BadFutureMapping.scala

val firstLove = future {
      Thread.sleep(500)
      "i love you"
    }
    val thenBetray = firstLove map {
      case loveLetter => {
        Console.println(loveLetter)
        Thread.sleep(500)
        "not really"
      }
    }
    thenBetray onSuccess {
      case partingWords => Console.println(partingWords)
    }

ProperFutureMapping.scala

val firstLove = Future {
  Thread.sleep(500)
  "i love you"
}

val thenBetray = firstLove map { loveLetter =>
    println(loveLetter)
    Thread.sleep(500)
    "not really"
}

thenBetray foreach println

WithAsyncAwait.scala

async {
  
  val firstLove = Future {
    Thread.sleep(500)
    "i love you"
  }

  val loveLetter = await(firstLove)
  
  println(loveLetter)
  
  val thenBetray = {
    Thread.sleep(500)
    "not really"
  }
  
  println(await(thenBetray))
}

WithForComprehensions.scala

for {
  loveLetter <- Future {
                        Thread.sleep(500)
                        "i love you"
                       }
  thenBetray <- Future {
                        println(loveLetter)
                        Thread.sleep(500)
                        "not really"
                       }
  } println(thenBetray)