There is a post from the author that documents what has diverged between Elixir ...

sorentwo on March 1, 2016 | parent | context | favorite | on: Elixir and Phoenix – hands-on introduction

There is a post from the author that documents what has diverged between Elixir in Action and Elixir 1.2. More than simply updating code examples, it actually gives context around all of the changes.

http://theerlangelist.com/article/eia_elixir_12