[Haskell-cafe] Existentially-quantified constructors, Eq and Show

[Benjamin Franksen]

On Thursday 08 December 2005 09:36, John Meacham wrote:
> On Thu, Dec 08, 2005 at 09:13:10AM +0100, Tomasz Zielonka wrote:
> > Shouldn't it be:
> > > data State
> > >     = Start
> > >
> > >     | Stop
> > >     | forall a . (Show a, Eq a) => State a
>
> ah. you are right. my bad.

But this is a rank-2 type, not an existentially quantified type?

Ben