We refactor a standard node callback style workflow into a composed task-based workflow.
Original Code:
const app = () => { fs.readFile('config.json', 'utf-8', (err, content) => { if (err) throw err; const newContents = content.replace(/8/g, '6'); fs.writeFile('config1.json', newContents, (err, _) => { if (err) throw err; console.log('success!'); }) }); } app();
Using Task:
const readFile = (filename) => new Task((rej, res) => fs.readFile(filename, 'utf-8', (err, content) => { err ? rej(err) : res(content); })); const writeFile = (filename, content) => new Task((rej, res) => fs.writeFile(filename, content, (err, success) => { err ? rej(err) : res(success); })); const TaskApp = readFile('config.json') .map(content => content.replace(/8/g, '6')) .chain(newContent => writeFile('config1.json', newContent)); TaskApp.fork(e => console.error(e), x => console.log('success!'));
Using Async:
const Async = require('crocks/Async'); const fs = require('fs'); const readF = (filename) => Async((rej, res) => fs.readFile(filename, 'utf-8', (err, content) => { err ? rej(err): res(content); })); const writeF = (filename, content) => Async((rej, res) => fs.writeFile(filename, content, (err, success) => { err ? rej(err) : res(success) })); const AsyncApp = readF('config.json') .map(content => content.replace(/8/g, '6')) .chain(newContent => writeF('config2.json', newContent)); AsyncApp.fork( e => console.error(e), x => console.log('success!!') );