Functor
From HaskellWiki
(Difference between revisions)
m (Remove Category:Standard classes - now in template) |
(Main article in category Functor) |
||
| Line 10: | Line 10: | ||
fmap (p . q) = (fmap p) . (fmap q) | fmap (p . q) = (fmap p) . (fmap q) | ||
| - | [[Category: | + | [[Category:Functor|*]] |
Revision as of 21:10, 1 November 2009
| 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)
