1

我想尝试使用 fp-ts 重写我的代码的某些部分，并考虑重构以下方法：

export const createApiServer = () => {
    logger.info("Starting World Server API");

    const apiServer = express()
        // 3rd party middleware
        .use(helmet())
        .use(bodyParser.json())
        .use(cors())
        // Root route
        .get("/", (_, result) => result.sendStatus(httpStatusCodes.OK))
        // 404 - Not Found
        .use((_, result) => result.sendStatus(httpStatusCodes.NOT_FOUND))
        // 500 - Internal Server Error
        .use(errorLoggerMiddleware)
        .use(errorResponseMiddleware);

    logger.verbose(`Initialized World Server API in ${process.uptime().toFixed(3)} seconds`);

    return apiServer;
};

在阅读了有关IO副作用的类型后，我尝试按如下方式使用它：

const info = (message: string) => new IO(() => log.info(message));
const verbose = (message: string) => new IO(() => log.verbose(message));

const setupApiServer = () =>
    new IO(() =>
        express()
            .use(helmet())
            .use(bodyParser.json())
            .use(cors())
            .get("/", (_, result) => result.sendStatus(httpStatusCodes.OK))
            .use((_, result) => result.sendStatus(httpStatusCodes.NOT_FOUND))
            .use(errorLoggerMiddleware)
            .use(errorResponseMiddleware)
    );

export const createApiServer = () =>
    info("Starting World Server API")
        .chain(setupApiServer)
        .chain((apiServer) =>
            verbose(`Initialized World Server API in ${process.uptime().toFixed(3)} seconds`)
                .map(() => apiServer)
        )
        .run();

在最后一个链调用中随意使用map方法来管道通过apiServer对象只是为了在接收它和进一步发送它之间登录，感觉很奇怪。我想知道这是否正确或者是否有任何不同的模式。

4

1 回答 1

2

您可以使用chainFirst.

chainFirst你可以重构这个

import { pipe } from "fp-ts/lib/pipeable";
import * as IO from "fp-ts/lib/IO";

declare const log: (m: string) => IO.IO<void>
declare const a: IO.IO<number>

pipe(
  a,
  IO.chain((a) => pipe(log(`Got ${a}`), IO.map(() => a)))
)

进入这个

pipe(
  a,
  IO.chainFirst((a) => log(`Got ${a}`))
)
于 2020-01-03T16:40:30.793 回答