Map (higher-order function): Difference between revisions

Revision as of 14:07, 14 June 2007

Revision as of 13:49, 25 July 2007

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==Haskell's Functor class==

In the [[Haskell (programming language)|Haskell programming language]], map is generalized to a [[Type polymorphism|polymorphic]] function called fmap using the Functor [[type class]]. For every Functor instance, fmap must be defined such that it obeys the Functor laws:

* <code>fmap id = id (-- identity)</code>

* <code>fmap (f . g) = fmap f . fmap g (-- composition)</code>

==References==