gistfile1.coffee

api = require('./urlmapper')('https://api.example.com/v1')

api.users.GET(limit: 1)
  .then ([user]) ->
    console.log user.name, user.age
    api.users[user.id].posts.GET()
  .then (posts) ->
    posts.forEach ({ content }) -> console.log content

urlmapper.coffee

require 'harmony-reflect'
Promise = require 'bluebird'

module.exports = createUrlMapper = (base) ->
  new Proxy {},
    get: (target, name) ->
      if /^[A-Z]+$/.test name
        (data) ->
          Promise.resolve $.ajax(base, method: name, data: data)
      else
        createUrlMapper "#{base}/#{encodeURIComponent name}"