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

newtype IdentityT f a = IdentityT {
- runIdentityT :: f a
}
mapIdentityT :: (m a -> n b) -> IdentityT m a -> IdentityT n b
liftCatch :: Catch e m a -> Catch e ( IdentityT m) a
liftCallCC :: CallCC m a b -> CallCC ( IdentityT m) a b

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

Instances details

MonadTrans ( IdentityT :: ( Type -> Type ) -> Type -> Type ) Source #
Instance details Defined in Control.Monad.Trans.Identity Methods lift :: Monad m => m a -> IdentityT m a Source #
Monad m => Monad ( IdentityT m) Source #
Instance details Defined in Control.Monad.Trans.Identity Methods (>>=) :: IdentityT m a -> (a -> IdentityT m b) -> IdentityT m b Source # (>>) :: IdentityT m a -> IdentityT m b -> IdentityT m b Source # return :: a -> IdentityT m a Source #
Functor m => Functor ( IdentityT m) Source #
Instance details Defined in Control.Monad.Trans.Identity Methods fmap :: (a -> b) -> IdentityT m a -> IdentityT m b Source # (<$) :: a -> IdentityT m b -> IdentityT m a Source #
MonadFix m => MonadFix ( IdentityT m) Source #
Instance details Defined in Control.Monad.Trans.Identity Methods mfix :: (a -> IdentityT m a) -> IdentityT m a Source #
MonadFail m => MonadFail ( IdentityT m) Source #
Instance details Defined in Control.Monad.Trans.Identity Methods fail :: String -> IdentityT m a Source #
Applicative m => Applicative ( IdentityT m) Source #
Instance details Defined in Control.Monad.Trans.Identity Methods pure :: a -> IdentityT m a Source # (<>) :: IdentityT m (a -> b) -> IdentityT m a -> IdentityT m b Source # liftA2 :: (a -> b -> c) -> IdentityT m a -> IdentityT m b -> IdentityT m c Source # (>) :: IdentityT m a -> IdentityT m b -> IdentityT m b Source # (<*) :: IdentityT m a -> IdentityT m b -> IdentityT m a Source #
Foldable f => Foldable ( IdentityT f) Source #
Instance details Defined in Control.Monad.Trans.Identity Methods fold :: Monoid m => IdentityT f m -> m Source # foldMap :: Monoid m => (a -> m) -> IdentityT f a -> m Source # foldMap' :: Monoid m => (a -> m) -> IdentityT f a -> m Source # foldr :: (a -> b -> b) -> b -> IdentityT f a -> b Source # foldr' :: (a -> b -> b) -> b -> IdentityT f a -> b Source # foldl :: (b -> a -> b) -> b -> IdentityT f a -> b Source # foldl' :: (b -> a -> b) -> b -> IdentityT f a -> b Source # foldr1 :: (a -> a -> a) -> IdentityT f a -> a Source # foldl1 :: (a -> a -> a) -> IdentityT f a -> a Source # toList :: IdentityT f a -> [a] Source # null :: IdentityT f a -> Bool Source # length :: IdentityT f a -> Int Source # elem :: Eq a => a -> IdentityT f a -> Bool Source # maximum :: Ord a => IdentityT f a -> a Source # minimum :: Ord a => IdentityT f a -> a Source # sum :: Num a => IdentityT f a -> a Source # product :: Num a => IdentityT f a -> a Source #
Traversable f => Traversable ( IdentityT f) Source #
Instance details Defined in Control.Monad.Trans.Identity Methods traverse :: Applicative f0 => (a -> f0 b) -> IdentityT f a -> f0 ( IdentityT f b) Source # sequenceA :: Applicative f0 => IdentityT f (f0 a) -> f0 ( IdentityT f a) Source # mapM :: Monad m => (a -> m b) -> IdentityT f a -> m ( IdentityT f b) Source # sequence :: Monad m => IdentityT f (m a) -> m ( IdentityT f a) Source #
Contravariant f => Contravariant ( IdentityT f) Source #
Instance details Defined in Control.Monad.Trans.Identity Methods contramap :: (a -> b) -> IdentityT f b -> IdentityT f a Source # (>$) :: b -> IdentityT f b -> IdentityT f a Source #
Eq1 f => Eq1 ( IdentityT f) Source #
Instance details Defined in Control.Monad.Trans.Identity Methods liftEq :: (a -> b -> Bool ) -> IdentityT f a -> IdentityT f b -> Bool Source #
Ord1 f => Ord1 ( IdentityT f) Source #
Instance details Defined in Control.Monad.Trans.Identity Methods liftCompare :: (a -> b -> Ordering ) -> IdentityT f a -> IdentityT f b -> Ordering Source #
Read1 f => Read1 ( IdentityT f) Source #
Instance details Defined in Control.Monad.Trans.Identity Methods liftReadsPrec :: ( Int -> ReadS a) -> ReadS [a] -> Int -> ReadS ( IdentityT f a) Source # liftReadList :: ( Int -> ReadS a) -> ReadS [a] -> ReadS [ IdentityT f a] Source # liftReadPrec :: ReadPrec a -> ReadPrec [a] -> ReadPrec ( IdentityT f a) Source # liftReadListPrec :: ReadPrec a -> ReadPrec [a] -> ReadPrec [ IdentityT f a] Source #
Show1 f => Show1 ( IdentityT f) Source #
Instance details Defined in Control.Monad.Trans.Identity Methods liftShowsPrec :: ( Int -> a -> ShowS ) -> ([a] -> ShowS ) -> Int -> IdentityT f a -> ShowS Source # liftShowList :: ( Int -> a -> ShowS ) -> ([a] -> ShowS ) -> [ IdentityT f a] -> ShowS Source #
MonadZip m => MonadZip ( IdentityT m) Source #
Instance details Defined in Control.Monad.Trans.Identity Methods mzip :: IdentityT m a -> IdentityT m b -> IdentityT m (a, b) Source # mzipWith :: (a -> b -> c) -> IdentityT m a -> IdentityT m b -> IdentityT m c Source # munzip :: IdentityT m (a, b) -> ( IdentityT m a, IdentityT m b) Source #
MonadIO m => MonadIO ( IdentityT m) Source #
Instance details Defined in Control.Monad.Trans.Identity Methods liftIO :: IO a -> IdentityT m a Source #
Alternative m => Alternative ( IdentityT m) Source #
Instance details Defined in Control.Monad.Trans.Identity Methods empty :: IdentityT m a Source # (<\|>) :: IdentityT m a -> IdentityT m a -> IdentityT m a Source # some :: IdentityT m a -> IdentityT m [a] Source # many :: IdentityT m a -> IdentityT m [a] Source #
MonadPlus m => MonadPlus ( IdentityT m) Source #
Instance details Defined in Control.Monad.Trans.Identity Methods mzero :: IdentityT m a Source # mplus :: IdentityT m a -> IdentityT m a -> IdentityT m a Source #
( Eq1 f, Eq a) => Eq ( IdentityT f a) Source #
Instance details Defined in Control.Monad.Trans.Identity Methods (==) :: IdentityT f a -> IdentityT f a -> Bool Source # (/=) :: IdentityT f a -> IdentityT f a -> Bool Source #
( Ord1 f, Ord a) => Ord ( IdentityT f a) Source #
Instance details Defined in Control.Monad.Trans.Identity Methods compare :: IdentityT f a -> IdentityT f a -> Ordering Source # (<) :: IdentityT f a -> IdentityT f a -> Bool Source # (<=) :: IdentityT f a -> IdentityT f a -> Bool Source # (>) :: IdentityT f a -> IdentityT f a -> Bool Source # (>=) :: IdentityT f a -> IdentityT f a -> Bool Source # max :: IdentityT f a -> IdentityT f a -> IdentityT f a Source # min :: IdentityT f a -> IdentityT f a -> IdentityT f a Source #
( Read1 f, Read a) => Read ( IdentityT f a) Source #
Instance details Defined in Control.Monad.Trans.Identity Methods readsPrec :: Int -> ReadS ( IdentityT f a) Source # readList :: ReadS [ IdentityT f a] Source # readPrec :: ReadPrec ( IdentityT f a) Source # readListPrec :: ReadPrec [ IdentityT f a] Source #
( Show1 f, Show a) => Show ( IdentityT f a) Source #
Instance details Defined in Control.Monad.Trans.Identity Methods showsPrec :: Int -> IdentityT f a -> ShowS Source # show :: IdentityT f a -> String Source # showList :: [ IdentityT 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.