pacta

pacta

This is an implementation of algebraic Promises in node.js having been convinced by James Coglan and Aanand Prasad.

Pacta's promises can be used as the following algebraic structures:

• Semigroups;
• Monoids;
• Functors;
• Applicative;
• Chains;
• Monads.

Note that Pacta does not handle errors or the concept of a failed promise as yet.

See the test suite for more information.

Usage

var Promise = require('pacta').Promise;

var p = new Promise();
setTimeout(function () {
  p.resolve('Foo');
}, 1000);

var p2 = new Promise();
setTimeout(function () {
  p2.resolve('bar');
}, 500);

var p3 = Promise.of('baz');

p.map(console.log); //=> "Foo"

p.map(function (x) {
  return x + '!';
}).map(console.log); //=> "Foo!"

p.concat(p2).concat(p3).map(function (x, y, z) {
  console.log('p says: ' + x);  //=> "p says: Foo"
  console.log('p2 says: ' + y); //=> "p2 says: bar"
  console.log('p3 says: ' + z); //=> "p3 says: baz"
});