An incredibly overwrought way to solve Advent Of Code 2023.
I've never written my own toy language, and writing one to solve Advent Of Code has been a bucket list item for me for a long time.
The language implemented by this interpreter is a Scheme-like, I guess? It's a functional, interpreted language that I wouldn't wish on my worst enemy.
Seriously, this language isn't recommended for use by anyone, ever, except maybe actual functional language experts who want to laugh at me.
Everything is an s-expression. Comments are delimited by square brackets.
Base types: 64-bit ints, strings, characters, booleans, and unit.
Compound types: NONE. Seriously. You have to roll your own out of functions! Except there's a tiny bit of support for lists, see below.
Keywords: let, \ (read 'lambda'), macro, if, trace, load, fail.
When evaluating lambda functions, the args get evaluated first then bound to the lambda variables. When evaluating macros, the args are left as an unevaluated closure until needed. Similarly, if doesn't evaluate its branches unless they're needed. trace s ... prints a message before continuing with the rest of the s-expression; it's for debugging. load file1 file2 ... tries to load and evaluate code from the given files, adding the symbols to the current environment. fail just fails; it's a panic.
Builtin functions: print, itoa (number to string), strcat, ord (char to number), chr (number to char), chars (string to list of chars) and list (convenience function to construct lists).
Operators: +, -, *, / (integer div), % (integer modulus), =, and >. Strings, integers, characters, and unit are ordered and comparable types; boolean is comparable but not ordered.
A "list" is a function that acts as a right fold. The only way to consume a list is with a right fold.
You've been warned. The error messages are atrocious and the performance is lousy. Don't use this for anything.