Functor
From HaskellWiki
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fmap id = id |
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fmap (p . q) = (fmap p) . (fmap q) |
fmap (p . q) = (fmap p) . (fmap q) |
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+ | [[Category:Standard classes]] |
Revision as of 04:32, 3 January 2006
import Control.Monad |
The Functor class is defined like this:
class Functor f where fmap :: (a -> b) -> f a -> f b
All instances of Functor should obey:
fmap id = id fmap (p . q) = (fmap p) . (fmap q)