:: (a -> b) -> [a] -> [b] is:exact

map f xs is the list obtained by applying f to each element of xs, i.e.,
map f [x1, x2, ..., xn] == [f x1, f x2, ..., f xn]
map f [x1, x2, ...] == [f x1, f x2, ...]
map f xs is the list obtained by applying f to each element of xs, i.e.,
map f [x1, x2, ..., xn] == [f x1, f x2, ..., f xn]
map f [x1, x2, ...] == [f x1, f x2, ...]
An infix synonym for fmap. The name of this operator is an allusion to $. Note the similarities between their types:
($)  ::              (a -> b) ->   a ->   b
(<$>) :: Functor f => (a -> b) -> f a -> f b
Whereas $ is function application, <$> is function application lifted over a Functor.

Examples

Convert from a Maybe Int to a Maybe String using show:
>>> show <$> Nothing
Nothing

>>> show <$> Just 3
Just "3"
Convert from an Either Int Int to an Either Int String using show:
>>> show <$> Left 17
Left 17

>>> show <$> Right 17
Right "17"
Double each element of a list:
>>> (*2) <$> [1,2,3]
[2,4,6]
Apply even to the second element of a pair:
>>> even <$> (2,2)
(2,True)
map = fmap
map generalized to Functor.
>>> map not (Just True)
Just False

>>> map not [True,False,True,True]
[False,True,False,False]
A synonym for fmap.
map = fmap
Apply a pure function to the result of a monadic computation
Promote a function to a monad.
Strict version of <$>.
Lift a function to actions. This function may be used as a value for fmap in a Functor instance.
This function may be used as a value for fmap in a Functor instance, provided that traverse is defined. (Using fmapDefault with a Traversable instance defined only by sequenceA will result in infinite recursion.)
fmapDefault f ≡ runIdentity . traverse (Identity . f)
Changes all the labels in the tree to another one, given by a function.
This function may be used as a value for fmap in a Functor instance, provided that traverse is defined. (Using fmapDefault with a Traversable instance defined only by sequenceA will result in infinite recursion.)
fmapDefault f ≡ runIdentity . traverse (Identity . f)
O(n) Map a function over a vector
Map over vector
Return the result of applying a function to every element of a sequence. Identical to fmap from Functor.
map f <x0,...,xn-1> = <f x0,...,f xn-1>
Axioms:
  • map f empty = empty
  • map f (lcons x xs) = lcons (f x) (map f xs)
This function is always unambiguous. Default running time: O( t * n ) where t is the running time of f
A suitable default definition for fmap for a Comonad. Promotes a function to a comonad. You can only safely use to define fmap if your Comonad defined extend, not just duplicate, since defining extend in terms of duplicate uses fmap!
fmap f = liftW f = extend (f . extract)