I wish that promises had a concept similar to this. It's simply too annoying for me to manually refactor a bunch of Promise.all() calls to manually adjust the concurrency of the logic flow compared to using the dependency pattern of async.auto().

And based on what I've seen this is a common problem in both async functions, generators, and promises. Since it is difficult to properly execute a tree of functional steps with the maximal concurrency I see code all the time which just runs async functions or promises in a series instead of taking advantage of the ability to concurrently execute two branches of the tree at the same time.

So when you require libraries, you can do so like:

    const fs = Promise.promisifyAll(require('fs'))
    // ... later    
    const fileContents = await fs.readFileAsync('filename.txt')

    const fs = require("fs");
    fs.exists(`${ __dirname }/1`, (exists1) => {
      fs.exists(`${ __dirname }/2`, (exists2) => {
        console.log(JSON.stringify([exists1, exists2]));
      });
    });

    const fs = require("mz/fs");
    Promise.all([
      fs.exists(`${ __dirname }/1`),
      fs.exists(`${ __dirname }/2`),
    ])
    .then((existers) => {
      console.log(JSON.stringify(existers));
    });

    const fs = require("mz/fs");
    (async () => {
      console.log(JSON.stringify(await Promise.all([
        fs.exists(`${ __dirname }/1`),
        fs.exists(`${ __dirname }/2`),
      ])));
    })();