Consider removing Bluebird

[OrKoN]

Hi,

I was wondering why do you need Bluebird as a dependency? I am packaging this module for AWS Lambda and want to optimize the size of the final bundle. Here is what I see: stripe-node takes 102 KB, bluebird requires 613 KB!

I think the library may not need such a heavy dependency. Is it possible to remove it?

[OrKoN]

It seems like you require bluebird only in this file https://github.com/stripe/stripe-node/blob/7abdb8913ab927bcde07f1d0b9b61ef1048b9269/lib/StripeMethod.basic.js

And the rest of occurrences is in the test files.

[ob-stripe]

@OrKoN The dependency was introduced when the library needed to support Node 0.x and native ES6 promises weren't available.

Now that the minimum required version is Node 4, I suppose we could remove the dependency in favor of native promises. That said, Bluebird seems to have significantly better performance than native promises (according to https://github.com/petkaantonov/bluebird/tree/master/benchmark) so this is something we'd need to consider carefully.

cc @brandur-stripe @jlomas-stripe, any thoughts on this?

[OrKoN]

@ob-stripe I think this info on bluebird's site may be outdated (results are from 2015-01-05). Alternatively, you can optionally accept a different promise implementation if someone wants to use Bluebird.

[ob-stripe]

you can optionally accept a different promise implementation if someone wants to use Bluebird.

I like this! I've prepared a patch in #439.

[OrKoN]

@ob-stripe I am positively surprised by how fast you respond 👍 I hope the PR can be merged soon. I think this will definitely help people who use Stripe with AWS Lambda and other similar services.

[ob-stripe]

@OrKoN I've just released version 5.6.0 of the library with native ES6 promises instead of Bluebird :) Thanks for the suggestion!