Control.Monad.Trans.State.Plus

Contents

Description

MonadPlus with left catch (MonadOr) for StateT.

Synopsis

The StatePlusT monad transformer

data StatePlusT s m a #

StatePlusT behaves similar to StateT monad transformer

Instances

Monad m => MonadState s (StatePlusT s m) #
Methods get :: StatePlusT s m s # put :: s -> StatePlusT s m () # state :: (s -> (a, s)) -> StatePlusT s m a #
MonadTrans (StatePlusT s) #
Methods lift :: Monad m => m a -> StatePlusT s m a #
Monad m => Monad (StatePlusT s m) #
Methods (>>=) :: StatePlusT s m a -> (a -> StatePlusT s m b) -> StatePlusT s m b # (>>) :: StatePlusT s m a -> StatePlusT s m b -> StatePlusT s m b # return :: a -> StatePlusT s m a # fail :: String -> StatePlusT s m a #
Functor m => Functor (StatePlusT s m) #
Methods fmap :: (a -> b) -> StatePlusT s m a -> StatePlusT s m b # (<$) :: a -> StatePlusT s m b -> StatePlusT s m a #
(Monad m, Functor m) => Applicative (StatePlusT s m) #
Methods pure :: a -> StatePlusT s m a # (<>) :: StatePlusT s m (a -> b) -> StatePlusT s m a -> StatePlusT s m b # (>) :: StatePlusT s m a -> StatePlusT s m b -> StatePlusT s m b # (<*) :: StatePlusT s m a -> StatePlusT s m b -> StatePlusT s m a #
MonadIO m => MonadIO (StatePlusT s m) #
Methods liftIO :: IO a -> StatePlusT s m a #
(Monad m, Functor m) => Alternative (StatePlusT s m) #
Methods empty :: StatePlusT s m a # (<\|>) :: StatePlusT s m a -> StatePlusT s m a -> StatePlusT s m a # some :: StatePlusT s m a -> StatePlusT s m [a] # many :: StatePlusT s m a -> StatePlusT s m [a] #
Monad m => MonadPlus (StatePlusT s m) #
Methods mzero :: StatePlusT s m a # mplus :: StatePlusT s m a -> StatePlusT s m a -> StatePlusT s m a #

runStatePlusT :: Monad m => StatePlusT s m a -> s -> m (Maybe a, s) #

Evaluate StatePlusT monad. In difference from runStateT it returns Nothing if mzero has been encountered. Just a otherwise.

Execute StatePlusT monad returning resulting state

Evaluate StatePlusT monad returning resulting value. See above for the semantics.