login-conceptual-desugared.scala

def login(dbConn: DbConnection, req Reuqest): Try[Response] =
  req.body match {
    case Failure(err) =>
      Failure(err)
    case Success(reqJsonStr) =>
      json.parse(reqJsonStr) match {
        case Failure(err) =>
          Failure(err)
        case Success(reqJson) =>
          validateAndDecode[LoginRequest](reqJson) match {
            case Failure(err) =>
              Failure(err)
            case Success(loginReq) =>
              dbConn.findUser(loginReq.username) match {
                ...
              }
          }
      }
  }