dumbstate.scala

import akka.actor.ActorSystem
import akka.stream.ActorMaterializer
import akka.stream.scaladsl.Source
import cats.data.State

object Main extends App {

  implicit val system = ActorSystem("akka")
  implicit val ec = system.dispatcher
  implicit val materializer = ActorMaterializer()

  // dumb state monad
  val s = State[String, Int] {
    case "world-state" => ("success", 1)
    case _ => ("blah", 0)
  }

  val done = Source(1 to 10)
    .map { d =>
      if (d == 10) for (z <- s) yield z + d // xform the value using comprehensions
      else s
    }
    .map { d => d.modify { case "success" => "awesome" } } // xform the state using set/get/modify
    .map { _.run("world-state").value } // run the monad xformer get retrieve the value
    .runForeach(println)

  done
    .map { d => println(d) }
    .map { _ => system.terminate() }
}