Control.Monad.Ref

Mutable references in the (strict) ST monad.

Documentation

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 either the ST monad or the IO monad.

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 IORef IO

MonadRef (STRef s) (ST s)