Broadcast.scala

def broadcast(connector: QueueConnector[Task]): Task[BroadcastResult] = {
  def processMessages(inbox: MVar[BroadcastMessage], 
                      consumers: Set[String => Task[Unit]]): Task[Unit] = // ...

  def consumeForever(inbox: MVar[BroadcastMessage]): Task[Unit] = // ...
  
  for {
    inbox <- MVar.empty[BroadcastMessage]
    f1 <- consumeForever(inbox).fork
    f2 <- processMessages(inbox, Set()).fork
  } yield BroadcastResult(inbox, f1.cancel *> f2.cancel)
}