Toy implementation of Lisp written in Zig.

$ zig run -- file.lisp

Or run the REPL:

$ zig run
> (+ 1 2)
3

• Zig

For release builds (recommended):

$ zig build -Doptimize=ReleaseFast
$ ./zig-out/bin/zig-lisp example/fib.lisp

Or build and run directly:

$ zig build-exe src/main.zig -O ReleaseFast
$ ./main example/fib.lisp

Debug builds will report memory leaks due to the lack of garbage collection in this toy implementation. The leaks occur during recursive function calls where temporary atoms are created but not fully tracked for cleanup.

For production use, always build with -Doptimize=ReleaseFast, which disables memory leak detection and provides better performance.

The memory leaks are not problematic for:

• Script execution (memory is reclaimed by OS on process exit)
• Short REPL sessions

However, long-running REPL sessions may accumulate memory over time.

See the example/ directory for sample Lisp programs:

• fib.lisp - Fibonacci sequence
• tak.lisp - Takeuchi function
• fizzbuzz.lisp - FizzBuzz

MIT

Yasuhiro Matsumoto (a.k.a. mattn)