#computation #query #framework #key #salsa #generic #on-demand


A generic framework for on-demand, incrementalized computation (experimental)

16 releases

new 0.0.216 May 20, 2024
0.0.215 May 13, 2024
0.0.213 Apr 29, 2024
0.0.207 Mar 25, 2024
0.0.203 Feb 26, 2024

#349 in Development tools

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2,160 downloads per month
Used in 21 crates (2 directly)

Apache-2.0 OR MIT



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.


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:

Getting in touch

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


~66K SLoC