pointer? PTR)
     Returns `#t' if `PTR' contains a `NULL' pointer, or `#f' otherwise.


 -- procedure: object->pointer
          (object->pointer X)
     Returns a pointer pointing to the Scheme object X, which should be
     a non-immediate object.  Note that data in the garbage collected
     heap moves during garbage collection.


 -- procedure: pointer?
          (pointer? X)
     Returns `#t' if `X' is a foreign pointer object, and `#f'
     otherwise.

      -- procedure: pointer=?
               (pointer=? PTR1 PTR2)
          Returns `#t' if the pointer-like objects `PTR1' and `PTR2'
          point to the same address.


 -- procedure: pointer->address
          (pointer->address PTR)
     Returns the address, to which the pointer `PTR' points.


 -- procedure: pointer->object
          (pointer->object PTR)
     Returns the Scheme object pointed to by the pointer `PTR'.


 -- procedure: pointer-offset
          (pointer-offset PTR N)
     Returns a new pointer representing the pointer `PTR' increased by
     `N'.


 -- procedure: pointer-u8-ref
          (pointer-u8-ref PTR)
     Returns the unsigned byte at the address designated by `PTR'.


 -- procedure: pointer-s8-ref
          (pointer-s8-ref PTR)
     Returns the signed byte at the address designated by `PTR'.


 -- procedure: pointer-u16-ref
          (pointer-u16-ref PTR)
     Returns the unsigned 16-bit integer at the address designated by
     `PTR'.


 -- procedure: pointer-s16-ref
          (pointer-s16-ref PTR)
     Returns the signed 16-bit integer at the address designated by
     `PTR'.


 -- procedure: pointer-u32-ref
          (pointer-u32-ref PTR)
     Returns the unsigned 32-bit integer at the address designated by
     `PTR'.


 -- procedure: pointer-s32-ref
          (pointer-s32-ref PTR)
     Returns the signed 32-bit integer at the address designated by
     `PTR'.


 -- procedure: pointer-f32-ref
          (pointer-f32-ref PTR)
     Returns the 32-bit float at the address designated by `PTR'.


 -- procedure: pointer-f64-ref
          (pointer-f64-ref PTR)
     Returns the 64-bit double at the address designated by `PTR'.


 -- procedure: pointer-u8-set!
          (pointer-u8-set! PTR N)
          (set! (pointer-u8-ref PTR) N)
     Stores the unsigned byte `N' at the address designated by `PTR'.


 -- procedure: pointer-s8-set!
          (pointer-s8-set! PTR N)
          (set! (pointer-s8-ref PTR) N)
     Stores the signed byte `N' at the address designated by `PTR'.


 -- procedure: pointer-u16-set!
          (pointer-u16-set! PTR N)
          (set! (pointer-u16-ref PTR) N)
     Stores the unsigned 16-bit integer `N' at the address designated
     by `PTR'.


 -- procedure: pointer-s16-set!
          (pointer-s16-set! PTR N)
          (set! (pointer-s16-ref PTR) N)
     Stores the signed 16-bit integer `N' at the address designated by
     `PTR'.


 -- procedure: pointer-u32-set!
          (pointer-u32-set! PTR N)
          (set! (pointer-u32-ref PTR) N)
     Stores the unsigned 32-bit integer `N' at the address designated
     by `PTR'.


 -- procedure: pointer-s32-set!
          (pointer-s32-set! PTR N)
          (set! (pointer-s32-ref PTR) N)
     Stores the 32-bit integer `N' at the address designated by `PTR'.


 -- procedure: pointer-f32-set!
          (pointer-f32-set! PTR N)
          (set! (pointer-f32-ref PTR) N)
     Stores the 32-bit floating-point number `N' at the address
     designated by `PTR'.


 -- procedure: pointer-f64-set!
          (pointer-f64-set! PTR N)
          (set! (pointer-f64-ref PTR) N)
     Stores the 64-bit floating-point number `N' at the address
     designated by `PTR'.


 -- procedure: align-to-word
          (align-to-word PTR-OR-INT)
     Accepts either a machine pointer or an integer as argument and
     returns a new pointer or integer aligned to the native word size
     of the host platform.


File: chicken.info,  Node: Tagged pointers,  Next: Extending procedures with data,  Prev: Foreign pointers,  Up: Unit lolevel

5.21.2 Tagged pointers
----------------------

"Tagged" pointers are foreign pointer objects with an extra tag object.

 -- procedure: tag-pointer
          (tag-pointer PTR TAG)
     Creates a new tagged pointer object from the foreign pointer `PTR'
     with the tag `TAG', which may an arbitrary Scheme object.


 -- procedure: tagged-pointer?
          (tagged-pointer? X TAG)
     Returns `#t', if `X' is a tagged pointer object with the tag `TAG'
     (using an `eq?' comparison), or `#f' otherwise.


 -- procedure: pointer-tag
          (pointer-tag PTR)
     If `PTR' is a tagged pointer object, its tag is returned. If `PTR'
     is a normal, untagged foreign pointer object `#f' is returned.
     Otherwise an error is signalled.


File: chicken.info,  Node: Extending procedures with data,  Next: Bytevectors,  Prev: Tagged pointers,  Up: Unit lolevel

5.21.3 Extending procedures with data
-------------------------------------

 -- procedure: extend-procedure
          (extend-procedure PROCEDURE X)
     Returns a copy of the procedure `PROCEDURE' which contains an
     additional data slot initialized to `X'. If `PROCEDURE' is already
     an extended procedure, then its data slot is changed to contain
     `X' and the same procedure is returned.


 -- procedure: extended-procedure?
          (extended-procedure? PROCEDURE)
     Returns `#t' if `PROCEDURE' is an extended procedure, or `#f'
     otherwise.


 -- procedure: procedure-data
          (procedure-data PROCEDURE)
     Returns the data object contained in the extended procedure
     `PROCEDURE', or `#f' if it is not an extended procedure.


 -- procedure: set-procedure-data!
          (set-procedure-data! PROCEDURE X)
     Changes the data object contained in the extended procedure
     `PROCEDURE' to `X'.


     (define foo
       (letrec ((f (lambda () (procedure-data x)))
                (x #f) )
         (set! x (extend-procedure f 123))
         x) )
     (foo)                                         ==> 123
     (set-procedure-data! foo 'hello)
     (foo)                                         ==> hello


File: chicken.info,  Node: Bytevectors,  Next: Data in unmanaged memory,  Prev: Extending procedures with data,  Up: Unit lolevel

5.21.4 Bytevectors
------------------

 -- procedure: byte-vector
          (byte-vector FIXNUM ...)
     Returns a freshly allocated byte-vector with `FIXNUM ...' as its
     initial contents.


 -- procedure: byte-vector?
          (byte-vector? X)
     Returns `#t' if `X' is a byte-vector object, or `#f' otherwise.


 -- procedure: byte-vector-fill!
          (byte-vector-fill! BYTE-VECTOR N)
     Sets each element of `BYTE-VECTOR' to `N', which should be an
     exact integer.


 -- procedure: byte-vector->list
          (byte-vector->list BYTE-VECTOR)
     Returns a list with elements taken from `BYTE-VECTOR'.


 -- procedure: byte-vector->string
          (byte-vector->string BYTE-VECTOR)
     Returns a string with the contents of `BYTE-VECTOR'.


 -- procedure: byte-vector-length
          (byte-vector-length BYTE-VECTOR)
     Returns the number of elements in `BYTE-VECTOR'.


 -- procedure: byte-vector-ref
          (byte-vector-ref BYTE-VECTOR INDEX)
     Returns the byte at the `INDEX'th position of `BYTE-VECTOR'.


 -- procedure: byte-vector-set!
          (byte-vector-set! BYTE-VECTOR INDEX N)
          (set! (byte-vector-ref BYTE-VECTOR INDEX) N)
     Sets the byte at the `INDEX'th position of `BYTE-VECTOR' to the
     value of the exact integer `n'.


 -- procedure: list->byte-vector
          (list->byte-vector LIST)
     Returns a byte-vector with elements taken from `LIST', where the
     elements of `LIST' should be exact integers.


 -- procedure: make-byte-vector
          (make-byte-vector SIZE [INIT])
     Creates a new byte-vector of size `SIZE'. If `INIT' is given, then
     it should be an exact integer with which every element of the
     byte-vector is initialized.


 -- procedure: make-static-byte-vector
          (make-static-byte-vector SIZE [INIT])
     As `make-byte-vector', but allocates the byte-vector in storage
     that is not subject to garbage collection.  To free the allocated
     memory, one has to call `object-release' explicitly.

     Exceptions: `(exn bounds)', `(exn runtime)'


 -- procedure: static-byte-vector->pointer
          (static-byte-vector->pointer PBYTE-VECTOR)
     Returns a pointer object pointing to the data in the statically
     allocated byte-vector `PBYTE-VECTOR'.


 -- procedure: string->byte-vector
          (string->byte-vector STRING)
     Returns a byte-vector with the contents of `STRING'.


File: chicken.info,  Node: Data in unmanaged memory,  Next: Locatives,  Prev: Bytevectors,  Up: Unit lolevel

5.21.5 Data in unmanaged memory
-------------------------------

 -- procedure: object-evict
          (object-evict X [ALLOCATOR])
     Copies the object `X' recursively into the memory pointed to by
     the foreign pointer object returned by `ALLOCATOR', which should
     be a procedure of a single argument (the number of bytes to
     allocate). The freshly copied object is returned.  This facility
     allows moving arbitrary objects into static memory, but care
     should be taken when mutating evicted data: setting slots in
     evicted vector-like objects to non-evicted data is not allowed. It
     is possible to set characters/bytes in evicted strings or
     byte-vectors, though.  It is advisable not to evict ports, because
     they might be mutated by certain file-operations.  `object-evict'
     is able to handle circular and shared structures, but evicted
     symbols are no longer unique: a fresh copy of the symbol is
     created, so


     (define x 'foo)
     (define y (object-evict 'foo))
     y                              ==> foo
     (eq? x y)                      ==> #f
     (define z (object-evict '(bar bar)))
     (eq? (car z) (cadr z))         ==> #t

     The `ALLOCATOR' defaults to `allocate'.


 -- procedure: object-evict-to-location
          (object-evict-to-location X PTR [LIMIT])
     As `object-evict' but moves the object at the address pointed to by
     the machine pointer `PTR'. If the number of copied bytes exceeds
     the optional `LIMIT' then an error is signalled (specifically a
     composite condition of types `exn' and `evict'. The latter provides
     a `limit' property which holds the exceeded limit. Two values are
     returned: the evicted object and a new pointer pointing to the
     first free address after the evicted object.


 -- procedure: object-evicted?
          (object-evicted? X)
     Returns `#t' if `X' is a non-immediate evicted data object, or
     `#f' otherwise.


 -- procedure: object-size
          (object-size X)
     Returns the number of bytes that would be needed to evict the data
     object `X'.


 -- procedure: object-release
          (object-release X [RELEASER])
     Frees memory occupied by the evicted object `X' recursively.
     `RELEASER' should be a procedure of a single argument (a foreign
     pointer object to the static memory to be freed) and defaults to
     `free'.


 -- procedure: object-unevict
          (object-unevict X [FULL])
     Copies the object `X' and nested objects back into the normal
     Scheme heap.  Symbols are re-interned into the symbol table.
     Strings and byte-vectors are not copied, unless `FULL' is given and
     not `#f'.


File: chicken.info,  Node: Locatives,  Next: Accessing toplevel variables,  Prev: Data in unmanaged memory,  Up: Unit lolevel

5.21.6 Locatives
----------------

A _locative_ is an object that points to an element of a containing
object, much like a "pointer" in low-level, imperative programming
languages like "C". The element can be accessed and changed indirectly,
by performing access or change operations on the locative. The
container object can be computed by calling the `location->object'
procedure.

   Locatives may be passed to foreign procedures that expect pointer
arguments.  The effect of creating locatives for evicted data (see
`object-evict') is undefined.

 -- procedure: make-locative
          (make-locative EXP [INDEX])
     Creates a locative that refers to the element of the non-immediate
     object `EXP' at position `INDEX'. `EXP' may be a vector, pair,
     string, byte-vector, SRFI-4 number-vector, or record. `INDEX'
     should be a fixnum. `INDEX' defaults to 0.


 -- procedure: make-weak-locative
          (make-weak-locative EXP [INDEX])
     Creates a "weak" locative. Even though the locative refers to an
     element of a container object, the container object will still be
     reclaimed by garbage collection if no other references to it exist.


 -- procedure: locative?
          (locative? X)
     Returns `#t' if `X' is a locative, or `#f' otherwise.


 -- procedure: locative-ref
          (locative-ref LOC)
     Returns the element to which the locative `LOC' refers. If the
     containing object has been reclaimed by garbage collection, an
     error is signalled.


 -- procedure: locative-set!
          (locative-set! LOC X)
          (set! (locative-ref LOC) X)
     Changes the element to which the locative `LOC' refers to `X'.  If
     the containing object has been reclaimed by garbage collection, an
     error is signalled.


 -- procedure: locative->object
          (locative->object LOC)
     Returns the object that contains the element referred to by `LOC'
     or `#f' if the container has been reclaimed by garbage collection.


File: chicken.info,  Node: Accessing toplevel variables,  Next: Low-level data access,  Prev: Locatives,  Up: Unit lolevel

5.21.7 Accessing toplevel variables
-----------------------------------

 -- procedure: global-bound?
          (global-bound? SYMBOL)
     Returns `#t', if the global ("toplevel") variable with the name
     `SYMBOL' is bound to a value, or `#f' otherwise.


 -- procedure: global-ref
          (global-ref SYMBOL)
     Returns the value of the global variable `SYMBOL'.  If no variable
     under that name is bound, an error is signalled.

     Note that it is not possible to access a toplevel binding with
     `global-ref' or `global-set!' if it has been hidden in compiled
     code via `(declare (hide ...))', or if the code has been compiled
     in `block' mode.


 -- procedure: global-set!
          (global-set! SYMBOL X)
          (set! (global-ref SYMBOL) X)
     Sets the global variable named `SYMBOL' to the value `X'.


File: chicken.info,  Node: Low-level data access,  Next: Procedure-call- and variable reference hooks,  Prev: Accessing toplevel variables,  Up: Unit lolevel

5.21.8 Low-level data access
----------------------------

 -- procedure: block-ref
          (block-ref BLOCK INDEX)
     Returns the contents of the `INDEX'th slot of the object `BLOCK'.
     `BLOCK' may be a vector, record structure, pair or symbol.


 -- procedure: block-set!
          (block-set! BLOCK INDEX X)
          (set! (block-ref BLOCK INDEX) X)
     Sets the contents of the `INDEX'th slot of the object `BLOCK' to
     the value of `X'.  `BLOCK' may be a vector, record structure, pair
     or symbol.


 -- procedure: object-copy
          (object-copy X)
     Copies `X' recursively and returns the fresh copy. Objects
     allocated in static memory are copied back into garbage collected
     storage.


 -- procedure: make-record-instance
          (make-record-instance SYMBOL ARG1 ...)
     Returns a new instance of the record type `SYMBOL', with its slots
     initialized to `ARG1 ...'.  To illustrate:


     (define-record point x y)

     expands into something quite similar to:


     (begin
       (define (make-point x y)
         (make-record-instance 'point x y) )
       (define (point? x)
         (and (record-instance? x)
              (eq? 'point (block-ref x 0)) ) )
       (define (point-x p) (block-ref p 1))
       (define (point-x-set! p x) (block-set! p 1 x))
       (define (point-y p) (block-ref p 2))
       (define (point-y-set! p y) (block-set! p 1 y)) )


 -- procedure: move-memory!
          (move-memory! FROM TO [BYTES])
     Copies `BYTES' bytes of memory from `FROM' to `TO'.  `FROM' and
     `TO' may be strings, primitive byte-vectors, SRFI-4 byte-vectors
     (see: *Note Unit srfi-4::), memory mapped files, foreign pointers
     (as obtained from a call to `foreign-lambda', for example) or
     locatives. if `BYTES' is not given and the size of the source or
     destination operand is known then the maximal number of bytes will
     be copied. Moving memory to the storage returned by locatives will
     cause havoc, if the locative refers to containers of non-immediate
     data, like vectors or pairs.


 -- procedure: number-of-bytes
          (number-of-bytes BLOCK)
     Returns the number of bytes that the object `BLOCK' contains.
     `BLOCK' may be any non-immediate value.


 -- procedure: number-of-slots
          (number-of-slots BLOCK)
     Returns the number of slots that the object `BLOCK' contains.
     `BLOCK' may be a vector, record structure, pair or symbol.


 -- procedure: record-instance?
          (record-instance? X)
     Returns `#t' if `X' is an instance of a record type.  See also:
     `make-record-instance'.

 -- procedure: record->vector
          (record->vector BLOCK)
     Returns a new vector with the type and the elements of the record
     `BLOCK'.


File: chicken.info,  Node: Procedure-call- and variable reference hooks,  Next: Magic,  Prev: Low-level data access,  Up: Unit lolevel

5.21.9 Procedure-call- and variable reference hooks
---------------------------------------------------

 -- procedure: set-invalid-procedure-call-handler!
          (set-invalid-procedure-call-handler! PROC)
     Sets an internal hook that is invoked when a call to an object
     other than a procedure is executed at runtime. The procedure
     `PROC' will in that case be called with two arguments: the object
     being called and a list of the passed arguments.


     ;;; Access sequence-elements as in ARC:

     (set-invalid-procedure-call-handler!
       (lambda (proc args)
         (cond [(string? proc) (apply string-ref proc args)]
               [(vector? proc) (apply vector-ref proc args)]
               [else (error "call of non-procedure" proc)] ) ) )

     ("hello" 4)    ==>  #\o

     This facility does not work in code compiled with the "unsafe"
     setting.


 -- procedure: unbound-variable-value
          (unbound-variable-value [X])
     Defines the value that is returned for unbound variables. Normally
     an error is signalled, use this procedure to override the check
     and return `X' instead. To set the default behavior (of signalling
     an error), call `unbound-variable-value' with no arguments.

     This facility does not work in code compiled with the "unsafe"
     setting.


File: chicken.info,  Node: Magic,  Prev: Procedure-call- and variable reference hooks,  Up: Unit lolevel

5.21.10 Magic
-------------

 -- procedure: object-become!
          (object-become! ALIST)
     Changes the identity of the value of the car of each pair in
     `ALIST' to the value of the cdr. Both values may not be immediate
     (i.e. exact integers, characters, booleans or the empty list).


     (define x "i used to be a string")
     (define y '#(and now i am a vector))
     (object-become! (list (cons x y)))
     x                                    ==> #(and now i am a vector)
     y                                    ==> #(and now i am a vector)
     (eq? x y)                            ==> #t

     Note: this operation invokes a major garbage collection.

     The effect of using `object-become!' on evicted data (see
     `object-evict') is undefined.


File: chicken.info,  Node: Unit tinyclos,  Prev: Unit lolevel,  Up: Supported language

5.22 Unit tinyclos
==================

This unit is a port of Gregor Kiczales TinyCLOS with numerous
modifications.

   This unit uses the `extras' unit.

* Menu:

* Defining forms::
* Base language::
* Introspection::
* Intercessory protocol::
* Additional protocol::
* Utility procedures::
* Builtin classes::


File: chicken.info,  Node: Defining forms,  Next: Base language,  Up: Unit tinyclos

5.22.1 Defining forms
---------------------

 -- syntax: define-class
          (define-class NAME (SUPERCLASS1 ...) (SLOTNAME1 ...) [METACLASS])
     Sets the variable `NAME' to a new class (a new instance of the
     class `<class>'). `SUPERCLASS1 ...' is a list of superclasses of
     the newly created class. If no superclasses are given, then
     `<object>' is assumed.  `SLOTNAME1 ...' are the names of the
     direct slots of the class. if `METACLASS' is provided, then the
     new class-instance is an instance of `METACLASS' instead of
     `<class>'.


     (define-class NAME (SUPER) (SLOT1 SLOT2) META)

     is equivalent to


     (define NAME
       (make META
         'name 'NAME
         'direct-supers (list SUPER)
         'direct-slots (list 'SLOT1 'SLOT2)) )

     Note that slots-names are not required to be symbols, so the
     following is perfectly valid:


     (define hidden-slot (list 'hidden))
     (define <myclass>
       (make <class>
          'direct-supers (list <object>)
          'direct-slots (list hidden-slot) ) )
     (define x1 (make <myclass>)
     (slot-set! x1 hidden-slot 99)


 -- syntax: define-generic
          (define-generic NAME [CLASS])
     Sets the variable `NAME' to contain a fresh generic function
     object without associated methods. If the optional argument `CLASS'
     is given, then the generic function will be an instance of that
     class.


 -- syntax: define-method
          (define-method (NAME (VARIABLE1 CLASS1) ... PARAMETERS ...) BODY ...)
     Adds a new method with the code `BODY ...' to the generic function
     that was assigned to the variable `name'.  `CLASS1 ...' is a list
     if classes that specialize this particular method. The method can
     have additional parameters `PARAMETERS', which do not specialize
     the method any further.  Extended lambda-lists are allowed
     (`#!optional, #!key' or `#!rest' argument lists), but can not be
     specialized.  Inside the body of the method the identifier
     `call-next-method' names a procedure of zero arguments that can be
     invoked to call the next applicable method with the same arguments.
     If no generic function is defined under this name, then a fresh
     generic function object is created and assigned to `NAME'.

     Note that only `define-generic' expands into a valid definition,
     so for internal lexically scoped definitions use `define-generic'.

     Currently methods defined with `define-method' should not be
     hidden (via `(declare (hide ...))', nor should such files be
     compiled in `block' mode, unless the methods are exported.


File: chicken.info,  Node: Base language,  Next: Introspection,  Prev: Defining forms,  Up: Unit tinyclos

5.22.2 Base language
--------------------

 -- procedure: add-method
          (add-method GENERIC METHOD)
     Adds the method object `METHOD' to the list of applicable methods
     for the generic function `GENERIC'.


 -- procedure: instance?
          (instance? X)
     Returns `#t' if `X' is an instance of a non-primitive class.


 -- procedure: make
          (make CLASS INITARG ...)
     Creates a new instance of `CLASS' and passes `INITARG ...' to the
     `initialize' method of this class.


 -- procedure: make-class
          (make-class SUPERCLASSES SLOTNAMES)
     Creates a new class object, where `SUPERCLASSES' should be the
     list of direct superclass objects and `SLOTNAMES' should be a list
     of symbols naming the slots of this class.


 -- procedure: make-generic
          (make-generic [NAME])
     Creates a new generic function object. If `NAME' is specified,
     then it should be a string.


 -- procedure: make-method
          (make-method SPECIALIZERS PROC)
     Creates a new method object specialized to the list of classes in
     `SPECIALIZERS'.


     (define-method (foo (x <bar>)) 123)
        <=> (add-method foo
                        (make-method
                           (list <bar>)
                           (lambda (call-next-method x) 123)))


 -- procedure: slot-ref
          (slot-ref INSTANCE SLOTNAME)
     Returns the value of the slot `SLOTNAME' of the object `INSTANCE'.


 -- procedure: slot-set!
          (slot-set! INSTANCE SLOTNAME VALUE)
          (set! (slot-ref INSTANCE SLOTNAME) VALUE)
     Sets the value of the slot `SLOTNAME' of the object `INSTANCE' to
     `VALUE'.


File: chicken.info,  Node: Introspection,  Next: Intercessory protocol,  Prev: Base language,  Up: Unit tinyclos

5.22.3 Introspection
--------------------

 -- procedure: class-cpl
          (class-cpl CLASS)
     Returns the class-precedence-list of `CLASS' as a list of classes.


 -- procedure: class-direct-slots
          (class-direct-slots CLASS)
     Returns the list of direct slots of `CLASS' as a list of lists,
     where each sublist contains the name of the slot.


 -- procedure: class-direct-supers
          (class-direct-supers CLASS)
     Returns the list of direct superclasses of `CLASS'.


 -- procedure: class-of
          (class-of X)
     Returns the class that the object `X' is an instance of.


 -- procedure: class-name
          (class-name CLASS)
     Returns name of `CLASS'.


 -- procedure: class-slots
          (class-slots CLASS)
     Returns the list of all slots of `CLASS' and its superclasses as a
     list of lists, where each sublist contains the name of the slot.


 -- procedure: generic-methods
          (generic-methods GENERIC)
     Returns the list of all methods associated with the generic
     function `GENERIC'.


 -- procedure: method-specializers
          (method-specializers METHOD)
     Returns the list of classes that specialize `METHOD'.


 -- procedure: method-procedure
          (method-procedure METHOD)
     Returns the procedure that contains the body of `METHOD'.


 -- procedure: subclass?
          (subclass? CLASS1 CLASS2)
     Returns `#t' is `CLASS1' is a subclass of `CLASS2', or `#f'
     otherwise. Note that the following holds:


     (subclass? X X) ==> #t

 -- procedure: instance-of?
          (instance-of? X CLASS)
     Returns `#t' if `X' is an instance of `CLASS' (or one of its
     subclasses).


File: chicken.info,  Node: Intercessory protocol,  Next: Additional protocol,  Prev: Introspection,  Up: Unit tinyclos

5.22.4 Intercessory protocol
----------------------------

These definitions allow interfacing to the Meta Object Protocol of
TinyCLOS. For serious use, it is recommended to consult the source code
(`tinyclos.scm').

 -- generic: allocate-instance
          (allocate-instance CLASS)
     Allocates storage for an instance of `CLASS' and returns the
     instance.


 -- generic: compute-apply-generic
          (compute-apply-generic GENERIC)
     Returns a procedure that will be called to apply the generic
     function methods to the arguments.


 -- generic: compute-apply-methods
          (compute-apply-methods GENERIC)
     Returns a procedure of two arguments, a list of applicable methods
     and a list of arguments and applies the methods.


 -- generic: compute-methods
          (compute-methods GENERIC)
     Returns a procedure of one argument. The procedure is called with
     the list of actual arguments passed to the generic function and
     should return a list of applicable methods, sorted by precedence.


 -- generic: compute-cpl
          (compute-cpl CLASS)
     Computes and returns the class-precedence-list of `CLASS'.


 -- generic: compute-getter-and-setter
          (compute-getter-and-setter CLASS SLOT ALLOCATOR)
     Returns two values, the procedures that get and set the contents
     of the slot `SLOT'.  `ALLOCATOR' is a procedure of one argument
     that gets an initalizer function and returns the getter and setter
     procedures for the allocated slot.


 -- generic: compute-method-more-specific?
          (compute-method-more-specific? GENERIC)
     Returns a procedure of three arguments (two methods and a list of
     arguments) that returns `#t' if the first method is more specific
     than the second one with respect to the list of arguments.
     Otherwise the returned predicate returns `#f'.


 -- generic: compute-slots
          (compute-slots CLASS)
     Computes and returns the list of slots of `CLASS'.


 -- generic: initialize
          (initialize INSTANCE INITARGS)
     Initializes the object `INSTANCE'. `INITARGS' is the list of
     initialization arguments that were passed to the `make' procedure.


File: chicken.info,  Node: Additional protocol,  Next: Utility procedures,  Prev: Intercessory protocol,  Up: Unit tinyclos

5.22.5 Additional protocol
--------------------------

 -- generic: describe-object
          (describe-object INSTANCE [PORT])
     Writes a description of `INSTANCE' to `PORT'.  Execution of the
     interpreter command `,d' will invoke this generic function.  If
     `PORT' is not given it defaults to the value of
     `(current-output-port)'.


 -- generic: print-object
          (print-object INSTANCE [PORT])
     Writes a textual representation of `INSTANCE' to `PORT'.  Any
     output of an instance with `display, write' and `print' will
     invoke this generic function.  If `PORT' is not given it defaults
     to the value of `(current-output-port)'.


File: chicken.info,  Node: Utility procedures,  Next: Builtin classes,  Prev: Additional protocol,  Up: Unit tinyclos

5.22.6 Utility procedures
-------------------------

 -- procedure: initialize-slots
          (initialize-slots INSTANCE INITARGS)
     This procedure takes a sequence of alternating slot-names and
     initialization values in `INITARGS' and initializes the
     corresponding slots in `INSTANCE'.


     (define-class <pos> () (x y))

     (define-method (initialize (pos <pos>) initargs)
       (call-next-method)
       (initialize-slots pos initargs))

     (define p1 (make <pos> 'x 1 'y 2))
     (define p2 (make <pos> 'x 3 'y 5))


File: chicken.info,  Node: Builtin classes,  Prev: Utility procedures,  Up: Unit tinyclos

5.22.7 Builtin classes
----------------------

The class hierarchy of builtin classes looks like this:


<top>
  <object>
    <class>
      <procedure-class>
        <procedure>
        <entity-class>
          <generic>
      <primitive-class>
    <c++-object>
  <primitive>
    <void>
    <boolean>
    <symbol>
    <char>
    <vector>
    <pair>
    <number>
      <integer>
        <exact>
      <inexact>
    <string>
    <port>
      <input-port>
      <output-port>
    <pointer>
      <tagged-pointer>
      <swig-pointer>
    <locative>
    <byte-vector>
      <u8vector>
      <s8vector>
      <u16vector>
      <s16vector>
      <u32vector>
      <s32vector>
      <f32vector>
      <f64vector>
    <structure>
      <char-set>
      <condition>
      <condition-variable>
      <environment>
      <hash-table>
      <lock>
      <mmap>
      <mutex>
      <promise>
      <queue>
      <read-table>
      <regexp>
      <tcp-listener>
      <thread>
      <time>
    <end-of-file>

 -- class: <primitive> -> <top>
     The parent class of the classes of all primitive Scheme objects.

 -- class: <boolean> -> <primitive>
 -- class: <symbol> -> <primitive>
 -- class: <char> -> <primitive>
 -- class: <vector> -> <primitive>
 -- class: <null> -> <primitive>
 -- class: <pair> -> <primitive>
 -- class: <number> -> <primitive>
 -- class: <integer> -> <primitive>
 -- class: <exact> -> <integer>
 -- class: <inexact> -> <number>
 -- class: <string> -> <primitive>
 -- class: <port> -> <primitive>
 -- class: <environment> -> <structure>
 -- class: <end-of-file> -> <primitive>
 -- class: <input-port> -> <port>
 -- class: <output-port> -> <port>
 -- class: <procedure> -> <procedure-class>
     The classes of primitive Scheme objects.

 -- class: <byte-vector> -> <primitive>
 -- class: <structure> -> <primitive>
 -- class: <hash-table> -> <structure>
 -- class: <queue> -> <structure>
     The classes of extended data types provided by the various library
     units.

 -- class: <class> -> <object>
     The parent class of all class objects.

 -- class: <entity-class> -> <class>
     The parent class of objects that can be invoked as a procedure and
     have slots.

 -- class: <generic> -> <entity-class>
     The parent class of generic function objects.

 -- class: <method> -> <class>
     The parent class of method objects.

 -- class: <object> -> <class>
     The parent class of all objects.

 -- class: <procedure-class> -> <class>
     The parent class of objects that can be invoked as a procedure.

 -- class: <condition> -> <structure>
     Class of condition objects.

 -- class: <array> -> <structure>
 -- class: <char-set> -> <structure>
 -- class: <time> -> <structure>
 -- class: <u8vector> -> <byte-vector>
 -- class: <s8vector> -> <byte-vector>
 -- class: <u16vector> -> <byte-vector>
 -- class: <s16vector> -> <byte-vector>
 -- class: <u32vector> -> <byte-vector>
 -- class: <s32vector> -> <byte-vector>
 -- class: <f32vector> -> <byte-vector>
 -- class: <f64vector> -> <byte-vector>
     The classes of data objects provided by the various supported
     SRFIs.

 -- class: <lock> -> <structure>
 -- class: <mmap> -> <structure>
     Classes of objects used in the `posix' library unit.

 -- class: <pointer> -> <primitive>
 -- class: <tagged-pointer> -> <pointer>
 -- class: <swig-pointer> -> <pointer>
     A machine pointer (untagged, tagged or pointing to SWIG-wrapped
     data).

 -- class: <locative> -> <primitive>
     A locative.

 -- class: <promise> -> <structure>
     The class of objects returned by `delay'.

 -- class: <tcp-listener> -> <structure>
     The class of an object returned by `tcp-listen'.

 -- class: <regexp> -> <structure>
     The class of an object returned by `regexp'.

 -- class: <c++-class> -> <object>
     The class of generated wrappers for C++ classes parsed by the
     "easy" Foreign Function interface.

   The CHICKEN distribution provides several examples in the file
`tests/tinyclos-examples.scm'.


File: chicken.info,  Node: Interface to external functions and variables,  Next: chicken-setup,  Prev: Supported language,  Up: Top

6 Interface to external functions and variables
***********************************************

* Menu:

* Accessing external objects::
* Foreign type specifiers::
* Embedding::
* Callbacks::
* Locations::
* Other support procedures::
* The Easy Foreign Function Interface::
* C interface::


File: chicken.info,  Node: Accessing external objects,  Next: Foreign type specifiers,  Up: Interface to external functions and variables

6.1 Accessing external objects
==============================

 -- syntax: foreign-code
          (foreign-code STRING)
     Executes the embedded C/C++ code `STRING', which should be a
     sequence of C statements, which are executed and return an
     unspecified result.


     (foreign-code "doSomeInitStuff();")     =>  #<unspecified>

     Code wrapped inside `foreign-code' may not invoke callbacks into
     Scheme.


 -- syntax: foreign-value
          (foreign-value STRING TYPE)
     Evaluates the embedded C/C++ expression `STRING', returning a
     value of type given in the foreign-type specifier `TYPE'.


     (print (foreign-value "my_version_string" c-string))


 -- syntax: foreign-declare
          (foreign-declare STRING ...)
     Include given strings verbatim into header of generated file.

 -- syntax: foreign-parse
          (foreign-parse STRING ...)
     Parse given strings and generate foreign-interface bindings. See
     *Note The Easy Foreign Function Interface:: for more information.

 -- syntax: foreign-parse/declare
          (foreign-parse/declare STRING ...)
     Parse and include strings into the generated code.

 -- syntax: define-foreign-type
          (define-foreign-type NAME TYPE [ARGCONVERT [RETCONVERT]])
     Defines an alias for `TYPE' with the name `NAME' (a symbol).
     `TYPE' may be a type-specifier or a string naming a C type. The
     namespace of foreign type specifiers is separate from the normal
     Scheme namespace.  The optional arguments `ARGCONVERT' and
     `RETCONVERT' should evaluate to procedures that map argument- and
     result-values to a value that can be transformed to `TYPE':


     (define-foreign-type char-vector
       nonnull-c-string
       (compose list->string vector->list)
       (compose list->vector string->list) )

     (define strlen
       (foreign-lambda int "strlen" char-vector) )

     (strlen '#(#\a #\b #\c))                      ==> 3

     (define memset
       (foreign-lambda char-vector "memset" char-vector char int) )

     (memset '#(#_ #_ #_) #\X 3)                ==> #(#\X #\X #\X)

     Foreign type-definitions are only visible in the compilation-unit
     in which they are defined, so use `include' to use the same
     definitions in multiple files.


 -- syntax: define-foreign-variable
          (define-foreign-variable NAME TYPE [STRING])
     Defines a foreign variable of name `NAME' (a symbol). `STRING'
     should be the real name of a foreign variable or parameterless
     macro. If `STRING' is not given, then the variable name `NAME' will
     be converted to a string and used instead. All references and
     assignments (via `set!') are modified to correctly convert values
     between Scheme and C representation. This foreign variable can
     only be accessed in the current compilation unit, but the name can
     be lexically shadowed.  Note that `STRING' can name an arbitrary C
     expression. If no assignments are performed, then `STRING' doesn't
     even have to specify an lvalue.


     #>
     enum { abc=3, def, ghi };
     <#

     (define-macro (define-simple-foreign-enum . items)
       `(begin
          ,@(map (match-lambda
                   [(name realname) `(define-foreign-variable ,name int ,realname)]
                   [name `(define-foreign-variable ,name int)] )
          items) ) )

     (define-simple-foreign-enum abc def ghi)

     ghi                               ==> 5


 -- syntax: define-foreign-record
          (define-foreign-record NAME [DECL ...] SLOT ...)
     Defines accessor procedures for a C structure definition. `NAME'
     should either be a symbol or a list of the form `(TYPENAME
     FOREIGNNAME)'. If `NAME' is a symbol, then a C declaration will be
     generated that defines a C struct named `struct NAME'. If `NAME'
     is a list, then no struct declaration will be generated.  A
     foreign-type specifier named `NAME' (or `TYPENAME') will be
     defined as a pointer to the given C structure.  A `SLOT'
     definition should be a list of one of the following forms:


     (TYPE SLOTNAME)

     or


     (TYPE SLOTNAME SIZE)

     The latter form defines an array of SIZE elements of the type TYPE
     embedded in the structure.  For every slot, the following accessor
     procedures will be generated:

      -- procedure: TYPENAME-SLOTNAME
               (TYPENAME-SLOTNAME FOREIGN-RECORD-POINTER [INDEX])
          A procedure of one argument (a pointer to a C structure),
          that returns the slot value of the slot `SLOTNAME'. If a
          `SIZE' has been given in the slot definition, then an
          additional argument `INDEX' is required that specifies the
          index of an array-element.

      -- procedure: TYPENAME-SLOTNAME-set!
               (TYPENAME-SLOTNAME-set! FOREIGN-RECORD-POINTER [INXDEX] VALUE)
          A procedure of two arguments (a pointer to a C structure) and
          a value, that sets the slot value of the slot `SLOTNAME' in
          the structure. If a `SIZE' has been given in the slot
          definition, then an additional argument `INDEX' is required
          for the array index.

     If a slot type is of the form `(const ...)', then no setter
     procedure will be generated.  Slots of the types `(struct ...)' or
     `(union ...)' are accessed as pointers to the embedded struct (or
     union) and no setter will be generated.

     Additionally, special record-declarations (`DECL ...') may be
     given, where each declaration consists of a list of the form
     `(KEYWORD ARGUMENT ...)'. The available declarations are:

      -- record declaration: constructor:
               (constructor: NAME)
          Generate a constructor-procedure with no arguments that has
          the name `NAME' (a symbol) that returns a pointer to a
          structure of this type. The storage will be allocated with
          `malloc(3)'.

      -- record declaration: destructor:
               (destructor: NAME)
          Generate a destructor function with the name `NAME' that
          takes a pointer to a structure of this type as its single
          argument and releases the storage with `free(3)'. If the
          argument is `#f', the destructor procedure does nothing.

      -- record declaration: rename:
               (rename: EXPRESSION)
          Evaluates `EXPRESSION' at compile-/macro-expansion-time and
          applies the result, which should be a procedure, to the
          string-representation of the name of each accessor-procedure
          generated. Another (or the same) string should be returned,
          which in turn is taken as the actual name of the accessor.

     An example:

          (require-for-syntax 'srfi-13)

          (define-foreign-record Some_Struct
            (rename: (compose string-downcase (cut string-translate <> "_" "-")))
            (constructor: make-some-struct)
            (destructor: free-some-struct)
            (int xCoord)
            (int yCoord) )

     will generate the following procedures:


     (make-some-struct)              --> C-POINTER
     (free-some-struct C-POINTER)

     (some-struct-xcoord C-POINTER)  --> NUMBER
     (some-struct-ycoord C-POINTER)  --> NUMBER

     (some-struct-xcoord-set! C-POINTER NUMBER)
     (some-struct-ycoord-set! C-POINTER NUMBER)


 -- syntax: define-foreign-enum
          (define-foreign-enum TYPENAME ITEM ...)
     Defines a foreign type (as with `define-foreign-type') that maps
     the elements of a C/C++ enum (or a enum-like list of constants) to
     and from a set of symbols. `TYPENAME' names a foreign type that
     converts a symbol argument from the set `ITEM ...' into the
     appropriate enum value when passed as an argument to a foreign
     function.  A list of symbols passed as an argument will be
     combined using `bitwise-ior'. An empty list will be passed as 0
     (zero).  Results of the enum type are automatically converted into
     a symbol (note that combinations are not supported in this case).
     `TYPENAME' may alternatively be a list of the form `(SCHEMENAME
     REALTYPE)' - in this case `REALTYPE' designates the native type
     used. The default native type is `"TYPENAME"'.  Additionally two
     procedures are generated named `SCHEMENAME->number' and
     `number->SCHEMENAME' which take one argument and convert a symbol
     (or a list of symbols) into its numeric value and vice versa.

     Here a heavily contrived example:


     #>
     enum foo { a_foo = 4, b_foo, c_foo };
     enum foo bar(enum foo x) { printf("%d\n", x); return b_foo; }
     <#

     (define-foreign-enum (foo (enum "foo")) a_foo b_foo (c c_foo))

     (define bar (foreign-lambda foo bar foo))

     (pp (bar '()))
     (pp (bar 'a_foo))
     (pp (bar '(b_foo c)))

 -- syntax: foreign-lambda
          (foreign-lambda RETURNTYPE NAME ARGTYPE ...)
     Represents a binding to an external routine. This form can be used
     in the position of an ordinary `lambda' expression. `NAME'
     specifies the name of the external procedure and should be a
     string or a symbol.


 -- syntax: foreign-lambda*
          (foreign-lambda* RETURNTYPE ((ARGTYPE VARIABLE) ...) STRING ...)
     Similar to `foreign-lambda', but instead of generating code to
     call an external function, the body of the C procedure is directly
     given in `STRING ...':


     (define my-strlen
       (foreign-lambda* int ((c-string str))
         "int n = 0;
          while(*(str++)) ++n;
          C_return(n);") )

     (my-strlen "one two three")             ==> 13

     For obscure technical reasons you should use the `C_return' macro
     instead of the normal `return' statement to return a result from
     the foreign lambda body as some cleanup code has to be run before
     execution commences in the calling code.

 -- syntax: foreign-safe-lambda
          (foreign-safe-lambda RETURNTYPE NAME ARGTYPE ...)
     This is similar to `foreign-lambda', but also allows the called
     function to call Scheme functions and allocate Scheme
     data-objects. See *Note Callbacks::.


 -- syntax: foreign-safe-lambda*
          (foreign-safe-lambda* RETURNTYPE ((ARGTYPE VARIABLE)...) STRING ...)
     This is similar to `foreign-lambda*', but also allows the called
     function to call Scheme functions and allocate Scheme
     data-objects. See *Note Callbacks::.


 -- syntax: foreign-primitive
          (foreign-primitive [RETURNTYPE] ((ARGTYPE VARIABLE) ...) STRING ...)
     This is also similar to `foreign-lambda*' but the code will be
     executed in a "primitive" CPS context, which means it will not
     actually return, but call it's continuation on exit. This means
     that code inside this form may allocate Scheme data on the C stack
     (the "nursery") with `C_alloc' (see below). If the `RETURNTYPE' is
     omitted it defaults to `void'.  You can return multiple values
     inside the body of the `foreign-primitive' form by calling this C
     function:


     C_values(N + 2, C_SCHEME_UNDEFINED, C_k, X1, ...)

     where `N' is the number of values to be returned, and `X1, ...'
     are the results, which should be Scheme data objects. When
     returning multiple values, the return-type should be omitted.

 -- syntax: $
          ($ [RETURNTYPE] NAME (TYPE ARGUMENT) ...)
     Invokes a C/C++ function by evaluating the arguments, performing
     the neccessary type-conversions for the foreign type-specifiers
     and calling `NAME' (which must be a symbol). If a return-type is
     given, then the result will be converted properly and returned.
     Callbacks into Scheme are not allowed inside the invoked foreign
     code. The type/argument lists may also be literal Scheme data or
     expressions of the form `(quote LITERAL)' or `(location ...)' - in
     this case the arguments are converted according to the type of the
     literal or are treated as a c-pointer, respectively.  Booleans,
     characters, numbers, strings, SRFI-4 number vectors and symbols
     are converted, all other data is passed as being of type
     `scheme-object'.


     ($ printf "%d times Hello, %s!\n" 1000 "world")

     (define f 99.2)

     (let-location ((double n))
       (let ((f ($ double modf (double f) (location n))))
         (cons n f) ) )

     If no return type is given, `void' is assumed. This macro expands
     into one of the `foreign-lambda*', `foreign-code' or
     `foreign-value' forms.


File: chicken.info,  Node: Foreign type specifiers,  Next: Embedding,  Prev: Accessing external objects,  Up: Interface to external functions and variables

6.2 Foreign type specifiers
===========================

Here is a list of valid foreign type specifiers:

`scheme-object'
     An arbitrary Scheme data object (immediate or non-immediate).

`bool'
     As argument: any value (`#f' is false, anything else is true).  As
     result: anything different from 0 and the `NULL'-pointer is `#t'.

`byte unsigned-byte'
     A byte.

`char unsigned-char'
     A character.

`short unsigned-short'
     A short integer number.

`int unsigned-int'

`int32 unsigned-int32'
     An small integer number in fixnum range (at least 30 bit).

`integer unsigned-integer'

`integer32 unsigned-integer32'

`integer64'
     Either a fixnum or a flonum in the range of a (unsigned) machine
     "int" or with 32/64 bit width.

`long unsigned-long'
     Either a fixnum or a flonum in the range of a (unsigned) machine
     "long" or with 32 bit width.

`float double'
     A floating-point number. If an exact integer is passed as an
     argument, then it is automatically converted to a float.

`number'
     A floating-point number. Similar to `double', but when used as a
     result type, then either an exact integer or a floating-point
     number is returned, depending on whether the result fits into an
     exact integer or not.

`symbol'
     A symbol, which will be passed to foreign code as a
     zero-terminated string.  When declared as the result of foreign
     code, the result should be a string and a symbol with the same
     name will be interned in the symbol table (and returned to the
     caller).

`scheme-pointer'
     An untyped pointer to the contents of a non-immediate Scheme object
     (not allowed as return type).  The value `#f' is also allowed and
     is passed as a `NULL' pointer.  Don't confuse this type with
     `(pointer ...)' which means something different (a machine-pointer
     object).

`nonnull-scheme-pointer'
     As `pointer', but guaranteed not to be `#f'.  Don't confuse this
     type with `(nonnull-pointer ...)' which means something different
     (a machine-pointer object).

`c-pointer'
     An untyped operating-system pointer or a locative.  The value `#f'
     is also allowed and is passed as a `NULL' pointer.  If uses as the
     type of a return value, a `NULL' pointer will be returned as `#f'.

`nonnull-c-pointer'
     As `c-pointer', but guaranteed not to be `#f/NULL'.

`scheme-or-c-pointer'
     An untyped pointer. If the argument is a machine-pointer object,
     the wrapped C pointer will be passed. If it is any other object,
     then this type is treated as `scheme-pointer'.

     Not allowed as a result type.

`[nonnull-] byte-vector'
     A byte-vector object, passed as a pointer to its contents.
     Arguments of type `byte-vector' may optionally be `#f', which is
     passed as a NULL pointer.  This is not allowed as a return type.

`[nonnull-] u8vector'
`[nonnull-] u16vector'
`[nonnull-] u32vector'
`[nonnull-] s8vector'
`[nonnull-] s16vector'
`[nonnull-] s32vector'
`[nonnull-] f32vector'
`[nonnull-] f64vector'
     A SRFI-4 number-vector object, passed as a pointer to its
     contents. Arguments of type `byte-vector' may optionally be `#f',
     which is passed as a NULL pointer.  These are not allowed as
     return types.

`c-string'
     A C string (zero-terminated). The value `#f' is also allowed and
     is passed as a `NULL' pointer. If uses as the type of a return
     value, a `NULL' pointer will be returned as `#f'. Note that the
     string is copied (with a zero-byte appended) when passed as an
     argument to a foreign function. Also a return value of this type
     is copied into garbage collected memory.

`nonnull-c-string'
     As `c-string', but guaranteed not to be `#f/NULL'.

`[nonnull-] c-string*'
     Similar to `[nonnull-]c-string', but if used as a result-type, the
     pointer returned by the foreign code will be freed (using the
     C-libraries `free()') after copying. This type specifier is not
     valid as a result type for callbacks defined with
     `define-external'.

`void'
     Specifies an undefined return value. Not allowed as argument type.

`(const TYPE)'
     The foreign type `TYPE' with an additional `const' specifier.

`(enum NAME)'
     An enumeration type. Handled internally as an `integer'.

`(pointer TYPE)'

`(c-pointer TYPE)'
     An operating-system pointer or a locative to an object of `TYPE'.

`(nonnull-pointer TYPE)'

`(nonnull-c-pointer TYPE)'
     As `(pointer TYPE)', but guaranteed not to be `#f/NULL'.

`(ref TYPE)'
     A C++ reference type. Reference types are handled the same way as
     pointers inside Scheme code.

`(struct NAME)'
     A struct of the name `NAME', which should be a string. Structs can
     not be directly passed as arguments to foreign function, neither
     can they be result values. Pointers to structs are allowed, though.

`(template TYPE ARGTYPE ...)'
     A C++ template type. For example `vector<int>' would be specified
     as `(template "vector" int)'. Template types can not be directly
     passed as arguments or returned as results.

`(union NAME)'
     A union of the name `NAME', which should be a string. Unions can
     not be directly passed as arguments to foreign function, neither
     can they be result values. Pointers to unions are allowed, though.

`(instance CNAME SCHEMECLASS)'
     A pointer to a C++ class instance. `CNAME' should designate the
     name of the C++ class, and `SCHEMECLASS' should be the class that
     wraps the instance pointer. Normally `SCHEMECLASS' should be a
     subclass of `<c++-object>'.

`(instance-ref CNAME SCHEMECLASS)'
     A reference to a C++ class instance.

`(function RESULTTYPE (ARGUMENTTYPE1 ... [...]) [CALLCONV])'
     A function pointer. `CALLCONV' specifies an optional calling
     convention and should be a string. The meaning of this string is
     entirely platform dependent.  The value `#f' is also allowed and
     is passed as a `NULL' pointer.


   Foreign types are mapped to C types in the following manner:

`bool'
     int

`[unsigned-]char'
     [unsigned] char

`[unsigned-]short'
     [unsigned] short

`[unsigned-]int'
     [unsigned] int

`[unsigned-]integer'
     [unsigned] int

`[unsigned-]long'
     [unsigned] long

`float'
     float

`double'
     double

`number'
     double

`[nonnull-]pointer'
     void *

`[nonnull-]c-pointer'
     void *

`[nonnull-]byte-vector'
     unsigned char *

`[nonnull-]u8vector'
     unsigned char *

`[nonnull-]s8vector'
     char *

`[nonnull-]u16vector'
     unsigned short *

`[nonnull-]s16vector'
     short *

`[nonnull-]u32vector'
     uint32_t *

`[nonnull-]s32vector'
     int32_t *

`[nonnull-]f32vector'
     float *

`[nonnull-]f64vector'
     double *

`[nonnull-]c-string'
     char *

`symbol'
     char *

`void'
     void

`([nonnull-]pointer TYPE)'
     TYPE *

`(enum NAME)'
     enum NAME

`(struct NAME)'
     struct NAME

`(ref TYPE)'
     TYPE &

`(template T1 T2 ...)'
     T1<T2, ...>

`(union NAME)'
     union NAME

`(function RTYPE (ATYPE ...) [CALLCONV])'
     [CALLCONV] RTYPE (*)(ATYPE, ...)

`(instance CNAME SNAME)'
     CNAME *

`(instance-ref CNAME SNAME)'
     CNAME &


File: chicken.info,  Node: Embedding,  Next: Callbacks,  Prev: Foreign type specifiers,  Up: Interface to external functions and variables

6.3 Embedding
=============

Compiled Scheme files can be linked with C code, provided the Scheme
code was compiled in "embedded" mode by passing `-DC_EMBEDDED' to the C
compiler (this will disable generation of a `main()' function). `csc'
will do this, when given the `-embedded' option. Alternatively pass
`-embedded' to `csc'.

   The following C API is available:

 -- C function: void CHICKEN_parse_command_line (int argc, char
          *argv[], int *heap, int *stack int *symbols)
     Parse the programs command-line contained in `argc' and `argv' and
     return the heap-, stack- and symbol table limits given by runtime
     options of the form `-:...', or choose default limits. The library
     procedure `argv' can access the command-line only if this function
     has been called by the containing application.

 -- C function: int CHICKEN_initialize (int heap, int stack, int
          symbols, void *toplevel)
     Initializes the Scheme execution context and memory. `heap' holds
     the number of bytes that are to be allocated for the secondary
     heap. `stack' holds the number of bytes for the primary heap.
     `symbols' contains the size of the symbol table. Passing `0' to
     one or more of these parameters will select a default size.
     `toplevel' should be a pointer to the toplevel entry point
     procedure. You should pass `C_toplevel' here. In any subsequent
     call to `CHICKEN_run' you can simply pass `NULL'.  Calling this
     function more than once has no effect. If enough memory is
     available and initialization was successful, then `1' is returned,
     otherwise this function returns `0'.

 -- C function: C_word CHICKEN_run (void *toplevel)
     Starts the Scheme program. Call this function once to execute all
     toplevel expressions in your compiled Scheme program. If the
     runtime system was not initialized before, then
     `CHICKEN_initialize' is called with default sizes.  `toplevel' is
     the toplevel entry-point procedure, you usually pass `C_toplevel'
     here.  The result value is the continuation that can be used to
     re-invoke the Scheme code from the point after it called
     `return-to-host' (see below).

     If you just need a Scheme interpreter, you can also pass
     `CHICKEN_default_toplevel' as the toplevel procedure, which just
     uses the default library units.

   Once `CHICKEN_run' has been called, Scheme code is executing until
all toplevel expressions have been evaluated or until `return-to-host'
is called inside the Scheme program.

 -- procedure: return-to-host
          (return-to-host)
     Exits the Scheme code and returns to the invoking context that
     called `CHICKEN_run' or `CHICKEN_continue'.

   After `return-to-host' has been executed and once `CHICKEN_run'
returns, you can invoke callbacks which have been defined with
`define-external'.  The `eval' library unit also provides "boilerplate"
callbacks, that simplify invoking Scheme code embedded in a C or C++
application a lot.

 -- C macro: int CHICKEN_eval (C_word exp, C_word *result)
     Evaluates the Scheme object passed in `exp', writing the result
     value to `result'.  The return value is 1 if the operation
     succeeded, or 0 if an error occurred. Call
     `CHICKEN_get_error_message' to obtain a description of the error.

 -- C macro: int CHICKEN_eval_string (char *str, C_word *result)
     Evaluates the Scheme expression passed in the string `str',
     writing the result value to `result'.

 -- C macro: int CHICKEN_eval_to_string (C_word exp, char *result, int
          size)
     Evaluates the Scheme expression passed in `exp', writing a textual
     representation of the result into `result'. `size' should specify
     the maximal size of the result string.

 -- C macro: int CHICKEN_eval_string_to_string (char *str, char
          *result, int size)
     Evaluates the Scheme expression passed in the string `str',
     writing a textual representation of the result into `result'.
     `size' should specify the maximal size of the result string.

 -- C macro: int CHICKEN_apply (C_word func, C_word args, C_word
          *result)
     Applies the procedure passed in `func' to the list of arguments
     `args', writing the result value to `result'.

 -- C macro: int CHICKEN_apply_to_string (C_word func, C_word args,
          char *result, int size)
     Applies the procedure passed in `func' to the list of arguments
     `args', writing a textual representation of the result into
     `result'.

 -- C macro: int CHICKEN_read (char *str, C_word *result)
     Reads a Scheme object from the string `str', writing the result
     value to `result'.

 -- C macro: int CHICKEN_load (char *filename)
     Loads the Scheme file `filename' (either in source form or
     compiled).

 -- C macro: void CHICKEN_get_error_message (char *result, int size)
     Returns a textual description of the most recent error that
     occurred in executing embedded Scheme code.

 -- C macro: int CHICKEN_yield (int *status)
     If threads have been spawned during earlier invocations of
     embedded Scheme code, then this function will run the next
     scheduled thread for one complete time-slice. This is useful, for
     example, inside an "idle" handler in a GUI application with
     background Scheme threads. Note that the `srfi-18' library unit
     has to be linked in for this.

   An example:


% cat x.scm
;;; x.scm

(define (bar x) (gc) (* x x))

(define-external (baz (int i)) double
  (sqrt i)

% cat y.c
/* y.c */

#include "chicken.h"
#include <assert.h>

extern double baz(int);

int main() {
  char buffer[ 256 ];
  int status;
  C_word val = C_SCHEME_UNDEFINED;
  C_word *data[ 1 ];

  data[ 0 ] = &val;

  CHICKEN_run(C_toplevel);

  status = CHICKEN_read("(bar 99)", &val);
  assert(status);

  C_gc_protect(data, 1);

  printf("data: %08x\n", val);

  status = CHICKEN_eval_string_to_string("(bar)", buffer, 255);
  assert(!status);

  CHICKEN_get_error_message(buffer, 255);
  printf("ouch: %s\n", buffer);

  status = CHICKEN_eval_string_to_string("(bar 23)", buffer, 255);
  assert(status);

  printf("-> %s\n", buffer);
  printf("data: %08x\n", val);

  status = CHICKEN_eval_to_string(val, buffer, 255);
  assert(status);
  printf("-> %s\n", buffer);

  printf("->` %g\n", baz(22));

  return 0;
}

% csc x.scm y.c -embedded

   It is also possible to re-enter the computation following the call
to `return-to-host' by calling `CHICKEN_continue':

 -- C function: C_word CHICKEN_continue (C_word k)
     Re-enters Scheme execution. `k' is the continuation received from
     the previous invocation of `CHICKEN_run' or `CHICKEN_continue'.
     When `return-to-host' is called again, this function returns
     another continuation that can be used to restart again.

     Note: if you invoke callbacks prior to calling `CHICKEN_continue',
     make sure that the continuation is not reclaimed by garbage
     collection. This can be avoided by using `C_gc_protect' or
     gc-roots.

   Another example:


% cat x.scm
(require-extension srfi-18)

(define m (make-mutex))

(define (t)
  (mutex-lock! m)
  (thread-sleep! 1)
  (print (thread-name (current-thread)))
  (mutex-unlock! m)
  (t) )

(thread-start! (make-thread t 'PING!))
(thread-start! (make-thread t 'PONG!))

(let loop ()
  (return-to-host)
  (thread-yield!)
  (loop) )

% cat y.c
#include "chicken.h"

int main()
{
  C_word k = CHICKEN_run(C_toplevel);

  for(;;)
    k = CHICKEN_continue(k);

  return 0;
}

% csc x.scm y.c -embedded

   A simpler interface For handling GC-safe references to Scheme data
are the so called "gc-roots":

 -- C function: void* CHICKEN_new_gc_root ()
     Returns a pointer to a "GC root", which is an object that holds a
     reference to a Scheme value that will always be valid, even after
     a garbage collection. The content of the gc root is initialized to
     an unspecified value.

 -- C function: void CHICKEN_delete_gc_root (void *root)
     Deletes the gc root.

 -- C macro: C_word CHICKEN_gc_root_ref (void *root)
     Returns the value stored in the gc root.

 -- C macro: void CHICKEN_gc_root_set (void *root, C_word value)
     Sets the content of the GC root to a new value.

   Sometimes it is handy to access global variables from C code:

 -- C function: void* CHICKEN_global_lookup (char *name)
     Returns a GC root that holds the global variable with the name
     `name'. If no such variable exists, `NULL' is returned.

 -- C function: C_word CHICKEN_global_ref (void *global)
     Returns the value of the global variable referenced by the GC root
     `global'.

 -- C function: void CHICKEN_global_set (void *global, C_word value)
     Sets the value of the global variable referenced by the GC root
     `global' to `value'.


File: chicken.info,  Node: Callbacks,  Next: Locations,  Prev: Embedding,  Up: Interface to external functions and variables

6.4 Callbacks
=============

To enable an external C function to call back to Scheme, the form
`foreign-safe-lambda' (or `foreign-safe-lambda*') has to be used. This
generates special code to save and restore important state information
during execution of C code. There are two ways of calling Scheme
procedures from C: the first is to invoke the runtime function
`C_callback' with the closure to be called and the number of arguments.
The second is to define an externally visible wrapper function around
a Scheme procedure with the `define-external' form.

   Note: the names of all functions, variables and macros exported by
the CHICKEN runtime system start with "`C_'". It is advisable to use a
different naming scheme for your own code to avoid name clashes.
Callbacks (defined by `define-external') do not capture the lexical
environment.

   Non-local exits leaving the scope of the invocation of a callback
from Scheme into C will not remove the C call-frame from the stack (and
will result in a memory leak).

 -- syntax: define-external
          (define-external [QUALIFIERS] (NAME (ARGUMENTTYPE1 VARIABLE1) ...) RETURNTYPE BODY ...)
          (define-external NAME TYPE [INIT])
     The first form defines an externally callable Scheme procedure.
     `NAME' should be a symbol, which, when converted to a string,
     represents a legal C identifier. `ARGUMENTTYPE1 ...' and
     `RETURNTYPE' are foreign type specifiers for the argument variables
     `VAR1 ...' and the result, respectively.  `QUALIFIERS' is an
     optional qualifier for the foreign procedure definition, like
     `__stdcall'.


     (define-external (foo (c-string x)) int (string-length x))

     The second form of `define-external' can be used to define
     variables that are accessible from foreign code. It declares a
     global variable named by the symbol `NAME' that has the type
     `TYPE'. `INIT' can be an arbitrary expression that is used to
     initialize the variable. `NAME' is accessible from Scheme just
     like any other foreign variable defined by
     `define-foreign-variable'.


     (define-external foo int 42)
     ((foreign-lambda* int ()
       "C_return(foo);"))           ==> 42

     Note: don't be tempted to assign strings or bytevectors to
     external variables. Garbage collection moves those objects around,
     so it is very bad idea to assign pointers to heap-data. If you
     have to do so, then copy the data object into statically allocated
     memory (for example by using `object-evict').

     Results of type `scheme-object' returned by `define-external' are
     always allocated in the secondary heap, that is, not in the stack.


 -- C function: C_word C_callback (C_word closure, int argc)
     This function can be used to invoke the Scheme procedure `closure'.
     `argc' should contain the number of arguments that are passed to
     the procedure on the temporary stack. Values are put onto the
     temporary stack with the `C_save' macro.

 -- C function: void C_callback_adjust_stack_limits (C_word *ptr)
     The runtime-system uses the stack as a special allocation area and
     internally holds pointers to estimated limits to distinguish
     between Scheme data objects inside the stack from objects outside
     of it.  If you invoke callbacks at wildly differing stack-levels,
     these limits may shift from invocation to invocation. Callbacks
     defined with `define-external' will perform appropriate
     adjustments automatically, but if you invoke `C_callback'
     manually, you should perform a `C_callback_adjust_stack_limits' to
     make sure the internal limits are set properly. `ptr' should point
     to some data object on the stack. The call will make sure the
     limits are adjusted so that the value pointed to by `ptr' is
     located in the stack.


File: chicken.info,  Node: Locations,  Next: Other support procedures,  Prev: Callbacks,  Up: Interface to external functions and variables

6.5 Locations
=============

It is also possible to define variables containing unboxed C data, so
called _locations_. It should be noted that locations may only contain
simple data, that is: everything that fits into a machine word, and
double-precision floating point values.

 -- syntax: define-location
          (define-location NAME TYPE [INIT])
     Identical to `(define-external NAME TYPE [INIT])', but the variable
     is not accessible from outside of the current compilation unit (it
     is declared `static').


 -- syntax: let-location
          (let-location ((NAME TYPE [INIT]) ...) BODY ...)
     Defines a lexically bound location.


 -- syntax: location
          (location NAME)
          (location X)
     This form returns a pointer object that contains the address of
     the variable `NAME'.  If the argument to `location' is not a
     location defined by `define-location', `define-external' or
     `let-location', then


     (location X)

     is essentially equivalent to


     (make-locative X)

     (See the manual chapter or `locatives' for more information about
     locatives.

     Note that `(location X)' may be abbreviated as `#$X'.


     (define-external foo int)
     ((foreign-lambda* void (((pointer int) ip)) "*ip = 123;")
       (location foo))
     foo                                                                               ==> 123

     This facility is especially useful in situations, where a C
     function returns more than one result value:


     #>
     #include <math.h>
     <#

     (define modf
       (foreign-lambda double "modf" double (pointer double)) )

     (let-location ([i double])
       (let ([f (modf 1.99 (location i))])
         (print "i=" i ", f=" f) ) )

   `location' returns a value of type `c-pointer', when given the name
of a callback-procedure defined with `define-external'.


File: chicken.info,  Node: Other support procedures,  Next: The Easy Foreign Function Interface,  Prev: Locations,  Up: Interface to external functions and variables

6.6 Other support procedures
============================

 -- procedure: argc+argv
          (argc+argv)
     Returns two values: an integer and a foreign-pointer object
     representing the `argc' and `argv' arguments passed to the current
     process.


File: chicken.info,  Node: The Easy Foreign Function Interface,  Next: C interface,  Prev: Other support procedures,  Up: Interface to external functions and variables

6.7 The _Easy_ Foreign Function Interface
=========================================

The compiler contains a builtin parser for a restricted subset of C and
C++ that allows the easy generation of foreign variable declarations,
procedure bindings and C++ class wrappers. The parser is invoked via
the declaration-specifier `foreign-parse', which extracts binding
information and generates the necessary code. An example:


(foreign-declare "
#include <math.h>

#define my_pi 3.14
")

(foreign-parse "extern double sin(double);")

(print (sin 3.14))

   The parser would generate code that is equivalent to


(foreign-declare "
#include <math.h>

#define my_pi 3.14
")

(define-foreign-variable my_pi float "my_pi")
(define sin (foreign-lambda double "sin" double))

   Note that the read syntax `#>[SPEC] ... <#' provides a somewhat
simpler way of using the parser. The example above could alternatively
be expressed as


#>!
#define my_pi 3.14

extern double sin(double);
<#

(print (sin 3.14))

   Another example, here using C++. Consider the following class:


// file: foo.h

class Foo {
 private:
  int x_;
 public:
  Foo(int x);
  void setX(int x);
  int getX();
};

   To generate a wrapper class that provides generic functions for the
constructor and the `setX' and `getX' methods, we can use the following
class definition:


; file: test-foo.scm

(require-extension tinyclos)

#>!
#include "Foo.h"
<#

(define x (make <Foo> 99))
(print (getX x))              ; prints ``99''
(setX x 42)
(print (getX x))              ; prints ``42''
(destroy x)

   Provided the file `foo.o' contains the implementation of the class
`Foo', the given example could be compiled like this (assuming a UNIX
like environment):


% csc test-foo.scm foo.o -c++

   Here is another example, a minimal "Hello world" application for QT.
We can see the three different ways of embedding C/C++ code in Scheme:


; compile like this:
; csc hello.scm -c++ -C -IQTDIR/include -L "-LQTDIR/lib -lqt"

(require-extension tinyclos)

; Include into generated code, but don't parse:
#>
#include <qapplication.h>
#include <qpushbutton.h>
<#

; Parse but don't embed: we only want wrappers for a few classes:
#>?
class QWidget
{
public:
  void resize(int, int);
  void show();
};

class QApplication
{
public:
  QApplication(int, char **);
  ~QApplication();
  void setMainWidget(QWidget *);
  void exec();
};

class QPushButton : public QWidget
{
public:
  QPushButton(char *, QWidget *);
  ~QPushButton();
}
<#

(define a (apply make <QApplication> (receive (argc+argv))))
(define hello (make <QPushButton> "hello world!" #f))
(resize hello 100 30)
(setMainWidget a hello)
(show hello)
(exec a)
(destroy hello)
(destroy a)

* Menu:

* #> ... <# Syntax::
* General operation::
* Pseudo declarations::
* Grammar::
* C notes::
* C++ notes::


File: chicken.info,  Node: #> ... <# Syntax,  Next: General operation,  Up: The Easy Foreign Function Interface

6.7.1 `#> ... <#' Syntax
------------------------

Occurrences of the special read syntax `#>[SPEC ...] ...<#' will be
handled according to `SPEC':

   If `SPEC' is the `?' character, the text following up to the next
`<#' will be processed as a `(declare (foreign-parse "..."))'
declaration (the code will be processed by the FFI parser described in
this section).

   If `SPEC' is the `!' character, the text will be embedded as


(foreign-parse(declare "...")

   It will be both included verbatim in the declaration section of the
generated C/C++ file and processed by the FFI parser.

   If `SPEC' is the `:' character, the text will be so it will be
executed at the location where it appears.

   If `SPEC' is a list of the form `(TAG ...)', then each `TAG' (which
should be a symbol) specifies what should be done with the text:

`declare'
     (foreign-declare "...")

`parse'
     (foreign-parse "...")

`execute'
     (foreign-code "...")

   If any other character follows the `#>', then the complete text will
be included verbatim in the declaration part of the generated file (as
in a `foreign-declare' form).


File: chicken.info,  Node: General operation,  Next: Pseudo declarations,  Prev: #> ... <# Syntax,  Up: The Easy Foreign Function Interface

6.7.2 General operation
-----------------------

The parser will generally perform the following functions

   1) Translate macro, enum-definitions and constants into
`define-foreign-variable' or `define-constant' forms

   2) Translate function prototypes into `foreign-lambda' forms

   3) Translate variable declarations into accessor procedures

   4) Handle basic preprocessor operations

   5) Translate simple C++ class definitions into TinyCLOS wrapper
classes and methods

   Basic token-substitution of macros defined via `#define' is
performed. The preprocessor commands `#ifdef', `#ifndef', `#else',
`#endif', `#undef' and `#error' are handled. The preprocessor commands
`#if' and `#elif' are not supported and will signal an error when
encountered by the parser, because C expressions (even if constant) are
not parsed.  The preprocessor command `#pragma' is allowed but will be
ignored.

   During processing of `foreign-parse' declarations the macro
`CHICKEN' is defined (similar to the C compiler option `-DCHICKEN').

   Macro- and type-definitions are available in subsequent
`foreign-parse' declarations.  C variables declared generate a
procedure with zero or one argument with the same name as the variable.
When called with no arguments, the procedure returns the current value
of the variable. When called with an argument, then the variable is set
to the value of that argument.  C and C++ style comments are supported.
Variables declared as `const' will generate normal Scheme variables,
bound to the initial value of the variable.

   Function-, member-function and constructor/destructor definitions
may be preceded by the `___safe' qualifier, which marks the function as
(possibly) performing a callback into Scheme. If a wrapped function
calls back into Scheme code, and `___safe' has not been given very
strange and hard to debug problems will occur. For backward
compatibilty, `___callback' is also allowed in place of `___safe'.

   Functions and member functions prefixed with `___discard' and a
result type that maps to a Scheme string (`c-string'), will have their
result type changed to `c-string*' instead.

   Constants (as declared by `#define' or `enum') are not visible
outside of the current Compilation units unless the `export_constants'
pseudo declaration has been used.  Only numeric or character constants
are directly supported.

   When given the option `-ffi', CHICKEN will compile a C/C++ file in
"Scheme" mode, that is, it wraps the C/C++ source inside `#>! ... <#'
and compiles it while generating Scheme bindings for exported
definitions.

   Function-arguments may be preceded by `___in', `___out' and
`___inout' qualifiers to specify values that are passed by reference to
a function, or returned by reference. Only basic types (booleans,
numbers and characters) can be passed using this method.  During the
call a pointer to a temporary piece of storage containing the initial
value (or a random value, for `___out' parameters) will be allocated
and passed to the wrapped function. This piece of storage is subject to
garbage collection and will move, should a callback into Scheme occur
that triggers a garbage collection. Multiple `__out' and `___inout'
parameters will be returned as multiple values, preceded by the normal
return value of thhe function (if not `void'). Here is a simple example:


#>!
#ifndef CHICKEN
#include <math.h>
#endif

double modf(double x, ___out double *iptr);
<#

(let-values ([(frac int) (modf 33.44)])
  ...)

   Function-arguments may be preceded by `___length(ID)', where `ID'
designates the name of another argument that must refer to a number
vector or string argument. The value of the former argument will be
computed at run-time and thus can be omitted:


#>!
(require-extension srfi-4)

double sumarray(double *arr, ___length(arr) int len)
{
  double sum = 0;

  while(len--) sum += *(arr++);

  return sum;
}
<#

(print (sumarray (f64vector 33 44 55.66)))

   The length variable may be positioned anywhere in the argument list.
Length markers may only be specified for arguments passed as SRFI-4
byte-vectors, byte-vectors (as provided by the `lolevel' library unit)
or strings.

   Structure and union definitions containing actual field declarations
generate getter procedures (and setter procedures when declared
`___mutable' or the `mutable_fields' pseudo declaration has been used)
The names of these procedures are computed by concatenating the struct
(or union) name, a hyphen (`"-"') and the field name, and the string
`"-set!"', in the case of setters. Structure definitions with fields
may not be used in positions where a type specifier is normally
expected. The field accessors operate on struct/union pointers only.
Additionally a zero-argument procedure named `make-<structname>' will
be generated that allocates enough storage to hold an instance of the
structure (or union).  Prefixing the definition with `___abstract' will
omit the creation procedure.


#>!
struct My_struct { int x; ___mutable float y; };

typedef struct My_struct My_struct;

My_struct *make_struct(int x, float y)
{
  My_struct *s = (My_struct *)malloc(sizeof(My_struct));
  s->x = x;
  s->y = y;
  return s;
}
<#

   will generate the following definitions:

     (make-My_struct) -> PTR
     (My_struct-x PTR) -> INT
     (My_struct-y PTR) -> FLOAT
     (My_struct-y-set! PTR FLOAT)
     (make_struct INT FLOAT) -> PTR

   Nested structs or unions are not supported (but pointers to nested
structs/unions are).

   All specially handled tokens preceded with `___' are defined as C
macros in the headerfile `chicken.h' and will usually expand into
nothing, so they don't invalidate the processed source code.

   C++ `namespace' declarations of the form `namespace NAME { ... }'
recognized but will be completely ignored.

   Keep in mind that this is not a fully general C/C++ parser. Taking
an arbitrary headerfile and feeding it to CHICKEN will in most cases
not work or generate riduculuous amounts of code. This FFI facility is
for carefully written headerfiles, and for declarations directly
embedded into Scheme code.


File: chicken.info,  Node: Pseudo declarations,  Next: Grammar,  Prev: General operation,  Up: The Easy Foreign Function Interface

6.7.3 Pseudo declarations
-------------------------

Using the `___declare(DECL, VALUE)' form, pseudo declarations can be
embedded into processed C/C++ code to provide additional control over
the wrapper generation. Pseudo declarations will be ignored when
processed by the system's C/C++ compiler.

   * abstract [values: <string>] Marks the C++ class given in
     `<string>' as being abstract, i.e. no constructor will be defined.
     Alternatively, a class definition may be prefixed with
     `___abstract'.

   * class_finalizers [values: yes, no] Automatically generates calls
     to `set-finalizer!' so that any unused references to instances of
     subsequently defined C++ class wrappers will be destroyed. This
     should be used with care: if the embedded C++ object which is
     represented by the reclaimed TinyCLOS instance is still in use in
     foreign code, then unpredictable things will happen.

   * mutable_fields [values: yes, no] Specifies that all struct or
     union fields should generate setter procedures (the default is to
     generate only setter procedures for fields declared `___mutable').

   * destructor_name [values: <string>] Specifies an alternative name
     for destructor methods (the default is `destroy'.

   * export_constants [values: yes (default), no] Define a global
     variable for constant-declarations (as with `#define' or `enum'),
     making the constant available outside the current compilation
     unit. Use the values `yes'/`1' for switching constant export on,
     or `no'/`0' for switching it off.

   * exception_handler [values: <string>] Defines C++ code to be
     executed when an exception is triggered inside a C++ class member
     function. The code should be one or more `catch' forms that
     perform any actions that should be taken in case an exception is
     thrown by the wrapped member function:


     #>!
     ___declare(exception_handler, "catch(...) { return 0; }")

     class Foo {
      public:
       Foo *bar(bool f) { if(f) throw 123; else return this; }
     };
     <#

     (define f1 (make <Foo>))
     (print (bar f1 #f))
     (print (bar f1 #t))

     will print `<Foo>' and `#f', respectively.

   * full_specialization [values: yes, no] Enables "full
     specialization" mode. In this mode all wrappers for functions,
     member functions and static member functions are created as fully
     specialized TinyCLOS methods. This can be used to handle
     overloaded C++ functions properly. Only a certain set of foreign
     argument types can be mapped to TinyCLOS classes, as listed in the
     following table:

    `char'
          <char>

    `bool'
          <bool>

    `c-string'
          <string>

    `unsigned-char'
          <exact>

    `byte'
          <exact>

    `unsigned-byte'
          <exact>

    `[unsigned-]int'
          <exact>

    `[unsigned-]short'
          <exact>

    `[unsigned-]long'
          <integer>

    `[unsigned-]integer'
          <integer>

    `float'
          <inexact>

    `double'
          <inexact>

    `number'
          <number>

    `(enum _)char'
          <exact>

    `(const T)char'
          (as T)

    `(function ...)'
          <pointer>

    `c-pointer'
          <pointer>

    `(pointer _)'
          <pointer>

    `(c-pointer _)'
          <pointer>

    `u8vector'
          <u8vector>

    `s8vector'
          <s8vector>

    `u16vector'
          <u16vector>

    `s16vector'
          <s16vector>

    `u32vector'
          <u32vector>

    `s32vector'
          <s32vector>

    `f32vector'
          <f32vector>

    `f64vector'
          <f64vector>

     All other foreign types are specialized as `<top>'.

     Full specialization can be enabled globally, or only for sections
     of code by enclosing it in


     ___declare(full_specialization, yes)
     ...
     int foo(int x);
     int foo(char *x);
     ...
     ___declare(full_specialization, no)

     Alternatively, member function definitions may be prefixed by
     `___specialize' for specializing only specific members.

   * prefix [values: <string>]

     Sets a prefix that should be be added to all generated Scheme
     identifiers. For example


     ___declare(prefix, "mylib:")
     #define SOME_CONST     42

     would generate the following code:


     (define-constant mylib:SOME_CONST 42)

     To switch prefixing off, use the values `no' or `0'. Prefixes are
     not applied to Class names.

   * rename [value: <string>]

     Defines to what a certain C/C++ name should be renamed. The value
     for this declaration should have the form
     `"<c-name>;<scheme-name>"', where `<c-name>' specifies the C/C++
     identifier occurring in the parsed text and `<scheme-name>' gives
     the name used in generated wrapper code.

   * scheme [value: <string>]

     Embeds the Scheme expression `<string>' in the generated Scheme
     code.

   * substitute [value: <string>]

     Declares a name-substitution for all generated Scheme identifiers.
     The value for this declaration should be a string containing a
     regular expression and a replacement string (separated by the `;'
     character):


     ___declare(substitute, "^SDL_;sdl:")

     extern void SDL_Quit();

     generates


     (define sdl:Quit
       (foreign-lambda integer "SDL_Quit") )

   * transform [values: <string>]

     Defines an arbitrary transformation procedure for names that match
     a given regular expression.  The value should be a string
     containing a regular expression and a Scheme expression that
     evaluates to a procedure of one argument. If the regex matches,
     the procedure will be called at compile time with the match-result
     (as returned by `string-match') and should return a string with
     the desired transformations applied:


     (require-for-syntax 'srfi-13)

     #>!
     ___declare(transform, "([A-Z]+)_(.*);(lambda (x) (string-append (cadr x) \"-\" (string-downcase (caddr x))))")

     void FOO_Bar(int x) { return x * 2; }
     <#

     (print (FOO-bar 33))

   * default_renaming [value: <string>]

     Chooses a standard name-transformation, converting underscores
     (`_') to hyphens (`-') and transforming "CamelCase" into
     "camel-case". All uppercase characters are also converted to
     lowercase.  The result is prefixed with the argument string
     (equivalent to the `prefix' pseudo declaration).

   * type [value: <string>]

     Declares a foreign type transformation, similar to
     `define-foreign-type'.  The value should be a list of two to four
     items, separated by the `;' character: a C typename, a Scheme
     foreign type specifier and optional argument- and result-value
     conversion procedures.


     ;;;; foreign type that converts to unicode (assumes 4-byte wchar_t):
     ;
     ; - Note: this is rather kludgy and is only meant to demonstrate the `type'
     ;         pseudo-declaration

     (require-extension srfi-4)

     (define mbstowcs (foreign-lambda int "mbstowcs" nonnull-u32vector c-string int))

     (define (str->ustr str)
       (let* ([len (string-length str)]
              [us (make-u32vector (add1 len) 0)] )
         (mbstowcs us str len)
         us) )

     #>!
     ___declare(type, "unicode;nonnull-u32vector;str->ustr")

     static void foo(unicode ws)
     {
       printf("\"%ls\"\n", ws);
     }
     <#

     (foo "this is a test!")

   * opaque [value: <string>]

     Similar to `type', but provides automatic argument- and result
     conversions to wrap a value into a structure:


     #>?
     ___declare(opaque, "myfile;(pointer \"FILE\")")

     myfile fopen(char *, char *);
     <#

     (fopen "somefile" "r")   ==> <myfile>

     `___declare(opaque, "TYPENAME;TYPE")' is basically equivalent to
     `___declare(type, "TYPENAME;TYPE;TYPE->RECORD;RECORD->TYPE")' where
     `TYPE->RECORD' and `RECORD->TYPE' are compiler-generated conversion
     functions that wrap objects of type `TYPE' into a record and back.



File: chicken.info,  Node: Grammar,  Next: C notes,  Prev: Pseudo declarations,  Up: The Easy Foreign Function Interface

6.7.4 Grammar
-------------

The parser understand the following grammar:


PROGRAM = PPCOMMAND
        | DECLARATION ";"

PPCOMMAND = "#define" ID [TOKEN ...]
          | "#ifdef" ID
          | "#ifndef" ID
          | "#else"
          | "#endif"
          | "#undef" ID
          | "#error" TOKEN ...
          | "#include" INCLUDEFILE
          | "#import" INCLUDEFILE
          | "#pragma" TOKEN ...

DECLARATION = FUNCTION
            | VARIABLE
            | ENUM
            | TYPEDEF
            | CLASS
            | CONSTANT
            | STRUCT
            | NAMESPACE
            | "___declare" "(" PSEUDODECL "," <tokens> ")"

STRUCT = ("struct" | "union") ID ["{" {["___mutable"] TYPE {"*"} ID {"," {"*"} ID}} "}]

NAMESPACE = "namespace" ID "{" DECLARATION ... "}"

INCLUDEFILE = "\"" ... "\""
            | "<" ... ">"

FUNCTION = {"___callback" | "___safe" | "___specialize" | "___discard"} [STORAGE] TYPE ID "(" ARGTYPE "," ... ")" [CODE]
         | {"___callback" | "___safe" | "___specialize" | "___discard"} [STORAGE] TYPE ID "(" "void" ")" [CODE]

ARGTYPE = [IOQUALIFIER] TYPE [ID ["[" ... "]"]]

IOQUALIFIER = "___in" | "___out" | "___inout" | LENQUALIFIER

LENQUALIFIER = "___length" "(" ID ")"

VARIABLE = [STORAGE] ENTITY ["=" INITDATA]

ENTITY = TYPE ID ["[" ... "]"]

STORAGE = "extern" | "static" | "volatile" | "inline"

CONSTANT = "const" TYPE ID "=" INITDATA

PSEUDODECL = "export_constants"
           | "prefix"
           | "substitute"
           | "abstract"
           | "type"
           | "scheme"
           | "rename"
           | "transform"
           | "full_specialization"
           | "destructor_name"
           | "class_finalizers"
           | "exception_handler"
           | "mutable_fields"

ENUM = "enum" "{" ID ["=" (NUMBER | ID)] "," ... "}"

TYPEDEF = "typedef" TYPE ["*" ...] [ID]

TYPE = ["const"] BASICTYPE [("*" ... | "&" | "<" TYPE "," ... ">" | "(" "*" [ID] ")" "(" TYPE "," ... ")")]

BASICTYPE = ["unsigned" | "signed"] "int"
          | ["unsigned" | "signed"] "char"
          | ["unsigned" | "signed"] "short" ["int"]
          | ["unsigned" | "signed"] "long" ["int"]
          | ["unsigned" | "signed"] "___byte"
          | "size_t"
          | "float"
          | "double"
          | "void"
          | "bool"
          | "___bool"
          | "___scheme_value"
          | "___scheme_pointer"
          | "___byte_vector"
          | "___pointer" TYPE "*"
          | "C_word"
          | "___fixnum"
          | "___number"
          | "___symbol"
          | "___u32"
          | "___s32"
          | "___s64"
          | "__int64"
          | "int64_t"
          | "struct" ID
          | "union" ID
          | "enum" ID
          | ID

CLASS = ["___abstract"] "class" ID [":" [QUALIFIER] ID "," ...] "{" MEMBER ... "}"

MEMBER = [QUALIFIER ":"] ["virtual"] (MEMBERVARIABLE | CONSTRUCTOR | DESTRUCTOR | MEMBERFUNCTION)

MEMBERVARIABLE = TYPE ID ["=" INITDATA]

MEMBERFUNCTION = {"___callback" | "static" | "___specialize" | "___discard"} TYPE ID "(" ARGTYPE "," ... ")" ["const"] ["=" "0"] [CODE]
               | {"___callback" | "static" | "___specialize" | "___discard"} TYPE ID "(" "void" ")" ["const"] ["=" "0"] [CODE]

CONSTRUCTOR = ["___callback" | "___safe"] ["explicit"] ID "(" ARGTYPE "," ... ")" [BASECONSTRUCTORS] [CODE]

DESTRUCTOR = ["___callback" | "___safe"] "~" ID "(" ["void"] ")" [CODE]

QUALIFIER = ("public" | "private" | "protected")

NUMBER = <a C integer or floating-point number, in decimal, octal or hexadecimal notation>

INITDATA = <everything up to end of chunk>

BASECONSTRUCTORS = <everything up to end of chunk>

CODE = <everything up to end of chunk>

   The following table shows how argument-types are translated:

`[unsigned] char'
     char

`[unsigned] short'
     [unsigned-]short

`[unsigned] int'
     [unsigned-]integer

`[unsigned] long'
     [unsigned-]long

`___u32'
     unsigned-integer32

`___s32'
     integer32

`___s64'
     integer64

`int64_t'
     integer64

`__int64'
     integer64

`float'
     float

`double'
     double

`size_t'
     unsigned-integer

`bool'
     int

`___bool'
     int

`___fixnum'
     int

`___number'
     number

`___symbol'
     symbol

`___scheme_value'
     scheme-object

`C_word'
     scheme-object

`___scheme_pointer'
     scheme-pointer

`char *'
     c-string

`signed char *'
     s8vector

`[signed] short *'
     s16vector

`[signed] int *'
     s32vector

`[signed] long *'
     s32vector

`unsigned char *'
     u8vector

`unsigned short *'
     u16vector

`unsigned int *'
     u32vector

`unsigned long *'
     u32vector

`float *'
     f32vector

`double *'
     f64vector

`___byte_vector'
     byte-vector

`CLASS *'
     (instance CLASS <CLASS>)

`CLASS &'
     (instance-ref CLASS <CLASS>)

`TYPE *'
     (pointer TYPE)

`TYPE &'
     (ref TYPE)

`TYPE<T1, ...>'
     (template TYPE T1 ...)

`TYPE1 (*)(TYPE2, ...)'
     (function TYPE1 (TYPE2 ...))

   The following table shows how result-types are translated:

`void'
     void

`[unsigned] char'
     char

`[unsigned] short'
     [unsigned-]short

`[unsigned] int'
     [unsigned-]integer

`[unsigned] long'
     [unsigned-]long

`___u32'
     unsigned-integer32

`___s32'
     integer32

`___s64'
     integer64

`int64_t'
     integer64

`__int64'
     integer64

`float'
     float

`double'
     double

`size_t'
     unsigned-integer

`bool'
     bool

`___bool'
     bool

`___fixnum'
     int

`___number'
     number

`___symbol'
     symbol

`___scheme_value'
     scheme-object

`char *'
     c-string

`TYPE *'
     (pointer TYPE)

`TYPE &'
     (ref TYPE)

`TYPE<T1, ...>'
     (template TYPE T1 ...)

`TYPE1 (*)(TYPE2, ...)'
     (function TYPE1 (TYPE2 ...))

`CLASS *'
     (instance CLASS <CLASS>)

`CLASS &'
     (instance-ref CLASS <CLASS>)

   The `___pointer' argument marker disables automatic simplification
of pointers to numbers: normally arguments of type `int *' are handled
as SRFI-4 `s32vector' number vectors. To force treatment as a pointer
argument, precede the argument type with `___pointer'.


File: chicken.info,  Node: C notes,  Next: C++ notes,  Prev: Grammar,  Up: The Easy Foreign Function Interface

6.7.5 C notes
-------------

Foreign variable definitions for macros are not exported from the
current compilation unit, but definitions for C variables and functions
are.

   `foreign-parse' does not embed the text into the generated C file,
use `foreign-declare' for that (or even better, use the `#>! ... <#'
syntax which does both).

   Functions with variable number of arguments are not supported.


File: chicken.info,  Node: C++ notes,  Prev: C notes,  Up: The Easy Foreign Function Interface

6.7.6 C++ notes
---------------

Each C++ class defines a TinyCLOS class, which is a subclass of
`<c++-object>'. Instances of this class contain a single slot named
`this', which holds a pointer to a heap-allocated C++ instance.  The
name of the TinyCLOS class is obtained by putting the C++ classname
between angled brackets (`<...>').  TinyCLOS classes are not seen by
C++ code.

   The C++ constructor is invoked by the `initialize' generic, which
accepts as many arguments as the constructor. If no constructor is
defined, a default-constructor will be provided taking no arguments.
To allow creating class instances from pointers created in foreign
code, the `initialize' generic will optionally accept an arguments list
of the form `'this POINTER', where `POINTER' is a foreign pointer
object. This will create a TinyCLOS instance for the given C++ object.

   To release the storage allocated for a C++ instance invoke the
`destroy' generic (the name can be changed by using the
`destructor_name' pseudo declaration).

   Static member functions are wrapped in a Scheme procedure named
`<class>::<member>'.

   Member variables and non-public member functions are ignored.

   Virtual member functions are not seen by C++ code. Overriding a
virtual member function with a TinyCLOS method will not work when the
member function is called by C++.

   Operator functions and default arguments are not supported.

   Exceptions must be explicitly handled by user code and may not be
thrown beyond an invocation of C++ by Scheme code.


File: chicken.info,  Node: C interface,  Prev: The Easy Foreign Function Interface,  Up: Interface to external functions and variables

6.8 C interface
===============

The following functions and macros are available for C code that invokes
Scheme or foreign procedures that are called by Scheme:

 -- C macro: void C_save (C_word x)
     Saves the Scheme data object `x' on the temporary stack.

 -- C macro: void C_restore
     Pops and returns the topmost value from the temporary stack.

 -- C macro: C_word C_fix (int integer)
 -- C macro: C_word C_make_character (int char_code)
 -- C macro: C_word C_SCHEME_END_OF_LIST
 -- C macro: C_word C_SCHEME_END_OF_FILE
 -- C macro: C_word C_SCHEME_FALSE
 -- C macro: C_word C_SCHEME_TRUE
     These macros return immediate Scheme data objects.

 -- C function: C_word C_string (C_word **ptr, int length, char *string)
 -- C function: C_word C_string2 (C_word **ptr, char
          *zero_terminated_string)
 -- C function: C_word C_intern2 (C_word **ptr, char
          *zero_terminated_string)
 -- C function: C_word C_intern3 (C_word **ptr, char
          *zero_terminated_string, C_word initial_value)
 -- C function: C_word C_pair (C_word **ptr, C_word car, C_word cdr)
 -- C function: C_word C_flonum (C_word **ptr, double number)
 -- C function: C_word C_int_to_num (C_word **ptr, int integer)
 -- C function: C_word C_mpointer (C_word **ptr, void *pointer)
 -- C function: C_word C_vector (C_word **ptr, int length, ...)
 -- C function: C_word C_list (C_word **ptr, int length, ...)
     These functions allocate memory from `ptr' and initialize a fresh
     data object. The new data object is returned. `ptr' should be the
     address of an allocation pointer created with `C_alloc'.

 -- C macro: C_word* C_alloc (int words)
     Allocates memory from the C stack (`C_alloc') and returns a
     pointer to it. `words' should be the number of words needed for
     all data objects that are to be created in this function.  Note
     that stack-allocated data objects have to be passed to Scheme
     callback functions, or they will not be seen by the garbage
     collector. This is really only usable for callback procedure
     invocations, make sure not to use it in normal code, because the
     allocated memory will be re-used after the foreign procedure
     returns. When invoking Scheme callback procedures a minor garbage
     collection is performed, so data allocated with `C_alloc' will
     already have moved to a safe place.

     Note that `C_alloc' is really just a wrapper around `alloca', and
     can also be simulated by declaring a stack-allocated array of
     `C_word's:

 -- C macro: int C_SIZEOF_LIST (int length)
 -- C macro: int C_SIZEOF_STRING (int length)
 -- C macro: int C_SIZEOF_VECTOR (int length)
 -- C macro: int C_SIZEOF_INTERNED_SYMBOL (int length)
 -- C macro: int C_SIZEOF_PAIR
 -- C macro: int C_SIZEOF_FLONUM
 -- C macro: int C_SIZEOF_POINTER
 -- C macro: int C_SIZEOF_LOCATIVE
 -- C macro: int C_SIZEOF_TAGGED_POINTER
     These are macros that return the size in words needed for a data
     object of a given type.

 -- C macro: int C_character_code (C_word character)
 -- C macro: int C_unfix (C_word fixnum)
 -- C macro: double C_flonum_magnitude (C_word flonum)
 -- C function: char* C_c_string (C_word string)
 -- C function: int C_num_to_int (C_word fixnum_or_flonum)
 -- C function: void* C_pointer_address (C_word pointer)
     These macros and functions can be used to convert Scheme data
     objects back to C data. Note that `C_c_string()' returns a pointer
     to the character buffer of the actual Scheme object and is not
     zero-terminated.

 -- C macro: int C_header_size (C_word x)
 -- C macro: int C_header_bits (C_word x)
     Return the number of elements and the type-bits of the
     non-immediate Scheme data object `x'.

 -- C macro: C_word C_block_item (C_word x, int index)
     This macro can be used to access slots of the non-immediate Scheme
     data object `x'.  `index' specifies the index of the slot to be
     fetched, starting at 0. Pairs have 2 slots, one for the car and
     one for the cdr. Vectors have one slot for each element.

 -- C macro: C_word C_u_i_car (C_word x)
 -- C macro: C_word C_u_i_car (C_word x)
     Aliases for `C_block_item(x, 0)' and `C_block_item(x, 1)',
     respectively.

 -- C macro: void* C_data_pointer (C_word x)
     Returns a pointer to the data-section of a non-immediate Scheme
     object.

 -- C macro: C_word C_make_header (C_word bits, C_word size)
     A macro to build a Scheme object header from its bits and size
     parts.

 -- C function: C_word C_mutate (C_word *slot, C_word val)
     Assign the Scheme value `val' to the location specified by `slot'.
     If the value points to data inside the nursery (the first
     heap-generation), then the garbage collector will remember to
     handle the data appropriately. Assigning nursery-pointers directly
     will otherwise result in lost data. Note that no copying takes
     place at the moment when `C_mutate' is called, but later - at the
     next (minor) garbage collection.

 -- C macro: C_word C_symbol_value (C_word symbol)
     Returns the global value of the variable with the name `symbol'.
     If the variable is unbound `C_SCHEME_UNBOUND' is returned. You can
     set a variable's value with `C_mutate(&C_symbol_value(SYMBOL),
     VALUE)'.

 -- C function: void C_gc_protect (C_word *ptrs[], int n)
     Registers `n' variables at address `ptrs' to be garbage collection
     roots.  The locations should not contain pointers to data
     allocated in the nursery, only immediate values or pointers to
     heap-data are valid. Any assignment of potential nursery data into
     a root-array should be done via `C_mutate()'. The variables have
     to be initialized to sensible values before the next garbage
     collection starts (when in doubt, set all locations in `ptrs' to
     `C_SCHEME_UNDEFINED') `C_gc_protect' may not called before the
     runtime system has been initialized (either by
     `CHICKEN_initialize', `CHICKEN_run' or `CHICKEN_invoke'.

     For a slightly simpler interface to creating and using GC roots see
     `CHICKEN_new_gc_root'.

 -- C function: void C_gc_unprotect (int n)
     Removes the last `n' registered variables from the set of root
     variables.

 -- C Variable: void (*C_post_gc_hook)(int mode)
     If not `NULL', the function pointed to by this variable will be
     called after each garbage collection with a flag indicating what
     kind of collection was performed (either `0' for a minor
     collection or `1' for a major collection). Minor collections
     happen very frequently, so the hook function should not consume
     too much time. The hook function may not invoke Scheme callbacks.

   An example:


% cat foo.scm
#>
extern int callout(int, int, int);
<#

(define callout (foreign-safe-lambda int "callout" int int int))

(define-external (callin (scheme-object xyz)) int
  (print "This is 'callin': " xyz)
  123)

(print (callout 1 2 3))

% cat bar.c
#include <stdio.h>
#include "chicken.h"

extern int callout(int, int, int);
extern int callin(C_word x);

int callout(int x, int y, int z)
{
  C_word *ptr = C_alloc(C_SIZEOF_LIST(3));
  C_word lst;

  printf("This is 'callout': %d, %d, %d\n", x, y, z);
  lst = C_list(&ptr, 3, C_fix(x), C_fix(y), C_fix(z));
  return callin(lst);  /* Note: `callin' will have GC'd the data in `ptr' */
}

% csc foo.scm bar.c -o foo
% foo
This is 'callout': 1, 2, 3
This is 'callin': (1 2 3)
123

   Notes:
   * Scheme procedures can call C functions, and C functions can call
     Scheme procedures, but for every pending C stack frame, the
     available size of the first heap generation (the "nursery") will
     be decreased, because the C stack is identical to the nursery. On
     systems with a small nursery this might result in thrashing, since
     the C code between the invocation of C from Scheme and the actual
     calling back to Scheme might build up several stack-frames or
     allocates large amounts of stack data.  To prevent this it is
     advisable to increase the default nursery size, either when
     compiling the file (using the `-nursery' option) or when running
     the executable (using the `-:s' runtime option).

   * Calls to Scheme/C may be nested arbitrarily, and Scheme
     continuations can be invoked as usual, but keep in mind that C
     stack frames will not be recovered, when a Scheme procedure call
     from C does not return normally.

   * When multiple threads are running concurrently, and control
     switches from one thread to another, then the continuation of the
     current thread is captured and saved. Any pending C stack frame
     still active from a callback will remain on the stack until the
     threads is re-activated again. This means that in a multithreading
     situation, when C callbacks are involved, the available nursery
     space can be smaller than expected.  So doing many nested
     Scheme->C->Scheme calls can reduce the available memory up to the
     point of thrashing. It is advisable to have only a single thread
     with pending C stack-frames at any given time.

   * Pointers to Scheme data objects should not be stored in local or
     global variables while calling back to Scheme.  Any Scheme object
     not passed back to Scheme will be reclaimed or moved by the
     garbage collector.

   * Calls from C to Scheme are never tail-recursive.

   * Continuations captured via `call-with-current-continuation' and
     passed to C code can be invoked like any other Scheme procedure.



File: chicken.info,  Node: chicken-setup,  Next: Additional files,  Prev: Interface to external functions and variables,  Up: Top

7 chicken-setup
***************

* Menu:

* Extension libraries::
* Installing extensions::
* Creating extensions::
* Procedures and macros available in setup scripts::
* Examples for extensions::
* `chicken-setup' reference::
* Windows notes::


File: chicken.info,  Node: Extension libraries,  Next: Installing extensions,  Up: chicken-setup

7.1 Extension libraries
=======================

Extension libraries are extensions to the core functionality provided
by the basic CHICKEN system, to be built and installed separately.  The
mechanism for loading compiled extensions is based on dynamically
loadable code and as such is only available on systems on which loading
compiled code at runtime is supported. Currently this are most
UNIX-compatible platforms that provide the `libdl' functionality like
Linux, Solaris, BSD or Mac OS X.  Windows with the Microsoft tools is
partially supported.

   Note: Extension may also be normal applications or shell scripts.


File: chicken.info,  Node: Installing extensions,  Next: Creating extensions,  Prev: Extension libraries,  Up: chicken-setup

7.2 Installing extensions
=========================

To install an extension library, run the `chicken-setup' program with
the extension name as argument. If the extension consists of a single
Scheme file, then it is compiled and installed in the extension
_repository_. If it is an archive containing addition files, then the
files are extracted and the contained _setup_ script is executed. This
setup script is a normal Scheme source file, which will be interpreted
by `chicken-setup'. The complete language supported by `csi' is
available, and the library units `srfi-1 regex utils posix tcp' are
loaded. Additional libraries can of course be loaded at run-time.

   The setup script should perform all necessary steps to build the new
library (or application). After a successful build, the extension can
be installed by invoking one of the procedures `install-extension',
`install-program' or `install-script'.  These procedures will copy a
number of given files into the extension repository or in the path
where the CHICKEN executables are located (in the case of executable
programs or scripts). Additionally the list of installed files, and
user-defined metadata is stored in the repository.

   If no extension name is given on the command-line, and if none of the
options `-list', `-version', `-repository' (without argument),
`-program-path' (without argument), `-fetch' or `-docindex' is given,
then all `.setup' scripts in the current directory are processed.


File: chicken.info,  Node: Creating extensions,  Next: Procedures and macros available in setup scripts,  Prev: Installing extensions,  Up: chicken-setup

7.3 Creating extensions
=======================

Extensions can be created by creating an (optionally gzipped) `tar'
archive named `EXTENSION.egg' containing all needed files plus a
`.setup' script in the root directory.  After `chicken-setup' has
extracted the files, the setup script will be invoked. There are no
additional constraints on the structure of the archive, but the setup
script has to be in the root path of the archive.


File: chicken.info,  Node: Procedures and macros available in setup scripts,  Next: Examples for extensions,  Prev: Creating extensions,  Up: chicken-setup

7.4 Procedures and macros available in setup scripts
====================================================

 -- procedure: install-extension
          (install-extension ID FILELIST [INFOLIST])
     Installs the extension library with the name `ID'. All files given
     in the list of strings `FILELIST' will be copied to the extension
     repository. It should be noted here that the extension id has to
     be identical to the name of the file implementing the extension.
     The extension may load or include other files, or may load other
     extensions at runtime specified by the `require-at-runtime'
     property.

     `FILELIST' may be a filename, a list of filenames, or a list of
     pairs of the form `(SOURCE DEST)' (if you want to copy into a
     particular sub-directory - the destination directory will be
     created as needed). If `DEST' is a relative pathname, it will be
     copied into the extension repository.

     The optional argument `INFOLIST' should be an association list that
     maps symbols to values, this list will be stored as `ID.setup' at
     the same location as the extension code. Currently the following
     properties are used:

      -- property: syntax
               (syntax)
          Marks the extension as syntax-only. No code is compiled, the
          extension is intended as a file containing macros to be
          loaded at compile/macro-expansion time.

      -- property: require-at-runtime
               (require-at-runtime ID ...)
          Specifies extensions that should be loaded (via `require') at
          runtime. This is mostly useful for syntax extensions that
          need additional support code at runtime.

      -- property: version
               (version STRING)
          Specifies version string.

      -- property: documentation
               (documentation FILENAME)
          The filename of a HTML document containing extension-specific
          documentation.  This file should be given in the file-list
          passed to `install-extension' and a link to it will be
          automatically included in the index page (accessible via
          `chicken-setup -docindex').

      -- property: examples
               (examples FILENAME ...)
          Copies the given files into the examples directory, which is
          usually `$prefix/share/chicken/examples' (equivalent to
          `$CHICKEN_HOME/examples' or `(make-pathname (chicken-home)
          "examples")').

      -- property: exports
               (exports EXPORT ...)
          Add export-information to the generated
          extension-information. `EXPORT' may be a symbol naming an
          exported toplevel variable or a string designating a file with
          exported variables, as generated by the `-emit-exports'
          option or the `emit-exports' declaration specifier.

     All other properties are currently ignored. The `FILELIST'
     argument may also be a single string.


 -- procedure: install-program
          (install-program ID FILELIST [INFOLIST])
     Similar to `install-extension', but installs an executable program
     in the executable path (usually `/usr/local/bin').

 -- procedure: install-script
          (install-script ID FILELIST [INFOLIST])
     Similar to `install-program', but additionally changes the file
     permissions of all files in `FILELIST' to executable (for
     installing shell-scripts).

 -- syntax: run
          (run FORM ...)
     Runs the shell command `FORM', which is wrapped in an implicit
     `quasiquote'.  `(run (csc ...))' is treated specially and passes
     `-v' (if `-verbose' has been given to `chicken-setup') and
     `-feature compiling-extension' options to the compiler.

 -- syntax: compile
          (compile FORM ...)
     Equivalent to `(run (csc FORM ...))'.

 -- syntax: make
          (make ((TARGET (DEPENDENT ...) COMMAND ...) ...) ARGUMENTS)
     A "make" macro that executes the expressions `COMMAND ...', when
     any of the dependents `DEPENDENT ...' have changed, to build
     `TARGET'. This is the same as the `make' extension, which is
     available separately. For more information, see make
     (http://www.call-with-current-continuation.org/eggs/make.html).

 -- procedure: patch
          (patch WHICH REGEX SUBST)
     Replaces all occurrences of the regular expression `REGEX' with
     the string `SUBST', in the file given in `WHICH'. If `WHICH' is a
     string, the file will be patched and overwritten. If `WHICH' is a
     list of the form `OLD NEW', then a different file named `NEW' will
     be generated.

 -- procedure: copy-file
          (copy-file FROM TO)
     Copies the file or directory (recursively) given in the string
     `FROM' to the destination file or directory `TO'.

 -- procedure: move-file
          (move-file FROM TO)
     Moves the file or directory (recursively) given in the string
     `FROM' to the destination file or directory `TO'.

 -- procedure: remove-file*
          (remove-file* PATH)
     Removes the file or directory given in the string `PATH'.

 -- procedure: create-directory
          (create-directory PATH)
     Creates the directory given in the string `PATH', with all parent
     directories as needed.

 -- procedure: find-library
          (find-library NAME PROC)
     Returns `#t' if the library named `libNAME.[a|so]' (unix) or
     `NAME.lib' (windows) could be found by compiling and linking a
     test program. `PROC' should be the name of a C function that must
     be provided by the library. If no such library was found or the
     function could not be resolved, `#f' is returned.

 -- procedure: find-header
          (find-header NAME)
     Returns `#t' if a C include-file with the given name is available,
     or `#f' otherwise.

 -- procedure: test-compile
          (test-compile CODE #!key cflags ldflags compile-only)
     Returns `#t' if the C code in `CODE' compiles and links
     successfully, or `#f' otherwise.  The keyword parameters `cflags'
     and `ldflags' accept additional compilation and linking flags. If
     `compile-only' is true, then no linking step takes place.

 -- parameter: installation-prefix
     Holds the prefix under which CHICKEN executables and libraries
     have been installed (either the value of the environment variable
     `CHICKEN_PREFIX' or whatever prefix was specified at the time the
     system was built.

 -- parameter: program-path
     Holds the path where executables are installed and defaults to
     either `$CHICKEN_PREFIX/bin', if the environment variable
     `CHICKEN_PREFIX' is set, `$CHICKEN_HOME' or the path where the
     CHICKEN binaries (`chicken', `csi', etc.) are installed.

 -- parameter: setup-root-directory
     Contains the path of the directory where `chicken-setup' was
     invoked.

 -- parameter: setup-build-directory
     Contains the path of the directory where the extension is built.
     This is not necessarily identical to `setup-root-directory'.

 -- parameter: setup-verbose-flag
     Reflects the setting of the `-verbose' option, i.e. is `#t', if
     `-verbose' was given.

 -- parameter: setup-install-flag
     Reflects the setting of the `--no-install' option, i.e. is `#f',
     if `-no-install' was given.


File: chicken.info,  Node: Examples for extensions,  Next: `chicken-setup' reference,  Prev: Procedures and macros available in setup scripts,  Up: chicken-setup

7.5 Examples for extensions
===========================

The simplest case is a single file that does not export any syntax. For
example

     ;;;; hello.scm

     (define (hello name)
       (print "Hello, " name " !") )

   After entering


$ chicken-setup hello

   at the shell prompt, the file `hello.scm' will be compiled into a
dynamically loadable library, with the default compiler options
`-optimize-level 2 -no-trace -shared'. If the compilation succeeds,
`hello.so' will be stored in the repository, together with a file named
`hello.setup' (not to be confused with a setup script - this `.setup'
file just contains an a-list with metadata).

   Use it like any other CHICKEN extension:


$ csi -q
#;1> (require-extension hello)
; loading /usr/local/lib/chicken/hello.so ...
#;2> (hello "me")
Hello, me!
#;3>

   For more elaborate build operations, when installing applications or
scripts, or when additional metadata should be stored for an extension,
a `setup' script is required and the script and all additional files
should be packaged in a gzipped `tar' archive.

   Here we create a simple application:

     ;;;; hello2.scm

     (print "Hello, ")
     (for-each (lambda (x) (printf "~A " x)) (command-line-arguments))
     (print "!")

   We also need a setup script:

     ;;;; hello2.setup

     (run (csc hello2.scm))  ; compile `hello2'
     (install-program 'hello2 "hello2") ; name of the extension and files to be installed

   To use it, just run `chicken-setup' in the same directory:


$ chicken-setup hello2

   Now the program `hello2' will be installed in the same location as
the other CHICKEN tools (like `chicken', `csi', etc.), which will
normally be `/usr/local/bin'.  Note that you need write-permissions for
those locations.

   Uninstallation is just as easy:


$ chicken-setup -uninstall hello2

   `chicken-setup' provides a `make' macro, so building operations can
be of arbitrary complexity. When running `chicken-setup' with an
argument `NAME', for which no associated file `NAME.setup', `NAME.egg'
or `NAME.scm' exists will ask you to download the extension via HTTP
from the default URL
`http://www.call-with-current-continuation.org/eggs'. You can use the
`-host' option to specify an alternative source location.

   If the given extension name contains a path prefix and the `-host'
option is given, then `chicken-setup' can also download and install
eggs from an arbitrary HTTP server. Alternatively you can pass a full
URL (including the `http://' prefix. Note that no dependency checks are
done when downloading eggs directly with the URL syntax.

   Finally a somewhat more complex example: We want to package a syntax
extension with additional support code that is to be loaded at run-time
of any Scheme code that uses that extension. We create a "glass"
lambda, a procedure with free variables that can be manipulated from
outside:

     ;;;; glass.scm

     (define-macro (glass-lambda llist vars . body)
       ;; Low-level macros are fun!
       (let ([lvar (gensym)]
     	[svar (gensym)]
     	[x (gensym)]
     	[y (gensym)]
     	[yn (gensym)] )
         `(let ,(map (lambda (v) (list v #f)) vars)
            (define (,svar ,x . ,y)
     	 (let* ([,yn (pair? ,y)]
     		[,y (and ,yn (car ,y))] )
     	   (case ,x
     	     ,@(map (lambda (v)
     		      `([,v] (if ,yn
     				 (set! ,v ,y)
     				 ,v) ) )
     		    vars)
     	     (else (error "variable not found" ,x)) ) ) )
            (define ,lvar (lambda ,llist ,@body))
            (extend-procedure ,lvar ,svar) ) ) )

   Here some support code that needs to be loaded at runtime:

     ;;;; glass-support.scm

     (require-extension lolevel)

     (define glass-lambda-accessor procedure-data)
     (define (glass-lambda-ref gl v) ((procedure-data gl) v))
     (define (glass-lambda-set! gl v x) ((procedure-data gl) v x))

   The setup script looks like this:

     (run (csc -s -O2 -d0 glass-support.scm))

     (install-extension
       'glass
       '("glass.scm" "glass-support.so")
       '((syntax) (require-at-runtime glass-support)) )

   The invocation of `install-extension' provides the files that are to
be copied into the extension repository, and a metadata list that
specifies that the extension `glass' is a syntax extension and that, if
it is declared to be used by other code (either with the
`require-extension' or `require-for-syntax' form), then client code
should perform an implicit `(require 'glass-support)' at startup.

   This can be conveniently packaged as an "egg":


$ tar cfz glass.egg glass.setup glass.scm glass-support.scm

   And now we use it:


$ chicken-setup glass
$ csi -quiet
#;1> (require-extension glass)
; loading /usr/local/lib/chicken/glass.scm ...
; loading /usr/local/lib/chicken/glass-support.so ...
#;2> (define foo (glass-lambda (x) (y) (+ x y)))
#;3> (glass-lambda-set! foo 'y 99)
#;4> (foo 33)
132


File: chicken.info,  Node: `chicken-setup' reference,  Next: Windows notes,  Prev: Examples for extensions,  Up: chicken-setup

7.6 `chicken-setup' reference
=============================

Available options:

   * `-h  -help' Show usage information and exit.

   * `-V  -version' Display version and exit.

   * `-R  -repository [PATHNAME]' When used without an argument, the
     path of the extension repository is displayed on standard output.
     When given an argument, the repository pathname (and the
     `repository-path' parameter) will be set to `PATHNAME' for all
     subsequent operations. The default repository path is the
     installation library directory (usually `/usr/local/lib/chicken'),
     or (if set) the directory given in the environment variable
     `CHICKEN_REPOSITORY'.  `PATHNAME' should be an absolute pathname.

   * `-P  -program-path [PATHNAME]' When used without an argument, the
     path for executables is displayed on standard output.  When given
     an argument, the program path for installing executables and
     scripts will be set to `PATHNAME' for all subsequent operations.
     `PATHNAME' should be an absolute pathname.

   * `-h  -host HOSTNAME[:PORT]' Specifies alternative host for
     downloading extensions, optionally with a TCP port number (which
     defaults to 80).

   * `-u  -uninstall EXTENSION' Removes all files that were installed
     for `EXTENSION' from the file-system, together with any metadata
     that has been stored.

   * `-l  -list [NAME ...]' List all installed extensions or show
     extension information.

   * `-r  -run FILENAME' Load and execute given file.

   * `-s  -script FILENAME' Executes the given Scheme source file with
     all remaining arguments and exit. The "she-bang" shell script
     header is recognized, so you can write Scheme scripts that use
     `chicken-setup' just as with `csi'.

   * `-e  -eval EXPRESSION' Evaluates the given expression(s).

   * `-v  -verbose' Display additional debug information.

   * `-k  -keep' Keep temporary files and directories.

   * `-c  -csc-option OPTION' Passes `OPTION' as an extra argument to
     invocations of the compiler-driver (`csc'). This works only if
     `csc' is invoked as `(run (csc ...))'.

   * `-d  -dont-ask' Do not ask the user before trying to download
     required extensions.

   * `-n  -no-install' Do not install generated binaries and/or support
     files. Any invocations of `install-program', `install-extension'
     or `install-script' will be be no-ops.

   * `-i  -docindex' Displays the path to the index-page of any
     installed extension-documentation. If the index page does not
     exist, it is created.

   * `-check' Downloads the repository-index and lists locally
     installed extensions for which a newer release is available for
     download.

   * `--' Ignore all following arguments.

   Note that the options are processed exactly in the order in which
they appear in the command-line.


File: chicken.info,  Node: Windows notes,  Prev: `chicken-setup' reference,  Up: chicken-setup

7.7 Windows notes
=================

`chicken-setup' works on Windows, when compiled with Visual C++, but
depends on the `tar' and `gunzip' tools to extract the contents of an
egg. The best way is to download an egg either manually (or with
`chicken-setup -fetch') and extract its contents with a separate program
(like `winzip'). the `CHICKEN_REPOSITORY' environment variable has to
be set (in addition to `CHICKEN_HOME') to a directory where your
compiled extensions should be located.

   The `.setup' scripts will not always work under Windows, and the
extensions may require libraries that are not provided for Windows or
work differently. Under these circumstances it is recommended to
perform the required steps to build an extension manually.


File: chicken.info,  Node: Additional files,  Next: Data Representation,  Prev: chicken-setup,  Up: Top

8 Additional files
******************

In addition to library units the following files are provided. Use them
by including the file in your code with the `include' special form.

* Menu:

* chicken-more-macros.scm::
* chicken-ffi-macros.scm::


File: chicken.info,  Node: chicken-more-macros.scm,  Next: chicken-ffi-macros.scm,  Up: Additional files

8.1 `chicken-more-macros.scm'
=============================

This file contains the definitions of all non-standard syntax forms.
You normally don't use this file directly, unless you have the following
situation: you use non-standard macros at run-time (in evaluated code)
in a compiled program and you want non-standard syntax to be available.
In this case, add

     (require-extension chicken-more-macros)

   to your code. This will load the definitions for non-standard macros
available in code evaluated by the program.

   See also the FAQ for a discussion about the different macro systems
and their ideosyncrasies.


File: chicken.info,  Node: chicken-ffi-macros.scm,  Prev: chicken-more-macros.scm,  Up: Additional files

8.2 `chicken-ffi-macros.scm'
============================

This file contains the definitions of macros for interfacing to foreign
code, and the definitions contained in this file are automatically made
available in compiled code.


File: chicken.info,  Node: Data Representation,  Next: Bugs and limitations,  Prev: Additional files,  Up: Top

9 Data Representation
*********************

There exist two different kinds of data objects in the CHICKEN system:
immediate and non-immediate objects. Immediate objects are represented
by a tagged machine word, which is usually of 32 bits length (64 bits
on 64-bit architectures). The immediate objects come in four different
flavors:

   * fixnums, that is, small exact integers, distinguished by the
     lowest order bit in the machine word set to 1. This gives fixnums
     a range of 31 bits for the actual numeric value (63 bit on 64 bit
     architectures).

   * characters, where the lowest four bits of machine words containing
     characters are equal to `C_CHARACTER_BITS'. The ASCII code of the
     character is encoded in bits 9 to 16, counting from 1 and starting
     at the lowest order position.

   * booleans, where the lowest four bits of machine words containing
     booleans are equal to `C_BOOLEAN_BITS'. Bit 5 (counting from 0 and
     starting at the lowest order position) is one if the boolean
     designates true, or 0 if it is false.

   * other values: the empty list, void and end-of-file. The lowest
     four bits of machine words containing these values are equal to
     `C_SPECIAL_BITS'. Bits 5 to 8 contain an identifying number for
     this type of object.  The following constants are defined:
     `C_SCHEME_END_OF_LIST C_SCHEME_UNDEFINED C_SCHEME_END_OF_FILE'


   Non-immediate objects are blocks of data represented by a pointer
into the heap. The first word of the data block contains a header,
which gives information about the type of the object. The header has
the size of a machine word, usually 32 bits (64 bits on 64 bit
architectures).

   * bits 1 to 24 (starting at the lowest order position) contain the
     length of the data object, which is either the number of bytes in a
     string (or byte-vector) or the the number of elements for a vector
     or for a structure type.

   * bits 25 to 28 contain the type code of the object.

   * bits 29 to 32 contain miscellaneous flags used for garbage
     collection or internal data type dispatching.  These flags are:
    `C_GC_FORWARDING_BIT'
          Flag used for forwarding garbage collected object pointers.

    `C_BYTEBLOCK_BIT'
          Flag that specifies whether this data object contains raw
          bytes (a string or byte-vector) or pointers to other data
          objects.

    `C_SPECIALBLOCK_BIT'
          Flag that specifies whether this object contains a "special"
          non-object pointer value in its first slot. An example for
          this kind of objects are closures, which are a vector-type
          object with the code-pointer as the first item.

    `C_8ALIGN_BIT'
          Flag that specifies whether the data area of this block
          should be aligned on an 8-byte boundary (floating-points
          numbers, for example).



   The actual data follows immediately after the header. Note that
block-addresses are always aligned to the native machine-word boundary.
Scheme data objects map to blocks in the following manner:

   * pairs: vector-like object (type bits `C_PAIR_TYPE'), where the car
     and the cdr are contained in the first and second slots,
     respectively.

   * vectors: vector object (type bits `C_VECTOR_TYPE').

   * strings: byte-vector object (type bits `C_STRING_TYPE').

   * procedures: special vector object (type bits `C_CLOSURE_TYPE').
     The first slot contains a pointer to a compiled C function. Any
     extra slots contain the free variables (since a flat closure
     representation is used).

   * flonum: a byte-vector object (type bits `C_FLONUM_BITS'). Slots
     one and two (or a single slot on 64 bit architectures) contain a
     64-bit floating-point number, in the representation used by the
     host systems C compiler.

   * symbol: a vector object (type bits `C_SYMBOL_TYPE'). Slots one and
     two contain the toplevel variable value and the print-name (a
     string) of the symbol, respectively.

   * port: a special vector object (type bits `C_PORT_TYPE'). The first
     slot contains a pointer to a file- stream, if this is a
     file-pointer, or NULL if not. The other slots contain housekeeping
     data used for this port.

   * structure: a vector object (type bits `C_STRUCTURE_TYPE'). The
     first slot contains a symbol that specifies the kind of structure
     this record is an instance of. The other slots contain the actual
     record items.

   * pointer: a special vector object (type bits `C_POINTER_TYPE'). The
     single slot contains a machine pointer.

   * tagged pointer: similar to a pointer (type bits
     `C_TAGGED_POINTER_TYPE'), but the object contains an additional
     slot with a tag (an arbitrary data object) that identifies the type
     of the pointer.


   Data objects may be allocated outside of the garbage collected heap,
as long as their layout follows the above mentioned scheme. But care
has to be taken not to mutate these objects with heap-data (i.e.
non-immediate objects), because this will confuse the garbage collector.

   For more information see the header file `chicken.h'.


File: chicken.info,  Node: Bugs and limitations,  Next: FAQ,  Prev: Data Representation,  Up: Top

10 Bugs and limitations
***********************

   * Compiling large files takes too much time.

   * If a known procedure has unused arguments, but is always called
     without those parameters, then the optimizer "repairs" the
     procedure in certain situations and removes the parameter from the
     lambda-list.

   * `port-position' currently works only for input ports.

   * Leaf routine optimization can theoretically result in code that
     thrashes, if tight loops perform excessively many mutations.



File: chicken.info,  Node: FAQ,  Next: Acknowledgements,  Prev: Bugs and limitations,  Up: Top

11 FAQ
******

11.1 General
============

   * Why yet another Scheme implementation?

     Since Scheme is a relatively simple language, a large number of
     implementations exist and    each has its specific advantages and
     disadvantages. Some are fast, some provide a rich    programming
     environment. Some are free, others are tailored to specific
     domains, and so on. The reasons    for the existance of CHICKEN
     are:

     CHICKEN is portable because it generates C code that runs on a
     large number of platforms.

     CHICKEN is extendable, since its code generation scheme and
     runtime system/garbage collector fits    neatly into a C
     environment.

     CHICKEN is free and can be freely distributed, including its
     source code.

     CHICKEN offers better performance than nearly all interpreter
     based implementations, but still    provides full Scheme semantics.

     As far as I know, CHICKEN is the first implementation of Scheme
     that uses Henry Baker's      "Cheney on the M.T.A" concept.

   * What to do if I find a bug?

     Send e-mail to `felix@call-with-current-continuation.org'    with
     some hints about the problem, like    version/build of the
     compiler, platform, system configuration, code that    causes the
     bug, etc.

   * Why are values defined with `define-foreign-variable' or
     `define-constant' or `define-inline' not seen outside of the
     containing source file?

     Accesses to foreign variables are translated directly into C
     constructs that access the variable,   so the Scheme name given to
     that variable does only exist during compile-time.    The same
     goes for constant- and inline-definitions: The name is only there
     to tell the compiler   that this reference is to be replaced with
     the actual value.

   * How does `cond-expand' know which features are registered in used
     units?

     Each unit used via `(declare (uses ...))' is registered as a
     feature and    so a symbol with the unit-name can be tested by
     `cond-expand' during macro-expansion-time.     Features registered
     using the `register-feature!' procedure are only    available
     during run-time of the compiled file. You can use the `eval-when'
     form    to register features at compile time.

   * How can I cut down the size of an executable?

     If you don't need `eval' or the stuff in the `extras' library unit,
       you can just use the `library' unit:


     	(declare (uses library))
     	(display "Hello, world!\n")

     (Don't forget to compile with the `-explicit-use' option)
     Compiled with Visual C++ this generates an excutable of around 240
     kilobytes.     It is theoretically possible to compile something
     without the library, but    a program would have to implement
     quite a lot of support code on its own.

   * Why does a loop that doesn't `cons' still trigger garbage
     collections?

     Under CHICKENs implementation policy, tail recursion is achieved
     simply by avoiding to    return from a function call. Since the
     programs is CPS converted, a continuous    sequence of nested
     procedure calls is performed. At some stage the stack-space    has
     to run out and the current procedure and its parameters (including
     the current continuation) are stored somewhere    in the runtime
     system. Now a minor garbage collection occurs and rescues all live
       data from the stack (the first heap generation) and moves it
     into the the second heap generation. Than the stack is cleared
     (using    a `longjmp') and execution can continue from the saved
     state.     With this method arbitrary recursion (in tail- or
     non-tail position) can happen,    provided the application doesn't
     run out of heap-space.     (The difference between a tail- and a
     non-tail call is that the tail-call has no    live data after it
     invokes its continuation - and so the amount of heap-space needed
     stays constant)

   * How can I obtain faster executables?

     There are a number of declaration specifiers that should be used
     to speed up    compiled files: declaring `(standard-bindings)' is
     mandatory, since this enables    most optimizations. Even if some
     standard procedures should be redefined, you can    list untouched
     bindings in the declaration.     Declaring `(extended-bindings)'
     lets the compiler choose faster versions of certain    internal
     library functions. This might give another speedup. You can also
     use the    the `usual-integrations' declaration, which is
     identical to declaring    `standard-bindings' and
     `extended-bindings'    (note that `usual-integrations' is set by
     default).     Declaring `(block)' tells the compiler that global
     procedures are not changed    outside the current compilation
     unit, this gives the compiler some more    opportunities for
     optimization.     If no floating point arithmetic is required,
     then declaring `(number-type fixnum)'    can give a big
     performance improvement, because the compiler can now inline
     most arithmetic operations.     Declaring `(unsafe)' will switch
     off most safety checks.     If threads are not used, you can
     declare `(disable-interrupts)'.     You should always use maximum
     optimizations settings for your C compiler.     Good GCC compiler
     options on Pentium (and compatible) hardware are:    `-Os
     -fomit-frame-pointer -fno-strict-aliasing'    Some programs are
     very sensitive to the setting of the nursery (the first
     heap-generation). You    should experiment with different nursery
     settings (either by compiling with the `-nursery'    option or by
     using the `-:s...' runtime option).

   * Why does the linker complain about a missing function
     `_C_..._toplevel'?

     This message indicates that your program uses a library-unit, but
     that the    object-file or library was not supplied to the linker.
     If you have the unit    `foo', which is contained in `foo.o' than
     you have to supply it to the    linker like this (assuming a GCC
     environment):


        % csc program.scm foo.o -o program

   * Why does the linker complain about a missing function
     `_C_toplevel'?

     This means you have compiled a library unit as an application.
     When a unit-declaration (as in `(declare (unit ...))')    is
     given, then this file has a specially named toplevel entry
     procedure. Just remove the declaration,    or compile this file to
     an object-module and link it to your application code.

   * Why are constants defined by `define-constant' not honoured in
     `case' constructs?

     `case' expands into a cascaded `if' expression, where the first
     item in each arm    is treated as a quoted list. So the `case'
     macro can not infer wether    a symbol is to be treated as a
     constant-name (defined via `define-constant') or    a literal
     symbol.

   * When I compile a file with `-unsafe' or unsafe declarations, it
     crashes during execution.

     The compiler option `-unsafe' or the declaration `(declare
     (unsafe))' disable    certain safety-checks to improve
     performance, so code that would normally    trigger an error will
     work unexpectedly or even crash the running application.     It is
     advisable to develop and debug a program in safe mode (without
     unsafe    declarations) and use this feature only if the
     application works properly.

   * Which non-standard procedures are treated specially when the
     `extended-bindings' or `usual-integrations' declaration or
     compiler option is used?

     The following extended bindings are handled specially:

     `bitwise-and' `bitwise-ior' `bitwise-xor' `bitwise-not' `add1'
     `sub1'  `fx+' `fx-' `fx*' `fx/' `fxmod'   `fx=' `fx>' `fx>='
     `fixnum?' `fxneg' `fxmax' `fxmin' `fxand' `fxior' `fxxor' `fxnot'
     `fxshl' `fxshr' `fp+' `fp-' `fp*' `fp/' `atom?'   `fp=' `fp>'
     `fp>=' `fpneg' `fpmax' `fpmin'   `arithmetic-shift' `signum'
     `flush-output' `thread-specific' `thread-specific-set!'
     `not-pair?' `null-list?' `print' `print*' `u8vector->bytevector'
     `s8vector->bytevector' `u16vector->bytevector'
     `s16vector->bytevector'   `u32vector->bytevector'
     `s32vector->bytevector' `f32vector->bytevector'
     `f64vector->bytevector' `block-ref'   `byte-vector-length'
     `u8vector-length'   `s8vector-length'   `u16vector-length'
     `s16vector-length'   `u32vector-length'   `s32vector-length'
     `f32vector-length'   `f64vector-length'   `u8vector-ref'
     `s8vector-ref'   `u16vector-ref'   `s16vector-ref'
     `u32vector-ref'   `s32vector-ref'   `f32vector-ref'
     `f64vector-ref'   `u8vector-set!'   `s8vector-set!'
     `u16vector-set!'   `s16vector-set!'   `u32vector-set!'
     `s32vector-set!'   `hash-table-ref'    `block-set!'
     `number-of-slots'     `first' `second' `third' `fourth'
     `null-pointer?' `pointer->object'     `make-record-instance'
     `locative-ref' `locative-set!' `locative?' `locative->object'
     `identity'     `cpu-time' `error' `call/cc'

   * Why does `define-reader-ctor' not work in my compiled program?

     The following piece of code does not work as expected:

          (eval-when (compile)
            (define-reader-ctor 'integer->char integer->char) )
          (print #,(integer->char 33))

     The problem is that the compiler reads the complete source-file
     before doing any processing on it,   so the sharp-comma form is
     encountered before the reader-ctor is defined. A possible solution
     is to include   the file containing the sharp-comma form, like
     this:

          (eval-when (compile)
            (define-reader-ctor 'integer->char integer->char) )

          (include "other-file")

          ;;; other-file.scm:
          (print #,(integer->char 33))

   * Why do I get a warning when I define a global variable named
     `match'?

     Even when the `match' unit is not used, the macros from that
     package are visible in the compiler.    The reason for this is
     that macros can not be accessed from library units (only when
     explicitly evaluated in running   code). To speed up
     macro-expansion time, the compiler and the interpreter both
     already provide the compiled   `match-...' macro definitions.
     Macros shadowed lexically are no problem, but global definitions
     of variables named identically to (global) macros are useless -
     the macro definition shadows the global   variable.    This
     problem can be solved in one of three ways:

     - Use a different name

     - Undefine the macro, like this:

          (eval-when (compile eval) (undefine-macro! 'match))

   * How can I enable case sensitive reading/writing in user code?

     To enable the `read' procedure to read symbols and identifiers
     case sensitive, you can set the   parameter `case-sensitivity' to
     `#t'.

   * When I use callback functions (from Scheme to C and back to Scheme
     again), I get weird crashes.

     There are two reasons why code involving callbacks can crash out
     of know apparent reason. The first is that it is   important to
     use `foreign-safe-lambda/foreign-safe-lambda*' for the C code that
     is   to call back into Scheme. If this is not done than sooner or
     later the available stack space will be exhausted.    The second
     reason is that if the C code uses a large amount of stack storage,
     or if Scheme-to-C-to-Scheme calls are   nested deeply, then the
     available nursery space on the stack will run low. To avoid this
     it might be advisable   to run the compiled code with a larger
     nursery setting, i.e. run the code with `-:s...' and a larger
     value than the default (for example `-:s300k'), or use the
     `-nursery' compiler option.    Note that this can decrease runtime
     performance on some platforms.

   * How can I change `match-error-control' during compilation?

     Use `eval-when', like this:

            (eval-when (compile)
              (match-error-control #:unspecified) )

   * Why doesn't CHICKEN support the full numeric tower by default?

     The short answer:

            % chicken-setup numbers
            % csi -q
            #;1> (use numbers)

     The long answer:

     There are a number of reasons for this:

     - For most applications of Scheme fixnums (exact word-sized
     integers) and flonums (64-bit floating-point    numbers) are more
     than sufficient;

     - Interfacing to C is simpler;

     - Dispatching of arithmetic operations is more efficient.

     There is an extension based on the GNU Multiprecision Package that
     implements most of the full   numeric tower, see
     http://www.call-with-current-continuation.org/eggs/numbers.html.

   * Toplevel-continuations captured in interpreted code don't seem to
     work.

     Consider the following piece of code:

            (define k (call-with-current-continuation (lambda (k) k)))
            (k k)

     When compiled, this will loop endlessly. But when interpreted, `(k
     k)' will return   to the read-eval-print loop! This happens
     because the continuation captured will eventually read the   next
     toplevel expression from the standard-input (or an input-file if
     loading from a file). At the moment   `k' was defined, the next
     expression was `(k k)'. But when `k'   is invoked, the next
     expression will be whatever follows after `(k k)'.    In other
     words, invoking a captured continuation will not rewind the
     file-position of the input source.    A solution is to wrap the
     whole code into a `(begin ...)' expression, so all toplevel
     expressions will be loaded together.

   * How can I specialize a generic function method to match instances
     of every class?

     Specializing a method on `<object>' doesn't work on primitive data
     objects like   numbers, strings, etc. so for example

            (define-method (foo (x <my-class>)) ...)
            (define-method (foo (x <object>)) ...)
            (foo 123)

     will signal an error, because to applicable method can be found.
     To specialize a method for primitive   objects, use `<top>':

            (define-method (foo (x <top>)) ...)

   * Does CHICKEN support native threads?

     Currently native threads are not supported. The runtime system is
     not reentrant, and the garbage-collection   algorithm would be
     made much more complicated, since the location of every object
     (whether it is allocated   on the stack or on the heap or
     completely outside the GC-able data space) has to be checked -
     this would   be rather complex and inefficient in a situation
     where multiple threads are involved.


11.2 Platform specific
======================

   * How do I generate a DLL under MS Windows (tm) ?

     Use `csc' in combination with the `-dll' option:


        C:\> csc foo.scm -dll

   * How do I generate a GUI application under Windows(tm)?

     Invoke `csc' with the `-windows' option. Or pass the
     `-DC_WINDOWS_GUI'    option to the C compiler and link with the
     GUI version of the runtime system (that's
     `libchicken-gui[-static].lib'.     The GUI runtime displays error
     messages in a message box and does some rudimentary command-line
     parsing.

   * Compiling very large files under Windows with the Microsoft C
     compiler fails with a message indicating insufficient heap space.

     It seems that the Microsoft C compiler can only handle files up to
     a certain size, and it doesn't utilize virtual memory as   well as
     the GNU C compiler, for example. Try closing running applications.
     If that fails, try to break up the Scheme code   into several
     library units.

   * When I run `csi' inside an emacs buffer under Windows, nothing
     happens.

     Invoke `csi' with the `-:c' runtime option. Under Windows the
     interpreter thinks it   is not running under control of a terminal
     and doesn't print the prompt and does not flush the output stream
     properly.

   * I load compiled code dynamically in a Windows GUI application and
     it crashes.

     Code compiled into a DLL to be loaded dynamically must be linked
     with the same runtime system as the loading   application. That
     means that all dynamically loaded entities (including extensions
     built and installed with   `chicken-setup') must be compiled with
     the `-windows' `csc' option.

   * On Windows, `csc.exe' seems to be doing something wrong.

     The Windows development tools include a C# compiler with the same
     name. Either invoke `csc.exe' with a full   pathname, or put the
     directory where you installed CHICKEN in front of the MS
     development tool path in the `PATH'   environment variable.


11.3 Customization
==================

   * How do I run custom startup code before the runtime-system is
     invoked?

     When you invoke the C compiler for your translated Scheme source
     program, add the C compiler option    `-DC_EMBEDDED', or pass
     `-embedded' to the `csc'    driver program, so no entry-point
     function will be generated (`main()').     When your are finished
     with your startup processing, invoke:


        CHICKEN_main(argc, argv, C_toplevel);

     where `C_toplevel' is the entry-point into the compiled Scheme
     code. You   should add the following  declarations at the head of
     your code:


       #include "chicken.h"
       extern void C_toplevel(C_word,C_word,C_word) C_noret;

   * How can I add compiled user passes?

     To add a compiled user pass instead of an interpreted one, create
     a library unit and recompile   the main unit of the compiler (in
     the file `chicken.scm') with an additional `uses'   declaration.
     Then link all compiler modules and your (compiled) extension to
     create a new version of   the compiler, like this (assuming all
     sources are in the   current directory):


       % cat userpass.scm
       ;;;; userpass.scm - My very own compiler pass

       (declare (unit userpass))

       ;; Perhaps more user passes/extensions are added:
       (let ([old (user-pass)])
         (user-pass
           (lambda (x)
             (let ([x2 (do-something-with x)])
     	  (if old
     	      (old x2)
     	      x2) ) ) ) )
       ...
       % csc -c -x userpass.scm
       % csc chicken.scm -c -o chicken-extended.o -uses userpass
       % gcc chicken-extended.o support.o easyffi.o compiler.o optimizer.o batch-driver.o c-platform.o \
         c-backend.o userpass.o `csc -ldflags -libs` -o chicken-extended

     On platforms that support it (Linux ELF, Solaris, Windows + VC++),
     compiled code can be loaded via `-extend'   just like source files
     (see `load' in the User's Manual).


11.4 Macros
===========

   * Why doesn't my fancy macro work in compiled code?

     Macro bodies that are defined and used in a compiled source-file
     are    evaluated during compilation and so have no access to
     definitions in the    compiled file. Note also that during
     compile-time macros are only available in    the same source file
     in which they are defined. Files included via `include'    are
     considered part of the containing file.

   * Why are macros not visible outside of the compilation unit in
     which they are defined?

     Macros are defined during compile time, so when a file has been
     compiled, the definitions are gone. An exception    to this rule
     are macros defined with `define-macro', which are also visible at
     run-time, i.e.     in `eval'. To use macros defined in other
     files, use the `include' special    form.



File: chicken.info,  Node: Acknowledgements,  Next: Bibliography,  Prev: FAQ,  Up: Top

12 Acknowledgements
*******************

Also many thanks to Nico Amtsberg, William Annis, Marc Baily, Peter
Barabas, Jonah Beckford, Arto Bendiken, Peter Bex, Jean-Franc,ois
Bignolles, Dave Bodenstab, Fabian Bo"hlke, T. Kurt Bond, Ashley Bone,
Dominique Boucher, Terence Brannon, Roy Bryant, Adam Buchbinder, Hans
Bulfone, Category 5, Taylor Campbell, Franklin Chen, Thomas Chust, Gian
Paolo Ciceri, John Cowan, Grzegorz Chrupa/la, James Crippen, Tollef Fog
Heen, Alejandro Forero Cuervo, Linh Dang, Brian Denheyer, Chris Double,
Jarod Eells, Petter Egesund, Steve Elkins, Daniel B. Faken, Graham
Fawcett, Fizzie, Kimura Fuyuki, Tony Garnock-Jones, Martin Gasbichler,
Joey Gibson, Johannes Gr/odem, Damian Gryski, Mario Domenech Goulart,
Andreas Gustafsson, Sven Hartrumpf, Jun-ichiro itojun Hagino, Matthias
Heiler, Karl M. Hegbloom, William P. Heinemann, Bill Hoffman, Bruce
Hoult, Hans Hu"bner, Markus Hu"lsmann, Goetz Isenmann, David Janssens,
Christian Jaeger, Dale Jordan, Valentin Kamyshenko, Daishi Kato, Peter
Keller, Ron Kneusel, Matthias Koeppe, Krysztof Kowa/lczyk, Todd R.
Kueny Sr, Goran Krampe, Micky Latowicki, John Lenz, Kirill Lisovsky,
Kon Lovett, Dennis Marti, Charles Martin, Bob McIsaac, Alain Mellan,
Eric Merrit, Perry Metzger, Scott G. Miller, Mikael, Bruce Mitchener,
Chris Moline, Eric E. Moore, Julian Morrison, Dan Muresan, Lars
Nilsson, Ian Oversby, o.t., Gene Pavlovsky, Levi Pearson, Nicolas
Pelletier, Carlos Pita, Pupeno, Davide Puricelli, Doug Quale, Eric
Raible, Joel Reymont, Andreas Rottman, David Rush, Lars Rustemeier,
Oskar Schirmer, Burton Samograd, Reed Sheridan, Ronald Schro"der,
Spencer Schumann, Alex Shinn, Shmul, Jeffrey B. Siegal, Andrey
Sidorenko, Michele Simionato, Volker Stolz, Dorai Sitaram, Robert
Skeels, Jason Songhurst, Clifford Stein, Sunnan, Zbigniew Szadkowski,
Mike Thomas, Christian Tismer, Andre van Tonder, John Tobey, Henrik
Tramberend, Vladimir Tsichevsky, Neil van Dyke, Sander Vesik,
Panagiotis Vossos, Shawn Wagner, Peter Wang, Ed Watkeys, Thomas
Weidner, Matthew Welland, Joerg Wittenberger, Peter Wright, Mark Wutka,
Richard Zidlicky and Houman Zolfaghari for bug-fixes, tips and
suggestions.

   Special thanks to Brandon van Every for contributing the CMake
(http://www.cmake.org) support and for helping with Windows build
issues.

   Also special thanks to Benedikt Rosenau for his constant
encouragement.

   CHICKEN contains code from several people:

   * Eli Barzilay: some performance tweaks used in TinyCLOS.

   * Mikael Djurfeldt: topological sort used by compiler.

   * Marc Feeley: pretty-printer.

   * Aubrey Jaffer: implementation of `dynamic-wind'.

   * Gregor Kiczales: original implementation of TinyCLOS.

   * Richard O'Keefe: sorting routines.

   * Olin Shivers: implementation of `let-optionals[*]' and reference
     implementations of SRFI-1, SRFI-13 and SRFI-14.

   * Dorai Sitaram: the PREGEXP regular expression package

   * Andrew Wilcox: queues.

   * Andrew Wright: pattern matcher.


File: chicken.info,  Node: Bibliography,  Next: Index,  Prev: Acknowledgements,  Up: Top

Bibliography
************

Henry Baker: _CONS Should Not CONS Its Arguments, Part II: Cheney on the M.T.A._
     `http://home.pipeline.com/\~hbaker1/CheneyMTA.html'

Revised^5 Report on the Algorithmic Language Scheme
     `http://www.schemers.org/Documents/Standards/R5RS'


File: chicken.info,  Node: Index,  Prev: Bibliography,  Up: Top

Index
*****

[index]
* Menu:

* #:                                     Macros and procedures implemented in the interpreter.
                                                              (line   9)
* #!...:                                 Non standard read syntax.
                                                              (line  77)
* #$EXPRESSION:                          Non standard read syntax.
                                                              (line  22)
* #%...:                                 Non standard read syntax.
                                                              (line  74)
* #'EXPRESSION:                          Non standard read syntax.
                                                              (line  19)
* #+FEATURE:                             Non standard read syntax.
                                                              (line  93)
* #,(CONSTRUCTORNAME DATUM ...):         Non standard read syntax.
                                                              (line  14)
* #:SYMBOL:                              Non standard read syntax.
                                                              (line  25)
* #;EXPRESSION:                          Non standard read syntax.
                                                              (line  11)
* #<#TAG:                                Non standard read syntax.
                                                              (line  44)
* #<<TAG:                                Non standard read syntax.
                                                              (line  29)
* #>:                                    Non standard read syntax.
                                                              (line  65)
* #>!:                                   Non standard read syntax.
                                                              (line  71)
* #>?:                                   Non standard read syntax.
                                                              (line  68)
* #ci...:                                Non standard read syntax.
                                                              (line  89)
* #cs...:                                Non standard read syntax.
                                                              (line  85)
* #| ... |#:                             Non standard read syntax.
                                                              (line   7)
* $:                                     Accessing external objects.
                                                              (line 290)
* (:                                     C interface.         (line 139)
* ->string:                              Strings.             (line  16)
* :optional:                             Binding forms for optional arguments.
                                                              (line   7)
* <array>:                               Builtin classes.     (line 116)
* <boolean>:                             Builtin classes.     (line  68)
* <byte-vector>:                         Builtin classes.     (line  87)
* <c++-class>:                           Builtin classes.     (line 152)
* <char-set>:                            Builtin classes.     (line 117)
* <char>:                                Builtin classes.     (line  70)
* <class>:                               Builtin classes.     (line  94)
* <condition>:                           Builtin classes.     (line 113)
* <end-of-file>:                         Builtin classes.     (line  81)
* <entity-class>:                        Builtin classes.     (line  97)
* <environment>:                         Builtin classes.     (line  80)
* <exact>:                               Builtin classes.     (line  76)
* <f32vector>:                           Builtin classes.     (line 125)
* <f64vector>:                           Builtin classes.     (line 126)
* <generic>:                             Builtin classes.     (line 101)
* <hash-table>:                          Builtin classes.     (line  89)
* <inexact>:                             Builtin classes.     (line  77)
* <input-port>:                          Builtin classes.     (line  82)
* <integer>:                             Builtin classes.     (line  75)
* <locative>:                            Builtin classes.     (line 140)
* <lock>:                                Builtin classes.     (line 130)
* <method>:                              Builtin classes.     (line 104)
* <mmap>:                                Builtin classes.     (line 131)
* <null>:                                Builtin classes.     (line  72)
* <number>:                              Builtin classes.     (line  74)
* <object>:                              Builtin classes.     (line 107)
* <output-port>:                         Builtin classes.     (line  83)
* <pair>:                                Builtin classes.     (line  73)
* <pointer>:                             Builtin classes.     (line 134)
* <port>:                                Builtin classes.     (line  79)
* <primitive>:                           Builtin classes.     (line  65)
* <procedure-class>:                     Builtin classes.     (line 110)
* <procedure>:                           Builtin classes.     (line  84)
* <promise>:                             Builtin classes.     (line 143)
* <queue>:                               Builtin classes.     (line  90)
* <regexp>:                              Builtin classes.     (line 149)
* <s16vector>:                           Builtin classes.     (line 122)
* <s32vector>:                           Builtin classes.     (line 124)
* <s8vector>:                            Builtin classes.     (line 120)
* <string>:                              Builtin classes.     (line  78)
* <structure>:                           Builtin classes.     (line  88)
* <swig-pointer>:                        Builtin classes.     (line 136)
* <symbol>:                              Builtin classes.     (line  69)
* <tagged-pointer>:                      Builtin classes.     (line 135)
* <tcp-listener>:                        Builtin classes.     (line 146)
* <time>:                                Builtin classes.     (line 118)
* <u16vector>:                           Builtin classes.     (line 121)
* <u32vector>:                           Builtin classes.     (line 123)
* <u8vector>:                            Builtin classes.     (line 119)
* <vector>:                              Builtin classes.     (line  71)
* _exit:                                 Raw exit.            (line   7)
* absolute-pathname?:                    Pathname operations. (line   7)
* add-method:                            Base language.       (line   7)
* add1:                                  Arithmetic.          (line   7)
* address->pointer:                      Foreign pointers.    (line   7)
* align-to-word:                         Foreign pointers.    (line 172)
* alist-ref:                             Lists.               (line   7)
* alist-update!:                         Lists.               (line  13)
* allocate:                              Foreign pointers.    (line  13)
* allocate-instance:                     Intercessory protocol.
                                                              (line  11)
* always-bound:                          Declarations.        (line  17)
* and-let*:                              Other binding forms. (line   7)
* andmap:                                Other control structures.
                                                              (line   7)
* argc+argv:                             Other support procedures.
                                                              (line   7)
* argv:                                  Environment information and system interface.
                                                              (line   7)
* arithmetic-shift:                      Arithmetic.          (line  18)
* assert:                                Other forms.         (line   7)
* atom?:                                 Lists.               (line  22)
* binary-search:                         Binary searching.    (line   7)
* bitwise-and:                           Arithmetic.          (line  14)
* bitwise-ior:                           Arithmetic.          (line  15)
* bitwise-not:                           Arithmetic.          (line  17)
* bitwise-xor:                           Arithmetic.          (line  16)
* block:                                 Declarations.        (line  22)
* block-global:                          Declarations.        (line  27)
* block-ref:                             Low-level data access.
                                                              (line   7)
* block-set!:                            Low-level data access.
                                                              (line  13)
* bound-to-procedure:                    Declarations.        (line  36)
* breakpoint:                            Exceptions.          (line  40)
* build-platform:                        Environment information and system interface.
                                                              (line  23)
* butlast:                               Lists.               (line  34)
* byte-vector:                           Bytevectors.         (line   7)
* byte-vector->f32vector:                Unit srfi-4.         (line  57)
* byte-vector->f64vector:                Unit srfi-4.         (line  58)
* byte-vector->list:                     Bytevectors.         (line  24)
* byte-vector->s16vector:                Unit srfi-4.         (line  54)
* byte-vector->s32vector:                Unit srfi-4.         (line  56)
* byte-vector->s8vector:                 Unit srfi-4.         (line  52)
* byte-vector->string:                   Bytevectors.         (line  29)
* byte-vector->u16vector:                Unit srfi-4.         (line  53)
* byte-vector->u32vector:                Unit srfi-4.         (line  55)
* byte-vector->u8vector:                 Unit srfi-4.         (line  51)
* byte-vector-fill!:                     Bytevectors.         (line  18)
* byte-vector-length:                    Bytevectors.         (line  34)
* byte-vector-ref:                       Bytevectors.         (line  39)
* byte-vector-set!:                      Bytevectors.         (line  44)
* byte-vector?:                          Bytevectors.         (line  13)
* c-options:                             Declarations.        (line  41)
* c-runtime:                             Environment information and system interface.
                                                              (line 110)
* C_alloc:                               C interface.         (line  41)
* C_block_item:                          C interface.         (line  86)
* C_c_string:                            C interface.         (line  73)
* C_callback:                            Callbacks.           (line  63)
* C_callback_adjust_stack_limits:        Callbacks.           (line  69)
* C_character_code:                      C interface.         (line  70)
* C_data_pointer:                        C interface.         (line  97)
* C_fix:                                 C interface.         (line  16)
* C_flonum:                              C interface.         (line  32)
* C_flonum_magnitude:                    C interface.         (line  72)
* C_gc_protect:                          C interface.         (line 120)
* C_gc_unprotect:                        C interface.         (line 135)
* C_header_bits:                         C interface.         (line  82)
* C_header_size:                         C interface.         (line  81)
* C_int_to_num:                          C interface.         (line  33)
* C_intern2:                             C interface.         (line  28)
* C_intern3:                             C interface.         (line  30)
* C_list:                                C interface.         (line  36)
* C_make_character:                      C interface.         (line  17)
* C_make_header:                         C interface.         (line 101)
* C_mpointer:                            C interface.         (line  34)
* C_mutate:                              C interface.         (line 105)
* C_num_to_int:                          C interface.         (line  74)
* C_pair:                                C interface.         (line  31)
* C_pointer_address:                     C interface.         (line  75)
* C_restore:                             C interface.         (line  13)
* C_save:                                C interface.         (line  10)
* C_SCHEME_END_OF_FILE:                  C interface.         (line  19)
* C_SCHEME_END_OF_LIST:                  C interface.         (line  18)
* C_SCHEME_FALSE:                        C interface.         (line  20)
* C_SCHEME_TRUE:                         C interface.         (line  21)
* C_SIZEOF_FLONUM:                       C interface.         (line  63)
* C_SIZEOF_INTERNED_SYMBOL:              C interface.         (line  61)
* C_SIZEOF_LIST:                         C interface.         (line  58)
* C_SIZEOF_LOCATIVE:                     C interface.         (line  65)
* C_SIZEOF_PAIR:                         C interface.         (line  62)
* C_SIZEOF_POINTER:                      C interface.         (line  64)
* C_SIZEOF_STRING:                       C interface.         (line  59)
* C_SIZEOF_TAGGED_POINTER:               C interface.         (line  66)
* C_SIZEOF_VECTOR:                       C interface.         (line  60)
* C_string:                              C interface.         (line  24)
* C_string2:                             C interface.         (line  26)
* C_symbol_value:                        C interface.         (line 114)
* C_u_i_car:                             C interface.         (line  92)
* C_unfix:                               C interface.         (line  71)
* C_vector:                              C interface.         (line  35)
* call-with-input-pipe:                  Pipes.               (line   7)
* call-with-input-string:                String-port extensions.
                                                              (line   7)
* call-with-output-pipe:                 Pipes.               (line   8)
* call-with-output-string:               String-port extensions.
                                                              (line  13)
* call/cc:                               Continuations.       (line   7)
* case-lambda:                           Binding forms for optional arguments.
                                                              (line  20)
* case-sensitive:                        Parameters.          (line  37)
* change-directory:                      Directories.         (line   7)
* change-file-mode:                      Permissions.         (line  30)
* change-file-owner:                     Permissions.         (line  38)
* char-name:                             User-defined named characters.
                                                              (line   7)
* check-c-syntax:                        Declarations.        (line  48)
* chicken-home:                          Environment information and system interface.
                                                              (line 118)
* chicken-version:                       Environment information and system interface.
                                                              (line  39)
* CHICKEN_apply:                         Embedding.           (line  89)
* CHICKEN_apply_to_string:               Embedding.           (line  94)
* CHICKEN_continue:                      Embedding.           (line 181)
* CHICKEN_delete_gc_root:                Embedding.           (line 239)
* CHICKEN_eval:                          Embedding.           (line  66)
* CHICKEN_eval_string:                   Embedding.           (line  72)
* CHICKEN_eval_string_to_string:         Embedding.           (line  83)
* CHICKEN_eval_to_string:                Embedding.           (line  77)
* CHICKEN_gc_root_ref:                   Embedding.           (line 242)
* CHICKEN_gc_root_set:                   Embedding.           (line 245)
* CHICKEN_get_error_message:             Embedding.           (line 107)
* CHICKEN_global_lookup:                 Embedding.           (line 250)
* CHICKEN_global_ref:                    Embedding.           (line 254)
* CHICKEN_global_set:                    Embedding.           (line 258)
* CHICKEN_initialize:                    Embedding.           (line  24)
* CHICKEN_load:                          Embedding.           (line 103)
* CHICKEN_new_gc_root:                   Embedding.           (line 233)
* CHICKEN_parse_command_line:            Embedding.           (line  16)
* CHICKEN_read:                          Embedding.           (line  99)
* CHICKEN_run:                           Embedding.           (line  37)
* CHICKEN_yield:                         Embedding.           (line 111)
* chop:                                  Lists.               (line  39)
* class-cpl:                             Introspection.       (line   7)
* class-direct-slots:                    Introspection.       (line  12)
* class-direct-supers:                   Introspection.       (line  18)
* class-name:                            Introspection.       (line  28)
* class-of:                              Introspection.       (line  23)
* class-slots:                           Introspection.       (line  33)
* close-input-pipe:                      Pipes.               (line  17)
* close-output-pipe:                     Pipes.               (line  18)
* command-line-arguments:                Parameters.          (line  49)
* compile:                               Procedures and macros available in setup scripts.
                                                              (line  89)
* complement:                            Combinators.         (line  16)
* compose:                               Combinators.         (line  22)
* compress:                              Lists.               (line  50)
* compress-literals:                     Declarations.        (line  54)
* compute-apply-generic:                 Intercessory protocol.
                                                              (line  17)
* compute-apply-methods:                 Intercessory protocol.
                                                              (line  23)
* compute-cpl:                           Intercessory protocol.
                                                              (line  36)
* compute-getter-and-setter:             Intercessory protocol.
                                                              (line  41)
* compute-method-more-specific?:         Intercessory protocol.
                                                              (line  49)
* compute-methods:                       Intercessory protocol.
                                                              (line  29)
* compute-slots:                         Intercessory protocol.
                                                              (line  57)
* conc:                                  Strings.             (line   7)
* cond-expand:                           Other forms.         (line  17)
* condition-case:                        Exceptions.          (line  11)
* conjoin:                               Combinators.         (line  34)
* constant:                              Declarations.        (line  62)
* constantly:                            Combinators.         (line   7)
* constructor::                          Accessing external objects.
                                                              (line 150)
* continuation-capture:                  Continuations.       (line  11)
* continuation-graft:                    Continuations.       (line  26)
* continuation-return:                   Continuations.       (line  31)
* continuation?:                         Continuations.       (line  22)
* copy-file:                             Procedures and macros available in setup scripts.
                                                              (line 109)
* copy-read-table:                       Reader extensions.   (line  45)
* cpu-time:                              Execution time.      (line   7)
* create-directory <1>:                  Procedures and macros available in setup scripts.
                                                              (line 123)
* create-directory:                      Directories.         (line  19)
* create-fifo:                           Fifos.               (line   7)
* create-pipe:                           Pipes.               (line  26)
* create-session:                        Permissions.         (line 130)
* create-symbolic-link:                  Hard and symbolic links.
                                                              (line  11)
* create-temporary-file:                 Temporary files.     (line   7)
* current-directory:                     Directories.         (line  12)
* current-effective-group-id:            Permissions.         (line  48)
* current-effective-user-id:             Permissions.         (line  47)
* current-environment:                   Environment access.  (line   7)
* current-error-port:                    File Input/Output.   (line   7)
* current-gc-milliseconds:               Execution time.      (line  25)
* current-group-id:                      Permissions.         (line  46)
* current-milliseconds:                  Execution time.      (line  15)
* current-process-id:                    Processes.           (line   7)
* current-read-table:                    Parameters.          (line  55)
* current-seconds:                       Execution time.      (line  21)
* current-user-id:                       Permissions.         (line  45)
* cut:                                   Other binding forms. (line  29)
* cute:                                  Other binding forms. (line  30)
* declare:                               Declarations.        (line   7)
* decompose-pathname:                    Pathname operations. (line  13)
* define-class:                          Defining forms.      (line   7)
* define-constant:                       Substitution forms and macros.
                                                              (line   7)
* define-extension:                      Making extra libraries and extensions available.
                                                              (line  84)
* define-external:                       Callbacks.           (line  26)
* define-for-syntax:                     Substitution forms and macros.
                                                              (line  63)
* define-foreign-enum:                   Accessing external objects.
                                                              (line 196)
* define-foreign-record:                 Accessing external objects.
                                                              (line 102)
* define-foreign-type:                   Accessing external objects.
                                                              (line  42)
* define-foreign-variable:               Accessing external objects.
                                                              (line  72)
* define-generic:                        Defining forms.      (line  42)
* define-inline:                         Substitution forms and macros.
                                                              (line  23)
* define-location:                       Locations.           (line  12)
* define-macro:                          Substitution forms and macros.
                                                              (line  40)
* define-method:                         Defining forms.      (line  50)
* define-reader-ctor:                    Reader extensions.   (line   7)
* define-record:                         Record structures.   (line   7)
* define-record-printer:                 Record structures.   (line  24)
* define-record-type:                    Record structures.   (line  49)
* define-values:                         Other binding forms. (line  37)
* delete-directory:                      Directories.         (line  24)
* delete-file:                           Files.               (line   7)
* delete-file*:                          Deleting a file without signalling an error.
                                                              (line   7)
* describe-object:                       Additional protocol. (line   7)
* destructor::                           Accessing external objects.
                                                              (line 157)
* directory:                             Directories.         (line  30)
* directory?:                            Directories.         (line  39)
* disable-interrupts:                    Declarations.        (line  84)
* disable-warning:                       Declarations.        (line  91)
* disjoin:                               Combinators.         (line  42)
* documentation:                         Procedures and macros available in setup scripts.
                                                              (line  44)
* duplicate-fileno:                      File descriptors and low-level I/O.
                                                              (line   7)
* dynamic-load-libraries:                Parameters.          (line  43)
* each:                                  Combinators.         (line  50)
* emit-exports:                          Declarations.        (line  74)
* emit-external-prototypes-first:        Declarations.        (line  78)
* enable-warnings:                       Interrupts and error-handling.
                                                              (line   7)
* ensure:                                Other forms.         (line  28)
* errno:                                 Environment information and system interface.
                                                              (line  46)
* errno/acces:                           ERRNO values.        (line  16)
* errno/again:                           ERRNO values.        (line  26)
* errno/badf:                            ERRNO values.        (line  13)
* errno/busy:                            ERRNO values.        (line  18)
* errno/child:                           ERRNO values.        (line  14)
* errno/exist:                           ERRNO values.        (line  28)
* errno/fault:                           ERRNO values.        (line  17)
* errno/intr:                            ERRNO values.        (line  10)
* errno/inval:                           ERRNO values.        (line  21)
* errno/io:                              ERRNO values.        (line  11)
* errno/isdir:                           ERRNO values.        (line  20)
* errno/mfile:                           ERRNO values.        (line  22)
* errno/noent:                           ERRNO values.        (line   8)
* errno/noexec:                          ERRNO values.        (line  12)
* errno/nomem:                           ERRNO values.        (line  15)
* errno/nospc:                           ERRNO values.        (line  23)
* errno/notdir:                          ERRNO values.        (line  19)
* errno/perm:                            ERRNO values.        (line   7)
* errno/pipe:                            ERRNO values.        (line  25)
* errno/rofs:                            ERRNO values.        (line  27)
* errno/spipe:                           ERRNO values.        (line  24)
* errno/srch:                            ERRNO values.        (line   9)
* errno/wouldblock:                      ERRNO values.        (line  29)
* error:                                 Interrupts and error-handling.
                                                              (line  16)
* eval:                                  Eval.                (line   7)
* eval-handler:                          Parameters.          (line  66)
* eval-when:                             Other forms.         (line  42)
* examples:                              Procedures and macros available in setup scripts.
                                                              (line  52)
* exit:                                  Environment information and system interface.
                                                              (line  17)
* exit-handler:                          Parameters.          (line  60)
* export:                                Declarations.        (line  68)
* exports:                               Procedures and macros available in setup scripts.
                                                              (line  59)
* extend-procedure:                      Extending procedures with data.
                                                              (line   7)
* extended-bindings:                     Declarations.        (line 191)
* extended-procedure?:                   Extending procedures with data.
                                                              (line  15)
* extension-information:                 Loading extension libraries.
                                                              (line  18)
* f32vector->byte-vector:                Unit srfi-4.         (line  35)
* f64vector->byte-vector:                Unit srfi-4.         (line  36)
* feature?:                              Feature identifiers. (line  23)
* features:                              Feature identifiers. (line  18)
* fifo?:                                 Fifos.               (line  16)
* file-access-time:                      Retrieving file attributes.
                                                              (line   7)
* file-change-time:                      Retrieving file attributes.
                                                              (line   8)
* file-close:                            File descriptors and low-level I/O.
                                                              (line  14)
* file-execute-access?:                  Permissions.         (line  22)
* file-exists?:                          Files.               (line  13)
* file-link:                             Hard and symbolic links.
                                                              (line  21)
* file-lock:                             Record locking.      (line   7)
* file-lock/blocking:                    Record locking.      (line  17)
* file-mkstemp:                          File descriptors and low-level I/O.
                                                              (line  32)
* file-modification-time:                Retrieving file attributes.
                                                              (line   9)
* file-open:                             File descriptors and low-level I/O.
                                                              (line  19)
* file-owner:                            Permissions.         (line   7)
* file-permissions:                      Permissions.         (line  13)
* file-position:                         Retrieving file attributes.
                                                              (line  30)
* file-read:                             File descriptors and low-level I/O.
                                                              (line  48)
* file-read-access?:                     Permissions.         (line  20)
* file-select:                           File descriptors and low-level I/O.
                                                              (line  58)
* file-size:                             Retrieving file attributes.
                                                              (line  36)
* file-stat:                             Retrieving file attributes.
                                                              (line  17)
* file-test-lock:                        Record locking.      (line  24)
* file-truncate:                         Changing file attributes.
                                                              (line   7)
* file-unlock:                           Record locking.      (line  32)
* file-write:                            File descriptors and low-level I/O.
                                                              (line  73)
* file-write-access?:                    Permissions.         (line  21)
* fileno/stderr:                         File descriptors and low-level I/O.
                                                              (line  82)
* fileno/stdin:                          File descriptors and low-level I/O.
                                                              (line  80)
* fileno/stdout:                         File descriptors and low-level I/O.
                                                              (line  81)
* find-files:                            Finding files.       (line   7)
* find-header:                           Procedures and macros available in setup scripts.
                                                              (line 136)
* find-library:                          Procedures and macros available in setup scripts.
                                                              (line 128)
* fixnum-arithmetic:                     Declarations.        (line 171)
* fixnum?:                               Arithmetic.          (line  31)
* flatten:                               Lists.               (line  60)
* flip:                                  Combinators.         (line  63)
* fluid-let:                             Other binding forms. (line  43)
* flush-output:                          File Input/Output.   (line  12)
* for-each-argv-line:                    Iterating over input lines and files.
                                                              (line  16)
* for-each-line:                         Iterating over input lines and files.
                                                              (line   7)
* force-finalizers:                      Parameters.          (line  73)
* foreign-code:                          Accessing external objects.
                                                              (line   7)
* foreign-declare:                       Accessing external objects.
                                                              (line  29)
* foreign-lambda:                        Accessing external objects.
                                                              (line 230)
* foreign-lambda*:                       Accessing external objects.
                                                              (line 238)
* foreign-parse:                         Accessing external objects.
                                                              (line  33)
* foreign-parse/declare:                 Accessing external objects.
                                                              (line  38)
* foreign-primitive:                     Accessing external objects.
                                                              (line 272)
* foreign-safe-lambda:                   Accessing external objects.
                                                              (line 258)
* foreign-safe-lambda*:                  Accessing external objects.
                                                              (line 265)
* foreign-value:                         Accessing external objects.
                                                              (line  20)
* format:                                Formatted output.    (line  10)
* fp*:                                   Arithmetic.          (line  87)
* fp+:                                   Arithmetic.          (line  85)
* fp-:                                   Arithmetic.          (line  86)
* fp/:                                   Arithmetic.          (line  88)
* fp<:                                   Arithmetic.          (line  94)
* fp<=:                                  Arithmetic.          (line  96)
* fp=:                                   Arithmetic.          (line  92)
* fp>:                                   Arithmetic.          (line  93)
* fp>=:                                  Arithmetic.          (line  95)
* fpmax:                                 Arithmetic.          (line  91)
* fpmin:                                 Arithmetic.          (line  90)
* fpneg:                                 Arithmetic.          (line  89)
* fprintf:                               Formatted output.    (line   7)
* free:                                  Foreign pointers.    (line  22)
* fx*:                                   Arithmetic.          (line  38)
* fx+:                                   Arithmetic.          (line  36)
* fx-:                                   Arithmetic.          (line  37)
* fx/:                                   Arithmetic.          (line  39)
* fx<:                                   Arithmetic.          (line  46)
* fx<=:                                  Arithmetic.          (line  48)
* fx=:                                   Arithmetic.          (line  44)
* fx>:                                   Arithmetic.          (line  45)
* fx>=:                                  Arithmetic.          (line  47)
* fxand:                                 Arithmetic.          (line  49)
* fxior:                                 Arithmetic.          (line  50)
* fxmax:                                 Arithmetic.          (line  43)
* fxmin:                                 Arithmetic.          (line  42)
* fxmod:                                 Arithmetic.          (line  40)
* fxneg:                                 Arithmetic.          (line  41)
* fxnot:                                 Arithmetic.          (line  52)
* fxshl:                                 Arithmetic.          (line  53)
* fxshr:                                 Arithmetic.          (line  54)
* fxxor:                                 Arithmetic.          (line  51)
* gc:                                    Garbage collection.  (line   7)
* generic-methods:                       Introspection.       (line  39)
* gensym:                                Generating uninterned symbols.
                                                              (line   7)
* get-call-chain:                        Interrupts and error-handling.
                                                              (line  26)
* get-groups:                            Permissions.         (line  69)
* get-host-name:                         Getting the hostname and system information.
                                                              (line   7)
* get-keyword:                           Keywords.            (line  15)
* get-line-number:                       Macros.              (line   7)
* get-output-string:                     String ports.        (line   7)
* getenv:                                Environment information and system interface.
                                                              (line  51)
* getter-with-setter:                    Setters.             (line  20)
* glob:                                  Directories.         (line  45)
* glob->regexp:                          Unit regex.          (line  29)
* global-bound?:                         Accessing toplevel variables.
                                                              (line   7)
* global-ref:                            Accessing toplevel variables.
                                                              (line  13)
* global-set!:                           Accessing toplevel variables.
                                                              (line  24)
* grep:                                  Unit regex.          (line  19)
* group-information:                     Permissions.         (line  61)
* hide:                                  Declarations.        (line  28)
* identity:                              Combinators.         (line  70)
* implicit-exit-handler:                 Parameters.          (line  79)
* import:                                Declarations.        (line  96)
* include:                               Other forms.         (line  67)
* initialize:                            Intercessory protocol.
                                                              (line  62)
* initialize-groups:                     Permissions.         (line  81)
* initialize-slots:                      Utility procedures.  (line   7)
* inline:                                Declarations.        (line 104)
* inline-limit:                          Declarations.        (line 117)
* install-extension:                     Procedures and macros available in setup scripts.
                                                              (line   7)
* install-program:                       Procedures and macros available in setup scripts.
                                                              (line  71)
* install-script:                        Procedures and macros available in setup scripts.
                                                              (line  76)
* installation-prefix:                   Procedures and macros available in setup scripts.
                                                              (line 148)
* instance-of?:                          Introspection.       (line  63)
* instance?:                             Base language.       (line  13)
* interrupts-enabled:                    Declarations.        (line 122)
* intersperse:                           Lists.               (line  66)
* join:                                  Lists.               (line  71)
* keep-shadowed-macros:                  Declarations.        (line 127)
* keyword->string:                       Keywords.            (line  36)
* keyword-style:                         Parameters.          (line  85)
* keyword?:                              Keywords.            (line  31)
* lambda-lift:                           Declarations.        (line 134)
* let*-values:                           Other binding forms. (line  55)
* let-location:                          Locations.           (line  19)
* let-optionals:                         Binding forms for optional arguments.
                                                              (line  42)
* let-optionals*:                        Binding forms for optional arguments.
                                                              (line  43)
* let-values:                            Other binding forms. (line  49)
* letrec-values:                         Other binding forms. (line  64)
* link-options:                          Declarations.        (line 139)
* list->byte-vector:                     Bytevectors.         (line  51)
* list->queue:                           Queues.              (line   7)
* list-of:                               Combinators.         (line  81)
* load:                                  Loading code.        (line   7)
* load-library:                          Loading code.        (line  56)
* load-noisily:                          Loading code.        (line  44)
* load-relative:                         Loading code.        (line  39)
* load-verbose:                          Parameters.          (line  91)
* local-time->seconds:                   Date and time routines.
                                                              (line  36)
* local-timezone-abbreviation:           Date and time routines.
                                                              (line  42)
* location:                              Locations.           (line  24)
* locative->object:                      Locatives.           (line  53)
* locative-ref:                          Locatives.           (line  38)
* locative-set!:                         Locatives.           (line  45)
* locative?:                             Locatives.           (line  33)
* machine-byte-order:                    Environment information and system interface.
                                                              (line  57)
* machine-type:                          Environment information and system interface.
                                                              (line  62)
* macro?:                                Macros.              (line  16)
* macroexpand:                           Macros.              (line  21)
* macroexpand-1:                         Macros.              (line  28)
* make <1>:                              Procedures and macros available in setup scripts.
                                                              (line  93)
* make:                                  Base language.       (line  18)
* make-absolute-pathname:                Pathname operations. (line  22)
* make-byte-vector:                      Bytevectors.         (line  57)
* make-class:                            Base language.       (line  24)
* make-generic:                          Base language.       (line  31)
* make-input-port:                       Input/Output extensions.
                                                              (line   7)
* make-locative:                         Locatives.           (line  18)
* make-method:                           Base language.       (line  37)
* make-output-port:                      Input/Output extensions.
                                                              (line  21)
* make-parameter:                        Parameters.          (line  25)
* make-pathname:                         Pathname operations. (line  21)
* make-queue:                            Queues.              (line  15)
* make-record-instance:                  Low-level data access.
                                                              (line  28)
* make-static-byte-vector:               Bytevectors.         (line  64)
* make-weak-locative:                    Locatives.           (line  26)
* make-XXXvector:                        Unit srfi-4.         (line  14)
* map-file-to-memory:                    Memory mapped I/O.   (line  12)
* match-error-control:                   Pattern Matching.    (line 266)
* memory-mapped-file-pointer:            Memory mapped I/O.   (line  28)
* memory-mapped-file?:                   Memory mapped I/O.   (line   7)
* memory-statistics:                     Garbage collection.  (line  15)
* merge:                                 Sorting.             (line   7)
* merge!:                                Sorting.             (line   8)
* method-procedure:                      Introspection.       (line  50)
* method-specializers:                   Introspection.       (line  45)
* move-file:                             Procedures and macros available in setup scripts.
                                                              (line 114)
* move-memory!:                          Low-level data access.
                                                              (line  51)
* no-argc-checks:                        Declarations.        (line 147)
* no-bound-checks:                       Declarations.        (line 151)
* no-procedure-checks:                   Declarations.        (line 155)
* noop:                                  Combinators.         (line  91)
* nth-value:                             Other forms.         (line  76)
* null-pointer:                          Foreign pointers.    (line  31)
* null-pointer?:                         Foreign pointers.    (line  36)
* number-of-bytes:                       Low-level data access.
                                                              (line  64)
* number-of-slots:                       Low-level data access.
                                                              (line  70)
* object->pointer:                       Foreign pointers.    (line  41)
* object-become!:                        Magic.               (line   7)
* object-copy:                           Low-level data access.
                                                              (line  21)
* object-evict:                          Data in unmanaged memory.
                                                              (line   7)
* object-evict-to-location:              Data in unmanaged memory.
                                                              (line  34)
* object-evicted?:                       Data in unmanaged memory.
                                                              (line  45)
* object-release:                        Data in unmanaged memory.
                                                              (line  57)
* object-size:                           Data in unmanaged memory.
                                                              (line  51)
* object-unevict:                        Data in unmanaged memory.
                                                              (line  65)
* open-input-file*:                      File descriptors and low-level I/O.
                                                              (line 103)
* open-input-pipe:                       Pipes.               (line  33)
* open-input-string:                     String ports.        (line  13)
* open-output-file*:                     File descriptors and low-level I/O.
                                                              (line 104)
* open-output-pipe:                      Pipes.               (line  41)
* open-output-string:                    String ports.        (line  18)
* open/append:                           File descriptors and low-level I/O.
                                                              (line  92)
* open/binary:                           File descriptors and low-level I/O.
                                                              (line  99)
* open/creat:                            File descriptors and low-level I/O.
                                                              (line  91)
* open/excl:                             File descriptors and low-level I/O.
                                                              (line  93)
* open/fsync:                            File descriptors and low-level I/O.
                                                              (line  98)
* open/noctty:                           File descriptors and low-level I/O.
                                                              (line  94)
* open/nonblock:                         File descriptors and low-level I/O.
                                                              (line  95)
* open/rdonly:                           File descriptors and low-level I/O.
                                                              (line  86)
* open/rdwr:                             File descriptors and low-level I/O.
                                                              (line  88)
* open/read:                             File descriptors and low-level I/O.
                                                              (line  89)
* open/sync:                             File descriptors and low-level I/O.
                                                              (line  97)
* open/text:                             File descriptors and low-level I/O.
                                                              (line 100)
* open/trunc:                            File descriptors and low-level I/O.
                                                              (line  96)
* open/write:                            File descriptors and low-level I/O.
                                                              (line  90)
* open/wronly:                           File descriptors and low-level I/O.
                                                              (line  87)
* ormap:                                 Other control structures.
                                                              (line  15)
* parameterize:                          Other binding forms. (line  75)
* parent-process-id:                     Processes.           (line  12)
* patch:                                 Procedures and macros available in setup scripts.
                                                              (line 101)
* pathname-directory:                    Pathname operations. (line  31)
* pathname-extension:                    Pathname operations. (line  37)
* pathname-file:                         Pathname operations. (line  34)
* pathname-replace-directory:            Pathname operations. (line  43)
* pathname-replace-extension:            Pathname operations. (line  49)
* pathname-replace-file:                 Pathname operations. (line  46)
* pathname-strip-directory:              Pathname operations. (line  55)
* pathname-strip-extension:              Pathname operations. (line  58)
* perm/irgrp:                            Permissions.         (line  91)
* perm/iroth:                            Permissions.         (line  94)
* perm/irusr:                            Permissions.         (line  88)
* perm/irwxg:                            Permissions.         (line  98)
* perm/irwxo:                            Permissions.         (line  99)
* perm/irwxu:                            Permissions.         (line  97)
* perm/isgid:                            Permissions.         (line 102)
* perm/isuid:                            Permissions.         (line 101)
* perm/isvtx:                            Permissions.         (line 100)
* perm/iwgrp:                            Permissions.         (line  92)
* perm/iwoth:                            Permissions.         (line  95)
* perm/iwusr:                            Permissions.         (line  89)
* perm/ixgrp:                            Permissions.         (line  93)
* perm/ixoth:                            Permissions.         (line  96)
* perm/ixusr:                            Permissions.         (line  90)
* pipe/buf:                              Pipes.               (line  49)
* pointer->address:                      Foreign pointers.    (line  59)
* pointer->object:                       Foreign pointers.    (line  64)
* pointer-f32-ref:                       Foreign pointers.    (line 109)
* pointer-f32-set!:                      Foreign pointers.    (line 158)
* pointer-f64-ref:                       Foreign pointers.    (line 114)
* pointer-f64-set!:                      Foreign pointers.    (line 165)
* pointer-offset:                        Foreign pointers.    (line  69)
* pointer-s16-ref:                       Foreign pointers.    (line  91)
* pointer-s16-set!:                      Foreign pointers.    (line 138)
* pointer-s32-ref:                       Foreign pointers.    (line 103)
* pointer-s32-set!:                      Foreign pointers.    (line 152)
* pointer-s8-ref:                        Foreign pointers.    (line  80)
* pointer-s8-set!:                       Foreign pointers.    (line 125)
* pointer-tag:                           Tagged pointers.     (line  21)
* pointer-u16-ref:                       Foreign pointers.    (line  85)
* pointer-u16-set!:                      Foreign pointers.    (line 131)
* pointer-u32-ref:                       Foreign pointers.    (line  97)
* pointer-u32-set!:                      Foreign pointers.    (line 145)
* pointer-u8-ref:                        Foreign pointers.    (line  75)
* pointer-u8-set!:                       Foreign pointers.    (line 119)
* pointer=?:                             Foreign pointers.    (line  53)
* pointer?:                              Foreign pointers.    (line  48)
* port->fileno:                          File descriptors and low-level I/O.
                                                              (line 113)
* port-for-each:                         Iterating over input lines and files.
                                                              (line  30)
* port-map:                              Iterating over input lines and files.
                                                              (line  31)
* port-name:                             File Input/Output.   (line  18)
* port-position:                         File Input/Output.   (line  25)
* port?:                                 Standard Input/Output.
                                                              (line   7)
* post-process:                          Declarations.        (line 160)
* pp:                                    Input/Output extensions.
                                                              (line  32)
* pretty-print:                          Input/Output extensions.
                                                              (line  31)
* pretty-print-width:                    Input/Output extensions.
                                                              (line  39)
* print:                                 Standard Input/Output.
                                                              (line  12)
* print*:                                Standard Input/Output.
                                                              (line  19)
* print-call-chain:                      Interrupts and error-handling.
                                                              (line  37)
* print-error-message:                   Interrupts and error-handling.
                                                              (line  43)
* print-object:                          Additional protocol. (line  15)
* printf:                                Formatted output.    (line   8)
* procedure-data:                        Extending procedures with data.
                                                              (line  21)
* procedure-information:                 Interrupts and error-handling.
                                                              (line  52)
* process:                               Processes.           (line  76)
* process-execute:                       Processes.           (line  17)
* process-fork:                          Processes.           (line  34)
* process-group-id:                      Permissions.         (line  55)
* process-run:                           Processes.           (line  42)
* process-signal:                        Processes.           (line  53)
* process-spawn:                         Windows specific notes.
                                                              (line  54)
* process-wait:                          Processes.           (line  60)
* program-path:                          Procedures and macros available in setup scripts.
                                                              (line 154)
* project:                               Combinators.         (line  75)
* promise?:                              Other control structures.
                                                              (line  22)
* provide:                               Loading extension libraries.
                                                              (line  25)
* provided?:                             Loading extension libraries.
                                                              (line  31)
* queue->list:                           Queues.              (line  25)
* queue-add!:                            Queues.              (line  33)
* queue-empty?:                          Queues.              (line  38)
* queue-first:                           Queues.              (line  43)
* queue-last:                            Queues.              (line  49)
* queue-push-back!:                      Queues.              (line  60)
* queue-push-back-list!:                 Queues.              (line  65)
* queue-remove!:                         Queues.              (line  55)
* queue?:                                Queues.              (line  20)
* random:                                Random numbers.      (line   7)
* randomize:                             Random numbers.      (line  12)
* rassoc:                                Lists.               (line  27)
* read-all:                              Reading a file's contents.
                                                              (line   7)
* read-file:                             Input/Output extensions.
                                                              (line  44)
* read-line:                             Input/Output extensions.
                                                              (line  58)
* read-lines:                            Input/Output extensions.
                                                              (line  68)
* read-string:                           Input/Output extensions.
                                                              (line  75)
* read-symbolic-link:                    Hard and symbolic links.
                                                              (line  17)
* read-token:                            Input/Output extensions.
                                                              (line  86)
* rec:                                   Other binding forms. (line  21)
* receive:                               Other binding forms. (line  83)
* record->vector:                        Low-level data access.
                                                              (line  81)
* record-instance?:                      Low-level data access.
                                                              (line  76)
* regexp:                                Unit regex.          (line  37)
* regexp-escape:                         Unit regex.          (line 139)
* regexp?:                               Unit regex.          (line  54)
* register-feature!:                     Feature identifiers. (line  29)
* regular-file?:                         Retrieving file attributes.
                                                              (line  42)
* remove-file*:                          Procedures and macros available in setup scripts.
                                                              (line 119)
* rename-file:                           Files.               (line  19)
* rename::                               Accessing external objects.
                                                              (line 164)
* repl:                                  Read-eval-print loop.
                                                              (line   7)
* repl-prompt:                           Parameters.          (line  96)
* repository-path:                       Loading extension libraries.
                                                              (line  11)
* require:                               Loading extension libraries.
                                                              (line  37)
* require-at-runtime:                    Procedures and macros available in setup scripts.
                                                              (line  34)
* require-extension:                     Making extra libraries and extensions available.
                                                              (line   7)
* require-for-syntax:                    Loading extension libraries.
                                                              (line  38)
* reset:                                 Interrupts and error-handling.
                                                              (line  57)
* reset-handler:                         Parameters.          (line 102)
* return-to-host:                        Embedding.           (line  55)
* reverse-list->string:                  String utilities.    (line   7)
* run:                                   Procedures and macros available in setup scripts.
                                                              (line  82)
* run-time-macros:                       Declarations.        (line 177)
* s16vector->byte-vector:                Unit srfi-4.         (line  32)
* s32vector->byte-vector:                Unit srfi-4.         (line  34)
* s8vector->byte-vector:                 Unit srfi-4.         (line  30)
* seconds->local-time:                   Date and time routines.
                                                              (line   7)
* seconds->string:                       Date and time routines.
                                                              (line  46)
* seconds->utc-time:                     Date and time routines.
                                                              (line  52)
* set!-values:                           Other binding forms. (line 100)
* set-alarm!:                            Signal handling.     (line   7)
* set-buffering-mode!:                   Setting the file buffering mode.
                                                              (line   7)
* set-describer!:                        Macros and procedures implemented in the interpreter.
                                                              (line  20)
* set-dynamic-load-mode!:                Loading code.        (line  76)
* set-extension-specifier!:              Loading extension libraries.
                                                              (line  61)
* set-file-position!:                    Changing file attributes.
                                                              (line  14)
* set-finalizer!:                        Garbage collection.  (line  24)
* set-gc-report!:                        Garbage collection.  (line  33)
* set-group-id!:                         Permissions.         (line 111)
* set-groups!:                           Permissions.         (line  74)
* set-invalid-procedure-call-handler!:   Procedure-call- and variable reference hooks.
                                                              (line   7)
* set-port-name!:                        File Input/Output.   (line  33)
* set-procedure-data!:                   Extending procedures with data.
                                                              (line  27)
* set-process-group-id!:                 Permissions.         (line 116)
* set-read-syntax!:                      Reader extensions.   (line  13)
* set-root-directory!:                   Directories.         (line  52)
* set-sharp-read-syntax!:                Reader extensions.   (line  40)
* set-signal-handler!:                   Signal handling.     (line  14)
* set-signal-mask!:                      Signal handling.     (line  23)
* set-user-id!:                          Permissions.         (line 106)
* setenv:                                Environment access.  (line  13)
* setter:                                Setters.             (line  10)
* setup-build-directory:                 Procedures and macros available in setup scripts.
                                                              (line 164)
* setup-install-flag:                    Procedures and macros available in setup scripts.
                                                              (line 172)
* setup-root-directory:                  Procedures and macros available in setup scripts.
                                                              (line 160)
* setup-verbose-flag:                    Procedures and macros available in setup scripts.
                                                              (line 168)
* shift!:                                Miscellaneous handy things.
                                                              (line   7)
* shuffle:                               Lists.               (line  87)
* signal/abrt:                           Signal handling.     (line  36)
* signal/alrm:                           Signal handling.     (line  39)
* signal/chld:                           Signal handling.     (line  44)
* signal/cont:                           Signal handling.     (line  45)
* signal/fpe:                            Signal handling.     (line  33)
* signal/hup:                            Signal handling.     (line  32)
* signal/ill:                            Signal handling.     (line  34)
* signal/int:                            Signal handling.     (line  31)
* signal/io:                             Signal handling.     (line  42)
* signal/kill:                           Signal handling.     (line  30)
* signal/pipe:                           Signal handling.     (line  48)
* signal/prof:                           Signal handling.     (line  41)
* signal/quit:                           Signal handling.     (line  38)
* signal/segv:                           Signal handling.     (line  35)
* signal/stop:                           Signal handling.     (line  46)
* signal/term:                           Signal handling.     (line  29)
* signal/trap:                           Signal handling.     (line  37)
* signal/tstp:                           Signal handling.     (line  47)
* signal/urg:                            Signal handling.     (line  43)
* signal/usr1:                           Signal handling.     (line  51)
* signal/usr2:                           Signal handling.     (line  52)
* signal/vtalrm:                         Signal handling.     (line  40)
* signal/winch:                          Signal handling.     (line  53)
* signal/xcpu:                           Signal handling.     (line  49)
* signal/xfsz:                           Signal handling.     (line  50)
* signum:                                Arithmetic.          (line 115)
* singlestep:                            Interrupts and error-handling.
                                                              (line  66)
* sleep:                                 Processes.           (line  96)
* slot-ref:                              Base language.       (line  50)
* slot-set!:                             Base language.       (line  55)
* software-type:                         Environment information and system interface.
                                                              (line  80)
* software-version:                      Environment information and system interface.
                                                              (line  93)
* sort:                                  Sorting.             (line  17)
* sort!:                                 Sorting.             (line  18)
* sorted?:                               Sorting.             (line  25)
* spawn/detach:                          Windows specific notes.
                                                              (line  44)
* spawn/nowait:                          Windows specific notes.
                                                              (line  42)
* spawn/nowaito:                         Windows specific notes.
                                                              (line  43)
* spawn/overlay:                         Windows specific notes.
                                                              (line  40)
* spawn/wait:                            Windows specific notes.
                                                              (line  41)
* sprintf:                               Formatted output.    (line   9)
* standard-bindings:                     Declarations.        (line 183)
* static-byte-vector->pointer:           Bytevectors.         (line  73)
* string->byte-vector:                   Bytevectors.         (line  79)
* string->keyword:                       Keywords.            (line  41)
* string->uninterned-symbol:             Generating uninterned symbols.
                                                              (line  13)
* string-chomp:                          Strings.             (line  30)
* string-chop:                           Strings.             (line  21)
* string-compare3:                       Strings.             (line  36)
* string-compare3-ci:                    Strings.             (line  39)
* string-intersperse:                    Strings.             (line  46)
* string-match:                          Unit regex.          (line  60)
* string-match-positions:                Unit regex.          (line  61)
* string-search:                         Unit regex.          (line  79)
* string-search-positions:               Unit regex.          (line  80)
* string-split:                          Strings.             (line  61)
* string-split-fields:                   Unit regex.          (line  87)
* string-substitute:                     Unit regex.          (line 109)
* string-substitute*:                    Unit regex.          (line 125)
* string-translate:                      Strings.             (line  73)
* string-translate*:                     Strings.             (line  83)
* sub1:                                  Arithmetic.          (line   8)
* subclass?:                             Introspection.       (line  55)
* subf32vector:                          Unit srfi-4.         (line  79)
* subf64vector:                          Unit srfi-4.         (line  80)
* subs16vector:                          Unit srfi-4.         (line  77)
* subs32vector:                          Unit srfi-4.         (line  78)
* subs8vector:                           Unit srfi-4.         (line  76)
* substring-ci=?:                        Strings.             (line 100)
* substring-index:                       Strings.             (line 110)
* substring-index-ci:                    Strings.             (line 111)
* substring=?:                           Strings.             (line  99)
* subu16vector:                          Unit srfi-4.         (line  74)
* subu32vector:                          Unit srfi-4.         (line  75)
* subu8vector:                           Unit srfi-4.         (line  73)
* switch:                                Conditional forms.   (line   7)
* symbolic-link?:                        Hard and symbolic links.
                                                              (line   7)
* syntax:                                Procedures and macros available in setup scripts.
                                                              (line  28)
* syntax-error:                          Macros.              (line  38)
* system:                                Environment information and system interface.
                                                              (line 127)
* system*:                               Executing shell commands with formatstring and error checking.
                                                              (line   7)
* system-information:                    Getting the hostname and system information.
                                                              (line  13)
* tag-pointer:                           Tagged pointers.     (line   9)
* tagged-pointer?:                       Tagged pointers.     (line  15)
* tail?:                                 Lists.               (line  92)
* tcp-abandon-port:                      Unit tcp.            (line  92)
* tcp-accept:                            Unit tcp.            (line  36)
* tcp-accept-ready?:                     Unit tcp.            (line  47)
* tcp-addresses:                         Unit tcp.            (line  75)
* tcp-buffer-size:                       Unit tcp.            (line  97)
* tcp-close:                             Unit tcp.            (line  31)
* tcp-connect:                           Unit tcp.            (line  64)
* tcp-listen:                            Unit tcp.            (line  16)
* tcp-listener-fileno:                   Unit tcp.            (line  59)
* tcp-listener-port:                     Unit tcp.            (line  53)
* tcp-listener?:                         Unit tcp.            (line  26)
* tcp-port-numbers:                      Unit tcp.            (line  84)
* terminal-name:                         Terminal ports.      (line   7)
* terminal-port?:                        Terminal ports.      (line  12)
* test-compile:                          Procedures and macros available in setup scripts.
                                                              (line 141)
* thread-quantum:                        Unit srfi-18.        (line  59)
* thread-quantum-set!:                   Unit srfi-18.        (line  65)
* thread-signal!:                        Unit srfi-18.        (line  52)
* time:                                  Other forms.         (line  82)
* time->string:                          Date and time routines.
                                                              (line  64)
* toplevel-command:                      Toplevel commands.   (line 105)
* TYPE:                                  Declarations.        (line 170)
* TYPENAME-SLOTNAME:                     Accessing external objects.
                                                              (line 125)
* TYPENAME-SLOTNAME-set!:                Accessing external objects.
                                                              (line 133)
* u16vector->byte-vector:                Unit srfi-4.         (line  31)
* u32vector->byte-vector:                Unit srfi-4.         (line  33)
* u8vector->byte-vector:                 Unit srfi-4.         (line  29)
* unbound-variable-value:                Procedure-call- and variable reference hooks.
                                                              (line  29)
* undefine-macro!:                       Macros.              (line  34)
* unit:                                  Declarations.        (line 209)
* unless:                                Conditional forms.   (line  13)
* unmap-file-from-memory:                Memory mapped I/O.   (line  34)
* unregister-feature!:                   Feature identifiers. (line  36)
* unsafe:                                Declarations.        (line 213)
* unsetenv:                              Environment access.  (line  20)
* unshift!:                              Miscellaneous handy things.
                                                              (line  19)
* use:                                   Making extra libraries and extensions available.
                                                              (line   8)
* user-information:                      Permissions.         (line 121)
* user-options-pass:                     Extending the compiler.
                                                              (line  16)
* user-pass:                             Extending the compiler.
                                                              (line  38)
* user-pass-2:                           Extending the compiler.
                                                              (line  43)
* user-post-analysis-pass:               Extending the compiler.
                                                              (line  49)
* user-preprocessor-pass:                Extending the compiler.
                                                              (line  32)
* user-read-pass:                        Extending the compiler.
                                                              (line  24)
* uses:                                  Declarations.        (line 222)
* usual-integrations:                    Declarations.        (line 199)
* utc-time->seconds:                     Date and time routines.
                                                              (line  58)
* vector-copy!:                          Vectors.             (line   7)
* vector-resize:                         Vectors.             (line  17)
* version:                               Procedures and macros available in setup scripts.
                                                              (line  40)
* void:                                  The unspecified value.
                                                              (line   7)
* warning:                               Interrupts and error-handling.
                                                              (line  61)
* when:                                  Conditional forms.   (line  19)
* with-error-output-to-port:             Input/Output extensions.
                                                              (line  93)
* with-input-from-pipe:                  Pipes.               (line  54)
* with-input-from-port:                  Input/Output extensions.
                                                              (line  99)
* with-input-from-string:                String-port extensions.
                                                              (line  19)
* with-output-to-pipe:                   Pipes.               (line  55)
* with-output-to-port:                   Input/Output extensions.
                                                              (line 105)
* with-output-to-string:                 String-port extensions.
                                                              (line  25)
* write-line:                            Input/Output extensions.
                                                              (line  59)
* write-string:                          Input/Output extensions.
                                                              (line  76)



Tag Table:
Node: Top3299
Node: Introduction7513
Node: Basic mode of operation9761
Node: Using the compiler11961
Node: Compiler command line format12616
Node: Runtime options27771
Node: An example30740
Node: Extending the compiler32274
Node: Distributing compiled C files35918
Node: Using the interpreter38164
Node: Interpreter command line format38589
Node: Writing Scheme scripts41663
Node: Toplevel commands43140
Node: Macros and procedures implemented in the interpreter46201
Node: Supported language47669
Node: Deviations from the standard48291
Node: Extensions to the standard50286
Node: Non standard read syntax58233
Node: Non-standard macros and special forms61188
Node: Making extra libraries and extensions available61645
Node: Binding forms for optional arguments66451
Node: Other binding forms68742
Node: Substitution forms and macros72381
Node: Conditional forms75868
Node: Record structures76490
Node: Other forms78593
Node: Pattern Matching82302
Node: Declarations95580
Node: Parameters105976
Node: Unit library110105
Node: Arithmetic110848
Node: File Input/Output113907
Node: Files115070
Node: String ports115703
Node: Feature identifiers116242
Node: Keywords117779
Node: Exceptions119299
Node: Environment information and system interface122937
Node: Execution time126489
Node: Interrupts and error-handling127514
Node: Garbage collection130300
Node: Other control structures131920
Node: String utilities132853
Node: Generating uninterned symbols133274
Node: Standard Input/Output133828
Node: User-defined named characters134577
Node: Vectors135914
Node: The unspecified value136785
Node: Continuations137030
Node: Setters138385
Node: Unit eval139291
Node: Loading code139704
Node: Read-eval-print loop143878
Node: Macros144357
Node: Loading extension libraries145698
Node: Reader extensions149388
Node: Eval151238
Node: Unit extras151557
Node: Lists152059
Node: String-port extensions154936
Node: Formatted output155976
Node: Hash tables157430
Node: Queues157819
Node: Sorting159777
Node: Random numbers160598
Node: Input/Output extensions161113
Node: Strings165576
Node: Combinators169791
Node: Binary searching172404
Node: Unit srfi-1172979
Node: Unit srfi-4173215
Node: Unit srfi-13177122
Node: Unit srfi-14177522
Node: Unit match177988
Node: Unit regex178376
Node: Unit srfi-18184114
Node: Unit posix186457
Node: Directories187509
Node: Pipes189377
Node: Fifos192668
Node: File descriptors and low-level I/O193136
Node: Retrieving file attributes197838
Node: Changing file attributes199601
Node: Processes200533
Node: Hard and symbolic links204679
Node: Permissions205444
Node: Record locking210143
Node: Signal handling211410
Node: Environment access213317
Node: Memory mapped I/O214121
Node: Date and time routines215955
Node: Raw exit218286
Node: ERRNO values218720
Node: Finding files219569
Node: Getting the hostname and system information220964
Node: Setting the file buffering mode221565
Node: Terminal ports222129
Node: How Scheme procedures relate to UNIX C functions222607
Node: Windows specific notes225268
Node: Unit utils227466
Node: Pathname operations228016
Node: Temporary files230160
Node: Deleting a file without signalling an error230675
Node: Iterating over input lines and files231144
Node: Executing shell commands with formatstring and error checking232751
Node: Reading a file's contents233305
Node: Miscellaneous handy things233954
Node: Unit tcp234801
Node: Unit lolevel239346
Node: Foreign pointers239887
Node: Tagged pointers244704
Node: Extending procedures with data245575
Node: Bytevectors246942
Node: Data in unmanaged memory249478
Node: Locatives252276
Node: Accessing toplevel variables254382
Node: Low-level data access255346
Node: Procedure-call- and variable reference hooks258272
Node: Magic259736
Node: Unit tinyclos260619
Node: Defining forms261022
Node: Base language263737
Node: Introspection265497
Node: Intercessory protocol267288
Node: Additional protocol269591
Node: Utility procedures270387
Node: Builtin classes271048
Node: Interface to external functions and variables275130
Node: Accessing external objects275558
Node: Foreign type specifiers288164
Node: Embedding295505
Node: Callbacks304442
Node: Locations308409
Node: Other support procedures310426
Node: The Easy Foreign Function Interface310853
Node: #> ... <# Syntax313836
Node: General operation315075
Node: Pseudo declarations321334
Node: Grammar329483
Node: C notes335675
Node: C++ notes336194
Node: C interface337830
Node: chicken-setup347485
Node: Extension libraries347864
Node: Installing extensions348588
Node: Creating extensions350192
Node: Procedures and macros available in setup scripts350786
Node: Examples for extensions358212
Node: `chicken-setup' reference363268
Node: Windows notes366265
Node: Additional files367115
Node: chicken-more-macros.scm367467
Node: chicken-ffi-macros.scm368201
Node: Data Representation368541
Node: Bugs and limitations373813
Node: FAQ374433
Node: Acknowledgements394348
Node: Bibliography397433
Node: Index397800

End Tag Table
