> As Mark Jones has allready said this thread should end or come to a > conclusion. Unfortunately he said more than that . He said that the > discussion was all about the difference a -> a and forall a. a -> a . And > that's not > true . One only has to read the first 2 or 4 emails about this thread of > discussion. I can't resist another comment. I think you are both right here. In Haskell there are no free type variables, it just looks as if there is because of a Haskell convention. If you write f :: a -> a it really means f :: forall a . a -> a So if "a -> a" appears as a type signature it is indeed equal to "forall a . a -> a" because Haskell has implicit forall quantifers for the free type variables of a signature. On the other hand, if we talk about a subexpression having type "a -> a" (which there is no syntax for in Haskell) this does not imply that it has type "forall a . a -> a", but rather that it has a type where the variable "a" has been bound in some outer scope. I think the source of all this debate is the convetion that type variables are implicitely quantified. I agree with Jon here, it was a mistake. -- Lennart
- Re: more detailed explanation about forall ... Claus Reinke
- Re: more detailed explanation about forall in Ha... Lennart Augustsson
- Re: more detailed explanation about forall ... Jan Brosius
- Re: more detailed explanation about forall in Ha... Frank Atanassow
- RE: more detailed explanation about forall in Ha... Frank Atanassow
- Re: more detailed explanation about forall in Ha... Ketil Malde
- Re: more detailed explanation about forall ... Frank Atanassow
- Re: more detailed explanation about forall ... Lars Lundgren
- RE: more detailed explanation about forall in Ha... Peter Douglass
- Re: more detailed explanation about forall in Ha... Jan Brosius
- Re: more detailed explanation about forall in Ha... Lennart Augustsson
- Re: more detailed explanation about forall ... Iavor Diatchki
- RE: more detailed explanation about forall in Ha... Peter Douglass
- Re: more detailed explanation about forall ... Jan Brosius
- Re: more detailed explanation about forall in Ha... Peter Hancock
- Re: more detailed explanation about forall ... Keith Wansbrough
- Re: more detailed explanation about forall in Ha... Marcin 'Qrczak' Kowalczyk
- Re: more detailed explanation about forall in Ha... Marcin 'Qrczak' Kowalczyk