Last-Modified: Wed Apr 30 14:13:24 1997 by Mark Kantrowitz
Maintainer: Mark Kantrowitz and Barry Margolin <firstname.lastname@example.org>
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;;; Answers to Frequently Asked Questions about Scheme *************
;;; Written by Mark Kantrowitz and Barry Margolin
This post contains part 1 of the Scheme FAQ.
If you think of questions that are appropriate for this FAQ, or would
like to improve an answer, please send email to us at email@example.com.
Note that the lisp-faq mailing list is for discussion of the content
of the FAQ posting only. It is not the place to ask questions about Scheme;
use either the firstname.lastname@example.org mailing list, the comp.lang.scheme
newsgroup or the Scheme Digest (email@example.com) for that. If a
question appears frequently in one of those forums, it will get added
to the FAQ list.
Copyright (c) 1993-94 by Mark Kantrowitz and Barry Margolin.
All rights reserved.
This FAQ may be freely redistributed in its entirety without
modification provided that this copyright notice is not removed. It
may not be sold for profit or incorporated in commercial documents
(e.g., published for sale on CD-ROM, floppy disks, books, magazines,
or other print form) without the prior written permission of the
copyright holder. Permission is expressly granted for this document
to be made available for file transfer from installations offering
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If this FAQ is reproduced in offline media (e.g., CD-ROM, print form,
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This article is provided AS IS without any express or implied warranty.
*** Topics Covered:
Topics Covered (Part 1):
[1-0] What is the purpose of this newsgroup?
[1-2] What is the difference between Scheme and Common Lisp?
[1-3] Scheme books, introductions, documentation, periodicals,
journals, and conference proceedings.
[1-4] Where can I learn about implementing Scheme interpreters and
[1-7] Standards for Scheme -- What are R4RS and IEEE P1178?
[1-8] How do I do object-oriented programming in Scheme?
[1-9] Repositories of Scheme Software
[1-10] Publicly Redistributable Scheme Software
[1-11] Formatting code in LaTeX (WEB and other literate programming tools)
[1-12] Where can I get an implementation of Prolog in Scheme?
[1-13] What does SICP, SCOOPS, R4RS, CAR, CDR, ... mean?
[1-14] Why is there no EVAL in Scheme?
[1-15] World-Wide Web (WWW) Resources
[1-16] Why is Scheme called 'Scheme'?
Topics Covered (Part 2):
[2-1] Free Scheme implementations.
[2-2] Commercial Scheme implementations.
[2-3] What Scheme-related discussion groups and mailing lists exist?
Search for \[#\] to get to question number # quickly.
*** Recent Changes:
;;; 20-OCT-94 mk Added FTP location for Scheme84.
;;; 3-NOV-94 mk FTP collections on altdorf.ai.mit.edu have moved to
;;; 3-NOV-94 mk Added Christian Queinnec's Lisp book to [1-4].
;;; 15-NOV-94 mk Updated location of Ken Dickey article.
;;; 22-NOV-94 mk Scheme Repository at Indiana University WWW page.
;;; 7-DEC-94 mk Updated EdScheme entry in [2-2].
;;; 16-JAN-95 mk Updated Schemers entry.
;;; 31-JAN-95 mk Added Manis' book to [1-3].
;;; 13-MAR-95 mk Updated EdScheme and 3DScheme for Windows in part 2.
;;; 7-APR-95 mk Added Scsh entry provided by Olin Shivers to [2-1].
;;; 14-APR-95 mk Updated description of the Schemer's Guide.
;;; 13-JUL-95 mk Updated 3d-Scheme entry in part 2.
;;; 17-AUG-95 mk Updated ELK entry in part 2.
;;; 11-SEP-95 mk Updated EdScheme and 3DScheme for Windows entries in part
;;; 19-FEB-96 mk Updated Schemer's entry in part 2.
;;; 19-MAR-96 mk Added entry on comp.lang.scheme.scsh to part 2.
;;; 13-NOV-96 mk Added entry for MzScheme.
;;; 30-APR-97 mk Added Inlab Scheme to [2-2].
Certain questions and topics come up frequently in the various network
discussion groups devoted to and related to Scheme. This file/article is
an attempt to gather these questions and their answers into a convenient
reference for Scheme programmers. It (or a reference to it) is posted
periodically. The hope is that this will cut down on the user time and
network bandwidth used to post, read and respond to the same questions
over and over, as well as providing education by answering questions
some readers may not even have thought to ask.
This is not a Scheme tutorial, nor is it an exhaustive list of all Scheme
intricacies. Scheme is a very powerful and expressive language, but with
that power comes many complexities. This list attempts to address the
ones that average Scheme programmers are likely to encounter. If you are
new to Scheme, see the answer to the question "How can I learn
The latest version of this file is available via anonymous FTP from CMU:
To obtain the files from CMU, connect by anonymous FTP to
using username "anonymous" and password "name@host" (substitute your
email address) or via AFS in the Andrew File System directory
and get the files scheme_1.faq and scheme_2.faq.
You can also obtain a copy of the FAQ by sending a message to
Send Scheme FAQ
in the message body.
An automatically generated HTML version of the Scheme FAQ is accessible by
WWW as part of the AI-related FAQs Mosaic page. The URL for this
The direct URL for the Lisp FAQ is
We've tried to minimize the overlap with the FAQ postings to the
comp.lang.lisp, comp.lang.clos and comp.ai newsgroups, so if you don't
find what you're looking for here, we suggest you try the FAQs for
those newsgroups. These FAQs should be available by anonymous ftp from
in the lisp-faq/, ai-faq/ and scheme-faq/ subdirectories or by email.
For instructions on email retrieval, send a mail message to
firstname.lastname@example.org with "help" and "index" on separate lines in
the body of the message.
If you need to cite the FAQ for some reason, use the following format:
Mark Kantrowitz and Barry Margolin, "Answers to Frequently Asked
Questions about Scheme", comp.lang.scheme, <month>, <year>,
Subject: [1-0] What is the purpose of this newsgroup?
The newsgroup comp.lang.scheme exists for general discussion of
topics related to the programming language Scheme. For example, possible
topics can include (but are not necessarily limited to):
announcements of Scheme books and products
discussion of programs and utilities written in Scheme
discussion of portability issues
questions about possible bugs in Scheme implementations
problems porting an implementation to some architecture
Postings should be of general interest to the Scheme community. See also
The comp.lang.scheme newsgroup is archived in
on a weekly basis.
Questions about Common Lisp should be directed to the newsgroup
comp.lang.lisp. Discussion of object oriented programming in Lisp to
the newsgroup comp.lang.clos. Discussion of functional programming
language issues in general should be directed to the newsgroup
comp.lang.functional. Discussion of AI programs implemented in Scheme
should sometimes be cross-posted to the newsgroup comp.ai.
Subject: [1-2] What is the difference between Scheme and Common Lisp?
Scheme is a dialect of Lisp that stresses conceptual elegance and
simplicity. It is specified in R4RS and IEEE standard P1178. (See
question [1-7] for details on standards for Scheme.) Scheme is much
smaller than Common Lisp; the specification is about 50 pages,
compared to Common Lisp's 1300 page draft standard. (See the Lisp FAQ
for details on standards for Common Lisp.) Advocates of Scheme often
find it amusing that the entire Scheme standard is shorter than the
index to Guy Steele's "Common Lisp: the Language, 2nd Edition".
Scheme is often used in computer science curricula and programming
language research, due to its ability to represent many programming
abstractions with its simple primitives. Common Lisp is often used for
real world programming because of its large library of utility
functions, a standard object-oriented programming facility (CLOS), and
a sophisticated condition handling system.
See question [1-8] for information about object-oriented programming
In Common Lisp, a simple program would look something like the
(defun fact (n)
(if (< n 2)
(* n (fact (1- n)))))
In Scheme, the equivalent program would like like this:
(if (< n 2)
(* n (fact (- n 1))))))
Experienced Lisp programmers might write this program as follows in order
to allow it to run in constant space:
(defun fact (n)
(labels ((tail-recursive-fact (counter accumulator)
(if (> counter n)
(tail-recursive-fact (1+ counter)
(* counter accumulator)))))
(tail-recursive-fact 1 1)))
Whereas in Scheme the same computation could be written as follows:
(lambda (counter accumulator)
(if (> counter n)
(tail-recursive-fact (+ counter 1)
(* counter accumulator))))))
(tail-recursive-fact 1 1))))
or perhaps (using IEEE named LETs):
(let loop ((counter n)
(if (< counter 2)
(loop (- counter 1)
(* accumulator counter))))))
Some Schemes allow one to use the syntax (define (fact n) ...) instead
of (define fact (lambda (n) ...)).
Subject: [1-3] Scheme books, introductions, documentation, periodicals,
journals, and conference proceedings.
Introductions to Scheme:
The following four books from MIT Press are listed in order of
increasing difficulty. The first is good for the complete novice,
the second for students with little or no previous exposure to programming,
and the third and fourth for more advanced students. The third and
fourth may also be used to learn a variety of powerful programming
language concepts. One of these books will suit your needs.
1. Daniel P. Friedman and M. Felleisen.
"The Little LISPer"
MIT Press (Cambridge, MA), 3rd printing, 1989. ISBN 0-262-56038-0.
Science Research Associates (Chicago), 3rd ed, 1989. 206 pages.
Good for a quick introduction. Uses Scheme instead of Common Lisp.
(The book uses a dialect of Scheme with footnotes about translating to
Scheme or Common Lisp. The footnotes won't allow a non-expert to use
Common Lisp for the advanced chapters because of the complexity.)
2. Brian Harvey and Matthew Wright
"Simply Scheme: Introducing Computer Science"
MIT Press, Cambridge, MA, 1994. 583 pages.
ISBN 0-262-08226-8. $49.95.
This book is ideal for students with little or no previous exposure to
programming. The book is designed to be used before SICP (the authors
call it a SICP "prequel"), and makes Scheme fun by sheltering the
students from potentially confusing technical details. Unlike Pascal
or C, the emphasis is on ideas, not obscure matters of syntax and
arbitrary rules of style. High schools who have shied away from using
Scheme because they found SICP to be too challenging should consider
using this book instead.
The text gradually and gently introduces students to some of the key
concepts of programming in Scheme. It starts off with functions and
function composition and continues with the notion of functions as
data (first-class functions) and programs that write programs
(higher-order functions). Since the complexity of the language is
hidden, students can get involved in some of the more interesting and
fun aspects of the language earlier than in other texts. Then the
book progresses through the more complicated concepts of lambda,
recursion, data abstraction and procedural abstraction, and concludes
with sequential techniques, but with careful attention to topics
students often find difficult. There are five chapters on recursion
alone! There's also a pitfalls section at the end of most chapters to
help students recognize and avoid common errors.
The book uses several programs as examples, including a tic-tac-toe
program, a pattern matcher, a miniature spreadsheet, and a simple
database program. Source code for the programs is available by
anonymous ftp from ftp://anarres.cs.berkeley.edu/pub/scheme/, or for $10 on
IBM or Macintosh diskettes from the publisher.
3. Harold Abelson and Gerald Jay Sussman, with Julie Sussman.
"Structure and Interpretation of Computer Programs"
MIT Press (Cambridge, MA) and McGraw-Hill (New York), 1985.
542 pages. ISBN 0-262-01077-1, $55. The teacher's manual, which is
also available from MIT Press (ISBN 0-262-51046-4 $20), does NOT
contain solutions to the exercises, but does contain hints on
teaching with the book.
Starts off introductory, but rapidly gets into powerful
Lisp-particular constructs, such as using closures,
building interpreters, compilers and object-oriented systems. Often
referred to by its acronym, SICP, which is pronounced "Sick-Pee". This
is the classical text for teaching program design using Scheme,
and everybody should read it at least once. MIT problem sets are
available from the repositories, and materials from Gustavus
Adolphus College are available from ftp.gac.edu:/pub/SICP/.
4. George Springer and Daniel P. Friedman
"Scheme and the Art of Programming"
MIT Press and McGraw Hill, 1990, 596 pages.
ISBN 0-262-19288-8, $50.
Introduces basic concepts of programming in Scheme. Also deals with
object oriented programming, co-routining, continuations. Gives
numerous examples. Has more of an emphasis on teaching Scheme than
SICP, and can be seen as an alternative to SICP. Source code from the
chapters is available from
5. Iain Ferguson, Edward Martin and Burt Kaufman.
Foreword by Daniel Friedman.
"The Schemer's Guide: Second Edition"
Schemers Inc., Ft. Lauderdale, FL, 1995. (see EdScheme entry in [2-2])
330 pages, ISBN 0-9628745-2-3, $35.95.
This book assumes no previous programming experience and is ideal
for high school or college students. The book presents
the elements of modern computer programming in an easy-to-follow and
entertaining manner. It gently introduces students to the Scheme
programming language, guiding them through such concepts as
functional programming, recursion, data structures, higher order
functions, delayed evaluation, and object-oriented programming. The
text concludes with a significant game-playing project
involving artificial intelligence. The book strikes a good balance
between theory and practice, while nurturing good programming
practices. The Schemer's Guide has a proven track record of several
years use in teaching the art of Scheme programming to high school
students and college undergraduates. A comprehensive teacher's guide
and an additional set of resource materials including worksheets,
quizzes, projects, and exams are available to instructors using this
text. (A Spanish translation will be available by August 1995.)
Older Introductions to Scheme:
1. Smith, Jerry D.
"Introduction to Scheme"
Prentice Hall (Englewood Cliffs, NJ), 1988, 324 pages.
Focuses on PC Scheme.
2. Michael Eisenberg
"Programming in Scheme"
Scientific Press (Redwood City, CA), 1988. 304 pages.
3. Two articles in BYTE Magazine, February 1988, by Abelson and
Sussman, and Clinger.
Online Introductions to Scheme:
1. The Ken Dickey article, "The Scheme Programming Language", in
COMPUTER LANGUAGES magazine, June 1992, is available from the
Scheme Repository at
The Revised^4 Report on the Algorithmic Language Scheme is also
available from the Scheme Repository.
2. The Info files from the MIT Scheme implementation.
3. "Introductory Scheme" by Joseph W. Lavinus and James D. Arthur,
<email@example.com>. Available from the Lisp Utilities
Repository as ftp://ftp.cs.cmu.edu/user/ai/lang/scheme/doc/intro/
Scheme and Artificial Intelligence:
1. Wolfgang Kreutzer and Bruce McKenzie
"Programming for Artificial Intelligence:
Methods, Tools and Applications"
Addison-Wesley (Reading, MA), 1990. 682 pages.
Discusses Scheme, Prolog, and Smalltalk, gives an overview of
the history and philosophy of AI, surveys three major
programming paradigms (procedural, declarative, and
object-oriented), and metaphors to AI programming.
Source code from the chapters is available from
as aibook.tar.Z. Some of the programs will only run under MacScheme.
Scheme-based Computer Science Texts:
1. Vincent Manis and James Little
"The Schematics of Computation"
Prentice-Hall, Inc., 1995. 848 pages
ISBN 0-13-834284-9 (North America), $41
ISBN 0-13-433772-7 (International).
For a copy of the publication announcement, see
General Scheme reference books include:
1. K. Dybvig
"The Scheme programming language"
Prentice Hall, 1987.
Good reference for Scheme.
Scheme-related periodicals include:
1. LISP Pointers.
Published by ACM SIGPLAN six times a year. Volume 1, Number 1
was April-May 1987.
Subscriptions: ACM Members $12; ACM Student Members $7; Non-ACM
members $25. Mail checks payable to the ACM to ACM Inc., PO Box
12115, Church Street Station, New York, NY 10249.
2. LISP and Symbolic Computation, Kluwer Academic Press. Volume 1
was published in 1989. (firstname.lastname@example.org is the editor). ISSN 0892-4635.
Subscriptions: Institutions $169; Individuals $80. Add $8 for
air mail. Kluwer Academic Publishers, PO Box 322, 3300 AH Dordrecht,
The Netherlands, or Kluwer Academic Publishers, PO Box 358, Accord
Station, Hingham, MA 02018-0358.
3. Proceedings of the biannual ACM Lisp and Functional Programming
Conference. (First one was in 1980.)
4. Proceedings of the annual Lisp Users and Vendors Conference.
See also the Scheme Bibliography from the Scheme Repository
(ftp://ftp.cs.indiana.edu/pub/scheme-repository/) for additional readings.
A large number of technical reports on Scheme are now available in the
text section (ftp://ftp.cs.indiana.edu/pub/scheme-repository/txt/).
Subject: [1-4] Where can I learn about implementing Scheme interpreters
There is no single book that is really comprehensive, so you will have
to combine reading the sources to the various free implementations
(e.g., Gambit [Feeley] and S48 [Rees]) with bits and pieces of tech
reports and various books.
Books about Scheme implementation include:
1. John Allen
"Anatomy of Lisp"
McGraw-Hill, 1978. 446 pages. ISBN 0-07-001115-X
2. Samuel Kamin
"Programming Languages, An Interpreter-Based Approach"
Addison-Wesley, Reading, Mass., 1990. ISBN 0-201-06824-9
Includes sources to several interpreters for Lisp-like
languages, and a pointer to sources via anonymous ftp.
3. Sharam Hekmatpour
"Lisp: A Portable Implementation"
Prentice Hall, 1985. ISBN 0-13-537490-X.
Describes a portable implementation of a small dynamic
Lisp interpreter (including C source code).
4. Peter Henderson
"Functional Programming: Application and Implementation"
Prentice-Hall (Englewood Cliffs, NJ), 1980. 355 pages.
5. Peter M. Kogge
"The Architecture of Symbolic Computers"
McGraw-Hill, 1991. ISBN 0-07-035596-7.
Includes sections on memory management, the SECD and
Warren Abstract Machines, and overviews of the various
Lisp Machine architectures.
6. Daniel P. Friedman, Mitchell Wand, and Christopher T. Haynes
"Essentials of Programming Languages"
MIT Press, 1992, 536 pages. ISBN 0-262-06145-7, $55.
Teaches fundamental concepts of programming language
design by using small interpreters as examples. Covers
most of the features of Scheme. Includes a discussion
of parameter passing techniques, object oriented languages,
and techniques for transforming interpreters to allow
their implementation in terms of any low-level language.
Also discusses scanners, parsers, and the derivation of
a compiler and virtual machine from an interpreter.
Source files available by anonymous ftp from
ftp://ftp.cs.indiana.edu/pub/eopl/ (220.127.116.11) or from the
Scheme Repository in
7. Peter Lee, editor, "Topics in Advanced Language Implementation",
The MIT Press, Cambridge, Mass., 1991.
Articles relevant to the implementation of functional
8. Also see the proceedings of the biannual ACM Lisp and Functional
Programming conferences, the implementation notes for CMU Common Lisp,
Peter Norvig's book ("Paradigms of AI Programming: Case Studies
in Common Lisp", Morgan Kaufmann, 1992. 946 pages. ISBN
1-55860-191-0), and SICP (Abelson & Sussman).
9. Christian Queinnec
"Les Langages Lisp"
InterEditions (in French), 1994. 500 pages.
ISBN 2-7296-0549-5, 61-2448-1. (?)
The book covers Lisp, Scheme and other related dialects,
their interpretation, semantics and compilation.
All of the programs described in the book are available by
anonymous ftp from
For more information, see the book's URL
or contact the author at Christian.Queinnec@inria.fr
Technical reports and journal articles about Scheme implementation include:
Mitchell Wand and Daniel P. Friedman, "Compiling Lambda Expressions
Using Continuations and Factorizations", Journal of Computer Languages
Guy Lewis Steele Jr., "Rabbit: A Compiler for Scheme", MIT AI Memo
474, Massachusetts Institute of Technology, Cambridge, MA, May 1978.
Guy Lewis Steele Jr., "Compiler Optimization Based on Viewing LAMBDA
as RENAME + GOTO", in "Artificial Intelligence: An MIT Perspective",
Patrick Henry Winston and Richard Henry Brown (eds.), MIT Press,
Cambridge, MA, 1980.
Jonathan A. Rees and Norman I. Adams, "T: A Dialect of Lisp or,
LAMBDA: The Ultimate Software Tool", Conference Record of the 1982 ACM
Symposium on Lisp and Functional Programming, 1982, 114-122.
R. Kent Dybvig, "C-Scheme", Computer Science Department Technical
Report #149 (MS Thesis), Indiana University, Bloomington, IA, 1983.
William Clinger, "The Scheme 311 compiler: An Exercise in Denotational
Semantics", Conference Record of the 1984 ACM Symposium on Lisp and
Functional Programming, 1984, 356-364.
Guillermo J. Rozas, "Liar, an Algol-like Compiler for Scheme", S.B.
Thesis, Department of Electrical Engineering and Computer Science,
Massachusetts Institute of Technology, January 1984.
David H. Bartley and John C. Jensen, "The Implementation of PC
Scheme", Proceedings of the 1986 ACM Conference on Lisp and Functional
Programming, 1986, 86-93.
David Kranz, Richard Kelsey, Jonathan A. Rees, Paul Hudak, James
Philbin and Norman I. Adams, "Orbit: An Optimizing Compiler for
Scheme", Proceedings of the SIGPLAN Notices '86 Symposium on Compiler
Construction, June 1986, 219-233. Published as SIGPLAN Notices 21(7),
Marc Feeley, "Deux Approches a' L'implantation du Language Scheme",
M.Sc. Thesis, De'partement d'Informatique et de Recherche
Ope'rationelle, University of Montreal, May 1986.
R. Kent Dybvig, "Three Implementation Models for Scheme", Department
of Computer Science Technical Report #87-011 (Ph.D. Dissertation),
University of North Carolina at Chapel Hill, Chapel Hill, North
Carolina, April 1987.
William D. Clinger, Anne H. Hartheimer and Eric M. Ost,
"Implementation Strategies for Continuations", Conference Record of
the 1988 ACM Conference on Lisp and Functional Programming, August
David Kranz, "Orbit: An Optimizing Compiler for Scheme", Computer
Science Technical report #632 (Ph.D. Dissertation), Yale University,
Joel F. Bartlett, "SCHEME->C a Portable Scheme-to-C Compiler",
Research Report 89/1, Dec. Western Research Laboratory, Palo Alto, CA,
Marc Feeley and James S. Miller, "A Parallel Virtual Machine for
Efficient Scheme Compilation", Proceedings of the 1990 ACM Conference
on Lisp and Functional Programming, Nice, France, June 1990.
Chris Hanson, "Efficient Stack Allocation for Tail-Recursive
Languages", Proceedings of the 1990 ACM Conference on Lisp and
Functional Programming, Nice, France, June 1990.
Robert Hieb, R. Kent Dybvig and Carl Bruggeman, "Representing Control
in the Presence of First-Class Continuations", Proceedings of the
SIGPLAN Notices '90 Conference on Programming Language Design and
Implementation, White Plains, New York, June 1990, 66-77.
Guillermo Rozas, "Taming the Y Operator", Proceedings of the 1992 ACM
Conference on Lisp and Functional Programming, San Francisco, CA,
June 1992, 226-234.
Dan Teodosiu, "HARE: An Optimizing Portable Compiler for Scheme", ACM
Sigplan Notices 26(1), January 1991.
Subject: [1-7] Standards for Scheme -- What are R4RS and IEEE P1178?
R4RS is the Revised^4 Report on the Algorithmic Language Scheme,
edited by W. Clinger and J. Rees. It appeared in ACM Lisp Pointers IV,
July-September 1991, and also as MIT AI Memo 848b. It serves as a kind
of standard for the language. It can be obtained by anonymous ftp at
the two Scheme Repositories, swiss-ftp.ai.mit.edu and ftp.cs.indiana.edu.
A HTML version is available as
IEEE P1178 is IEEE Standard 1178-1990, "IEEE Standard for the Scheme
Programming Language", published by IEEE in 1991. ISBN 1-55937-125-0.
It is now also an ANSI standard. It may be ordered from IEEE by
calling 1-800-678-IEEE or 908-981-1393 or writing IEEE Service
Center, 445 Hoes Lane, P.O. Box 1331, Piscataway, NJ 08855-1331,
and using order number SH14209 ($28 for IEEE members, $40 others).
Subject: [1-8] How do I do object-oriented programming in Scheme?
Some Scheme implementations (for example, MacScheme, Feel, Oaklisp, XScheme,
and PC-Scheme) include built-in object-oriented extensions.
BOS (Bryan's Object System) is a very small object system for Scheme.
It is based around generic functions and multiple inheritance. BOS
provides more or less the same features as Meroon and the Tiny CLOS
base language. Even though it has not been optimised, it should be
quite a bit faster than those because it does not include a MOP.
BOS has been tested under Scheme 48 and SCM, and should run under any
fairly modern Scheme implementation (especially any which runs SLIB)
with little or no change. It is available by anonymous ftp from
and the CMU AI Repository in
For more information, write to Bryan O'Sullivan <email@example.com>.
MEROON is a package written in Scheme to provide the basic facilities
of an object-oriented programming style through three macros:
define-class, define-generic, and define-method. MEROON offers simple
inheritance, reflective metaclasses and simple dispatching generic
functions with support for multimethods. MEROON also offers indexed
fields subsuming Scheme vectors without inheritance restrictions.
Meroon runs in Scheme->C, PC-Scheme, Chez Scheme, Elk, Bigloo, SCM
with SLIB, and MacGambit. MEROON sources and documentation may be
found in the Scheme Repository as
and also from
The file meroonet*.tar.gz is a toy version of meroon. For more
information, contact Christian Queinnec <firstname.lastname@example.org>
SCOOPS (Scheme Object Oriented Programming System) is an object system
for Scheme written by Amitabh Srivastava/Texas Instruments with
re-writes by Steve Sherin <email@example.com>. [Email to this
address bounced 7/7/93.] This package needs first-class environments.
It is available from the Scheme Repository as
Tiny CLOS is a Scheme implementation of a `kernelized' CLOS, with a
metaobject protocol. The implementation is even simpler than the
simple CLOS found in `The Art of the Metaobject Protocol,' weighing in
at around 850 lines of code, including (some) comments and
documentation. Tiny CLOS is available by anonymous ftp from
parcftp.xerox.com:/pub/mops/. Tiny CLOS runs in MIT Scheme 11.74 and
should run with only minor modifications in other Schemes as well. If
you want to be added to the firstname.lastname@example.org mailing list
(technical questions and discussion only), send mail to Gregor Kiczales
YASOS (Yet Another Scheme Object System) is fairly functional in style
and uses delegation. The implementation includes multiple inheritance
and "send to super" and is much smaller than class-based OO systems.
See Ken Dickey, "Scheming with Objects", AI Expert 7(10):24-33,
October 1992. A copy of the article and YASOS code is available from
the Scheme Repository in pub/scheme-repository/txt/swob.txt. YASOS is also
included as part of SLIB. For further information, contact Ken Dickey
Subject: [1-9] Repositories of Scheme Software
There are several repositories of publicly redistributable and
public domain Scheme code.
CMU AI Repository, Scheme Section:
The Scheme Section of the CMU Artificial Intelligence Repository
is accessible by anonymous ftp to
through the AFS directory
or by WWW from the URL
and includes more than 200 megabytes of sources and other materials
of interest to Scheme programmers, including all freely
distributable implementations and many programs. Unlike the Scheme
Repository at Indiana University, the entire contents of the CMU AI
Repository has been keyword indexed to provide convenient browsing
of the contents.
The repository has standardized on using 'tar' for producing
archives of files and 'gzip' for compression.
To search the keyword index by mail, send a message to:
with one or more lines containing calls to the keys command, such as:
keys scheme awk
in the message body. Keywords may be regular expressions and are
compared with the index in a case-insensitive conjunctive fashion.
You'll get a response by return mail. Do not include anything else in
the Subject line of the message or in the message body. For help on
the query mail server, include:
A Mosaic interface to the keyword searching program is in the
works. We also plan to make the source code (including indexes) to
this program available, as soon as it is stable.
Most of the Scheme Section of the AI Repository appears on Prime Time
Freeware for AI, Issue 1-1, a mixed-media book/CD-ROM publication. It
includes two ISO-9660 CD-ROMs bound into a 224 page book and sells
(list) for US$60 plus applicable sales tax and shipping and handling
charges. Payable through Visa, Mastercard, postal money orders in US
funds, and checks in US funds drawn on a US bank. For more
information write to Prime Time Freeware, 370 Altair Way, Suite 150,
Sunnyvale, CA 94086 USA, call 408-433-9662, 408-433-0727 (fax),
or send email to email@example.com.
Contributions of software and other materials are always welcome but
must be accompanied by an unambiguous copyright statement that grants
permission for free use, copying, and distribution -- either a
declaration by the author that the materials are in the public domain,
that the materials are subject to the GNU General Public License (cite
version), or that the materials are subject to copyright, but the
copyright holder grants permission for free use, copying, and
distribution. (We will tell you if the copying permissions are too
restrictive for us to include the materials in the repository.)
Inclusion of materials in the repository does not modify their
copyright status in any way. Materials may be placed in:
When you put anything in this directory, please send mail to
giving us permission to distribute the files, and state whether
this permission is just for the AI Repository, or also includes
publication on the CD-ROM version (Prime Time Freeware for AI).
We would also appreciate if you would include a 0.doc file for your
package; see /user/ai/new/package.doc for a template. (If you don't
have the time to write your own, we can write it for you based on
the information in your package.)
The Scheme Section of the AI Repository is maintained by Mark Kantrowitz
Scheme Repository at Indiana University:
The Scheme Repository at Indiana University contains a Scheme
bibliography, copies of the R4RS report and other papers, sample
Scheme code for a variety of purposes, several utilities, and some
implementations. The Scheme code includes code for calendar
calculations, Earley parser, FORMAT for Scheme, a scheme version of
the Gabriel benchmarks, Marc Feeley's minimal object support for
Scheme, a Scheme pretty-printer, a Prolog interpreter written in
Scheme, a random number generator in Scheme, an implementation of
SCOOPS, code from Abelson and Sussman's SICP book, Aubrey Jaffer's
IEEE/R4RS compliance test, an implementation of matrices, a Scheme
implementation of the Common Lisp FORMAT function, a Scheme front end
to Adobe Illustrator PostScript, and a LALR(1) parser (ZEBU). The
repository was established by Ozan S. Yigit and is currently
maintained by David Eby and John Zuckerman. Send administrative
The repository is accessible by anonymous ftp at
or by WWW to
The repository is mirrored in INRIA, courtesy of Christian Queinnec
[Ecole Polytechnique and INRIA-Rocquencourt], ftp.inria.fr:/lang/Scheme/
and also ftp://faui80.informatik.uni-erlangen.de/pub/scheme/
Other Scheme Collections:
Scheme Implementations may also be found at ftp://swiss-ftp.ai.mit.edu/archive/
The R4RS report is available in
or as MIT AI Memo 848b (email firstname.lastname@example.org for more information).
The swiss-ftp archive includes SCOOPS, CL2Scheme, extend-syntax,
btree, Gabriel benchmarks, FORMAT for Scheme, etc.
The GI (German Computer Science Society) Scheme Archive contains a
variety of scheme programs, utilities, code from theses, and other
materials. It also mirrors the Scheme Repository. It is
accessible by anonymous ftp to faui80.informatik.uni-erlangen.de
(login as 'ftp', giving your email address as the password).
pub/scheme/gi # GI Scheme Archive
pub/scheme/yorku # Internet Scheme Repository
Direct questions to email@example.com.
The GI Scheme Archive is supported by the German Computer Society Special
Interest Group on AI programming and sponsored by the Bavarian AI Center
FORWISS -- Research Institute for Knowledge Based Systems.
Subject: [1-10] Publicly Redistributable Scheme Software
SLIB (Standard Scheme Library) is a portable scheme library that
provides compatibility and utility functions for many of the
standard scheme implementations, including Chez, ELK 2.1, GAMBIT,
MITScheme, scheme->C, Scheme48, T3.1, VSCM and Scm4e. It is available by
anonymous ftp from
Now includes a FAQ file.
TEST.SCM is an IEEE and R4RS conformance test suite. It is available
PSD (Portable Scheme Debugger) is available by anonymous ftp
from Tampere University of Technology, Finland,
With PSD, you can run a Scheme program in an Emacs buffer, set
breakpoints, single step evaluation and access and modify the
program's variables. It works by instrumenting the original source
code, so it should run with any R4RS compliant Scheme. It has been
tested with SCM and Elk 1.5, but should work with other Schemes with a
minimal amount of porting, if at all. Includes documentation and
user's manual. Written by Pertti Kellom\"aki, firstname.lastname@example.org
The Lisp Pointers article describing PSD (Lisp Pointers VI(1):15-23,
January-March 1993) is available as
SCLINT is a lint-like program for Scheme. It checks for consistency of
indentation, syntax of special forms, and the number of arguments to
primitive and most user-defined procedures. This is not a full
implementation, but rather a quick hack. It is used in teaching
programming at the Tampere University of Technology. It is available
by anonymous ftp from
For further information, write to Pertti Kellom\"aki <email@example.com>.
A bibliography of work in functional programming can be obtained by
anonymous ftp from ftp://tamdhu.dcs.st-andrews.ac.uk/pub/staple/
(18.104.22.168). It uses a refer-like format with %T for title, %A
for authors %I for a unique index entry %S for source (possibly a
reference to another index) %K for keywords and %C for comments.
Compiled by Tony Davie, <firstname.lastname@example.org>. [Email bounced, 7/7/93.]
Scheme Utilities -- brokaw.lcs.mit.edu:/pub/scmutils.tar 22.214.171.124
[This collection seems to no longer be located on brokaw -- does
anybody know the current location?]
A collection of Scheme implementations of data structures and
algorithms is available by anonymous ftp from
as the file scheme-algorithms.tar. For more information, contact
Pertti Kellom\"aki <email@example.com>.
6.001. The User's Manual, example code, and problem sets from MIT's
course "Structure and Interpretation of Computer Programs" are
available by anonymous ftp from swiss-ftp.ai.mit.edu:/archive/6.001/
Steele's Constraint System. Chris Hanson's implementation of Steele's
constraint system is available for anonymous ftp from
A compressed version is also stored there. The software is source code
for MIT Scheme. It should run in release 7.1.3. Most of the MIT Scheme
dependencies could be eliminated, but it also uses the following
procedures which aren't in standard Scheme: error, bkpt, macros,
dynamic binding, and string output ports. The code corresponds pretty
closely to Guy Steele's PhD thesis implementation, which you can
obtain in printed form from the MIT AI Lab publications office as
AI-TR-595 for $15.00 (email firstname.lastname@example.org for more
information). For more information, send email to Chris Hanson
JACAL is a symbolic mathematics system for the simplification and
manipulation of equations and single and multiple valued algebraic
expressions constructed of numbers, variables, radicals, and algebraic
functions, differential, and holonomic functions. In addition, vectors
and matrices of the above objects are included. JACAL is written in
Scheme and requires SLIB. JACAL source is available via anonymous FTP
Contact email@example.com for more information.
Zebu 0.9 is an LALR(1) parser generator for Scheme written by
William M. Wells III. It lives in the Scheme Repository
and works with PC-Scheme from TI and MIT C-Scheme 6.2 (but not with
anything after 7.0).
Thomas is a compiler for the Dylan programming language. The Thomas
system is written in Scheme and runs under MIT's CScheme, DEC's
Scheme->C, and Marc Feeley's Gambit. It can run on a wide range of
machines including the Macintosh, PC compatibles, Vax, MIPS, Alpha,
and 680x0. Thomas generates IEEE compatible Scheme code. Thomas is
available to the public by anonymous ftp at
For more information on Thomas and Dylan, see part 4 of the Lisp FAQ.
MATCH is a pattern matching macro package for Scheme. Pattern
matching allows complicated control decisions based on data structure
to be expressed in a concise manner. This document describes several
pattern matching macros for Scheme, and an associated mechanism for
defining new forms of structured data. This macro package works with
any Scheme that supports defmacro (which is obtainable by loading
SLIB), such as Chez Scheme (release 4 or greater). MATCH is available
by anonymous ftp from titan.cs.rice.edu:/public/wright/match.tar.Z
[126.96.36.199] and includes the macro source code and documentation. A
copy should be available from the Scheme Repository shortly. For
further information, write to Andrew Wright, <firstname.lastname@example.org>.
Soft Scheme provides the benefits of static typing for dynamically
typed Scheme. Like a static type checker, a soft type checker infers
types for variables and expressions. But rather than reject programs
containing untypable fragments, a soft type checker inserts explicit
run-time checks to transform untypable programs to typable form.
These run-time checks indicate potential program errors, enabling
programmers to detect errors prior to program execution. Soft type
checking minimizes the number of run-time checks in the compiled code,
enabling dynamically typed languages to attain the efficiency of
statically typed languages like ML. Soft Scheme is available by
anonymous ftp from
For more information, write to Andrew Wright <email@example.com>.
ChezSybase is a Chez Scheme interface to the Sybase database.
It uses the Chez Scheme foreign function interface to provide a
high-level Scheme interface to the Sybase db-lib (the API to the
Sybase database). Most of the db-lib calls and datatypes are
supported, with the possible exception of spotty support for text and
image data, and there is no analog to the datetime datatype. It is
available by anonymous ftp from
For more information, write to Karl O. Pinc <firstname.lastname@example.org>.
Subject: [1-11] Formatting code in LaTeX
SLaTeX is a R4RS-compliant Scheme program that allows you to write
program code "as is" in your LaTeX or TeX source. It is particularly
geared to the programming languages Scheme and Common Lisp, and has
been tested in Chez Scheme, Common Lisp, MIT C Scheme, Elk, Scheme->C,
SCM and UMB Scheme on Unix; and MIT C Scheme and SCM on MSDOS. The
formatting of the code includes assigning appropriate fonts to the
various tokens in the code (keywords, variables, constants, data), at
the same time retaining the proper indentation when going to the
non-monospace (non-typewriter) provided by TeX. SLaTeX comes with two
databases that recognize the standard keywords/variables/constants of
Scheme and Common Lisp respectively. These can be modified by the
user using easy TeX commands. In addition, the user can inform SLaTeX
to typeset arbitrary identifiers as specially suited TeX expressions
(i.e., beyond just fonting them). The code-typesetting program SLaTeX
is available by anonymous ftp from
Send bug reports to email@example.com.
SchemeWEB provides simple support for literate programming in Lisp.
SchemeWEB version 2.0 is a Unix filter that allows you to generate
both Lisp and LaTeX code from one source file. The generated LaTeX
code formats Lisp programs in typewriter font obeying the spacing in
the source file. Comments can include arbitrary LaTeX commands.
SchemeWEB was originally developed for the Scheme dialect of Lisp, but
it can easily be used with most other dialects. Version 2.0 is
available in the Scheme Repository as
or in the Comprehensive TeX Archive Network (CTAN) in the directory
The Literate Programming FAQ lists a number of alternatives, both
language-independent and Scheme-specific. The Literate Programming FAQ
is posted once a quarter to the comp.programming.literate newsgroup
and is available by anonymous ftp from rtfm.mit.edu. A copy may also be
requested by sending an email message to firstname.lastname@example.org
in the body of the message.
Subject: [1-12] Where can I get an implementation of Prolog in Scheme?
Prolog in Scheme is a collection of macros that expand syntax for
clauses, elations, and so on. It is written in Scheme and has support
for delayed goals and interval arithmetic. It is known to run in Chez
Scheme and in Elk, and is intended to be portable to other Scheme
implementations. It relies on continuations, and so is not easily
ported to Common Lisp. Available from the University of Calgary by
anonymous ftp from
Questions and comments may be addressed to Alan Dewar
<email@example.com> or John Cleary <firstname.lastname@example.org>.
Schelog is an embedding of Prolog in Scheme. It represents Prolog
goals as procedures in Scheme, and includes macros to simulate a
Prolog-style syntax for clauses, relations and queries. The embedding
permits the user to combine Prolog and Scheme code freely, in the same
s-expression, if desired. Documentation and examples are included.
Schelog should run in any R4RS Scheme, has been tested in SCM and Chez
Scheme, and will run in any Scheme implementation that supports SLIB (see
entry in [1-10] above). Schelog (version 2) is available by anonymous
ftp from titan.cs.rice.edu:/public/dorai/schelog2.tar.Z. Its use of
higher-order continuations is probably a major obstacle to porting it
to Common Lisp. For more information, please contact the author Dorai
Subject: [1-13] What does SICP, SCOOPS, R4RS, CAR, CDR, ... mean?
Glossary of acronyms:
CAR Originally meant "Contents of Address portion of Register",
which is what CAR actually did on the IBM 704.
CDR Originally meant "Contents of Decrement portion of
Register", which is what CDR actually did
on the IBM 704. Pronounced "Cudder".
ANSI American National Standards Institute
SICP Abelson and Sussman's book "Structure and
Interpretation of Computer Programs".
EOPL Essentials of Programming Languages
SCOOPS An experimental object-oriented programming
language for Scheme.
R3RS Revised^3 Report on the Algorithmic Language Scheme.
R4RS Revised^4 Report on the Algorithmic Language Scheme.
Subject: [1-14] Why is there no EVAL in Scheme?
The answer to this question is based on information provided by
Guillermo J. Rozas and Aubrey Jaffer.
There are three major positions in the Scheme community regarding EVAL:
1. No EVAL: EVAL is antithetical to a Pascal-like (compiler based,
externally statically linked) implementation for Scheme, such as
some people have or wish to see.
2. Single Argument: There is a single distinguished top-level
environment, and EVAL always evaluates its argument there.
(This is the approach taken in Common Lisp, where EVAL evaluates
its argument in the current dynamic environment and in a null
3. Two Arguments: There are multiple environments in which
the user might want to evaluate expressions, so EVAL should take
two arguments, the second being an environment. In particular,
in some systems with first-class environments, there is no
a-priori single distinguished top-level environment, and
defaulting the environment does not fit those dialects well.
Not every dialect of Scheme has EVAL. Most do, but some with different
names and arguments. Jaffer's SLIB package uses LOAD as defined in
R4RS to define EVAL for those implementations that don't support EVAL
(e.g., by writing the code out to a file and then loading it).
Rozas's compromise proposal for EVAL was accepted for R5RS, but it is
unclear whether there will ever be a R5RS.
Subject: [1-15] World-Wide Web (WWW) Resources
The World Wide Web (WWW) is a hypermedia document that spans the
Internet. It uses the http (HyperText Transfer Protocol) for the
light-weight exchange of files over the Internet. NCSA Mosaic is a
World Wide Web browser developed at the National Center for
Supercomputing Applications (NCSA).
Mosaic's popularity derives, in part, from its ability to communicate
using more traditional Internet protocols like FTP, Gopher, WAIS, and
NNTP, in addition to http. Mosaic can display text, hypertext links,
and inlined graphics directly. When Mosaic encounters a file type it
can't handle internally, such as Postscript documents, mpeg movies,
sound files, and JPEG images, it uses an external viewer (or player)
like Ghostscript to handle the file. Mosaic also includes facilities
for exploring the Internet. In other words, Mosaic is an multimedia
interface to the Internet.
The hypertext documents viewed with Mosaic are written in HTML
(HyperText Markup Language), which is a subset of SGML (Standard
Generalized Markup Language). All that is needed is just a few more
improvements, such as the ability to format tables and mathematics,
and a WYSIWYG editor, for HTML to greatly facilitate electronic
journals and other publications.
NCSA Mosaic for the X Window System is available by anonymous ftp from
as source code and binaries for Sun, SGI, IBM RS/6000, DEC Alpha OSF/1, DEC
Ultrix, and HP-UX. Questions about NCSA Mosaic should be directed to
email@example.com (X-Windows version), firstname.lastname@example.org
(Macintosh), and email@example.com (Microsoft Windows).
A simple HTML version of the Scheme FAQ (this FAQ) is available as
The Scheme home page at MIT is
It includes a nifty little form that lets you execute small examples
of Scheme code.
The Scheme Underground web page is
Subject: [1-16] Why is Scheme called 'Scheme'?
According to Steele and Gabriel's "The Evolution of Lisp" paper,
Scheme was originally called Schemer, in the tradition of the AI
languages Planner and Conniver. But the ITS operating system had a
6-character limitation of file names, so the names were shortened to
PLNR, CNVR, and SCHEME. Eventually the truncated name Scheme stuck.