Example of how to create an Extension Method on a Companion Object

ExtensionMethodsOnCompanionObjects.scala

object ExtensionMethodsOnCompanionObjects {

  implicit class ListFactoryOps(val list: List.type) extends AnyVal {
    def fizzbuzz(n: Int): List[String] =
      (0 to n).map {
        case n if n % 15 == 0 => "FizzBuzz"
        case n if n % 3  == 0 => "Fizz"
        case n if n % 5  == 0 => "Buzz"
        case n                => n.toString
      }.toList
  }

  def lengthFromArgs(args: Array[String]): Int = args.headOption.fold(15)(_.toInt)

  def main(args: Array[String]): Unit =
    List.fizzbuzz(lengthFromArgs(args)).foreach(println)

}