uPickle implicits for Response

upickle-response.scala

sealed trait Response[+T]
object Response {
  case class Failure(error: String) extends Response[Nothing]
  case class Success[+T](value: T) extends Response[T]
}

object Picklers {
  import Response._
  import upickle.Js
  import upickle.Aliases._

  implicit def FailureR: R[Failure] = R[Failure] {
    case Js.Arr(Js.Num(0), x) => Failure(upickle.readJs[String](x))
  }

  implicit def SuccessR[T: R]: R[Success[T]] = R[Success[T]] {
    case Js.Arr(Js.Num(1), x) => Success(upickle.readJs[T](x))
  }

  implicit def ResponseR[T: R]: R[Response[T]] = R[Response[T]](
    SuccessR[T].read orElse FailureR.read
  )

  implicit def FailureW[T: W]: W[Failure] = W[Failure](ResponseW[T].write)

  implicit def SuccessW[T: W]: W[Success[T]] = W[Success[T]](ResponseW[T].write)

  implicit def ResponseW[T: W]: W[Response[T]] = W[Response[T]] {
    case Failure(s) => Js.Arr(Js.Num(0), upickle.writeJs(s))
    case Success(t) => Js.Arr(Js.Num(1), upickle.writeJs(t))
  }
}