mapBetween関数 trait版

mapBetween.scala

object mapBetween {
  def main(args:Array[String]) = {
    val range = new Range(1, 10, 1) with ExtSeq[Int]
    println(range.mapBetween(_+_) mkString ",")
    println(range.mapBetween(_*_) mkString ",")
    println(range.mapBetween(_-_) mkString ",")

    val range2 = 1 to 10
    println(range2.mapBetween(_+_) mkString ",")
    println(range2.mapBetween(_*_) mkString ",")
    println(range2.mapBetween(_-_) mkString ",")
  }

  implicit def seqToExtSeq[A](seq: Seq[A]): ExtSeq[A] = {
    import scala.collection.mutable.ArrayBuffer
    new ArrayBuffer[A]() with ExtSeq[A] ++= seq
  }
}

trait ExtSeq[+A] extends Seq[A] {
  def mapBetween[B](f:(A,A)=>B): Iterator[B] = {
    super.sliding(2).map(s=>f(s(0),s(1)))
  }
}