Control.Monad.MVar

Lift MVar operations so you can do them within monads stacked on top of IO. Analogous to MonadIO

Documentation

data MVar a

An MVar (pronounced "em-var") is a synchronising variable, used for communication between concurrent threads. It can be thought of as a a box, which may be empty or full.

Instances

Typeable1 MVar

Eq (MVar a)

newEmptyMVar :: MonadIO m => m (MVar a)

newMVar :: MonadIO m => a -> m (MVar a)

takeMVar :: MonadIO m => MVar a -> m a

putMVar :: MonadIO m => MVar a -> a -> m ()

readMVar :: MonadIO m => MVar a -> m a

swapMVar :: MonadIO m => MVar a -> a -> m a

tryTakeMVar :: MonadIO m => MVar a -> m (Maybe a)

tryPutMVar :: MonadIO m => MVar a -> a -> m Bool

isEmptyMVar :: MonadIO m => MVar a -> m Bool

modifyMVar :: MonadControlIO m => MVar a -> (a -> m (a, b)) -> m b

addMVarFinalizer :: MonadControlIO m => MVar a -> m () -> m ()

modifyMVar_ :: MonadControlIO m => MVar a -> (a -> m a) -> m ()

withMVar :: MonadControlIO m => MVar a -> (a -> m b) -> m b

liftIO :: MonadIO m => forall a. IO a -> m a

Lift a computation from the IO monad.

class MonadIO m => MonadControlIO m

MonadControlIO is the class of IO-based monads supporting an extra operation liftControlIO, enabling control operations on IO to be lifted into the monad.

Instances

MonadControlIO IO

MonadControlIO m => MonadControlIO (ListT m)

MonadControlIO m => MonadControlIO (MaybeT m)

MonadControlIO m => MonadControlIO (IdentityT m)

MonadControlIO m => MonadControlIO (Action m)

MonadControlIO m => MonadControlIO (StateT s m)

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

MonadControlIO m => MonadControlIO (ReaderT r m)

MonadControlIO m => MonadControlIO (StateT s m)

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

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

(Monoid w, MonadControlIO m) => MonadControlIO (RWST r w s m)

(Monoid w, MonadControlIO m) => MonadControlIO (RWST r w s m)