Simulation.Aivika.Trans.Event

Tested with: GHC 7.10.1

The module defines the Event monad which is very similar to the Dynamics monad but only now the computation is strongly synchronized with the event queue.

Event Monad

data Event m a

A value in the Event monad transformer represents a polymorphic time varying function which is strongly synchronized with the event queue.

Instances

Monad m => EventLift Event m

MonadDES m => ResultComputing Event m

class EventLift t m where

A type class to lift the Event computations into other computations.

Methods

liftEvent :: Event m a -> t m a

Lift the specified Event computation into another computation.

Instances

Monad m => EventLift Event m

MonadDES m => EventLift Cont m

MonadDES m => EventLift Process m

data EventProcessing

Defines how the events are processed.

Constructors

CurrentEvents

either process all earlier and then current events, or raise an error if the current simulation time is less than the actual time of the event queue (safe within the Event computation as this is protected by the type system)

EarlierEvents

either process all earlier events not affecting the events at the current simulation time, or raise an error if the current simulation time is less than the actual time of the event queue (safe within the Event computation as this is protected by the type system)

CurrentEventsOrFromPast

either process all earlier and then current events, or do nothing if the current simulation time is less than the actual time of the event queue (do not use unless the documentation states the opposite)

EarlierEventsOrFromPast

either process all earlier events, or do nothing if the current simulation time is less than the actual time of the event queue (do not use unless the documentation states the opposite)

Instances

Eq EventProcessing

Ord EventProcessing

Show EventProcessing

runEventInStartTime :: MonadDES m => Event m a -> Simulation m a

Run the Event computation in the start time involving all pending CurrentEvents in the processing too.

runEventInStopTime :: MonadDES m => Event m a -> Simulation m a

Run the Event computation in the stop time involving all pending CurrentEvents in the processing too.

Event Queue

class EventQueueing m where

A type class of monads that allow enqueueing the events.

Minimal complete definition

newEventQueue, enqueueEvent, runEventWith, eventQueueCount

Associated Types

data EventQueue m :: *

It represents the event queue.

Methods

newEventQueue :: Specs m -> m (EventQueue m)

Create a new event queue by the specified specs with simulation session.

enqueueEvent :: Double -> Event m () -> Event m ()

Enqueue the event which must be actuated at the specified time.

runEvent :: Event m a -> Dynamics m a

Run the EventT computation in the current simulation time within the DynamicsT computation involving all pending CurrentEvents in the processing too.

runEventWith :: EventProcessing -> Event m a -> Dynamics m a

Run the EventT computation in the current simulation time within the DynamicsT computation specifying what pending events should be involved in the processing.

eventQueueCount :: Event m Int

Return the number of pending events that should be yet actuated.

enqueueEventWithCancellation :: MonadDES m => Double -> Event m () -> Event m (EventCancellation m)

Enqueue the event with an ability to cancel it.

enqueueEventWithTimes :: MonadDES m => [Double] -> Event m () -> Event m ()

Actuate the event handler in the specified time points.

enqueueEventWithIntegTimes :: MonadDES m => Event m () -> Event m ()

Actuate the event handler in the integration time points.

yieldEvent :: MonadDES m => Event m () -> Event m ()

Enqueue the event which must be actuated with the current modeling time but later.

Cancelling Event

data EventCancellation m

It allows cancelling the event.

cancelEvent :: EventCancellation m -> Event m ()

Cancel the event.

eventCancelled :: EventCancellation m -> Event m Bool

Test whether the event was cancelled.

eventFinished :: EventCancellation m -> Event m Bool

Test whether the event was processed and finished.

Error Handling

catchEvent :: (MonadException m, Exception e) => Event m a -> (e -> Event m a) -> Event m a

Exception handling within Event computations.

finallyEvent :: MonadException m => Event m a -> Event m b -> Event m a

A computation with finalization part like the finally function.

throwEvent :: (MonadException m, Exception e) => e -> Event m a

Like the standard throw function.

Memoization

memoEvent :: MonadDES m => Event m a -> Simulation m (Event m a)

Memoize the Event computation, always returning the same value within a simulation run.

memoEventInTime :: MonadDES m => Event m a -> Simulation m (Event m a)

Memoize the Event computation, always returning the same value in the same modeling time. After the time changes, the value is recalculated by demand.

It is possible to implement this function efficiently, for the Event computation is always synchronized with the event queue which time flows in one direction only. This synchronization is a key difference between the Event and Dynamics computations.

Disposable

newtype DisposableEvent m

Defines a computation disposing some entity.

Constructors

DisposableEvent

Fields

disposeEvent :: Event m ()

Dispose something within the Event computation.

Instances

Monad m => Monoid (DisposableEvent m)

Debugging

traceEvent :: MonadDES m => String -> Event m a -> Event m a

Show the debug message with the current simulation time.