A simple pubsub

howl.ex

defmodule Howl do
  use GenServer
  require Logger

  @type type  :: :n | :p | :c | :a | :r | :rc
  @type scope :: :l | :g
  @type name  :: term
  @type key   :: {type, scope, name}

  # Client API
  def subscribe(topic) do
    :gproc.reg({:p,:l,topic})
  end

  def subscribers(topic) do
    :gproc.lookup_pids({:p, :l, topic})
  end

  def broadcast(topic, message) do
    :gproc.send({:p, :l, topic}, message)
  end

  # Server API
  def init(args) do
    :gproc.reg({:p, :l, args[:topic]})
  
    {:ok, []}
  end

  def handle_info(message, state) do
    IO.inspect "Got #{inspect message} in process #{inspect self()}"
    
    {:noreply, state}
  end
end