Factorial Operator

f.scala

object f {
  def f(x: BigInt):BigInt = if(x < 2) 1 else x * f(x-1)
  implicit def factorial_operator(x: BigInt) = new { def ! = f(x) }

  def main(args: Array[String]){
    args.foreach {
      i => {
        println(i + "!  = " + (BigInt.apply(i)!) )
      }
    }
  }
}