aivika-transformers-4.3.2: Transformers for the Aivika simulation library

CopyrightCopyright (c) 2009-2015, David Sorokin <>
MaintainerDavid Sorokin <>
Safe HaskellSafe



Tested with: GHC 7.10.1

This module defines a plain and more fast version of an updatable reference that depends on the event queue but that doesn't supply with the signal notification.



class Monad m => MonadRef m where Source

A monad within which we can create mutable references.

Associated Types

data Ref m a Source

The ProtoRef type represents a mutable variable similar to the IORef variable but only dependent on the event queue, which allows synchronizing the reference with the model explicitly through the Event monad.


newRef :: a -> Simulation m (Ref m a) Source

Create a new reference.

readRef :: Ref m a -> Event m a Source

Read the value of a reference.

writeRef :: Ref m a -> a -> Event m () Source

Write a new value into the reference.

modifyRef :: Ref m a -> (a -> a) -> Event m () Source

Mutate the contents of the reference.

equalRef :: Ref m a -> Ref m a -> Bool Source

Compare two references for equality.

class MonadRef m => MonadRef0 m where Source

A kind of reference that can be created within more low level computation than Simulation.


newRef0 :: a -> m (Ref m a) Source

Create a new reference within more low level computation than Simulation.