Ah yes, OK, I missed the point that the timeout is applied to the entire continuation, not just the part of the computation until the next await. Bluefin can't currently do that. I think I could make it do that, using the same implementation strategy as awaitYield (fork a thread, communicate through an MVar) but I wonder what the point is, given that Bluefin allows you to run the continuation at most once. Is the use case of "run the continuation in a modified environment (e.g. with a timeout)" really that compelling? Maybe it is! But I don't see it yet.

On the other hand, I don't see any difficulty with implementing a scheduler using Await/Yield. I don't think it needs access to the full continuation.