gistfile1.scala

   get("/a/:id", operation(getA)) {
    val id = params("id")
    val idType = params.getOrElse("id_type", "a_id")

    new AsyncResult {
      val is: Future[_] = resolveId(id, idType) flatMap { aid =>
        val frm = future { s  /*}oing something more in the real code */  }map { s =>
          responseMetaData(s.id)
        }
        frm flatMap { rm => 
          url(s"/endpoint", Map("aid" -> aid, "detail_id" -> rm.detail_id))
        }
      } rescue { case e => future { e } }
    }
  }