<$>

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 <$> (2,2)
(2,True)
The document (x <$> y) concatenates document x and y with a line in between. (infixr 5)
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 <$> (2,2)
(2,True)
The document (x <$> y) concatenates document x and y with a line in between. (infixr 5)
The document (x <$> y) concatenates document x and y with a line in between. (infixr 5)
Map a linear function over a derivative tower.
f <$>^ u :: Aps f b is a delayed representation of f <$> u :: f b, so that it can be fused with other applicative operations. f <$>^ u is a shorthand for f <$> liftAps u.
Shorthand for: f <$> field (req k).
Shorthand for: f <$> optional (field (req k)).