implicit.scala

object Main extends App {
  implicit val queue: dispatch.queue = "goodbyeQueue"
  
  def sayHello = () => {println("hello")}
  def sayGoodbye = () => {println("goodbye")}

  dispatch.async(sayHello)("helloQueue")
  dispatch async sayGoodbye
}

object dispatch {
  type queue = String
  
  def async(cb: () => Unit)(implicit queue: queue) = {
    println(s"Executing in $queue")
    cb()
  }
}