gistfile1.scala

import scala.util._
def binarySearch(number: Int, numbers: List[Int]): Try[Int] = {
  def Y[A,B]( f:((A => B), A ) => B, x:A ):B = f( (y:A) => Y(f,y),x)
  Success(Y( (f: ((Int, Int)) => (Int, Int), n: (Int, Int)) => {
    if (n._1 == n._2) return Failure(new NoSuchElementException)
    ((mid: Int) => {
      ((numbers(mid), number) match {
        case (l, r) if l > r  => f(n._1, mid)
        case (l, r) if l < r  => f(mid + 1, n._2)
        case _                => (mid, -1)
      })
    })((n._1 + n._2) / 2)
  }, (0, numbers.length))._1)
}
println(binarySearch(50, Range(10, 100, 20).toList).getOrElse(None) != None)
println(binarySearch(10, Range(10, 100, 20).toList).getOrElse(None) != None)
println(binarySearch(5,  Range(10, 100, 20).toList).getOrElse(None) == None)
println(binarySearch(500, Range(10, 100, 20).toList).getOrElse(None) == None)