#femtolisp

A compact interpreter for a minimal lisp/scheme dialect.

This is a reanimation of https://github.com/lambdaconservatory/femtolisp with bigger plans.

Supported OS: 9front, Unix-like operating systems (OpenBSD, NetBSD, Linux, etc).

Supported CPUs: any decent 32 or 64-bit, little or big endian.

Tested on: 9front/arm64, OpenBSD/386, NetBSD/sparc64, Alpine/amd64, Android/arm64.

Some of the changes from the original include:

• aggressive clean up, removal, renaming and refactoring
• seamless arbitrary precision integers
• [ and ], { and } are synonyms to ( and )
• λ as a shorthand for lambda
• some of the previously available (but not merged) patches from the community and Julia are applied
• c***r of empty list returns empty list
• "boot" image is built into the executable
• vm opcode definitions and tables are generated from a single file
• fixed bootstrap (makes it work properly when opcodes change)
• built-in symbols aren't constants and can be redefined

#Building

#POSIX

meson setup build -Dbuildtype=release
ninja -C build test

#Plan 9

mk all test

#Characteristics

• lexical scope, lisp-1
• unrestricted macros
• case-sensitive
• simple compacting copying garbage collector
• Scheme-style varargs (dotted formal argument lists)
• "human-readable" bytecode with self-hosted compiler
• circular structure can be printed and read
• #. read macro for eval-when-read and readably printing builtins
• read macros for backquote
• symbol character-escaping printer
• exceptions
• gensyms (can be usefully read back in, too)
• #| multiline comments |#, #;(block comment..., lots of other lexical syntax
• generic compare function, cyclic equal
• cvalues system providing C data types and a C FFI
• constructor notation for nicely printing arbitrary values