Data.STRef.Persistent

Mutable references in the persistent ST monad.

STRefs

data STRef s a

Instances

Monad m => MonadRef (STRef s) (STT s m)

MonadRef Operations

class Monad m => MonadRef r m | m -> r where

The MonadRef type class abstracts over the details of manipulating references, allowing one to write code that uses references and can operate in any monad that supports reference operations.

Methods

newRef :: a -> m (r a)

Create a new reference

readRef :: r a -> m a

Read the value of a reference

writeRef :: r a -> a -> m ()

Write a new value to a reference

modifyRef :: r a -> (a -> a) -> m ()

Mutate the contents of a reference

Instances

MonadRef TVar STM

MonadRef IORef IO

MonadRef r m => MonadRef r (MaybeT m)

MonadRef r m => MonadRef r (ListT m)

MonadRef r m => MonadRef r (IdentityT m)

(Monoid w, MonadRef r m) => MonadRef r (WriterT w m)

(Monoid w, MonadRef r m) => MonadRef r (WriterT w m)

MonadRef r m => MonadRef r (StateT s m)

MonadRef r m => MonadRef r (StateT s m)

MonadRef r m => MonadRef r (ReaderT r' m)

(Error e, MonadRef r m) => MonadRef r (ErrorT e m)

MonadRef r m => MonadRef r (ContT r' m)

MonadRef (STRef s) (ST s)

Monad m => MonadRef (STRef s) (STT s m)

modifyRef' :: MonadRef r m => r a -> (a -> a) -> m ()