Simple pekko hello world example / published by https://github.com/dacr/code-examples-manager #d2822abf-e20d-4cc6-8ab6-00a50b1888d8/8a3aabe64f2b3b00ea770cc03abf93078728e570

pekko-actors-hello-world.sc

// summary : Simple pekko hello world example
// keywords : scala, actors, pekko, helloworld, @testable
// publish : gist
// authors : David Crosson
// license : Apache NON-AI License Version 2.0 (https://raw.githubusercontent.com/non-ai-licenses/non-ai-licenses/main/NON-AI-APACHE2)
// id : d2822abf-e20d-4cc6-8ab6-00a50b1888d8
// created-on : 2023-06-24T18:56:35+02:00
// managed-by : https://github.com/dacr/code-examples-manager
// run-with : scala-cli $file

// ---------------------
//> using scala "3.4.2"
//> using repository "https://repository.apache.org/content/groups/snapshots"
//> using dep "org.apache.pekko::pekko-actor:1.0.0-RC3+7-029806f8-SNAPSHOT"
// ---------------------

import scala.concurrent.{ExecutionContextExecutor, Await}
import scala.concurrent.duration.Duration
import org.apache.pekko.actor.{Actor, ActorRef, ActorSystem, PoisonPill, Props, Terminated}
// import akka.pattern.ask // Required to get responses using ? (but take care, of course...)


// ---------------------------------------------------------------------------
object A {
  case class Start()
  case class AMsg(txt:String)
  def props(b: ActorRef) = Props(new A(b))
}

class A(b: ActorRef) extends Actor {
  override def receive = {
    case A.Start() =>
      b ! B.BMsg("hello world")
      //sender ! "OK"
    case A.AMsg(txt) =>
      println(s"B says $txt")
      context.system.terminate()
    case x =>
      println(s"Unsupported message received $x")
  }
}


// ---------------------------------------------------------------------------
object B {
  case class BMsg(txt:String)
  def props() = Props(new B())
}

class B() extends Actor {
  override def receive = {
    case B.BMsg(txt) =>
      sender() ! A.AMsg(s"message size is ${txt.size} for $txt")
  }
}

// ---------------------------------------------------------------------------
object Toto {
  val system = ActorSystem("HalSystem")
  //implicit val executionContext: ExecutionContextExecutor = system.dispatcher

  val b = system.actorOf(B.props())
  val a = system.actorOf(A.props(b))

  a ! A.Start()
  //val rcf  = (a ? A.Start()) (Timeout(10, TimeUnit.SECONDS))
  //rcf.foreach(rc => println(rc))
}

Toto.system // Just to boot as object inits (statics) are lazy
Await.result(Toto.system.whenTerminated, Duration.Inf)