Scsh 0.6.2 Release notes					-*- outline -*-

We are pleased to release scsh version 0.6.2.  This release
incorporates many SRFIs into scsh. The enhanced module language of the
recent Scheme 48 releases is now also part of scsh. In addition most
of the known bugs of the previous version have been fixed.


The text below gives a general description of scsh, instructions for obtaining
it, pointers to discussion forums, and a description of the new features in
release 0.6.2.  (Emacs should display this document is in outline mode. Say
c-h m for instructions on how to move through it by sections (e.g., c-c c-n,
c-c c-p).)

* Contents
==========
What is scsh
  Scsh as a scripting language
  Scsh as a systems-programming language
  Scsh is a portable programming environment
Obtaining and installing scsh
Getting in touch
The World-Wide What?
New in this release
  SRFIs
  port->socket
  New forms in the module language
  API changes
  PDF version of the manual
  Bugfixes
New in 0.6.1
New in 0.6.0
Thanks


* What is scsh
==============
Scsh is a broad-spectrum systems-programming environment for Unix embedded
in R5RS Scheme. It has an open-source copyright, and runs on most major
Unix systems.

** Scsh as a scripting language
-------------------------------
Scsh has a high-level process notation for doing shell-script like tasks:
running programs, establishing pipelines and I/O redirection. For example, the
shell pipeline

    gunzip < paper.tex.gz | detex | spell | lpr -Ppulp &

would be written in scsh as

    (& (| (gunzip) (detex) (spell) (lpr -Ppulp))	; Background a pipeline
       (< paper.tex.gz))				; with this redirection

Scsh embeds this process notation within a full Scheme implementation.
The process notation is realized as a set of macro definitions, and is
carefully designed to allow full integration with standard Scheme code.
Scsh isn't Scheme-like; it is Scheme.

At the scripting level, scsh also has an Awk design, also implemented
as a macro that can be embedded inside general Scheme code.

Scripts can be written as standalone Scheme source files, with a leading
    #!/usr/local/bin/scsh -s
trigger line.


** Scsh as a systems-programming language
-----------------------------------------
Scsh additionally provides the low-level access to the operating system
normally associated with C. The current release provides full access to Posix,
plus important non-Posix extensions, such as complete sockets support.
"Complete Posix" means: fork, exec & wait, sockets, full read, write, open &
close, seek & tell, complete file-system access, including stat,
chmod/chgrp/chown, symlink, FIFO & directory access, tty & pty support, file
locking, pipes, select, file-name pattern-matching, time & date, environment
variables, signal handlers, and more.

In brief, you can now write Unix systems programs in Scheme instead of C.
For example, we have implemented an extensible HTTP server at MIT entirely
in scsh.

As important as full access to the OS is the manner in which it is provided.
Scsh integrates the OS support into Scheme in a manner which respects the
general structure of the language. The details of the design are discussed
in a joint MIT Lab for Computer Science/University of Hong Kong technical
report, "A Scheme Shell," also to appear in a revised format in the "Journal 
of Lisp and Symbolic Computation."  This paper is also available by ftp:
    ftp://ftp.scsh.net/pub/scsh/papers/scsh-paper.ps


** Scsh is a portable programming environment
---------------------------------------------
Scsh is designed for portability. It is implemented on top of Scheme 48,
a byte-code-interpreter Scheme implementation. The Scheme 48 virtual machine
can be compiled on any system with a C compiler; the rest of Scheme 48 is
machine-independent across 32-bit processors. Scsh's OS interface is
also quite portable, providing a consistent interface across different
Unix platforms. We currently have scsh implementations for:
    AIX
    BSD/OS
    CXUX
    FreeBSD
    HP-UX
    IRIX
    Linux
    NetBSD
    OpenBSD
    Solaris
    SunOS
    Ultrix
    Win32
    Darwin/Mac OS X

Scsh code should run without change across these systems.
Porting to new platforms is usually not difficult.


* Obtaining and installing scsh
===============================
You can get a copy of scsh via anonymous ftp, from
    ftp://ftp.scsh.net/pub/scsh/scsh.tar.gz
The tar file includes a detailed manual and a paper describing
the design of the system.

For the lazily curious, we also have the manual separately available as
    ftp://ftp.scsh.net/pub/scsh/0.6/scsh-manual.ps
Just click 'n view.

You *should* be able to build scsh on the standard platforms with exactly five
commands: gunzip, tar, cd, ./configure, and make. The configure script figures
out the special flags and switches needed to make the build work (thanks to
the GNU project for the autoconfig tool that makes this possible).

After doing the make, you can start up a Scheme shell and try it out
by saying
    ./go
See the manual for full details on the command-line switches.

If it's harder than this, and your system is standard, we'd like to know
about it.


* Getting in touch
==================
There are two main ways to join in scsh-related discussion: the mailing-list
    scsh@zurich.ai.mit.edu
and the netnews group 
    comp.lang.scheme.scsh
These two forums should be equivalent, being bi-directionally gatewayed 
at MIT, but due to technical problems it's better to read them both.

Bugs can be reported to
    scsh-bugs@zurich.ai.mit.edu
or via the Scsh project's bugs section on SourceForge:
    http://sourceforge.net/projects/scsh/

If you do not netnews hierarchy, or wish to join the mailing
list for other reasons, send mail to
    scsh-request@zurich.ai.mit.edu


* The World-Wide What?
======================
We even have one of those dot-com cyberweb things: 
    http://www.scsh.net
We manage the project using SourceForge:
    http://sourceforge.net/projects/scsh/

* New in this release
=====================

** SRFIs
   In addition to SRFIs 1, 8, 13, 14 and 23 scsh now features SRFIs 2,
   5, 6, 7, 9, 11, 16, 17 and 19. See http://srfi.schemers.org/ for a
   detailed description. The SRFIs are available in packages srfi-N
   where N is the number of the SRFI.

** port->socket
   New procedure port->socket to turn a port into a socket object was
   added to the network code.

** New forms in the module language
   The module language supports the new forms modify, subset and
   with-prefix from Scheme 48 version 0.57.

** API changes
   Fork, fork/pipe, fork/pipe+ take an optional argument
   continue-threads? to determine whether all threads should continue
   to run in the child.

   exec-path-list is now a preseved thread fluid

** PDF version of the manual
   There is now a PDF version of the manual generated by pdflatex.

** Bugfixes
   - Added default argument to tty-info as described in the manual
   - Conversion to s48_value in tty1.c
   - Fixed another hygiene problem in SRE
   - Plugged space leak in bind-listen-accept-loop
   - Aligned CWD and umask in various file operations
   - Better releasing of port locks
   - Corrected exception of time
   - Set-cloexec to #t for unrevealed ports.
   - Included scsh paper in the distribution.
   - Fixed accept for AF_UNIX
   - (setenv var #f) now deletes var from environment
   - Quoted { and } within literal strings of regexps

* New in 0.6.1
==============

** API changes
  For sre's, BOW, EOW, WORD, and WORD+ (which were already unsupported
  in 0.6.0 on most platforms) are gone for good.

** Bugfixes
  Most of the known bugs of version 0.6.0 have been fixed, many thanks for
  the precise reports! See the project page on SourceForge for a list
  of the remaining known bugs. Here is a brief overview of the fixes:

  - GC_PROTECT'ed the necessary variables (specifically, where >1 arg to
    a function 'may GC') (Thanks to Steven Jenkins for dealing with this)
  - Fixed various race conditons in the signal handling and process reaping code
  - Fixed bug in set-process-group
  - If $HOME is unset, consult (user-info (user-uid)) for the value of 
    home-directory
  - Fix external-call-from-callback problem leading to spurious
        gc-protection-mismatch exceptions.
  - Let s48-do-gc return 0 so the PreScheme compiler will emit the correct
        signature of the function.
  - scsh/linux/tty-consts.scm: num-ttychars seems to be 32 not 19.
  - scsh/top.scm: Return 0 exit status for -c and -e.
  - *.c: Replaced // comments.
  - scsh/syslog1.c: Remove LOG_LPR from list of syslog levels.
  - scsh/network1.c: Pass SYSCALL argument to ERRNO-ERROR.
  - scsh/syscalls1.c: Disable timer interrupts before execve
  - scsh/network.scm: Correct name extraction in bind-socket
  - Added export for with-error-output-port
  - Install HTML version of manual under $(libdir)
  - ./configure is more rebost wrt $(srcdir)
  - Fixed installation of the S48 manual
  - Replaced several /tmp by /var/tmp 
  - Catch EISDIR in delete-filesys-object
  - flush-all-ports is now non-blocking

* New in 0.6.0
==============

** Scsh is now based on Scheme 48 0.53  
  With the move from Scheme 48 version 0.36 to version 0.53 in this
  release the underlying system received a massive update. The most
  significant changes include:
    User level threads
    Advanced garbage collector
    Improved foreign function interface to C

  The most significant change for Scsh users is the addition of a
  user-level thread system. Scsh provides various features to deal
  with this new power in a system programming environment: An event
  based interface to interrupts, thread local process state and
  thread-safe system calls.

** A manual for Scheme 48 has been included
  Richard Kelsey, the author of Scheme 48, has graciously allowed us
  to retrofit the current Scheme 48 manual for inclusion in this scsh
  release.

** Interfaces to dot-locking, crypt and syslog
  Scsh now provides advisory file locking via the dot-locking scheme
  and a direct binding to the crypt function. Furthermore we added
  a complete, system-independent and thread-safe interface to syslog.

** API changes
  Some features of the previous releases are currently not
  supported as we did not have the time to implement them. Please tell
  us, if you can't get along without them. Here is a listing of these
  currently dereleased features:
    select
    select!
    ODBC support
    bufpol/line

  The following procedures received new names in this release:
    sleep (now process-sleep)
    sleep-until (now process-sleep-until)

  network-info, service-info and protocol-info now return #f on non-success.

  The default directory for creating temporary files has changed: It's
  now the value of $TMPDIR if set and /var/tmp otherwise.

  The nth procedure is still there but is now officially obsolete.  It
  will go away in a future release.

** HTML version of the manual
  There is now a HTML version of the scsh manual generated by tex2page

* Thanks
========

We would like to thank the members of local-resistance cells for the
Underground everywhere for bug reports, bug fixes, design review and comments
that were incorporated into this release. We really appreciate their help,
particularly in the task of porting scsh to new platforms.

	
Brought to you by the Scheme Underground. Go forth and write elegant systems
programs.
    -Olin Shivers, Brian Carlstrom, Martin Gasbichler & Mike Sperber

