m2-syn

syn for Macaulay2: a Rust crate that turns M2 code into a fully typed syntax tree, lets you walk and rewrite it, and prints it back out. The language server is built on it.

• Typed tree: a SourceFile of Cells, and each construct is its own type (Expr::Lambda, Expr::If, …), so matching on it is checked by the compiler.
• Round trip: an untouched file prints back byte for byte, comments included.
• Visit, VisitMut, Fold: override the node you care about, the rest is walked for you.
• quote_m2! / parse_quote_m2!: write M2 code with $(value) interpolation instead of gluing strings.

#![allow(unused)]
fn main() {
use m2_syn::nodes::Symbol;
use m2_syn::{ParsedFile, visit_mut::VisitMut};

struct Rename;

impl VisitMut for Rename {
    fn visit_symbol_mut(&mut self, symbol: &mut Symbol) {
        if symbol.text() == "left" {
            symbol.set_text("renamed");
        }
    }
}

let file = ParsedFile::from_source("left + right")?.edit(|cst| {
    Rename.visit_source_file_mut(cst);
});
assert_eq!(file.to_source(), "renamed+ right");
}

cargo add m2-syn
cargo run --example inspect -- file.m2   # in the repo: dump a file's tree

As a macro engine

The ProcMacro trait takes cells in and gives cells out, and with quote_m2! the output is written as M2. Right now these macros run from Rust, not from inside M2; for macros you call from M2 code, there’s ProceduralMacros.

The API is still moving between minor versions.

Repository · docs.rs