transformers-0.5.2.0: Concrete functor and monad transformers

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

MonadTrans (IdentityT *) # |
Methods lift :: Monad m => m a -> IdentityT * m a Source #
Monad m => Monad (IdentityT * m) # |
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 # fail :: String -> IdentityT * m a Source #
Functor m => Functor (IdentityT * m) # |
Methods fmap :: (a -> b) -> IdentityT * m a -> IdentityT * m b Source # (<$) :: a -> IdentityT * m b -> IdentityT * m a Source #
MonadFix m => MonadFix (IdentityT * m) # |
Methods mfix :: (a -> IdentityT * m a) -> IdentityT * m a Source #
MonadFail m => MonadFail (IdentityT * m) # |
Methods fail :: String -> IdentityT * m a Source #
Applicative m => Applicative (IdentityT * m) # |
Methods pure :: a -> IdentityT * m a Source # (<*>) :: IdentityT * m (a -> b) -> IdentityT * m a -> IdentityT * m b 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) # |
Methods fold :: Monoid m => IdentityT * f m -> 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) # |
Methods traverse :: Applicative f => (a -> f b) -> IdentityT * f a -> f (IdentityT * f b) Source # sequenceA :: Applicative f => IdentityT * f (f a) -> f (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 #
Eq1 f => Eq1 (IdentityT * f) # |
Methods liftEq :: (a -> b -> Bool) -> IdentityT * f a -> IdentityT * f b -> Bool Source #
Ord1 f => Ord1 (IdentityT * f) # |
Methods liftCompare :: (a -> b -> Ordering) -> IdentityT * f a -> IdentityT * f b -> Ordering Source #
Read1 f => Read1 (IdentityT * f) # |
Methods liftReadsPrec :: (Int -> ReadS a) -> ReadS [a] -> Int -> ReadS (IdentityT * f a) Source # liftReadList :: (Int -> ReadS a) -> ReadS [a] -> ReadS [IdentityT * f a] Source #
Show1 f => Show1 (IdentityT * f) # |
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) # |
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) # |
Methods liftIO :: IO a -> IdentityT * m a Source #
Alternative m => Alternative (IdentityT * m) # |
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) # |
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) # |
Methods (==) :: IdentityT * f a -> IdentityT * f a -> Bool # (/=) :: IdentityT * f a -> IdentityT * f a -> Bool #
(Ord1 f, Ord a) => Ord (IdentityT * f a) # |
Methods compare :: IdentityT * f a -> IdentityT * f a -> Ordering # (<) :: IdentityT * f a -> IdentityT * f a -> Bool # (<=) :: IdentityT * f a -> IdentityT * f a -> Bool # (>) :: IdentityT * f a -> IdentityT * f a -> Bool # (>=) :: IdentityT * f a -> IdentityT * f a -> Bool # max :: IdentityT * f a -> IdentityT * f a -> IdentityT * f a # min :: IdentityT * f a -> IdentityT * f a -> IdentityT * f a #
(Read1 f, Read a) => Read (IdentityT * f a) # |
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) # |
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.