NodeIOWithTask_17.cjs

const { Task } = require('types')
const fs = require('fs');

const app_ = () =>
    fs.readFile('config.json', 'utf-8', (err, contents) => {
        console.log(err, contents)
        if (err) throw err;

        const newContents = contents.replace(/3/g, '6');

        fs.writeFile('config1.json', newContents, (err) => {
            if (err) throw err;
            console.log('success');
        });
    });

const readFile = (path, enc) =>
    Task((rej, res) =>
        fs.readFile(path, enc, (err, contents) =>
            err ? rej(err) : res(contents)
        )

    )
const writeFile = (path, contents) =>
    Task((rej, res) =>
        fs.writeFile(path, contents, (err, contents) =>
            err ? rej(err) : res(contents)
        )

    )


const app = () =>
    readFile('config.json', 'utf-8') // Task(contents)
        .map(contents => contents.replace(/3/g, '6'))
        .chain(newContents => writeFile('config.json', newContents))

//  I could not import Test correctly so it will not work

app().fork(console.error, () => console.log('success'));