gistfile1.scala

import scala.language.{implicitConversions, existentials}

class Encoder[T]
implicit object StringEncoder extends Encoder[String]

case class Encodable(encoder: Encoder[_], obj: Any)
implicit def obj2encodable[T: Encoder](obj: T): Encodable = Encodable(implicitly[Encoder[T]], obj)

trait Resource {
    def request(): Encodable
}

object Res1 extends Resource {
    def request() = "hello"
}