私と仕事どっちが大事なの！

どっちが大事なの.scala

trait DocchiGaDaiji[A, B] {
  def docchi(a: A, b: B): Either[A, B]
}

object WatashiToShigoto {

  case class Watashi
  case class Shigoto

  implicit object WatashiToShigotoDocchigaDaiji extends DocchiGaDaiji[Watashi, Shigoto]{
    override def docchi(a: Watashi, b: Shigoto): Either[Watashi, Shigoto] = {
      Right(b)
    }
  }
}

object Main {
  import WatashiToShigoto._
  
  def main(args: String*): Either[Watashi, Shigoto] = {
    docchi(Watashi(), Shigoto())
  }

  def docchi[A, B](a: A, b: B)(implicit ev: DocchiGaDaiji[A, B]): Either[A, B] = {
    ev.docchi(a, b)
  }
}