gistfile1.txt

// Inherit from Y.Promise as you would from any other class
function ListPromise() {
    ListPromise.superclass.constructor.apply(this, arguments);
}
Y.extend(ListPromise, Y.Promise, {
    map: function (fn, context) {
        return this.then(function (values) {
            return Y.Array.map(values, fn, context);
        });
    },
    filter: function (fn, context) {
        return this.then(function (values) {
            return Y.Array.filter(values, fn, context);
        });
    }
});

var list = new ListPromise(function (resolve) {
    // this is not async, but it's just an example
    resolve([1, 2, 3]);
});

list.map(function (x) {
    return x * x;
}).filter(function (x) {
  return x > 3;
}).then(function (values) {
    console.log(values); // [14, 9]
});