Effects need to be fully known

[omentic]

I have hit the second half of the issue in #661 again (and figured I'd open a second issue since it was very unrelated to the original issue). This commented-out code fails to compile: https://gist.github.com/omentic/58b553920b4c8402b04c2873901291df#file-iter-scala-L464

It produces a very long "failed to typecheck overload" error, but it seems like the core issue is

Possible overload: iter::take of type [T](Int){() => Unit / { Yield[T] }} => Unit / { Yield[T] }
  Effects need to be fully known: Yield[T]

I suppose this is probably another case needing a heuristic?

[b-studios]

Yes that's right. At take it is not possible to know which effect to handle.

While you probably mean Int, in general it could be anything.

You can always annotate the type argument to work around it: take[Int] { ... }.

[omentic]

Ah - thanks a bunch! 😃

[effekt]$ java -jar bin/effekt examples/iter.effekt 
hello!
Cons(3, Cons(2, Cons(1, Cons(1, Cons(0, Nil())))))
Cons(144, Cons(34, Cons(8, Cons(2, Cons(0, Nil())))))

[b-studios]

Since you work on streams you might be interested in #527. Maybe you have some insights that you would like to share?