Control.Concurrent.Actor

This module implements Erlang-style actors (what Erlang calls processes).

Types

data ActorMessage msg => ActorHandle msg

An ActorHandle acts as a reference to a specific actor.

class ActorMessage msg

The ActorMessage class must be implemented by any type that will be sent as a message to actors. Any given type of actor will have one ActorMessage type that is sent to that actor. This ensures type safety. Currently this is simply a dummy class with nothing in it, but things may be added in the future.

Instances

ActorMessage ()

class (ActorMessage msg, MonadActorSuper m) => MonadActor msg m

The MonadActor typeclass. This provides the actorCtx function, which all of the actor monad's functionality is based on.

Minimal complete definition

actorCtx

Instances

(ActorMessage msg, MonadActor msg m, MonadTrans t, MonadActorSuper (t m)) => MonadActor msg (t m)

ActorMessage msg => MonadActor msg (ActorM msg)

data ActorM msg a

The base actor monad.

Instances

ActorMessage msg => MonadBase IO (ActorM msg)

ActorMessage msg => MonadBaseControl IO (ActorM msg)

ActorMessage msg => MonadActor msg (ActorM msg)

Monad (ActorM msg)

Functor (ActorM msg)

Applicative (ActorM msg)

MonadThrow (ActorM msg)

MonadIO (ActorM msg)

data StM (ActorM msg) = StMA {

• unStMA :: StM (ReaderT (ActorContext msg) IO) a

}

Sending Messages

send :: (MonadIO m, ActorMessage msg) => ActorHandle msg -> msg -> m ()

Sends a message to the given actor handle.

Receiving Messages

receive :: (ActorMessage msg, MonadActor msg m) => m msg

Reads a message from the actor's mail box. If there are no messages, blocks until one is received. If you don't want this, use receiveMaybe instead.

receiveMaybe :: (ActorMessage msg, MonadActor msg m) => m (Maybe msg)

Reads a message from the actor's mail box. If there are no messages, returns Nothing.

receiveSTM :: (ActorMessage msg, MonadActor msg m) => m (STM msg)

An ActorM action which returns an STM action to receive a message.

Spawning Actors

spawnActor :: ActorMessage msg => ActorM msg () -> IO (ActorHandle msg)

Spawns the given actor on another thread and returns a handle to it.

runActor :: ActorMessage msg => ActorM msg () -> IO ()

Runs the given actor on the current thread. This function effectively turns the current thread into the actor's thread. Obviously, this means that this function will block until the actor exits. You probably want to use this for your "main" actor.

Getting Information

self :: (ActorMessage msg, MonadActor msg m) => m (ActorHandle msg)

Gets a handle to the current actor.

actorThread :: ActorMessage msg => ActorHandle msg -> ThreadId

Gets the thread ID for the given actor handle.