instance Functor Set, was: Re: Export lists in modules
waldmann at imn.htwk-leipzig.de
Wed Mar 1 03:07:34 EST 2006
Jim Apple wrote:
> class MyMap f a b where
> myMap :: (a -> b) -> f a -> f b
> instance (Functor f) => MyMap f a b where
> myMap = fmap
> instance (Ord a, Ord b) => MyMap Data.Set.Set a b where
> myMap = Data.Set.map
OK (I guess).
But my point was that I want to use
"do notation" for Sets (in fact, for any kind of collection)
so I'd need the original Functor and Monad.
I couldn't use ghc's Rebindable Syntax feature
because the types for (>>=) would not match?
-- Johannes Waldmann -- Tel/Fax (0341) 3076 6479/80 --
---- http://www.imn.htwk-leipzig.de/~waldmann/ -------
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