ZIO learning - promise allow one fiber to communicate with an other one / published by https://github.com/dacr/code-examples-manager #1a10f606-24f5-45a1-9577-dad815cd2146/f0234d16a783ec0acd7948bfdc130fc0f174270f

zio-learning-20-fibers-communication-with-promise.sc

// summary : ZIO learning - promise allow one fiber to communicate with an other one
// keywords : scala, zio, learning, pure-functional, @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 : 1a10f606-24f5-45a1-9577-dad815cd2146
// created-on : 2021-04-06T15:32:12+02:00
// managed-by : https://github.com/dacr/code-examples-manager
// run-with : scala-cli $file

// ---------------------
//> using scala "3.4.2"
//> using dep "dev.zio::zio:2.0.13"
// ---------------------
/*
 inspired from
   - [John A De Goes - ZIO: Next-Generation Effects in Scala](https://www.youtube.com/watch?v=mkSHhsJXjdc)
   - +35:00
 */

import zio.*

object Encapsulated extends ZIOAppDefault {

  def completeWhenReady[E](promise: Promise[E, Int]) = {
    Clock.sleep(100.millis).flatMap { case x =>
      promise.complete(ZIO.succeed(42))
    }
  }

  def run = for {
    p      <- Promise.make[Error, Int]
    _      <- completeWhenReady(p).fork
    _      <- Clock.sleep(50.millis) // do so work
    result <- p.await
    _      <- Console.printLine(s"result=$result")
  } yield result
}

// -------------------------------------------------------------
Encapsulated.main(Array.empty)