HarkDB VS pareas

Not sure Futhark is very suitable for this, but a similarly brave person did use it to write some SQL-ish primitives last year, including a group-by operation: https://github.com/philass/HarkDB/blob/master/futhark/groupby.fut

Compared to Halide:

* Futhark does not expose a scheduling language that gives you precise control over code generation. This is probably the main selling point of Halide.

* Futhark has a much broader focus than Halide, which is mainly oriented towards image processing. Futhark wants to support arbitrary data parallel computation. E.g. see this compiler written in Futhark: https://github.com/Snektron/pareas

Compared to Sycl:

* Futhark is a non-embedded language that is more high level than Sycl. The goals are similar in the sense that both systems to try make (data) parallel programming more accessible. The vision behind Futhark is that the conventional functional programming vocabulary is actually a pretty good fit for parallelism, and that an aggressively optimising compiler can reduce or eliminate the overhead of abstraction. I don't think Sycl is as focused on high levels of abstraction, but rather focuses on being a relatively low-level portable programming interface.