hello, here is (a simplifed version of) what i run into while playing with continuations. i guess the important thing is the type sugnature, not the definition. > f :: ((forall b. b) -> Int) -> Int > f = f on this hugs (version May 2003) reports: INTERNAL ERROR: depTypeExp i am a bit rusty on how one calculates the rank of a type, but perhaps this is a rank-3 type? bye iavor