defmodule Events do
  def log(msg) do
    {h,m,s} = :erlang.time
    :io.fwrite("~2.B:~2.B:~2.B => ~s~n",[h,m,s,msg])
  end

  def task do
    log("Task start")
    receive do
      :go -> :ok
    end
    log("Task resumed")
  end

  def main do
    log("Program start")
    pid = spawn(Events,:task,[])
    log("Program sleeping")
    :timer.sleep(1000)
    log("Program signalling event")
    send(pid, :go)
    :timer.sleep(100)
  end
end

Events.main