Data.Functor.Compat

Documentation

class Functor f where

The Functor class is used for types that can be mapped over. Instances of Functor should satisfy the following laws:

fmap id  ==  id
fmap (f . g)  ==  fmap f . fmap g

The instances of Functor for lists, Maybe and IO satisfy these laws.

Minimal complete definition

fmap

Methods

fmap :: (a -> b) -> f a -> f b

(<$) :: a -> f b -> f a infixl 4

Replace all locations in the input with the same value. The default definition is fmap . const, but this may be overridden with a more efficient version.

Instances

Functor []

Functor IO

Functor Id

Functor ArgOrder

Functor OptDescr

Functor ArgDescr

Functor ZipList

Functor Handler

Functor ReadPrec

Functor ReadP

Functor Maybe

Functor ((->) r)

Functor (Either a)

Functor ((,) a)

Ix i => Functor (Array i)

Functor (StateL s)

Functor (StateR s)

Functor (Const m)

Monad m => Functor (WrappedMonad m)

Functor (Proxy *)

Arrow a => Functor (WrappedArrow a b)

Functor f => Functor (Alt * f)

($>) :: Functor f => f a -> b -> f b infixl 4

Flipped version of <$.

Since: 4.7.0.0

void :: Functor f => f a -> f ()

void value discards or ignores the result of evaluation, such as the return value of an IO action.