Control.Monad.Backend

Defines the BackendT transformer, which is a variant of the StateT transformer, such that the state is within an MVar.

Documentation

newtype BackendT s m a

The BackendT transformer is a StateT, where the state is encapsulated into a MVar.

Constructors

BackendT (MVar s -> m (MVar s, a))

Instances

(Monad m, MonadIO m) => MonadState s (BackendT s m)

Methods

get :: BackendT s m s

put :: s -> BackendT s m ()

state :: (s -> (a, s)) -> BackendT s m a

Monad m => Monad (BackendT s m)

Methods

(>>=) :: BackendT s m a -> (a -> BackendT s m b) -> BackendT s m b

(>>) :: BackendT s m a -> BackendT s m b -> BackendT s m b

return :: a -> BackendT s m a

fail :: String -> BackendT s m a

Functor m => Functor (BackendT s m)

Methods

fmap :: (a -> b) -> BackendT s m a -> BackendT s m b

(<$) :: a -> BackendT s m b -> BackendT s m a

Monad m => Applicative (BackendT s m)

Methods

pure :: a -> BackendT s m a

(<*>) :: BackendT s m (a -> b) -> BackendT s m a -> BackendT s m b

(*>) :: BackendT s m a -> BackendT s m b -> BackendT s m b

(<*) :: BackendT s m a -> BackendT s m b -> BackendT s m a

(Monad m, MonadIO m) => MonadIO (BackendT s m)

Methods

liftIO :: IO a -> BackendT s m a

runBackendT :: BackendT s m a -> MVar s -> m (MVar s, a)

runBackendT unwraps the BackendT monad.