Karate Chop Kata in Scala

chop.scala

def chop(needle : Int, haystack : Array[Int]) : Int = {
  if (haystack.length == 0) return -1
  val midPoint = haystack.length / 2
  val midValue = haystack(midPoint)

  if (midValue == needle) 
    midPoint
  else if (needle < midValue) 
    chop(needle, haystack.slice(0, midPoint))
  else
    chop(needle, haystack.slice(midPoint + 1, haystack.length)) match {
      case -1    => -1
      case index => midPoint + 1 + index
    }
}