Copyright	(c) 2007 Magnus Therning
License	BSD-style (see the file LICENSE)
Maintainer	R.Paterson@city.ac.uk
Stability	experimental
Portability	portable
Safe Haskell	Safe
Language	Haskell98

Control.Monad.Trans.Identity

Contents

The identity monad transformer
Lifting other operations

Description

The identity monad transformer.

This is useful for functions parameterized by a monad transformer.

Synopsis

The identity monad transformer

newtype IdentityT f a Source

The trivial monad transformer, which maps a monad to an equivalent monad.

Constructors

IdentityT
Fields runIdentityT :: f a

Instances

MonadTrans (IdentityT (TYPE Lifted))
Methods lift :: Monad m => m a -> IdentityT (TYPE Lifted) m a Source
Monad m => Monad (IdentityT (TYPE Lifted) m)
Methods (>>=) :: IdentityT (TYPE Lifted) m a -> (a -> IdentityT (TYPE Lifted) m b) -> IdentityT (TYPE Lifted) m b Source (>>) :: IdentityT (TYPE Lifted) m a -> IdentityT (TYPE Lifted) m b -> IdentityT (TYPE Lifted) m b Source return :: a -> IdentityT (TYPE Lifted) m a Source fail :: String -> IdentityT (TYPE Lifted) m a Source
Functor m => Functor (IdentityT (TYPE Lifted) m)
Methods fmap :: (a -> b) -> IdentityT (TYPE Lifted) m a -> IdentityT (TYPE Lifted) m b Source (<$) :: a -> IdentityT (TYPE Lifted) m b -> IdentityT (TYPE Lifted) m a Source
MonadFix m => MonadFix (IdentityT (TYPE Lifted) m)
Methods mfix :: (a -> IdentityT (TYPE Lifted) m a) -> IdentityT (TYPE Lifted) m a Source
MonadFail m => MonadFail (IdentityT (TYPE Lifted) m)
Methods fail :: String -> IdentityT (TYPE Lifted) m a Source
Applicative m => Applicative (IdentityT (TYPE Lifted) m)
Methods pure :: a -> IdentityT (TYPE Lifted) m a Source (<>) :: IdentityT (TYPE Lifted) m (a -> b) -> IdentityT (TYPE Lifted) m a -> IdentityT (TYPE Lifted) m b Source (>) :: IdentityT (TYPE Lifted) m a -> IdentityT (TYPE Lifted) m b -> IdentityT (TYPE Lifted) m b Source (<*) :: IdentityT (TYPE Lifted) m a -> IdentityT (TYPE Lifted) m b -> IdentityT (TYPE Lifted) m a Source
Foldable f => Foldable (IdentityT (TYPE Lifted) f)
Methods fold :: Monoid m => IdentityT (TYPE Lifted) f m -> m Source foldMap :: Monoid m => (a -> m) -> IdentityT (TYPE Lifted) f a -> m Source foldr :: (a -> b -> b) -> b -> IdentityT (TYPE Lifted) f a -> b Source foldr' :: (a -> b -> b) -> b -> IdentityT (TYPE Lifted) f a -> b Source foldl :: (b -> a -> b) -> b -> IdentityT (TYPE Lifted) f a -> b Source foldl' :: (b -> a -> b) -> b -> IdentityT (TYPE Lifted) f a -> b Source foldr1 :: (a -> a -> a) -> IdentityT (TYPE Lifted) f a -> a Source foldl1 :: (a -> a -> a) -> IdentityT (TYPE Lifted) f a -> a Source toList :: IdentityT (TYPE Lifted) f a -> [a] Source null :: IdentityT (TYPE Lifted) f a -> Bool Source length :: IdentityT (TYPE Lifted) f a -> Int Source elem :: Eq a => a -> IdentityT (TYPE Lifted) f a -> Bool Source maximum :: Ord a => IdentityT (TYPE Lifted) f a -> a Source minimum :: Ord a => IdentityT (TYPE Lifted) f a -> a Source sum :: Num a => IdentityT (TYPE Lifted) f a -> a Source product :: Num a => IdentityT (TYPE Lifted) f a -> a Source
Traversable f => Traversable (IdentityT (TYPE Lifted) f)
Methods traverse :: Applicative f => (a -> f b) -> IdentityT (TYPE Lifted) f a -> f (IdentityT (TYPE Lifted) f b) Source sequenceA :: Applicative f => IdentityT (TYPE Lifted) f (f a) -> f (IdentityT (TYPE Lifted) f a) Source mapM :: Monad m => (a -> m b) -> IdentityT (TYPE Lifted) f a -> m (IdentityT (TYPE Lifted) f b) Source sequence :: Monad m => IdentityT (TYPE Lifted) f (m a) -> m (IdentityT (TYPE Lifted) f a) Source
Eq1 f => Eq1 (IdentityT (TYPE Lifted) f)
Methods liftEq :: (a -> b -> Bool) -> IdentityT (TYPE Lifted) f a -> IdentityT (TYPE Lifted) f b -> Bool Source
Ord1 f => Ord1 (IdentityT (TYPE Lifted) f)
Methods liftCompare :: (a -> b -> Ordering) -> IdentityT (TYPE Lifted) f a -> IdentityT (TYPE Lifted) f b -> Ordering Source
Read1 f => Read1 (IdentityT (TYPE Lifted) f)
Methods liftReadsPrec :: (Int -> ReadS a) -> ReadS [a] -> Int -> ReadS (IdentityT (TYPE Lifted) f a) Source liftReadList :: (Int -> ReadS a) -> ReadS [a] -> ReadS [IdentityT (TYPE Lifted) f a] Source
Show1 f => Show1 (IdentityT (TYPE Lifted) f)
Methods liftShowsPrec :: (Int -> a -> ShowS) -> ([a] -> ShowS) -> Int -> IdentityT (TYPE Lifted) f a -> ShowS Source liftShowList :: (Int -> a -> ShowS) -> ([a] -> ShowS) -> [IdentityT (TYPE Lifted) f a] -> ShowS Source
MonadIO m => MonadIO (IdentityT (TYPE Lifted) m)
Methods liftIO :: IO a -> IdentityT (TYPE Lifted) m a Source
MonadZip m => MonadZip (IdentityT (TYPE Lifted) m)
Methods mzip :: IdentityT (TYPE Lifted) m a -> IdentityT (TYPE Lifted) m b -> IdentityT (TYPE Lifted) m (a, b) Source mzipWith :: (a -> b -> c) -> IdentityT (TYPE Lifted) m a -> IdentityT (TYPE Lifted) m b -> IdentityT (TYPE Lifted) m c Source munzip :: IdentityT (TYPE Lifted) m (a, b) -> (IdentityT (TYPE Lifted) m a, IdentityT (TYPE Lifted) m b) Source
Alternative m => Alternative (IdentityT (TYPE Lifted) m)
Methods empty :: IdentityT (TYPE Lifted) m a Source (<\|>) :: IdentityT (TYPE Lifted) m a -> IdentityT (TYPE Lifted) m a -> IdentityT (TYPE Lifted) m a Source some :: IdentityT (TYPE Lifted) m a -> IdentityT (TYPE Lifted) m [a] Source many :: IdentityT (TYPE Lifted) m a -> IdentityT (TYPE Lifted) m [a] Source
MonadPlus m => MonadPlus (IdentityT (TYPE Lifted) m)
Methods mzero :: IdentityT (TYPE Lifted) m a Source mplus :: IdentityT (TYPE Lifted) m a -> IdentityT (TYPE Lifted) m a -> IdentityT (TYPE Lifted) m a Source
(Eq1 f, Eq a) => Eq (IdentityT (TYPE Lifted) f a)
Methods (==) :: IdentityT (TYPE Lifted) f a -> IdentityT (TYPE Lifted) f a -> Bool (/=) :: IdentityT (TYPE Lifted) f a -> IdentityT (TYPE Lifted) f a -> Bool
(Ord1 f, Ord a) => Ord (IdentityT (TYPE Lifted) f a)
Methods compare :: IdentityT (TYPE Lifted) f a -> IdentityT (TYPE Lifted) f a -> Ordering (<) :: IdentityT (TYPE Lifted) f a -> IdentityT (TYPE Lifted) f a -> Bool (<=) :: IdentityT (TYPE Lifted) f a -> IdentityT (TYPE Lifted) f a -> Bool (>) :: IdentityT (TYPE Lifted) f a -> IdentityT (TYPE Lifted) f a -> Bool (>=) :: IdentityT (TYPE Lifted) f a -> IdentityT (TYPE Lifted) f a -> Bool max :: IdentityT (TYPE Lifted) f a -> IdentityT (TYPE Lifted) f a -> IdentityT (TYPE Lifted) f a min :: IdentityT (TYPE Lifted) f a -> IdentityT (TYPE Lifted) f a -> IdentityT (TYPE Lifted) f a
(Read1 f, Read a) => Read (IdentityT (TYPE Lifted) f a)
Methods readsPrec :: Int -> ReadS (IdentityT (TYPE Lifted) f a) Source readList :: ReadS [IdentityT (TYPE Lifted) f a] Source readPrec :: ReadPrec (IdentityT (TYPE Lifted) f a) Source readListPrec :: ReadPrec [IdentityT (TYPE Lifted) f a] Source
(Show1 f, Show a) => Show (IdentityT (TYPE Lifted) f a)
Methods showsPrec :: Int -> IdentityT (TYPE Lifted) f a -> ShowS Source show :: IdentityT (TYPE Lifted) f a -> String Source showList :: [IdentityT (TYPE Lifted) f a] -> ShowS Source

mapIdentityT :: (m a -> n b) -> IdentityT m a -> IdentityT n b Source

Lift a unary operation to the new monad.

Lifting other operations

liftCatch :: Catch e m a -> Catch e (IdentityT m) a Source

Lift a catchE operation to the new monad.

liftCallCC :: CallCC m a b -> CallCC (IdentityT m) a b Source

Lift a callCC operation to the new monad.