Data.MRef.Classes

This module defines the "MRef" abstraction, which is a set of type-classes for things that behave like Control.Concurrent.MVar.MVars. See the documentation there for more info.

This interface may be subject to future expansion. Presently, rather than providing something like Control.Concurrent.MVar.tryTakeMVar, instances for "Data.StateRef.Classes.ReadRef sr m (Maybe a)" are provided, giving Data.StateRef.Classes.readRef the same type tryTakeMRef would have if it existed. There is currently nothing like Control.Concurrent.MVar.tryPutMVar, though. Perhaps there should be. Or, perhaps this is the sort of thing the weird (to me) signature of Data.IORef.atomicModifyIORef is for, and an argument for a similar signature for Data.StateRef.Classes.modifyStateRef or the addition of a new atomicModifyStateRef function.

I would like to resolve these questions in version 0.3 of this package.

Documentation

class Monad m => NewMRef sr m a | sr -> a where

Methods

newMRef :: a -> m sr

See Control.Concurrent.MVar.newMVar

newEmptyMRef :: m sr

See Control.Concurrent.MVar.newEmptyMVar

Instances

NewMRef (TVar (Maybe a)) IO a

NewMRef (TVar (Maybe a)) STM a

MonadIO m => NewMRef (MVar a) m a

NewMRef (TMVar a) IO a

NewMRef (TMVar a) STM a

class Monad m => TakeMRef sr m a | sr -> a where

Methods

takeMRef :: sr -> m a

See Control.Concurrent.MVar.takeMVar

Instances

TakeMRef (TVar (Maybe a)) IO a

TakeMRef (TVar (Maybe a)) STM a

MonadIO m => TakeMRef (MVar a) m a

TakeMRef (TMVar a) IO a

TakeMRef (TMVar a) STM a

class Monad m => PutMRef sr m a | sr -> a where

Methods

putMRef :: sr -> a -> m ()

See Control.Concurrent.MVar.putMVar

Instances

PutMRef (TVar (Maybe a)) IO a

PutMRef (TVar (Maybe a)) STM a

MonadIO m => PutMRef (MVar a) m a

PutMRef (TMVar a) IO a

PutMRef (TMVar a) STM a

class Monad m => DefaultMRef sr m a | sr -> a, m a -> sr

Instances

DefaultMRef (MVar a) IO a

DefaultMRef (TMVar a) STM a