21.applicatives-for-concurrent-actions.js

const Task = require('data.task');

const Db = {
  find: id =>
    new Task((rej, res) =>
      setTimeout(
        () =>
          res({ id: id, title: `Project ${id}`}),
        100
      )
    )
};

const reportHeader = (p1, p2) =>
  `Report: ${p1.title} compared to ${p2.title}`;

/**
 * Db.find(20).chain(proj1 =>
 *    Db.find(8).map(proj2 =>
 *        reportHeader(proj1, proj2)))
 */

Task.of(p1 => p2 => reportHeader(p1, p2))
  .ap(Db.find(20))
  .ap(Db.find(8))
  .fork(
    console.error,
    console.log
  );