stateref-0.3: Abstraction for things that work like IORef.

Safe HaskellSafe
LanguageHaskell98

Data.MRef.Types

Description

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

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

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

Documentation

data MRef m a where #

Constructors

MRef :: (TakeMRef sr m a, PutMRef sr m a) => !sr -> MRef m a 

class HasMRef m where #

Minimal complete definition

newMRef, newEmptyMRef

Methods

newMRef :: a -> m (MRef m a) #

newEmptyMRef :: m (MRef m a) #

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

Minimal complete definition

newMReference, newEmptyMReference

Methods

newMReference :: a -> m sr #

newEmptyMReference :: m sr #

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

Minimal complete definition

takeMReference

Methods

takeMReference :: sr -> m a #

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

Minimal complete definition

putMReference

Methods

putMReference :: sr -> a -> m () #