Idea for modelling serialized PHP data in Scala

PhpValue.scala

sealed trait PhpValue {
  def \(field: PhpValue): Seq[PhpValue] = Seq.empty[PhpValue]
  def \\(field: PhpValue): Seq[PhpValue] = Seq.empty[PhpValue]
}

sealed trait PhpArrayLike extends PhpValue {
  def fields: Map[PhpValue, PhpValue]

  override def \(field: PhpValue): Seq[PhpValue] =
    fields.toSeq.collect {
      case (f, v) if f == field => v
    }

  override def \\(field: PhpValue): Seq[PhpValue] =
    fields.toSeq.foldLeft(Seq.empty[PhpValue]) { (accum, pair) =>
      pair match {
        case (f, v) if f == field => accum ++ (v +: (v \\ field))
        case (f, v)               => accum ++ (v \\ field)
      }
    }
}

final case class PhpInt(value: Int) extends PhpValue
final case class PhpDouble(value: Double) extends PhpValue
final case class PhpBoolean(value: Boolean) extends PhpValue
final case class PhpString(value: Array[Byte]) extends PhpValue
final case class PhpArray(fields: Map[PhpValue, PhpValue]) extends PhpArrayLike
final case class PhpObject(className: String, fields: Map[PhpValue, PhpValue]) extends PhpArrayLike
final case object PhpNull extends PhpValue