[Haskell-cafe] Confused about type seen in the wild

[Jason Dagit]

On Thu, Apr 10, 2014 at 9:27 AM, Albert Y. C. Lai <trebla at vex.net> wrote:

>
>
Yes, GHC accepts "X => Y => Z" and makes it "(X, Y) => Z". In fact, go
> wilder:
>
> whee :: Show a => Eq a => a => Bool
> whee x = x == x && null (show x)
>
> It is valid and it means (Show a, Eq a) => a -> Bool. Try it!
>

What extensions do you have turned on? I'm trying this is ghci (7.6.3) and
I can't get it to work even with DataKinds and ConstraintKinds.

Jason
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