Control.Monad.Trans

The MonadTrans class.

Inspired by the paper /Functional Programming with Overloading and Higher-Order Polymorphism/, Mark P Jones (http://www.cse.ogi.edu/~mpj/) Advanced School of Functional Programming, 1995.

Documentation

class MonadTrans t where

Methods

lift :: Monad m => m a -> t m a

tmap :: (Monad m, Monad n) => (forall a. m a -> n a) -> (forall b. n b -> m b) -> t m c -> t n c

Instances

MonadTrans ListT

MonadTrans (StateT s)

MonadTrans (ReaderT r)

MonadTrans (StateT s)

Monoid w => MonadTrans (WriterT w)

Monoid w => MonadTrans (WriterT w)

MonadTrans (ContT r)

Error e => MonadTrans (ErrorT e)

class Monad m => MonadIO m where

Methods

liftIO :: IO a -> m a

Instances

MonadIO IO

MonadIO m => MonadIO (ListT m)

MonadIO m => MonadIO (StateT s m)

MonadIO m => MonadIO (ReaderT r m)

MonadIO m => MonadIO (StateT s m)

(Monoid w, MonadIO m) => MonadIO (WriterT w m)

(Monoid w, MonadIO m) => MonadIO (WriterT w m)

MonadIO m => MonadIO (ContT r m)

(Error e, MonadIO m) => MonadIO (ErrorT e m)