Pattern for blue compatible modules

module.js

modules.export = (function(){
  var Promise = require('bluebird');
  var fs = Promise.promisifyAll(require('fs'));
  return function(params, cb) {
    return fs.doSomeStuffAsync(params)
      .then(function(result){
        return someOtherAsync(result);
      })
      .then(function(moreResults){
        return someMoreAsync(moreResults);
      })
      .finally(cb || function(){ });
  };
})();

This looks real good! I think usually the client worries about error handling, and Bluebird.prototype.asCallback is your friend here! :)

/* promise-fn.js */
'use strict';

// I like calling bluebird Bluebird because otherwise it clobbers global.Promise in newer versions of v8 / ES2015.
var Bluebird = require('bluebird');
var fs = require('fs');

Bromise.promisifyAll(fs);

module.exports = function(params, cb) {
  return fs.doSomeStuffAsync(param)
    .then(function(result) {
      return someOtherAsync(result);
    })
    .then(function(moreResults) {
      return someMoreAsync(moreResults);
    })
    .asCallback(cb);
};

Now it can be consumed like

/* index.js */
'use strict';

var Bluebird = require('bluebird');
var promiseFn = require('./promise-fn');

// A promise that can be caught
promiseFn({ foo: 'derp' }).catch(console.error.bind(console));

// A promise that can be chained
promiseFn({foo: 1}).then(function(results) {
  console.info('peep these results ====>', results);
}).catch(console.error.bind(console));

// Something that can be used with a callback
promiseFn({foo: 1}, function(err, results) {
  if (err) return console.error(err);
  console.info(results);
});

Thanks for advice! Working it in now