Promise + Fiber

fiber.js

/* @flow */
'use strict';

const Promise = require('bluebird');
const Fiber   = require('fibers');

const fiber = function <T: any> (callback: () => T): Promise<T> {
    return new Promise(function (resolve: Function, reject: Function): void {
        Fiber(function (): void {
            let fiber: Fiber     = Fiber.current;
            let yielded: boolean = false;

            let value: T;
            try {
                value = callback(function next (): void {
                    if (yielded) {
                        yielded = false;
                        fiber.run();
                    }
                    else {
                        yielded = true;
                        Fiber.yield();
                    }
                });

                if (yielded) {
                    resolve(value);
                }
                else {
                    throw new Error('fiber not yielded');
                }
            }
            catch (error) {
                reject(error);
            }
            finally {
                fiber = null;
            }
        }).run();
    });
};

module.exports = fiber;

await fiber(function (next) {
    next(); // pause
    next(); // resume
});