Control.Monad.Trans.Identity

Contents

Description

The identity monad transformer.

This is useful for functions parameterized by a monad transformer.

Synopsis

The identity monad transformer

newtype IdentityT m a

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

Constructors

IdentityT
Fields runIdentityT :: m a

Instances

MonadTrans IdentityT
Monad m => Monad (IdentityT m)
Functor m => Functor (IdentityT m)
(Monad (IdentityT m), MonadFix m) => MonadFix (IdentityT m)
(Monad (IdentityT m), MonadPlus m) => MonadPlus (IdentityT m)
(Functor (IdentityT m), Applicative m) => Applicative (IdentityT m)
Foldable f => Foldable (IdentityT f)
(Functor (IdentityT f), Foldable (IdentityT f), Traversable f) => Traversable (IdentityT f)
(Applicative (IdentityT m), Alternative m) => Alternative (IdentityT m)
(Monad (IdentityT m), MonadIO m) => MonadIO (IdentityT m)

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

Lift a unary operation to the new monad.

Lifting other operations

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

Lift a catchError operation to the new monad.

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

Lift a callCC operation to the new monad.