case class Person(val name:String, val age:Int)

object Person {

    implicit def PersonEncodeJson: EncodeJson[Person] =  {
        EncodeJson((p: Person) => ("name":= p.name) ->: ("age":= p.age) ->: jEmptyObject)
    }

}

val a = Person("Anton", 22)
val json:String = a.toJson.toString