Re: [Haskell-cafe] Solved but strange error in type inference

Yes but as I understood it the type inferer was taking your type annotation for granted, and apparently in fact it re-specifies it. What you said was in reality:

f :: forall. a -> a f x = undefined :: forall a1. a1 And it turned it into: f :: forall. a -> a f x = undefined :: a (here, 'a' would be *scoped*)

There's something I don't get... 2012/1/4 Yucheng Zhang

On Wed, Jan 4, 2012 at 9:41 PM, Yves Parès wrote:

...

Would you try:

f :: a -> a f x = undefined :: a

And tell me if it works? IMO it doesn't.

It works.

As I understand, in this situation we are specializing the 'undefined :: forall a. a' to a more specific dependent type.