From kelsey@research.nj.nec.COM Tue Mar 29 19:39:45 EST 1994
Article: 8466 of comp.lang.scheme
Xref: glinda.oz.cs.cmu.edu comp.lang.scheme:8466
Path: honeydew.srv.cs.cmu.edu!das-news.harvard.edu!noc.near.net!pad-thai.aktis.com!bloom-beacon.mit.edu!INTERNET!news-mail-gateway
From: kelsey@research.nj.nec.COM
Newsgroups: comp.lang.scheme
Subject: Scheme 48 is available for beta-test
Date: 25 Mar 1994 15:55:03 -0500
Organization: The Internet
Lines: 62
Sender: news@athena.mit.edu
Distribution: world
Message-ID: <9403252049.AA11992@sting14>
NNTP-Posting-Host: bloom-beacon.mit.edu
To: scheme@martigny.ai.mit.edu


You are invited to beta-test Scheme 48, a Scheme implementation based
on a virtual machine architecture.  Compressed tar files are in

    cs.indiana.edu:/pub/scheme-repository/imp/scheme48-0.36.tar.Z
    martigny.ai.mit.edu:/archive/s48/scheme48-0.36.tar.gz

Scheme 48 is designed to be straightforward, flexible, reliable, and
fast.  It should be easily portable to 32-bit byte-addressed machines
that have POSIX and ANSI C support.

In addition to the usual Scheme built-in procedures and a development
environment, library software includes support for hygienic macros (as
described in the Revised^4 Scheme report), multitasking, records,
exception handling, hash tables, arrays, weak pointers, and FORMAT.

Scheme 48 implements and exploits an experimental module system
loosely derived from Standard ML and Scheme Xerox.  The development
environment supports interactive changes to modules and interfaces.
This feature makes the module system significantly easier to work with
than it would be otherwise.

The virtual machine executes a byte-code instruction set similar to
the target of the Scheme 311 compiler [Clinger, LFP 1984].  The
interpreter for the virtual instruction set is itself written in
Pre-Scheme, a systems programming dialect of Scheme.  A Pre-Scheme
compiler applies intensive source-to-source rewrites to the
interpreter source code and emits low-level C code.  When the output
is then compiled by an optimizing C compiler such as gcc, the result
is an efficient and portable emulator.

The virtual machine is initialized from a specified memory image
containing byte-compiled Scheme code and data.  Images, including
small stand-alone applications, are built either using a static linker
or by writing out a procedure from an executing program.  A standard
memory image contains a Scheme run-time library (APPEND, READ, WRITE,
etc.), a compiler from Scheme to the virtual instruction set, and a
command processor and debugger.  In this way Scheme 48 can be
configured to look like a conventional Lisp interpreter.

Scheme 48 is available under the following license:

     Use of this program for non-commercial purposes is permitted
  provided that such use is acknowledged both in the software itself
  and in accompanying documentation.

     Use of this program for commercial purposes is also permitted,
  but only if, in addition to the acknowledgement required for
  non-commercial users, written notification of such use is provided
  by the commercial user to the authors prior to the fabrication and
  distribution of the resulting software.

     This software is provided ``as is'' without express or implied
  warranty.

Richard Kelsey
Jonathan Rees