Can't compose other effects with `with_stack`

[duvenaud]

Now that stacks have landed, I'm reviving quicksort. However, I can't seem to manipulate a reference inside of a with_stack. Here's a MWE:

def func {h} (xs: Ref h Nat) : {State h} Unit =
  with_stack Unit \stack.
    xs := 0

gives

Type error:
Expected: {State h.1}
  Actual: {State h|a}
(Solving for: [a])

    xs := 0
       ^^^

[dougalm]

Thanks for catching that. Fix is in #1206. Do you need pop too?

[duvenaud]

Thanks! D'oh, I should have been able to fix that myself. I already wrote pop myself though, thanks for the offer.