gistfile1.scala

// At the external API level, use TypeTag
def extract[T: TypeTag](jsv: JsValue): T =
    extractImpl[T](jsv, typeOf[T])

// But use Type for everything else
def extractImpl[T](jsv: JsValue, tpe: Type): T = {
  // no need for m
  val ex = jsv match {
    case JsNumber(n) => n
    case JsString(s) => s
    case JsArray(l) => {
      // deep serialization
      val intpe = tpe.typeSymbol.asType.typeParams.head.asType.toTypeIn(tpe)
      l.map(in(_, intpe))
    }
    //..
  }
}
 
def in[T](js: JsValue, tpe: Type): T = {
  // no need for m
  //..
}