Lots of indented function calls is just poor design. You get the same thing in Scala when you start dealing with lots of Futures inappropriately.

Just choose a decent abstraction for callbacks. I prefer promises, but async.js does a good job as well.

The `flatMap` function on a Future in scala might be built into the language, but it is implemented and scala and not significantly different (in my mind), to Bluebird being implemented in javascript.