Hello World scala actors

_originalActors.scala

import scala.actors._
import scala.actors.Actor._

class Message(val message: String = "")

val helloActor = actor {
  var nextActor : Option[Actor] = None
  while(true) {
    receive {
      case a : Actor => nextActor = Option(a)
      case msg : Message => nextActor match 
        { 
          case Some(a: Actor) => a ! new Message(msg.message + "Hello")
          case None => {}
        }
    }
  }
}

val worldActor = actor {
  var nextActor : Option[Actor] = None
  while(true) {
    receive {
      case a : Actor => nextActor = Option(a)
      case msg : Message => nextActor match 
        { 
          case Some(a: Actor) => a ! new Message(msg.message + " World")
          case None => {}
        }
    }
  }
}

helloActor ! worldActor

worldActor ! actor {
  while(true) {
    receive {
      case msg : Message => println(msg.message)
    }
  }
}

helloActor ! new Message

while(true){}

HelloWorldActors-NestedReceives.scala

import scala.actors._
import scala.actors.Actor._

val helloActor = actor {
  receive {
    case nextActor : Actor => {
      println("Hello Actor linked to " + nextActor)
      while(true) {
        receive {
          case message : String => {
            println("Hello Actor receives message (\""+ message + "\")")
            nextActor ! message + " Hello"
          }
        }
      }
    }
  }
}

val worldActor = actor {
  receive {
    case nextActor : Actor => {
      println("World Actor linked to " + nextActor)
      while(true) {
        receive {
          case message : String => {
            println("World Actor receives message (\""+ message + "\")")
            nextActor ! message + " World"
          }
        }
      }
    }
  }
}

val printActor = actor {
  while(true) {
    receive {
      case message: String => println("Print Actor receives message (\""+ message + "\")")
    }
  }
}

println("Send link messages")
helloActor ! worldActor
worldActor ! printActor

println("Sent messages")
helloActor ! "I say"

println("ok")
readLine

HelloWorldActors.scala

import scala.actors._
import scala.actors.Actor._

val helloActor : Actor = actor {
  var nextActor : Option[Actor] = None
  receive {
      case a : Actor => {
        nextActor = Some(a)
        println("Hello Actor "+ helloActor +" linked to " + a)
      }
  }
  while(true) {
    receive {
      case message : String => {
        println("Hello Actor "+ helloActor +" receives message (\""+ message + "\")")
        nextActor.get ! message + " Hello"
      }
    }
  }
}

val worldActor : Actor = actor {
  var nextActor : Option[Actor] = None
  receive {
      case a : Actor => {
        nextActor = Some(a)
        println("World Actor "+ worldActor +" linked to " + a)
      }
  }
  while(true) {
    receive {
      case message : String => {
        println("World Actor "+ worldActor +" receives message (\""+ message + "\")")
        nextActor.get ! message + " World"
      }
    }
  }
}

val printActor : Actor = actor {
  while(true) {
    receive {
      case message: String => println("Print Actor "+ printActor +" receives message (\""+ message + "\")")
    }
  }
}

println("Send link messages")
helloActor ! worldActor
worldActor ! printActor

println("Sent messages")
helloActor ! "I say"

println("ok")
readLine

HelloWorldActorsFromScratch.scala

// this is the simplest thing that would compile and run.
// no guarantees that it'll work in all cases
object ThreadHelper{
  private val t1 = new ThreadLocal[Actor]

  def start(actor: Actor) = {
    (new Thread(){
      override def run {
        t1.set(actor)
    	actor.act
      }
    }).start
    actor
  }

  def getActor = t1.get
}

object Actor{
  def actor(body: => Unit) : Actor = {
    val a = new Actor{
      def act = body
    }
    ThreadHelper.start(a);
  }
  
  def receive(respond: PartialFunction[Any, Any]) = {
    var actor = ThreadHelper.getActor
    while(actor.messageQueue.isEmpty){ }
    var nextMessage = actor.messageQueue.dequeue
    if(respond.isDefinedAt(nextMessage)) respond(nextMessage)
  }
}

trait Actor{
  def act

  val messageQueue = new scala.collection.mutable.Queue[Any] 
  
  def ! (message: Any) = {
     messageQueue.enqueue(message)
  }
}

import Actor._;

val helloActor : Actor = actor {
  var nextActor : Option[Actor] = None
  receive {
      case a : Actor => {
        nextActor = Some(a)
        println("Hello Actor "+ helloActor +" linked to " + a)
      }
  }
  while(true) {
    receive {
      case message : String => {
        println("Hello Actor "+ helloActor +" receives message (\""+ message + "\")")
        nextActor.get ! message + " Hello"
      }
    }
  }
}

val worldActor : Actor = actor {
  var nextActor : Option[Actor] = None
  receive {
      case a : Actor => {
        nextActor = Some(a)
        println("World Actor "+ worldActor +" linked to " + a)
      }
  }
  while(true) {
    receive {
      case message : String => {
        println("World Actor "+ worldActor +" receives message (\""+ message + "\")")
        nextActor.get ! message + " Hello"
      }
    }
  }
}

val printActor : Actor = actor {
  while(true) {
    receive {
      case message: String => println("Print Actor "+ printActor +" receives message (\""+ message + "\")")
    }
  }
}

println("Send link messages")
helloActor ! worldActor
worldActor ! printActor

println("Sent messages")
helloActor ! "I say"

println("ok")
readLine

output.txt

Send link messages
Hello Actor scala.actors.Actor$$anon$1@1f3785d3 linked to scala.actors.Actor$$anon$1@7632efa7
Sent messages
ok
World Actor scala.actors.Actor$$anon$1@7632efa7 linked to scala.actors.Actor$$anon$1@2565a3c2
Hello Actor scala.actors.Actor$$anon$1@1f3785d3 receives message ("I say")
World Actor scala.actors.Actor$$anon$1@7632efa7 receives message ("I say Hello")
Print Actor scala.actors.Actor$$anon$1@2565a3c2 receives message ("I say Hello Hello")