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Comment by anon-3988 | Hacker News Reader

I don't really get it, but is this related to delimited continuation as well?

Yes, see for instance https://github.com/ocaml-multicore/ocaml-effects-tutorial.

That's just an implementation detail. I don't think there's anything about effects that _requires_ delimited continuations to implement them.

If you want multishot continuations then I don't really know of any way other than delimited continuations (other than undelimeted continuations or simulating delimited continuations, on the heap).

Why can't the handler be invoked as if it was called from the effect invocation site, then return?

But apart from that and to answer your question there is an alternative to delimited continuations, and that's undelimited continuations (which essentially requires allocating call frames on the heap).

The handler doesn't have to follow the pattern of "do its work, resume the computation, go away."

It can instead do things like "do some work, resume the computation, do some more work."

Or even more invasively, "stash the computation somewhere, return from the handler site, let the rest of the program run for a while, then resume the computation."

> Why can't the handler be invoked as if it was called from the effect invocation site, then return?

Then it would just be (equivalent to) a function call.

Yes. Multishot resumption for algebraic effects is implemented with delimited continuations.

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