[Haskell] Swapping parameters and type classes
mads_lindstroem at yahoo.dk
Sun Sep 16 10:52:00 EDT 2007
If I have this type:
data Foo a b = ...
and this class
class Bar (x :: * -> *) where ...
I can imagine two ways to make Foo an instance of Bar. Either I must
"apply" the 'a' or the 'b' in (Foo a b). Otherwise it will not have the
right kind. To "apply" the 'a' I can do:
instance Bar (Foo a) where ...
But what if I want to "apply" the 'b' ? How do I do that ?
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