243 lines
8.6 KiB
Plaintext
243 lines
8.6 KiB
Plaintext
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Scsh 0.6.0 Release notes -*- outline -*-
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We are pleased to release scsh version 0.6.0. The new release is
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based on a newer version of Scheme 48 than the previous releases. The
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update of the underlying system is a massive switch and provides many
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new features, most notably a sophisticated thread system. We tried to
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make as less changes as possible to the API, see Section "API changes"
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for details. Unfortunately, due to the number of changes that were
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necessary to the internal structures, this release will probably
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contain some bugs. Don't hesitate to report bugs, we rely on your feedback!
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The text below gives a general description of scsh, instructions for obtaining
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it, pointers to discussion forums, and a description of the new features in
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release 0.6.0. (Emacs should display this document is in outline mode. Say
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c-h m for instructions on how to move through it by sections (e.g., c-c c-n,
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c-c c-p).)
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* Contents
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==========
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What is scsh
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Scsh as a scripting language
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Scsh as a systems-programming language
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Scsh is a portable programming environment
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Obtaining and installing scsh
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Getting in touch
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The World-Wide What?
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New in this release
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Scsh is now based on Scheme 48 0.53
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API changes
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Bugfixes
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Thanks
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* What is scsh
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==============
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Scsh is a broad-spectrum systems-programming environment for Unix embedded
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in R4RS Scheme. It has an open-source copyright, and runs on most major
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Unix systems.
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** Scsh as a scripting language
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-------------------------------
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Scsh has a high-level process notation for doing shell-script like tasks:
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running programs, establishing pipelines and I/O redirection. For example, the
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shell pipeline
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gunzip < paper.tex.gz | detex | spell | lpr -Ppulp &
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would be written in scsh as
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(& (| (gunzip) (detex) (spell) (lpr -Ppulp)) ; Background a pipeline
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(< paper.tex.gz)) ; with this redirection
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Scsh embeds this process notation within a full Scheme implementation.
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The process notation is realized as a set of macro definitions, and is
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carefully designed to allow full integration with standard Scheme code.
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Scsh isn't Scheme-like; it is Scheme.
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At the scripting level, scsh also has an Awk design, also implemented
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as a macro that can be embedded inside general Scheme code.
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Scripts can be written as standalone Scheme source files, with a leading
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#!/usr/local/bin/scsh -s
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trigger line.
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** Scsh as a systems-programming language
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-----------------------------------------
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Scsh additionally provides the low-level access to the operating system
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normally associated with C. The current release provides full access to Posix,
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plus important non-Posix extensions, such as complete sockets support.
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"Complete Posix" means: fork, exec & wait, sockets, full read, write, open &
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close, seek & tell, complete file-system access, including stat,
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chmod/chgrp/chown, symlink, FIFO & directory access, tty & pty support, file
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locking, pipes, select, file-name pattern-matching, time & date, environment
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variables, signal handlers, and more.
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In brief, you can now write Unix systems programs in Scheme instead of C.
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For example, we have implemented an extensible HTTP server at MIT entirely
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in scsh.
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As important as full access to the OS is the manner in which it is provided.
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Scsh integrates the OS support into Scheme in a manner which respects the
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general structure of the language. The details of the design are discussed
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in a joint MIT Lab for Computer Science/University of Hong Kong technical
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report, "A Scheme Shell," also to appear in a revised format in the *Journal
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of Lisp and Symbolic Computation." This paper is also available by ftp:
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ftp://ftp-swiss.ai.mit.edu/pub/su/scsh/scsh-paper.ps
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** Scsh is a portable programming environment
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---------------------------------------------
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Scsh is designed for portability. It is implemented on top of Scheme 48,
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a byte-code-interpreter Scheme implementation. The Scheme 48 virtual machine
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can be compiled on any system with a C compiler; the rest of Scheme 48 is
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machine-independent across 32-bit processors. Scsh's OS interface is
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also quite portable, providing a consistent interface across different
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Unix platforms. We currently have scsh implementations for:
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AIX
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BSD/OS
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CXUX
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FreeBSD
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HP-UX
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IRIX
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Linux
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NetBSD
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Solaris
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SunOS
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Ultrix
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Win32
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Darwin/Mac OS X
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Scsh code should run without change across these systems.
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Porting to new platforms is usually not difficult.
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* Obtaining and installing scsh
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===============================
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You can get a copy of scsh via anonymous ftp, from
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ftp://ftp-swiss.ai.mit.edu/pub/su/scsh/scsh.tar.gz
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The tar file includes a detailed manual and a paper describing
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the design of the system.
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For the lazily curious, we also have the manual separately available as
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ftp://ftp-swiss.ai.mit.edu/pub/su/scsh/scsh-manual.ps
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Just click 'n view.
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You *should* be able to build scsh on the standard platforms with exactly five
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commands: gunzip, tar, cd, ./configure, and make. The configure script figures
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out the special flags and switches needed to make the build work (thanks to
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the GNU project for the autoconfig tool that makes this possible).
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After doing the make, you can start up a Scheme shell and try it out
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by saying
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./go
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See the manual for full details on the command-line switches.
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If it's harder than this, and your system is standard, we'd like to know
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about it.
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* Getting in touch
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==================
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There are two main ways to join in scsh-related discussion: the mailing-list
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scsh@zurich.ai.mit.edu
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and the netnews group
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comp.lang.scheme.scsh
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These two forums should be equivalent, being bi-directionally gatewayed
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at MIT, but due to technical problems it's better to read them both.
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Bugs can be reported to
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scsh-bugs@zurich.ai.mit.edu
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or via the Scsh project's bugs section on SourceForge:
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http://sourceforge.net/projects/scsh/
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If you do not netnews hierarchy, or wish to join the mailing
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list for other reasons, send mail to
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scsh-request@zurich.ai.mit.edu
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* The World-Wide What?
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======================
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We even have one of those dot-com cyberweb things:
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http://www.swiss.ai.mit.edu/ftpdir/scsh/
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We now manage the project using SourceForge:
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http://sourceforge.net/projects/scsh/
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* New in this release
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====================
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** Scsh is now based on Scheme 48 0.53
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With the move from Scheme 48 version 0.36 to version 0.53 in this
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release the underlying system received a massive update. The most
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significant changes include:
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User level threads
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Advanced garbage collector
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Improved foreign function interface to C
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The most significant change for Scsh users is the addition of a
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user-level thread system. Scsh provides various features to deal
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with this new power in a system programming environment: An event
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based interface to interrupts, thread local process state and
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thread-safe system calls.
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** Interface to syslog
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** API changes
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Some procedures of the previous releases are currently not
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supported as we did not have the time to implement them. Please tell
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us, if you can't get along without them. Here is a listing of these
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currently dereleased procedures:
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select
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select!
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The following procedures received new names in this release:
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sleep (now process-sleep)
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sleep-until (now process-sleep-until
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network-info, service-info and protocol-info now return #f on non-success
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** Undocumented features
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The distributed code base provides some additional features but
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these are currently neither documented nor do we guarantee that the
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interfaces are stable. You may rest assured that we release these
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features soon. If you come across anything of this code, proceed at
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your own risk.
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** Bugfixes
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Most of the known bugs of version 0.5.3 have been fixed. See the
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project page on SourceForge for a list of the remaining known bugs.
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* Thanks
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========
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We would like to thank the members of local-resistance cells for the
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Underground everywhere for bug reports, bug fixes, design review and comments
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that were incorporated into this release. We really appreciate their help,
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particularly in the task of porting scsh to new platforms.
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Friedrich Dominicus
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Jay Nietling
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Tim Bradshaw
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Robert Brown
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Eric Marsden
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Paul Emsley
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Pawel Turnau
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Hannu Koivisto
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Andy Gaynor
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Francisco Vides Fernandez
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Tim Burgess
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Brian Denheyer
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Harvey Stein
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Eric Hilsdale
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Andreas Bernauer
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Reini Urban
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We'd like to thank everyone else for their patience; we are sorry that
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it took almost two years from the start of the port to this release.
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Brought to you by the Scheme Underground. Go forth and write elegant systems
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programs.
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-Olin Shivers, Brian Carlstrom, Martin Gasbichler & Mike Sperber
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