Control.Monad.Trans.Either

Documentation

newtype EitherT l m a

Constructors

EitherT

Fields

runEitherT :: m (Either l a)

Instances

MonadTrans (EitherT l)

Monad m => Monad (EitherT l m)

Functor f => Functor (EitherT l f)

Applicative f => Applicative (EitherT l f)

MonadIO m => MonadIO (EitherT l m)

(Applicative m, Monoid a) => Monoid (EitherT l m a)

left :: Monad m => l -> EitherT l m a