We refactor a standard node callback style workflow into a composed task-based workflow.

 

For example we have the code as following:

 

We want to wrap async functions (readFile and writeFile) into Task. Therefore it becomes composeable.

const Task = require('data.task')const fs = require('fs')const readFile = name =>   new Task((rej, res) =>           fs.readFile(name, 'utf-8',                      (err, contents) => err ? rej(err) : res(contents)));const writeFile = (name, content) =>   new Task((rej, res) =>           fs.writeFile(name, contents,                        (err, _) => err ? rej(err): res(content)));const app = () =>   readFile('config.json') //return Task()    .map(contents => contents.replace(/8/g, '6'))    .chain(replaced => wirteFile('config.json',  replaced));  //flat Task(Task()) --> Task()app.fork(console.error, console.log);