# salsa

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*A generic framework for on-demand, incrementalized computation.*

## Obligatory warning

Very much a WORK IN PROGRESS at this point. Ready for experimental use
but expect frequent breaking changes.

## Credits

This system is heavily inspired by [adapton](http://adapton.org/), [glimmer](https://github.com/glimmerjs/glimmer-vm), 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](https://github.com/salsa-rs/salsa/blob/master/examples/hello_world/main.rs);
- check out the [Salsa book](https://salsa-rs.github.io/salsa);
- watch one of our [videos](https://salsa-rs.github.io/salsa/videos.html).

## Getting in touch

The bulk of the discussion happens in the [issues](https://github.com/salsa-rs/salsa/issues)
and [pull requests](https://github.com/salsa-rs/salsa/pulls),
but we have a [zulip chat](https://salsa.zulipchat.com/) as well.