Play-Mongo GeoPoint implicit read/write

MongoGeoPoint

package jdaily

import play.api.Play
import play.api.Play.current
import play.api.libs.json._
import play.api.libs.json.Reads._
import play.api.libs.functional.syntax._

/**
 * Created by jdaily on 1/27/14.
 */
case class MongoGeoPoint(Longitude: Double, Latitude: Double)

object MongoGeoPoint {

  val pointWrites = Writes[MongoGeoPoint]( p => Json.obj("type" -> "Point",
    "coordinates" -> Json.arr(JsNumber(p.Longitude), JsNumber(p.Latitude))))

  val pointReads =  (__ \ 'type).read[String](constraints.verifying[String](_ == "Point")) andKeep
    (__ \ 'coordinates).read[MongoGeoPoint](minLength[List[Double]](2).map(l => MongoGeoPoint(l(0), l(1))))

  // Conversions
  implicit val pointFormat = Format(pointReads, pointWrites)
}