rust-analyzer/crates/ra-salsa

salsa

A generic framework for on-demand, incrementalized computation.

Obligatory warning

This is a fork of https://github.com/salsa-rs/salsa/ adjusted to rust-analyzer's needs.

Credits

This system is heavily inspired by adapton, glimmer, and rustc's query system. So credit goes to Eduard-Mihai Burtescu, Matthew Hammer, Yehuda Katz, and Michael Woerister.

Key idea

The key idea of salsa is that you define your program as a set of queries. Every query is used like function K -> V that maps from some key of type K to a value of type V. Queries come in two basic varieties:

• Inputs: the base inputs to your system. You can change these whenever you like.
• Functions: pure functions (no side effects) that transform your inputs into other values. The results of queries is memoized to avoid recomputing them a lot. When you make changes to the inputs, we'll figure out (fairly intelligently) when we can re-use these memoized values and when we have to recompute them.

Want to learn more?

To learn more about Salsa, try one of the following:

• read the heavily commented hello_world example;
• check out the Salsa book;
• watch one of our videos.

Getting in touch

The bulk of the discussion happens in the issues and pull requests, but we have a zulip chat as well.