object Main extends App {

  def fizzBuzz(num: Int, mapping: Map[Int, String]): List[Either[Int, String]] =
    (1 to num).toList map { i ⇒
      mapping.toList.sorted flatMap {
        case (k, v) if i % k == 0 ⇒ List(v)
        case _ ⇒ Nil
      } match {
        case Nil ⇒ Left(i)
        case rs ⇒ Right(rs.mkString)
      }
    }

  fizzBuzz(16, Map(3 → "Fizz", 5 → "Buzz")) foreach println

}