base-4.8.1.0: Basic libraries

Copyright	(c) Andy Gill 2001, (c) Oregon Graduate Institute of Science and Technology 2001
License	BSD-style (see the file LICENSE)
Maintainer	ross@soi.city.ac.uk
Stability	experimental
Portability	portable
Safe Haskell	Trustworthy
Language	Haskell2010

Data.Functor.Identity

Description

The identity functor and monad.

This trivial type constructor serves two purposes:

It can be used with functions parameterized by functor or monad classes.
It can be used as a base monad to which a series of monad transformers may be applied to construct a composite monad. Most monad transformer modules include the special case of applying the transformer to Identity . For example, State s is an abbreviation for StateT s Identity .

Since: 4.8.0.0

Synopsis

newtype Identity a = Identity {
- runIdentity :: a
}

Documentation

newtype Identity a Source

Identity functor and monad. (a non-strict monad)

Since: 4.8.0.0

Constructors

Fields

runIdentity :: a

Instances

Monad Identity Source

Methods

(>>=) :: Identity a -> (a -> Identity b) -> Identity b Source

(>>) :: Identity a -> Identity b -> Identity b Source

return :: a -> Identity a Source

fail :: String -> Identity a Source

Functor Identity Source

Methods

fmap :: (a -> b) -> Identity a -> Identity b Source

(<$) :: a -> Identity b -> Identity a Source

MonadFix Identity Source

Methods

mfix :: (a -> Identity a) -> Identity a Source

Applicative Identity Source

Methods

pure :: a -> Identity a Source

(<*>) :: Identity (a -> b) -> Identity a -> Identity b Source

(*>) :: Identity a -> Identity b -> Identity b Source

(<*) :: Identity a -> Identity b -> Identity a Source

Foldable Identity Source

Methods

fold :: Monoid m => Identity m -> m Source

foldMap :: Monoid m => (a -> m) -> Identity a -> m Source

foldr :: (a -> b -> b) -> b -> Identity a -> b Source

foldr' :: (a -> b -> b) -> b -> Identity a -> b Source

foldl :: (b -> a -> b) -> b -> Identity a -> b Source

foldl' :: (b -> a -> b) -> b -> Identity a -> b Source

foldr1 :: (a -> a -> a) -> Identity a -> a Source

foldl1 :: (a -> a -> a) -> Identity a -> a Source

toList :: Identity a -> [a] Source

null :: Identity a -> Bool Source

length :: Identity a -> Int Source

elem :: Eq a => a -> Identity a -> Bool Source

maximum :: Ord a => Identity a -> a Source

minimum :: Ord a => Identity a -> a Source

sum :: Num a => Identity a -> a Source

product :: Num a => Identity a -> a Source

Traversable Identity Source

Methods

traverse :: Applicative f => (a -> f b) -> Identity a -> f (Identity b) Source

sequenceA :: Applicative f => Identity (f a) -> f (Identity a) Source

mapM :: Monad m => (a -> m b) -> Identity a -> m (Identity b) Source

sequence :: Monad m => Identity (m a) -> m (Identity a) Source

Generic1 Identity Source

Associated Types

type Rep1 (Identity :: * -> *) :: * -> * Source

Methods

from1 :: Identity a -> Rep1 Identity a Source

to1 :: Rep1 Identity a -> Identity a Source

MonadZip Identity Source

Methods

mzip :: Identity a -> Identity b -> Identity (a, b) Source

mzipWith :: (a -> b -> c) -> Identity a -> Identity b -> Identity c Source

munzip :: Identity (a, b) -> (Identity a, Identity b) Source

Eq a => Eq (Identity a) Source

Methods

(==) :: Identity a -> Identity a -> Bool

(/=) :: Identity a -> Identity a -> Bool

Data a => Data (Identity a) Source

Methods

gfoldl :: (forall d b. Data d => c (d -> b) -> d -> c b) -> (forall g. g -> c g) -> Identity a -> c (Identity a) Source

gunfold :: (forall b r. Data b => c (b -> r) -> c r) -> (forall r. r -> c r) -> Constr -> c (Identity a) Source

toConstr :: Identity a -> Constr Source

dataTypeOf :: Identity a -> DataType Source

dataCast1 :: Typeable (* -> *) t => (forall d. Data d => c (t d)) -> Maybe (c (Identity a)) Source

dataCast2 :: Typeable (* -> * -> *) t => (forall d e. (Data d, Data e) => c (t d e)) -> Maybe (c (Identity a)) Source

gmapT :: (forall b. Data b => b -> b) -> Identity a -> Identity a Source

gmapQl :: (r -> r' -> r) -> r -> (forall d. Data d => d -> r') -> Identity a -> r Source

gmapQr :: (r' -> r -> r) -> r -> (forall d. Data d => d -> r') -> Identity a -> r Source

gmapQ :: (forall d. Data d => d -> u) -> Identity a -> [u] Source

gmapQi :: Int -> (forall d. Data d => d -> u) -> Identity a -> u Source

gmapM :: Monad m => (forall d. Data d => d -> m d) -> Identity a -> m (Identity a) Source

gmapMp :: MonadPlus m => (forall d. Data d => d -> m d) -> Identity a -> m (Identity a) Source

gmapMo :: MonadPlus m => (forall d. Data d => d -> m d) -> Identity a -> m (Identity a) Source

Ord a => Ord (Identity a) Source

Methods

compare :: Identity a -> Identity a -> Ordering

(<) :: Identity a -> Identity a -> Bool

(<=) :: Identity a -> Identity a -> Bool

(>) :: Identity a -> Identity a -> Bool

(>=) :: Identity a -> Identity a -> Bool

max :: Identity a -> Identity a -> Identity a

min :: Identity a -> Identity a -> Identity a

Read a => Read (Identity a) Source

This instance would be equivalent to the derived instances of the Identity newtype if the runIdentity field were removed

Methods

readsPrec :: Int -> ReadS (Identity a) Source

readList :: ReadS [Identity a] Source

readPrec :: ReadPrec (Identity a) Source

readListPrec :: ReadPrec [Identity a] Source

Show a => Show (Identity a) Source

This instance would be equivalent to the derived instances of the Identity newtype if the runIdentity field were removed

Methods

showsPrec :: Int -> Identity a -> ShowS Source

show :: Identity a -> String Source

showList :: [Identity a] -> ShowS Source

Generic (Identity a) Source

Associated Types

type Rep (Identity a) :: * -> * Source

Methods

from :: Identity a -> Rep (Identity a) x Source

to :: Rep (Identity a) x -> Identity a Source

type Rep1 Identity Source

type Rep (Identity a) Source