generator.js

    /**
     * List the subdirectories in a directory
     * @param p the path to the directory
     */
    function *listDirectories(p: string) {
        return new Promise((resolve, reject) => {
            fs.readdir(p, (err, files) => {
                files.forEach(f => {
                    fs.stat(f, (err, stats) => {
                        if(stats.isDirectory()) 
                            yield f
                    })
                })
            })
        })
    }