使我的 readPackageFiles 适合“并行”函数答案

【问题标题】：Conforming my readPackageFiles to fit inside "Parallel" function使我的 readPackageFiles 适合“并行”函数
【发布时间】：2019-05-21 16:29:46
【问题描述】：

我从这个SO question 获得了很多关于抓取目录和搜索文件的帮助。我正在尝试使我的readPackageFiles 函数使用给我的Parallel 函数；但是，我正在努力让它发挥作用。

错误：

UnhandledPromiseRejectionWarning: TypeError: Cannot use 'in' operator to search for 'throws' in 1
    at readFile (/Users/harwood/udev/dotcom-components/tools/dependency-version-comparison/node_modules/jsonfile/index.js:22:16)
    at Promise (/Users/harwood/udev/dotcom-components/tools/dependency-version-comparison/node_modules/universalify/index.js:13:12)
    at new Promise (<anonymous>)
    at readFile (/Users/harwood/udev/dotcom-components/tools/dependency-version-comparison/node_modules/universalify/index.js:7:14)
    at Array.map (<anonymous>)
    at /Users/harwood/udev/dotcom-components/tools/dependency-version-comparison/dist/index.js:1:1833
    at <anonymous>
(node:70097) UnhandledPromiseRejectionWarning: Unhandled promise rejection. This error originated either by throwing inside of an async function without a catch block, or by rejecting a promise which was not handled with .catch(). (rejection id: 63)
(node:70097) [DEP0018] DeprecationWarning: Unhandled promise rejections are deprecated. In the future, promise rejections that are not handled will terminate the Node.js process with a non-zero exit code.
/Users/harwood/udev/dotcom-components/tools/dependency-version-comparison/node_modules/jsonfile/index.js:43
    callback(null, obj)

问题：如何使 readPackageFiles 与 Parallel 配合使用？

import {readdir, stat, readJson} from 'fs-extra';
import {join, basename} from 'path';

const Parallel = p =>
  ({
    map: async f =>
      Promise.all((await p).map(f))
    ,
    filter: async f =>
      Promise.all((await p).filter(f))
    ,
    flatMap: async f =>
      Promise.all((await p).map(f)).then(ys => [].concat(...ys))
    ,
  });
const files = async (path = '.') =>
  (await stat(path)).isDirectory()
  ? Parallel(readdir(path))
    .flatMap(f => files(join(path, f)))
  : [path];

const search = async (query, path = ".") =>
  Parallel (files (path))
    .filter (f => basename (f) === query);

// How can I write this to use Parallel    
const readPackageFiles = async (packages) => await Promise.all(packages.map(async x => (await readJson(x))));

// this will not work but it's my attempt

const readPackageFilesNOTWORKING = async(path = ".") =>
  Parallel (search('package.json', path))
    .map (readJson)

用法：

search('package.json', '.')
  .then(readPackageFiles)
  .then(console.log);

【问题讨论】：

标签： javascript function asynchronous functional-programming refactoring

【解决方案1】：

我希望您能仔细查看链接的问答。我怀疑你需要这样的东西，而这个函数 readPackages 在我与你分享的 first link 中 -

const { readFile } =
  require ("fs") .promises

const readPackages = async (path = ".") =>
  Parallel (search ("package.json", path))
    .map (readFile)
    .then
      ( buffers =>
          buffers .map (b => JSON .parse (String (b)))
      )

readPackages (".") .then (console.log, console.error)
// [ ... ]

请注意，我的任何答案都不需要fs-extra。

【讨论】：