Simon Marlow wrote:
So the upshot is: you can use unsafeDupablePerformIO right now, or you can wait until I've tested and committed this patch to get tail-recursion with unsafePerformIO.
Wow, thank you for the detailed answer! That was really interesting.
I've no idea how it works in Hugs, you'll have to ask them :)
At least I can tell you how it is done in that other interpreter I mentioned. The reason that you can be better for that example is that the argument of badStack is not shared. No need to push an update frame for it. I am pretty sure that it is the same with the other compiler, both for Curry not for Haskell btw., but like you I am not sure with Hugs. If the ghc does not take into account what is statically not shared, I guess there is potential for a good optimization here which would go well beyond unsafe programs. Greetings and thanks! Bernd