Comment by arxanas
1 day ago
It's quite possible that I have different, smaller-scale problems than you have! So my feedback might not be as relevant
I wrote detailed commentary here: https://github.com/s-arash/ascent/discussions/72
Re Rust bindings and your specific comment:
- Deploying Soufflé and doing FFI is much more difficult for me in practice, just in terms of the overhead to set up a working build. (I'm not going to be able to justify setting up a Soufflé ruleset for Bazel, and then adding Rust-Soufflé binding generation, etc. at my workplace.)
- User-defined functors, or integrating normal data structures/functions/libraries into your Soufflé program, seems painful. If you're doing integrations with random existing systems, then reducing the friction here is essential. (In slide 16 of the talk, you can see how I embedded a constructive `Trace` type and a `GlobSet` into an actual Ascent value+lattice.)
- On the other hand, you might need Soufflé's component system for structuring larger programs whereas I might not (see above GitHub discussion).
Non-specifically:
- Several features like generative clauses, user-defined aggregations, lattices, etc. seem convenient in practice.
- I had worse performance with Soufflé than Ascent for my program for some query-planning reason that I couldn't figure out. I don't really know why; see https://github.com/souffle-lang/souffle/discussions/2557
> - I had worse performance with Soufflé than Ascent for my program for some query-planning reason that I couldn't figure out. I don't really know why; see https://github.com/souffle-lang/souffle/discussions/2557
I think the basic issue is that ADTs are simply not indexed--so to the degree that you write a query that would necessitate an index on a subtree of an ADT, you will face asymptotic blowup, as the way ADTs work will force you to scan-then-test across all ADTs (associated with that top-level tag). The issue is discussed in Section 5.2 of this paper here: https://arxiv.org/pdf/2411.14330
Ah, yes, but I think Ascent also doesn't index ADTs. In this case, based on some other information, it seems like Soufflé _can_ plan the queries better if it has profiling data. It seems like Ascent just happened to pick a better query plan in my case without the profiling data.
Thanks for the link to the paper!
It's true that Ascent does not index ADTs either, but there are some tricks that you can use when you control the container type to get similar performance by, e.g., storing a pre-computed hash. I believe Arash, the main author of Ascent, was exploiting this trick for Rc<...> members and seeing good performance gains. It is a bit nuanced, you're right that Ascent doesn't pervasively index ADTs out of the box for sure.