Re: [Haskell-cafe] What does the `forall` mean ?

12 Nov 2009


      David Virebayre wrote:
...
On Thu, Nov 12, 2009 at 8:52 PM, Andrew Coppin
 wrote:
...
I just meant it's not immediately clear how
...
foo :: forall x. (x -> x -> y)
...
is different from
...
foo :: (forall x. x -> x) -> y
...
It takes a bit of getting used to.
That still confuses me.
The difference is when the x variable gets bound - but to comprehend 
that, you have to realise that x gets bound at some point, which is 
non-obvious...