My first sample of Scala

uriunescape.scala

val uriEscaped = args(0)

implicit def listToArray[T: ClassManifest](list: List[T]): Array[T] =
  list.toArray

implicit def arrayToList[T](arr: Array[T]): List[T] =
  (arr: scala.collection.mutable.WrappedArray[T]).toList

def unescapeHexChars(char1: Char, char2: Char): Byte = {
  Integer.decode("0x" + char1 + char2).toByte
}

def unescape(str: List[Char]): List[Byte] = {
  str match {
    case '%' :: xs => unescapeHexChars(xs.head, xs.tail.head) ::
                      unescape(xs.tail.tail)
    case x :: xs => x.toByte :: unescape(xs)
    case Nil => Nil
  }
}

println(new String(unescape(uriEscaped toCharArray), "Shift_JIS"))

/*
% _JAVA_OPTIONS=-Dfile.encoding=UTF-8 scala /tmp/test.scala %92%b4%8bv%81X%82%cc%93%8c%8e%ba%97%96%89w%81B%89%bd%94N%82%d4%82%e8%82%be%81H10%94N%82%ad%82%e7%82%a2%82%a9%81H 
Picked up _JAVA_OPTIONS: -Dfile.encoding=UTF-8
超久々の東室蘭駅。何年ぶりだ？10年くらいか？
*/