Working though the book "Programming Phoenix", in one code example:

def player_id(video) do
    ~r/^.*(?:youtu.be\/|v\/|e\/|u\/\w+\/|embed\/|v=)(?<id>[^#\&\?]*).*/
    |> Regex.named_captures(video.url)
    |> get_in(["id"])
  end

But when I type this snippet in, it shows like this

OS: OS X El Capitan
Emacs version: 24.5.1 (Using spacemacs setup)
Elixir-mode: 20151211.412