Topic 2

Topic 2

object TopicPlayground extends App {
  val t: Topic[String] = scalaz.stream.async.topic()

  val sub1 = t.subscribe

  val out1 = sub1
    .flatMap(x => Process.tell(s"raw value: $x") ++ Process.emitO(x.length))
    .runLog

  val otherThread = future {
    out1.attemptRun // Added this here - now out1 is really attached to the topic
  }
  // Need to give out1 some time to start up.
  // I doubt you'd do this in actual code.
  // topics seem more useful for hooking up things like
  // sensors that produce a continual stream of data,
  // and where individual values can be dropped on
  // floor.
  Thread.sleep(100)

  t.publishOne("foo").run // don't just call publishOne; need to run the resulting task
  t.close.run // Don't just call close; need to run the resulting task

  // Need to wait for the output
  val result = Await.result(otherThread, Duration.Inf)

  println(s"result: $result")
  // and the output is now: result: \/-(Vector(-\/(raw value: foo), \/-(foo)))
}