malcolm.wallace at me.com
Tue Jul 20 14:47:34 EDT 2010
> H98 and H2010 allow a context to be given for datatypes, e.g. the
> "Eq a" in
> data Eq a => Foo a = Constr a
> I have made a proposal to remove support for that context (ticket
Although I would prefer that contexts of datatypes did the right and
useful thing, in the absence of a proposal of that nature, I am quite
happy to add my +1 to their removal instead.
As Igloo notes, GADTs are a more viable way to achieve the storing of
the dictionary within the constructor, e.g.
data OrdTree a where
Leaf :: a -> OrdTree a
Branch :: Ord a => OrdTree a -> OrdTree a -> OrdTree a
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