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

Documentation

newtype Identity a Source

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

Since: 4.8.0.0

Constructors

Identity
Fields runIdentity :: a

Instances

Monad Identity
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
Methods fmap :: (a -> b) -> Identity a -> Identity b Source (<$) :: a -> Identity b -> Identity a Source
MonadFix Identity
Methods mfix :: (a -> Identity a) -> Identity a Source
Applicative Identity
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
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
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
Associated Types type Rep1 (Identity :: * -> TYPE Lifted) :: * -> * Source Methods from1 :: Identity a -> Rep1 Identity a Source to1 :: Rep1 Identity a -> Identity a Source
MonadZip Identity
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
Show1 Identity
Methods liftShowsPrec :: (Int -> a -> ShowS) -> ([a] -> ShowS) -> Int -> Identity a -> ShowS Source liftShowList :: (Int -> a -> ShowS) -> ([a] -> ShowS) -> [Identity a] -> ShowS Source
Read1 Identity
Methods liftReadsPrec :: (Int -> ReadS a) -> ReadS [a] -> Int -> ReadS (Identity a) Source liftReadList :: (Int -> ReadS a) -> ReadS [a] -> ReadS [Identity a] Source
Ord1 Identity
Methods liftCompare :: (a -> b -> Ordering) -> Identity a -> Identity b -> Ordering Source
Eq1 Identity
Methods liftEq :: (a -> b -> Bool) -> Identity a -> Identity b -> Bool Source
Bounded a => Bounded (Identity a)
Methods minBound :: Identity a Source maxBound :: Identity a Source
Enum a => Enum (Identity a)
Methods succ :: Identity a -> Identity a Source pred :: Identity a -> Identity a Source toEnum :: Int -> Identity a Source fromEnum :: Identity a -> Int Source enumFrom :: Identity a -> [Identity a] Source enumFromThen :: Identity a -> Identity a -> [Identity a] Source enumFromTo :: Identity a -> Identity a -> [Identity a] Source enumFromThenTo :: Identity a -> Identity a -> Identity a -> [Identity a] Source
Eq a => Eq (Identity a)
Methods (==) :: Identity a -> Identity a -> Bool Source (/=) :: Identity a -> Identity a -> Bool Source
Data a => Data (Identity a)
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 (TYPE Lifted -> TYPE Lifted) t => (forall d. Data d => c (t d)) -> Maybe (c (Identity a)) Source dataCast2 :: Typeable (TYPE Lifted -> TYPE Lifted -> TYPE Lifted) 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)
Methods compare :: Identity a -> Identity a -> Ordering Source (<) :: Identity a -> Identity a -> Bool Source (<=) :: Identity a -> Identity a -> Bool Source (>) :: Identity a -> Identity a -> Bool Source (>=) :: Identity a -> Identity a -> Bool Source max :: Identity a -> Identity a -> Identity a Source min :: Identity a -> Identity a -> Identity a Source
Read a => Read (Identity a)	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)	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
Ix a => Ix (Identity a)
Methods range :: (Identity a, Identity a) -> [Identity a] Source index :: (Identity a, Identity a) -> Identity a -> Int Source unsafeIndex :: (Identity a, Identity a) -> Identity a -> Int inRange :: (Identity a, Identity a) -> Identity a -> Bool Source rangeSize :: (Identity a, Identity a) -> Int Source unsafeRangeSize :: (Identity a, Identity a) -> Int
Generic (Identity a)
Associated Types type Rep (Identity a) :: * -> * Source Methods from :: Identity a -> Rep (Identity a) x Source to :: Rep (Identity a) x -> Identity a Source
Semigroup a => Semigroup (Identity a)
Methods (<>) :: Identity a -> Identity a -> Identity a Source sconcat :: NonEmpty (Identity a) -> Identity a Source stimes :: Integral b => b -> Identity a -> Identity a Source
Monoid a => Monoid (Identity a)
Methods mempty :: Identity a Source mappend :: Identity a -> Identity a -> Identity a Source mconcat :: [Identity a] -> Identity a Source
Storable a => Storable (Identity a)
Methods sizeOf :: Identity a -> Int Source alignment :: Identity a -> Int Source peekElemOff :: Ptr (Identity a) -> Int -> IO (Identity a) Source pokeElemOff :: Ptr (Identity a) -> Int -> Identity a -> IO () Source peekByteOff :: Ptr b -> Int -> IO (Identity a) Source pokeByteOff :: Ptr b -> Int -> Identity a -> IO () Source peek :: Ptr (Identity a) -> IO (Identity a) Source poke :: Ptr (Identity a) -> Identity a -> IO () Source
type Rep1 Identity = D1 (MetaData "Identity" "Data.Functor.Identity" "base" True) (C1 (MetaCons "Identity" PrefixI True) (S1 (MetaSel (Just Symbol "runIdentity") NoSourceUnpackedness NoSourceStrictness DecidedLazy) Par1))
type Rep (Identity a) = D1 (MetaData "Identity" "Data.Functor.Identity" "base" True) (C1 (MetaCons "Identity" PrefixI True) (S1 (MetaSel (Just Symbol "runIdentity") NoSourceUnpackedness NoSourceStrictness DecidedLazy) (Rec0 a)))