base-compat-0.9.3: A compatibility layer for base

Data.Functor.Compat

Synopsis

# 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 #

(<$) :: a -> f b -> f a infixl 4 # Replace all locations in the input with the same value. The default definition is fmap . const, but this may be overridden with a more efficient version. Instances  Functor [] Methodsfmap :: (a -> b) -> [a] -> [b] #(<$) :: a -> [b] -> [a] # Methodsfmap :: (a -> b) -> Maybe a -> Maybe b #(<$) :: a -> Maybe b -> Maybe a # Methodsfmap :: (a -> b) -> IO a -> IO b #(<$) :: a -> IO b -> IO a # Methodsfmap :: (a -> b) -> V1 a -> V1 b #(<$) :: a -> V1 b -> V1 a # Methodsfmap :: (a -> b) -> U1 a -> U1 b #(<$) :: a -> U1 b -> U1 a # Methodsfmap :: (a -> b) -> Par1 a -> Par1 b #(<$) :: a -> Par1 b -> Par1 a # Methodsfmap :: (a -> b) -> P a -> P b #(<$) :: a -> P b -> P a # Methodsfmap :: (a -> b) -> Complex a -> Complex b #(<$) :: a -> Complex b -> Complex a # Methodsfmap :: (a -> b) -> ZipList a -> ZipList b #(<$) :: a -> ZipList b -> ZipList a # Methodsfmap :: (a -> b) -> STM a -> STM b #(<$) :: a -> STM b -> STM a # Methodsfmap :: (a -> b) -> Dual a -> Dual b #(<$) :: a -> Dual b -> Dual a # Methodsfmap :: (a -> b) -> Sum a -> Sum b #(<$) :: a -> Sum b -> Sum a # Methodsfmap :: (a -> b) -> Product a -> Product b #(<$) :: a -> Product b -> Product a # Methodsfmap :: (a -> b) -> First a -> First b #(<$) :: a -> First b -> First a # Methodsfmap :: (a -> b) -> Last a -> Last b #(<$) :: a -> Last b -> Last a # Methodsfmap :: (a -> b) -> ReadPrec a -> ReadPrec b #(<$) :: a -> ReadPrec b -> ReadPrec a # Methodsfmap :: (a -> b) -> ReadP a -> ReadP b #(<$) :: a -> ReadP b -> ReadP a # Functor ((->) r) Methodsfmap :: (a -> b) -> (r -> a) -> r -> b #(<$) :: a -> (r -> b) -> r -> a # Methodsfmap :: (a -> b) -> Either a a -> Either a b #(<$) :: a -> Either a b -> Either a a # Functor f => Functor (Rec1 f) Methodsfmap :: (a -> b) -> Rec1 f a -> Rec1 f b #(<$) :: a -> Rec1 f b -> Rec1 f a # Methodsfmap :: (a -> b) -> URec Char a -> URec Char b #(<$) :: a -> URec Char b -> URec Char a # Methodsfmap :: (a -> b) -> URec Double a -> URec Double b #(<$) :: a -> URec Double b -> URec Double a # Methodsfmap :: (a -> b) -> URec Float a -> URec Float b #(<$) :: a -> URec Float b -> URec Float a # Methodsfmap :: (a -> b) -> URec Int a -> URec Int b #(<$) :: a -> URec Int b -> URec Int a # Methodsfmap :: (a -> b) -> URec Word a -> URec Word b #(<$) :: a -> URec Word b -> URec Word a # Functor (URec (Ptr ())) Methodsfmap :: (a -> b) -> URec (Ptr ()) a -> URec (Ptr ()) b #(<$) :: a -> URec (Ptr ()) b -> URec (Ptr ()) a # Functor ((,) a) Methodsfmap :: (a -> b) -> (a, a) -> (a, b) #(<$) :: a -> (a, b) -> (a, a) # Functor (ST s) Methodsfmap :: (a -> b) -> ST s a -> ST s b #(<$) :: a -> ST s b -> ST s a # Functor (ST s) Methodsfmap :: (a -> b) -> ST s a -> ST s b #(<$) :: a -> ST s b -> ST s a # Monad m => Functor (WrappedMonad m) Methodsfmap :: (a -> b) -> WrappedMonad m a -> WrappedMonad m b #(<$) :: a -> WrappedMonad m b -> WrappedMonad m a # Methodsfmap :: (a -> b) -> Proxy * a -> Proxy * b #(<$) :: a -> Proxy * b -> Proxy * a # Functor (K1 i c) Methodsfmap :: (a -> b) -> K1 i c a -> K1 i c b #(<$) :: a -> K1 i c b -> K1 i c a # (Functor g, Functor f) => Functor ((:+:) f g) Methodsfmap :: (a -> b) -> (f :+: g) a -> (f :+: g) b #(<$) :: a -> (f :+: g) b -> (f :+: g) a # (Functor g, Functor f) => Functor ((:*:) f g) Methodsfmap :: (a -> b) -> (f :*: g) a -> (f :*: g) b #(<$) :: a -> (f :*: g) b -> (f :*: g) a # (Functor g, Functor f) => Functor ((:.:) f g) Methodsfmap :: (a -> b) -> (f :.: g) a -> (f :.: g) b #(<$) :: a -> (f :.: g) b -> (f :.: g) a # Arrow a => Functor (WrappedArrow a b) Methodsfmap :: (a -> b) -> WrappedArrow a b a -> WrappedArrow a b b #(<$) :: a -> WrappedArrow a b b -> WrappedArrow a b a # Methodsfmap :: (a -> b) -> Const * m a -> Const * m b #(<$) :: a -> Const * m b -> Const * m a # Functor f => Functor (Alt * f) Methodsfmap :: (a -> b) -> Alt * f a -> Alt * f b #(<$) :: a -> Alt * f b -> Alt * f a # Functor f => Functor (M1 i c f) Methodsfmap :: (a -> b) -> M1 i c f a -> M1 i c f b #(<$) :: a -> M1 i c f b -> M1 i c f a #

($>) :: Functor f => f a -> b -> f b infixl 4 # Flipped version of <$.

#### Examples

Replace the contents of a Maybe Int with a constant String:

>>> Nothing $> "foo" Nothing >>> Just 90210$> "foo"
Just "foo"


Replace the contents of an Either Int Int with a constant String, resulting in an Either Int String:

>>> Left 8675309 $> "foo" Left 8675309 >>> Right 8675309$> "foo"
Right "foo"


Replace each element of a list with a constant String:

>>> [1,2,3] $> "foo" ["foo","foo","foo"]  Replace the second element of a pair with a constant String: >>> (1,2)$> "foo"
(1,"foo")


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.

#### Examples

Replace the contents of a Maybe Int with unit:

>>> void Nothing
Nothing
>>> void (Just 3)
Just ()


Replace the contents of an Either Int Int with unit, resulting in an Either Int '()':

>>> void (Left 8675309)
Left 8675309
>>> void (Right 8675309)
Right ()


Replace every element of a list with unit:

>>> void [1,2,3]
[(),(),()]


Replace the second element of a pair with unit:

>>> void (1,2)
(1,())


Discard the result of an IO action:

>>> mapM print [1,2]
1
2
[(),()]
>>> void \$ mapM print [1,2]
1
2