aivika-transformers-5.4: Transformers for the Aivika simulation library

CopyrightCopyright (c) 2009-2017 David Sorokin <>
MaintainerDavid Sorokin <>
Safe HaskellNone



Tested with: GHC 8.0.1

This module defines a plain and more fast version of an updatable and lazy 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.

Minimal complete definition

newRef, readRef, writeRef, modifyRef, equalRef

Associated Types

data Ref m a Source #

The Ref 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.

Minimal complete definition



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

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