ref: 3c817d2e586dd916e39d54b2722c2e41a17c898d
dir: /README.md/
# 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](http://9front.org), 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.
Also runs on: MacOS 4.x-9.x, DOS.
Some of the changes from the original include:
* aggressive clean up, removal, renaming and refactoring
* docstrings - `(define (f ...) "Docs here" ...)` and `(help ...)`
* proper `(void)` and `void?`
* better error reporting - disassembly at the current instruction, location of syntax errors
* seamless bignums
* `[` 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](https://github.com/JuliaLang/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
Two ways to learn about more changes:
* https://todo.sr.ht/~ft/femtolisp?search=status:closed
* https://git.sr.ht/~ft/femtolisp/log
## Building
### POSIX
meson setup build -Dbuildtype=release
ninja -C build test
### Plan 9
mk all test
### MacOS 4.x-9.x (m68k or PowerPC)
Clone and build [Retro68](https://git.sr.ht/~ft/retro68). This fork grabs the
necessary patches for more things to work as expected:
git clone https://git.sr.ht/~ft/retro68
mkdir retro68-build
cd retro68-build
../retro68/build-toolchain.bash --multiversal --ninja --no-carbon
# wait until everything builds, make sure it did not error out
Now build femtolisp:
cd femtolisp
ln -s ../retro68-build/toolchain cross/macos-toolchain
# for PowerPC:
meson setup build . -Dbuildtype=minsize --cross-file cross/powerpc-apple.txt
# for m68k:
meson setup build . -Dbuildtype=minsize --cross-file cross/m68k-apple.txt
ninja -C build
Either `build/flisp.dsk` or `build/flisp.bin` is the file to get on your Mac.
NOTE: this isn't a full-fledged port and is going to stay low priority unless somebody
wants to spend time polishing it.
### DOS
Build DJGPP cross-compiler, then:
ln -s djgpp-toolchain-prefix cross/djgpp-toolchain
meson setup build . -Dbuildtype=minsize --cross-file cross/djgpp.txt
ninja -C build
Result is `build/flisp.exe`.
## 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