Scheme 9 from Empty Space

S9fES is an interpreter for a broad subset of R4RS Scheme. It is written in ANSI C (C89) and Scheme.

The S9fES code strives to be comprehensible rather than fast. It is aimed at people who want to study the implementation of Scheme (in a language other than Scheme).

Latest update: 2007-10-30

Scheme 9 - The Book

The Scheme 9 book discusses the implementation in detail and covers the theory behind the scenes.

Before you ask

Why in earth write another half-baked implementation of Scheme?
It is better than getting drunk at a bar.

Is S9fES based on any other implementation?
It is loosely based on Sketchy LISP, but S9fES is smaller, sometimes faster, and has a simpler implementation model.

How complete is it?
S9fES implements R4RS modulo a few omissions. See the man page for details.

Why are newer versions only R4RS-compliant?
Because R4RS is elegant and sufficient. You may also consider this as a statement regarding R6RS. Fortunately, alternatives begin to emerge.

What are its conditions of use?
Don't worry, be happy. (Hacker ethic (sense 1) applies.)

Where is it?
Here:

s9fes.tgz	[~40KB]	latest version: source code, man page, test suite
s9fes-book.tgz	[~40KB]	snapshot of the version discussed in the book
s9fes-exe.zip	[~35KB]	"EXE file" for the unmentionable horror (may be slightly outdated)

Copyright (C) 2007 Nils M Holm <nmh @ t3x . org>
Above artwork is based on the movie "Plan 9 from Outer Space" and used under the assumption of fair use.