[Haskell-cafe] Typeclass question

David Menendez dave at zednenem.com
Sat Dec 27 14:44:42 EST 2008

On Sat, Dec 27, 2008 at 2:24 PM, Andrew Wagner <wagner.andrew at gmail.com> wrote:
> I'm sure there's a way to do this, but it's escaping me at present. I want
> to do something like this:
> data Foo = Bar a => Foo a Bool ...
> That is, I want to create a new type, Foo, whose constructor takes both a
> Boolean and a value of a type of class Bar.

Try this:

    {-# LANGUAGE ExistentialQuantification #-}

    data Foo = forall a. Bar a => Foo a Bool

Dave Menendez <dave at zednenem.com>

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