applicative functors

index.js

import fs from 'fs';
import { add, prop, lift } from 'ramda';
import Task from 'data.task';
import Box from './Box';
import Maybe from './Maybe';
var marked = require('marked');
var TerminalRenderer = require('marked-terminal');

marked.setOptions({
  // Define custom renderer
  renderer: new TerminalRenderer()
});

// ------------
// Applicative functor

const t1 = Task.of(10)
const t2 = Task.of(5)
// What if I want to do this:
// add(t1, t2);
// Nan

// using map
// t1.map(add) 
// Task.of(add(10))
// Now we want to apply add(10) to Task(5) 


// you can do it like so
t1.map(fn => {
  return t2.map(fn);
})
.fork(
  err => console.log('error', err),
  data => console.log(data)
);


// Here comes ap
Task.of(add).ap(t1).ap(t2)
.fork(
  err => console.log('error', err),
  data => console.log(data)
);

// It's called lifting a func

lift(add)(t1, t2)
  .fork(
    err => console.log('error', err),
    data => console.log(data)
  );



// more advance ex
//
const readPkg = readFile('package.json');

const readDoc = readPkg
  .map(JSON.parse)
  .map(prop('doc'))
  .chain(readFile);

const displayInfos = (pkg, readme) => readme.concat('\n' + '```json\n' + pkg + '```');

const a = lift(displayInfos)(readPkg, readDoc)
  .map(marked)
  .fork(
    err => console.log('error', err),
    data => console.log(data)
  );