[scala] result code: either

processRequestEither.scala

def processRequestEither(userId: UUID, requestId: UUID): BusinessResult = {
  val result: Either[BusinessResult, BusinessResult] = for {
    user <- either(getUser(userId), BusinessResult.UserNotFound)
    request <- either(getRequestById(requestId), BusinessResult.RequestNotFound)
    _ <- either(checkAccess(request, user).toOption, BusinessResult.NotOwner)
  } yield BusinessResult.Ok

  result.fold(identity, identity)
}

private def either[T](opt: Option[T], result: BusinessResult) =
  opt.fold[Either[BusinessResult, T]](Left(result))(Right(_)).right