salsa

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, glimmer, and rustc's query system. So credit goes to Eduard-Mihai Burtescu, Matthew Hammer, Yehuda Katz, and Michael Woerister.

Goals

It tries to hit a few goals:

• No need for a base crate that declares the "complete set of queries"
• Each query can define its own storage and doesn't have to be memoized
• Each module only has to know about the queries that it depends on and that it provides (but no others)
• Compiles to fast code, with no allocation, dynamic dispatch, etc on the "memoized hit" fast path
• Can recover from cycles gracefully (though I didn't really show that)
• Should support arenas and other lifetime-based things without requiring lifetimes everywhere when you're not using them (untested)

Example

There is a working hello_world example which is probably the best documentation. More to come when I expand out a few more patterns.