[jordwalke]

Note that multicore includes two separate "features": the algebraic effects abstractions, and the multi-core runtime (domain heaps). From what I understand, OCaml's multi-core effort will include both of these as well as some improvements to garbage collection.

[sgrove]

It's hard to say which is more exciting for me, but it probably comes down to effect handlers in a production-capable (if not production-ready) language that can work across different compilation target. Lots of interesting tooling that can be built on top of that!