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/Haskell 8

Data.Functor.Identity

Copyright (c) Andy Gill 2001
(c) Oregon Graduate Institute of Science and Technology 2001
License BSD-style (see the file LICENSE)
Maintainer [email protected]
Stability experimental
Portability portable
Safe Haskell Trustworthy
Language Haskell2010

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

newtype Identity a Source

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

Since: 4.8.0.0

Constructors

Identity

Fields

Instances

Monad Identity

Since: 4.8.0.0

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

Since: 4.8.0.0

Methods

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

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

MonadFix Identity

Since: 4.8.0.0

Methods

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

Applicative Identity

Since: 4.8.0.0

Methods

pure :: a -> Identity a Source

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

liftA2 :: (a -> b -> c) -> Identity a -> Identity b -> Identity c Source

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

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

Foldable Identity

Since: 4.8.0.0

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

MonadZip Identity

Since: 4.8.0.0

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

Since: 4.9.0.0

Methods

liftShowsPrec :: (Int -> a -> ShowS) -> ([a] -> ShowS) -> Int -> Identity a -> ShowS Source

liftShowList :: (Int -> a -> ShowS) -> ([a] -> ShowS) -> [Identity a] -> ShowS Source

Read1 Identity

Since: 4.9.0.0
Ord1 Identity

Since: 4.9.0.0

Methods

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

Eq1 Identity

Since: 4.9.0.0

Methods

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

Bounded a => Bounded (Identity a)
Enum a => Enum (Identity a)
Eq a => Eq (Identity a)

Methods

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

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

Floating a => Floating (Identity a)
Fractional a => Fractional (Identity a)
Integral a => Integral (Identity a)
Data a => Data (Identity a)

Since: 4.9.0.0

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

Num a => Num (Identity a)
Ord a => Ord (Identity a)
Read a => Read (Identity a)

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

Since: 4.8.0.0
Real a => Real (Identity a)
RealFloat a => RealFloat (Identity a)
RealFrac a => RealFrac (Identity a)

Methods

properFraction :: Integral b => Identity a -> (b, Identity a) Source

truncate :: Integral b => Identity a -> b Source

round :: Integral b => Identity a -> b Source

ceiling :: Integral b => Identity a -> b Source

floor :: Integral b => Identity a -> b 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

Since: 4.8.0.0
Ix a => Ix (Identity a)
IsString a => IsString (Identity a)

Methods

fromString :: String -> Identity a Source

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)

Since: 4.9.0.0
Monoid a => Monoid (Identity a)
FiniteBits a => FiniteBits (Identity a)
Bits a => Bits (Identity a)
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

Generic1 * Identity

Associated Types

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

Methods

from1 :: f a -> Rep1 Identity f a Source

to1 :: Rep1 Identity f a -> f a Source

type Rep (Identity a)
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)))
type Rep1 * Identity
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))

© The University of Glasgow and others
Licensed under a BSD-style license (see top of the page).
https://downloads.haskell.org/~ghc/8.2.1/docs/html/libraries/base-4.10.0.0/Data-Functor-Identity.html