DeepControl.Monad.Maybe

This module is just a concise mimic for Maybe Monad in mtl(monad-transformer-library). The qualifier "concise" means that this module doesn't make no attempt to transform functions of any kind of Monad automatically. So when making some new data type of MaybeT, you have to manually define involved Monad instances, for example MonadReader, MonadWriter or MonadState, by making use of the transformation functions such as trans, trans2, etc. Admittedly it is tedious though, you can deeply understand monad-transformation mechanism instead.

Level-1

newtype MaybeT m a

Constructors

MaybeT

Fields

runMaybeT :: m (Maybe a)

Instances

MonadTrans MaybeT

Monad m => Monad (MaybeT m)

Functor m => Functor (MaybeT m)

Monad m => Applicative (MaybeT m)

MonadIO m => MonadIO (MaybeT m)

mapMaybeT :: (m (Maybe a) -> n (Maybe b)) -> MaybeT m a -> MaybeT n b

liftCatch :: Catch e m (Maybe a) -> Catch e (MaybeT m) a