[shock]

> I don't want tens of thousands of kernel threads blocked on results

If that is because of the memory consumption of kernel threads, be aware you are trading less memory consumption for increased cognitive complexity (if you agree that asynchronicity is more complex than synchronicity).

[erik_seaberg]

True, if hardware cost nothing we might still be on python. Chaining futures with f1.thenApply(arg -> f2) hasn't been that bad, but kotlin's coroutine DSL does look better.