{-# LANGUAGE DeriveDataTypeable #-}{-# LANGUAGE DeriveGeneric #-}{-# LANGUAGE DeriveTraversable #-}{-# LANGUAGE GeneralizedNewtypeDeriving #-}{-# LANGUAGE NoImplicitPrelude #-}{-# LANGUAGE Trustworthy #-}------------------------------------------------------------------------------- |-- Module : 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 : ross@soi.city.ac.uk-- Stability : experimental-- Portability : portable---- 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-----------------------------------------------------------------------------moduleData.Functor.Identity(Identity (..),)whereimportControl.Monad.Fix importData.Bits (Bits ,FiniteBits )importData.Coerce importData.Foldable importData.Functor.Utils ((#.) )importForeign.Storable (Storable )importGHC.Ix (Ix )importGHC.Base (Applicative (..),Eq(..),Functor (..),Monad (..),Semigroup ,Monoid ,Ord(..),($) ,(.) )importGHC.Enum (Bounded ,Enum )importGHC.Float (Floating ,RealFloat )importGHC.Generics (Generic ,Generic1 )importGHC.Num (Num )importGHC.Read (Read (..),lex ,readParen )importGHC.Real (Fractional ,Integral ,Real ,RealFrac )importGHC.Show (Show (..),showParen ,showString )importGHC.Types(Bool(..))-- | Identity functor and monad. (a non-strict monad)---- @since 4.8.0.0newtypeIdentity a =Identity {Identity a -> a
runIdentity ::a }deriving(Bits -- ^ @since 4.9.0.0,Bounded -- ^ @since 4.9.0.0,Enum -- ^ @since 4.9.0.0,Eq-- ^ @since 4.8.0.0,FiniteBits -- ^ @since 4.9.0.0,Floating -- ^ @since 4.9.0.0,Fractional -- ^ @since 4.9.0.0,Generic -- ^ @since 4.8.0.0,Generic1 -- ^ @since 4.8.0.0,Integral -- ^ @since 4.9.0.0,Ix -- ^ @since 4.9.0.0,Semigroup -- ^ @since 4.9.0.0,Monoid -- ^ @since 4.9.0.0,Num -- ^ @since 4.9.0.0,Ord-- ^ @since 4.8.0.0,Real -- ^ @since 4.9.0.0,RealFrac -- ^ @since 4.9.0.0,RealFloat -- ^ @since 4.9.0.0,Storable -- ^ @since 4.9.0.0)-- | This instance would be equivalent to the derived instances of the-- 'Identity' newtype if the 'runIdentity' field were removed---- @since 4.8.0.0instance(Read a )=>Read (Identity a )wherereadsPrec :: Int -> ReadS (Identity a)
readsPrec Int
d =Bool -> ReadS (Identity a) -> ReadS (Identity a)
forall a. Bool -> ReadS a -> ReadS a
readParen (Int
d Int -> Int -> Bool
forall a. Ord a => a -> a -> Bool
>Int
10)(ReadS (Identity a) -> ReadS (Identity a))
-> ReadS (Identity a) -> ReadS (Identity a)
forall a b. (a -> b) -> a -> b
$ \String
r ->[(a -> Identity a
forall a. a -> Identity a
Identity a
x ,String
t )|(String
"Identity",String
s )<-ReadS String
lex String
r ,(a
x ,String
t )<-Int -> ReadS a
forall a. Read a => Int -> ReadS a
readsPrec Int
11String
s ]-- | This instance would be equivalent to the derived instances of the-- 'Identity' newtype if the 'runIdentity' field were removed---- @since 4.8.0.0instance(Show a )=>Show (Identity a )whereshowsPrec :: Int -> Identity a -> ShowS
showsPrec Int
d (Identity a
x )=Bool -> ShowS -> ShowS
showParen (Int
d Int -> Int -> Bool
forall a. Ord a => a -> a -> Bool
>Int
10)(ShowS -> ShowS) -> ShowS -> ShowS
forall a b. (a -> b) -> a -> b
$ String -> ShowS
showString String
"Identity "ShowS -> ShowS -> ShowS
forall b c a. (b -> c) -> (a -> b) -> a -> c
. Int -> a -> ShowS
forall a. Show a => Int -> a -> ShowS
showsPrec Int
11a
x -- ----------------------------------------------------------------------------- Identity instances for Functor and Monad-- | @since 4.8.0.0instanceFoldable Identity wherefoldMap :: (a -> m) -> Identity a -> m
foldMap =(a -> m) -> Identity a -> m
coerceelem :: a -> Identity a -> Bool
elem =((a -> Bool) -> (Identity a -> a) -> Identity a -> Bool
forall b c a. (b -> c) -> (a -> b) -> a -> c
. Identity a -> a
forall a. Identity a -> a
runIdentity )((a -> Bool) -> Identity a -> Bool)
-> (a -> a -> Bool) -> a -> Identity a -> Bool
forall b c a. Coercible b c => (b -> c) -> (a -> b) -> a -> c
#. a -> a -> Bool
forall a. Eq a => a -> a -> Bool
(==)foldl :: (b -> a -> b) -> b -> Identity a -> b
foldl =(b -> a -> b) -> b -> Identity a -> b
coercefoldl' :: (b -> a -> b) -> b -> Identity a -> b
foldl' =(b -> a -> b) -> b -> Identity a -> b
coercefoldl1 :: (a -> a -> a) -> Identity a -> a
foldl1 a -> a -> a
_=Identity a -> a
forall a. Identity a -> a
runIdentity foldr :: (a -> b -> b) -> b -> Identity a -> b
foldr a -> b -> b
f b
z (Identity a
x )=a -> b -> b
f a
x b
z foldr' :: (a -> b -> b) -> b -> Identity a -> b
foldr' =(a -> b -> b) -> b -> Identity a -> b
forall (t :: * -> *) a b.
Foldable t =>
(a -> b -> b) -> b -> t a -> b
foldr foldr1 :: (a -> a -> a) -> Identity a -> a
foldr1 a -> a -> a
_=Identity a -> a
forall a. Identity a -> a
runIdentity length :: Identity a -> Int
length Identity a
_=Int
1maximum :: Identity a -> a
maximum =Identity a -> a
forall a. Identity a -> a
runIdentity minimum :: Identity a -> a
minimum =Identity a -> a
forall a. Identity a -> a
runIdentity null :: Identity a -> Bool
null Identity a
_=Bool
Falseproduct :: Identity a -> a
product =Identity a -> a
forall a. Identity a -> a
runIdentity sum :: Identity a -> a
sum =Identity a -> a
forall a. Identity a -> a
runIdentity toList :: Identity a -> [a]
toList (Identity a
x )=[a
x ]-- | @since 4.8.0.0instanceFunctor Identity wherefmap :: (a -> b) -> Identity a -> Identity b
fmap =(a -> b) -> Identity a -> Identity b
coerce-- | @since 4.8.0.0instanceApplicative Identity wherepure :: a -> Identity a
pure =a -> Identity a
forall a. a -> Identity a
Identity <*> :: Identity (a -> b) -> Identity a -> Identity b
(<*>) =Identity (a -> b) -> Identity a -> Identity b
coerceliftA2 :: (a -> b -> c) -> Identity a -> Identity b -> Identity c
liftA2 =(a -> b -> c) -> Identity a -> Identity b -> Identity c
coerce-- | @since 4.8.0.0instanceMonad Identity whereIdentity a
m >>= :: Identity a -> (a -> Identity b) -> Identity b
>>= a -> Identity b
k =a -> Identity b
k (Identity a -> a
forall a. Identity a -> a
runIdentity Identity a
m )-- | @since 4.8.0.0instanceMonadFix Identity wheremfix :: (a -> Identity a) -> Identity a
mfix a -> Identity a
f =a -> Identity a
forall a. a -> Identity a
Identity ((a -> a) -> a
forall a. (a -> a) -> a
fix (Identity a -> a
forall a. Identity a -> a
runIdentity (Identity a -> a) -> (a -> Identity a) -> a -> a
forall b c a. (b -> c) -> (a -> b) -> a -> c
. a -> Identity a
f ))