A simple DSL for gen_fsm. This generates regular gen_fsm functions (so, for example, each state/event combination is a separate function head)

gistfile1.ex

defmodule Listen.NewFSM do

  use Daves.Fsm,  register: {:local, :listen_fsm},
                  initial_state: :start,
                  init_params: []

  @timeout 3*1000

  defrecord CallInfo, from: "", to: "", suspicious_segments: 0

  ####################
  #
  # Events → our external API

  events do
    call_initiated(from, to)
    suspicious_phrase_heard
    hang_up
  end

  ####################
  #
  # States → transitions we implement

  in_state(:start) do
    { :call_initiated, from, to } ->
      IO.puts "Initiating a call from #{from} to #{to}"
      next_state(:listening, CallInfo.new(from: from, to: to))
  end

  in_state(:listening) do
    { :hang_up } ->
      debug("Hangup", context)
      next_state(:start, nil)

    { :suspicious_phrase_heard } ->
      debug("Heard something suspicious", context)
      next_state(:transcribing, context.update_suspicious_segments(&1+1), @timeout)
  end

  in_state(:transcribing) do
    { :hang_up } ->
      debug("Report on call", context)
      next_state(:start, CallData.new)

    { :timeout } ->
      next_state(:listening, context)
  end




  # Helpers

  defp debug(msg, CallInfo[from: from, to: to, suspicious_segments: suspicious_segments]) do
    IO.puts("Call from #{from} to #{to}: #{msg}")
    if suspicious_segments > 0 do
      IO.puts("    (suspicious_segments: #{suspicious_segments})")
    end
  end

end