Re: Scoped type variables

Ben Rudiak-Gould wrote:

Simon PJ thinks that Haskell' should include scoped type variables, and I tend to agree. But I'm unhappy with one aspect of the way they're implemented in GHC. What I don't like is that given a signature like

x :: a -> a

there's no way to tell, looking at it in isolation, whether a is free or bound in the type.

I'd quite like to see a flag that switches off implicit "forall" quantification altogether, or maybe just warned about it (since I use -Wall -Werror anyway). id :: forall a. a -> a const :: forall a b. a -> b -> a etc.