example.scala

package example

import argonaut._
import Argonaut._

sealed trait WidgetType
object WidgetType {
  case object Sprocket extends WidgetType
  case object Cog extends WidgetType
  case object Doowazzle extends WidgetType
}

object json {
  implicit val WidgetTypeCodec: CodecJson[WidgetType] = {
    import WidgetType._
    CodecJson({
      case Sprocket => "sprocket".asJson
      case Cog => "cog".asJson
      case Doowazzle => "doowazzle".asJson
    },
    { j =>
      j.as[String].flatMap {
        case "sprocket" => DecodeResult.ok(Sprocket)
        case "cog" => DecodeResult.ok(Cog)
        case "doowazzle" => DecodeResult.ok(Doowazzle)
        case _ => DecodeResult.fail("example.WidgetType", j.history)
      }
    })
  }
}