Process communication with Elixir

ping_pong.ex

defmodule PingPong do

  def start do
    ping_pid = spawn __MODULE__, :ping, []
    pong_pid = spawn __MODULE__, :pong, []
    send ping_pid, {pong_pid, :ping}
    {ping_pid, pong_pid}
  end

  def ping do
    receive do
      {from, :ping} ->
        IO.puts "PING!"
        :timer.sleep 1000
        send from, {self(), :pong}
    end
    ping()
  end

  def pong do
    receive do
      {from, :pong} ->
        IO.puts "PONG!"
        :timer.sleep 1000
        send from, {self(), :ping}
    end
    pong()
  end

end