yes-lang

Yet anothEr Scripting Language

Simple interpreter in Rust:

• "manual" tokenization
• single-/multi-line comments
• prefix & infix operators
• Pratt parser impl
• tree-walking interpreter
• immutable scope-based bindings
• functions as a first class citizens
• lexer, parser, interpreter & REPL in <2k LoC

Goals:

• learn by doing
• easy to understand
• easy to implement
• easy to follow
• test coverage

Non-goals:

• IO
• stdlib
• safety
• collections
• performance
• type-safety
• production-readiness
• usability in general

Build

cargo build

cargo test

Run

Example: fib.yes.

$ cargo run --release examples/fib.yes
[...]
true

REPL

$ cargo run
[...]
REPL: enter :q to quit.
> let f = (fn (x) { fn(y) { x + y } });
<function>
> let hi = f("hello ");
<function>
> hi("world")
hello world
> f(40)(2)
42
> :load examples/fib.yes
true
> fib(10)
55
> :q
$