Scodec Discrimination by tag value range

RangeDiscriminatorCodec.scala

 class RangeDiscriminatorCodec[T](start: Int, end: Int, tag: Codec[Int], child: Codec[Int ~ T]) extends Codec[Int ~ T] {
    override def sizeBound = tag.sizeBound | child.sizeBound
    override def encode(value: Int ~ T) = value match {
      case t ~ _ if t >= start && t <= end => child.encode(value)
      case _                               => Attempt.failure(Err("out of range"))
    }
    override def decode(bits: BitVector) = tag.decode(bits) match {
      case Attempt.Successful(DecodeResult(value, remainder)) =>
        if (value >= start && value <= end)
          child.decode(remainder)
        else
          Attempt.failure(Err("out of range"))
      case Attempt.Failure(err) => Attempt.failure(err)
    }
  }