The beauty of promises is they are values. Async and sync calls are handles the same within a `then` statement. In this example, async, sync and error handling are handled gracefully.

gistfile1.coffee

Promise = require('bluebird')

i = 0
printAsync = (cb) ->
  setTimeout ->
    console.log i++
    cb()
  ,  Math.floor((Math.random()*10)+1) # random 1..10

print = (action) ->
  switch action
    when "error"
      throw new Error("No more 'return cb() if cb' everywhere. Exceptions handle gracefully")
    when "asyncnum"
      vow = Promise.pending()
      printAsync vow.callback
      vow.promise
    else
      console.log action

Promise
  .try(print, "red")
  .then ->
    print "asyncnum"
  .then ->
    print "white"
  .then ->
    print "blue"
  .then ->
    print "asyncnum"
  .then ->
    print "error"
  .then ->
    print "never reached because of error"
  .catch (e) ->
    console.log e.stack