Data.RefMonad

Description

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

Synopsis

Documentation

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

Class of monads with references.

Minimal complete definition

Methods

newRef :: a -> m (r a) Source #

readRef :: r a -> m a Source #

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

Instances

RefMonad IO IORef Source #
Methods newRef :: a -> IO (IORef a) Source # readRef :: IORef a -> IO a Source # writeRef :: IORef a -> a -> IO () Source #
RefMonad (ST s) (STRef s) Source #
Methods newRef :: a -> ST s (STRef s a) Source # readRef :: STRef s a -> ST s a Source # writeRef :: STRef s a -> a -> ST s () Source #

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

Change the contents of a ref