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.

Methods

newRef :: a -> m (r a)

readRef :: r a -> m a

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

Instances

RefMonad IO IORef

Monad (ST s) => RefMonad (ST s) (STRef s)

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

Change the contents of a ref