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S5IOF (Scheme 5 In One File) - A Minimal R5RS Scheme System

S5IOF is a portable interpreter for a subset of the Scheme programming language. It can be built from a single C source file s5iof.c; there are no OS- or hardware-specific parts, no compiler-specific tricks, no dependency on platform-specific building tools. There is no distributive to install: just compile the file with your favorite C compiler, link it with the standard C runtime libraries and be done with it. For some platforms, precompiled binaries are available (please see releases).

Installation

There is no installation to speak of; just grab the file and compile it with your favorite C compiler.

Here's how you can compile S5IOF on a unix box:

gcc -o s5iof -O3 -DNDEBUG s5iof.c -lm

Please note that some compilers may issue hundreds of warnings; we recommend to add -Wno-parentheses-equality for Clang and -D_CRT_SECURE_NO_WARNINGS for Windows headers (unless you want to hear that fopen is no longer a reasonable way to open files). Some compilers link <math.h> library automatically, some require explicit option like -lm above.

If you specify high optimization settings as in the example above, be ready for long compilation times. But it's usually worth the wait: the executable is smaller and faster (which is important because the speed was traded for code size).

The resulting interpreter has no dependencies and can be run from any location.

Scheme Compatibility

S5IOF is true to basic Scheme principles -- it features precise garbage collector, supports proper tail recursion, call/cc, dynamic-wind, multiple return values, and has a hygienic macro system. It is mostly R5RS-compatible, but it has the following known limitations and deviations from the standard:

  • fixnums are limited to 24 bits, flonums are doubles
  • no support for bignums/rational/complex numbers
  • eval ignores its optional second argument; environment functions are stubs
  • some run-time errors such as zero division and fixnum overflows trigger asserts in C code unless NDEBUG is defined during compilation
  • transcript-on and transcript-off are not implemented

SIOF supports some common extensions:

  • error (not based on exceptions)
  • file-exists?, delete-file, rename-file
  • exit, abort, reset, command-line
  • get-environment-variable, system, current-jiffy, jiffies-per-second

Origins

S5IOF's original code is written in #F, a language for building Scheme-like systems. Its #F source code can be found there in examples directory:

s5iof.sf

S5IOF's on-the-fly compiler is derived from Marc Feeley's Scheme Interpreter (see gambit/bench/src/scheme.scm in the Gambit Scheme repository). Hygienic macroexpander is derived from Al Petrofsky's alexpander v1.65 (please see the #F source file for the original copyright notice). Supporting library code comes from #F's LibS library.

Family

Please see S4IOF for a smaller system without hygienic macros, SIOF for the latest (and biggest) single-file scheme implementation.