16進文字列をAscii文字列に変換

hexToStr.scala

import scala.annotation.tailrec
def hexToStr(s:String):String = {
  @tailrec def r(target:String,result:String):String = {
    target splitAt 2 match {
      case (xx,xs) if !xx.isEmpty => r(xs,result + Integer.parseInt(xx,16).toChar)
      case _ => result
    }
  }
  r(s,"")
}

val target = 'a' to 'z' mkString
val hexTarget = target map {"%02x" format _.toInt} mkString
assert(target == hexToStr(hexTarget))