mapBetween関数 trait版

ExSeq.scala

trait ExSeq[+A] {
  self: Seq[A] =>

  def mapBetween[B](f:(A,A)=>B): Iterator[B] = {
    sliding(2).map(s=>f(s(0),s(1)))
  }

}
object ExSeq {

  import scala.collection.immutable.Range

  def apply(r: Range): ExSeq[Int] = new Range(r.start, r.end, r.step) with ExSeq[Int]

}

mapBetween.scala

object mapBetween {

  def main(args: Array[String]) {
    val range2 = 1 to 10
    println(range2.mapBetween(_ + _) mkString ",")
    println(range2.mapBetween(_ * _) mkString ",")
    println(range2.mapBetween(_ - _) mkString ",")
  }

  implicit def seqToExtSeq[A](seq: Seq[A]) = new {
    def mapBetween[B](f: (A, A) => B): Iterator[B] = {
      seq.sliding(2).map(s => f(s(0), s(1)))
    }
  }

}