k-combinator.scala

object Functional {
  /*
   *  Adds the k-combinator to an object. This lets you apply a function to the
   *  calling object; useful for accessing entire collections in the middle of
   *  a series of transformations. This lets you do horrible, side-effecting
   *  things to mutable collections, so try to avoid that.
   *
   *  Example:
   *
   *    List(1, 2, 3).map(_ * 2).k{ x => println(x) }.filter(_ > 4)
   *
   *  Prints "List(2, 4, 6)" and returns List(6)
   */
  class KCombinator[T](x: T) {
    def k(f: (T) => Unit): T = {
      f(x)
      x
    }
  }
  implicit def addKCombinator[T](x: T) = new KCombinator[T](x)
}