monads.js

var _Container = function(val) { this.val = val }
var Container = function(val) { return new _Container(val); }
Container.prototype.map = function(f) {
  return new Container(f(this.val));
}
Container.prototype.flatMap = function(f) {
  return f(this.val);
}
var c = new Container(2);
// functor
c.map(function(x) { return x+2});
// monad
c.flatMap(function(x){ return x+2}).flatMap(function(x) {return x* -1 });

Yep! https://gist.github.com/pselle/fd156a219c56aab529f3#comment-1318385