salsa

A generic framework for on-demand, incrementalized computation.

Obligatory warning

Very much a WORK IN PROGRESS at this point. Not really ready for use.

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.