It's been in development for more than 5 years and looks a bit like a boondoggle though, as the goal is not just to remove the GIL and provide "native threads" but
> use algebraic effects to compose concurrency and supports parallelism through domains and incremental GC. Rather than adding a specific multicore scheduler into the runtime system, we’re providing the minimum required toolset in the form of pluggable schedulers.
They're doing lots of great heavy lifting to get effects and handlers into a production language, and I don't think it's fair to write them off like this. Yes, it's hard, but they seem to be making positive progress.
> They're doing lots of great heavy lifting to get effects and handlers into a production language
Sure, but at the end of the day what it means is 5 years into the effort OCaml still as limited threading-wise as it was at the start of the effort. And that is what most users (and non-users) care about in a world where 2/4 is your mobile baseline and where AMD's R3-3300G is expected to be 6/12 for $99.
> use algebraic effects to compose concurrency and supports parallelism through domains and incremental GC. Rather than adding a specific multicore scheduler into the runtime system, we’re providing the minimum required toolset in the form of pluggable schedulers.