Salsa: Incremental Computation for Rust

Salsa is a framework for incremental recomputation. You define inputs and pure functions over them. Salsa memoizes every function call. When inputs change, it re-executes only the functions whose dependencies actually changed — skipping everything else.

Salsa powers rust-analyzer (Rust IDE), ty (Python type checker), and Cairo, all of which need sub-second response times on large codebases after small edits.

The Mental Model