No output as I try to convert an async method into a promise

I am trying to convert each method of async.js into a promise and was trying the map method to start with.

const promise = require('bluebird');
const async = require('async');


let arr = [1, 2, 3, 4, 5];

promise.promisifyAll(async);

async.mapAsync(arr, Math.sqrt)
    .then((r) => console.log(r))
    .catch((err) => console.log(err));

As I run the program, it prints an empty output. What could be the reason for this? It looks like, the promise is neither resolved nor rejected!

Reference:

• async map
• Promisify all

via Suhail Gupta