Control.Monad.EventT

Documentation

data EventT t m a

A monad transformer which adds an event queue and related operations to an underlying monad. The "t" parameter specifies the type of the simulation time.

Several hooks are provided to allow special handling of various events, such as the progression of time, the scheduling or canceling or dispatch of an event, etc.

Instances

MonadReader r m => MonadReader r (EventT t m)

MonadState s m => MonadState s (EventT t m)

MonadError e m => MonadError e (EventT t m)

MonadWriter w m => MonadWriter w (EventT t m)

MonadTrans (EventT t)

Monad m => Monad (EventT t m)

Monad m => Functor (EventT t m)

MonadPlus m => MonadPlus (EventT t m)

MonadCont m => MonadCont (EventT t m)

MonadIO m => MonadIO (EventT t m)

Monad m => MonadSimControl (EventT t m)

Monad m => MonadTime (EventT t m) t

(Monad m, Ord t) => MonadEventQueueInfo (EventT t m) t

Monad m => RetryEvent (EventT t m) t

Monad m => GetCurrentEvent (EventT t m) t

(Monad m, Ord t) => CancelEvent (EventT t m) t

(Monad m, Ord t, Num t, MonadEvent (EventT t m) e) => ScheduleEvent (EventT t m) t e

(MonadIO m, RealFrac t, Pretty t) => MonadEvent (EventT t m) (SetDebugHandlers t m)

(Monad m, Pretty t) => MonadEvent (EventT t m) (EventDescriptor (EventT t m) t)

Monad m => MonadEvent (EventT t m) (EventT t m a)

type EventM = EventT Double IO

EventM is a shorthand for an event graph monad in IO with clock of type Double

runEventT :: Monad m => EventT t m a -> EventT_RState t m -> EventT_RWState t m -> m (a, EventT_RWState t m)

Run an EventT wrapped action. This is a "raw" action - there is no interaction with the state (including event graph) except whatever the action itself does.

runEventGraph :: (Monad m, MonadEvent (EventT t m) e, Ord t, Num t, Pretty t) => e -> m (EventT_RState t m, EventT_RWState t m)

Initialize the event queue and other stuff, enqueue the provided "start event", and run the queue until it's empty or until the simulation is paused.

runEventGraphWithState :: (Monad m, Ord t, Pretty t) => EventT_RState t m -> EventT_RWState t m -> m (EventT_RWState t m)

Repeatedly pull and run the next event in the queue until it's empty or until the simulation is paused using pauseSimulation or something equivalent.

newEventT_RState :: EventT_RState t m

A new instance of the read-only portion of the EventT internal state.

newEventT_RWState :: (Monad m, Ord t) => t -> EventT_RWState t m

A new instance of the read/write portion of the EventT internal state. The parameter is the initial time value.

onClockChanged :: HandlerAccessor t m (t, t) ()

Fires whenever the clock changes, and is passed a tuple containing (old time, new time)

onEventDispatch :: HandlerAccessor t m (EventDescriptor (EventT t m) t) ()

Fires just before an event is dispatched. Is passed an EventDescriptor describing the event about to be run.

onEventComplete :: HandlerAccessor t m (EventDescriptor (EventT t m) t) ()

Fires after an event returns. Is passed an EventDescriptor for the event that just finished.

onEventSchedule :: HandlerAccessor t m (EventDescriptor (EventT t m) t) ()

Fires after an event is scheduled. Is passed an EventDescriptor for the event.

onEventCancel :: HandlerAccessor t m (Either EventID (EventDescriptor (EventT t m) t)) ()

Fires after an event is canceled. Is passed either an EventID (if the cancellation failed) or an EventDescriptor for the event that was canceled.

addHandler :: Monad m => HandlerAccessor t m a b -> (a -> EventT t m b) -> EventT t m HandlerID

Add an event handler to be called when the specified event happens.

removeHandler :: Monad m => HandlerAccessor t m a b -> HandlerID -> EventT t m (Maybe (a -> EventT t m b))

Remove an event handler given its ID, and return it if it was in the set.

data SetDebugHandlers t m

(warning: very likely to change or disappear)

An event which installs some very primitive logging event handlers useful for watching what's going on inside the event queue.

Constructors

SetDebugHandlers DebugHandlerOptions

Instances

Pretty (SetDebugHandlers t m)

(MonadIO m, RealFrac t, Pretty t) => MonadEvent (EventT t m) (SetDebugHandlers t m)

data DebugHandlerOptions

(warning: very likely to change or disappear)

A collection of Bools telling SetDebugHandlers which handlers to install.

Constructors

DebugHandlerOptions

Fields

sync :: Bool

Run roughly in sync with the wall clock (using seconds as the simulation time unit)

showDispatches :: Bool

Print event dispatches to stderr as they occur

showCancels :: Bool

Print event cancellations to stderr as they occur

showSchedules :: Bool

Print event scheduling actions to stderr as they occur

dumpQueue :: Bool

Dump the entire contents of the event queue to stderr every time an event is dispatched

Instances

Show DebugHandlerOptions

defaultHandlerOptions :: DebugHandlerOptions