Haskell, Java

Java and Crystal are not equivalent - neither have preemptible threads. Lots of other languages have co-routines or other cooperative systems - async/await are really just variants of that.

I didn't check if Gossamer is actually preemptible.

I believe the short list of production languages with preemptible M:N schedulers are limited to:

Erlang/Elixir

Haskell

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