Data.RefMonad

Monads with references, taken from John Hughes's "Global Variables in Haskell" (http://citeseer.ist.psu.edu/473734.html).

Documentation

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

Class of monads with references.

Minimal complete definition

newRef, readRef, writeRef

Methods

newRef :: a -> m (r a)

readRef :: r a -> m a

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

Instances

RefMonad IO IORef

Methods

newRef :: a -> IO (IORef a)

readRef :: IORef a -> IO a

writeRef :: IORef a -> a -> IO ()

RefMonad (ST s) (STRef s)

Methods

newRef :: a -> ST s (STRef s a)

readRef :: STRef s a -> ST s a

writeRef :: STRef s a -> a -> ST s ()

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

Change the contents of a ref