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# file: code_lock.ex
# Translated from: http://erlang.org/doc/design_principles/statem.html#example-revisited
# callback mode: :state_functions
#
defmodule CodeLockCommon do
  # Admittedly gratuitous use of a macro
  #
  def handle_event(:cast, {:down, button}, data) do
    {:keep_state, Map.put(data, :button, button)}
  end

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# file: pushbutton.ex
# Translated from: http://erlang.org/doc/man/gen_statem.html#example
# callback mode: :handle_event_function
# i.e. one callback function handle_event/4 for all states
#
defmodule Pushbutton do
  @behaviour :gen_statem

  # The registered server name
  defp name(),

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# file: pushbutton.ex
# Translated from: http://erlang.org/doc/man/gen_statem.html#example
# callback mode: :state_functions
# i.e. one callback function per state, so the each possible
# state has to be represented as a bare atom which directly
# identifies the module function to be called (:gen_fsm like).
#
# This example has two states :on and :off.
# Therefore there is an on/3 and an off/3 callback function.
#

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defmodule CodeLock do
  @name :code_lock

  ## Start and stop
  def start_link(code) do
    :gen_statem.start_link({:local,@name}, __MODULE__, code, [])
  end
  def stop, do: :gen_statem.stop @name

  def callback_mode, do: [:state_functions,:state_enter]

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\documentclass{article}
    \usepackage[utf8]{inputenc}
    \usepackage{listings,xcolor}
    \usepackage[T1]{fontenc}
    \usepackage{xcolor}
    \usepackage[scaled=0.9]{DejaVuSansMono}
\definecolor{commentgreen}{RGB}{2,112,10}
\definecolor{eminence}{RGB}{108,48,130}
\definecolor{weborange}{RGB}{255,165,0}
\definecolor{frenchplum}{RGB}{129,20,83}

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I learned a little bit about building queries (even with Rails/ARel) of postgres JSONB columns in my side project that I wanted to share.

I have a model that represents a Japanese word:

{"id"=>4111,
 "type"=>"vocabulary",
 "characters"=>"洗う",
 "meanings"=>[{
    "meaning"=>"To Wash", 

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#2
defmodule :'Elixir.Why' do
  @blah __ENV__.file
  @file File.read!(@blah)
  @num String.at(@file, 1) |> String.to_integer()

  @doc false
  def unquote(:"$handle_undefined_function")(function, _args) do
    filename = __MODULE__.module_info()[:compile][:source] |> to_string()
    File.read!(filename)

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class CamelCaseMiddleware
  def call(parent_type, parent_object, field_definition, field_args, query_context, next_middleware)
    next_middleware.call([parent_type, parent_object, field_definition, transform_arguments(field_args), query_context])
  end

  def transform_arguments(field_args)
    transformed_args = {}
    types = {}

    field_args.each_value do |arg_value|

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How to connect and debug Elixir or Phoenix App at Heroku?

Heroku has a great feature called heroku ps:exec which allows you to connect to running nodes. You can use this command to connect your elixir nodes easily. And debug your nodes like in your network.

Step 1

Let's start with Procfile To run a named app at heroku your procfile should specify the app name like:

web: MIX_ENV=prod elixir --sname coolelixirapp -S mix run --no-halt

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Learning FP the hard way: Experiences on the Elm language

by Ossi Hanhinen, @ohanhi

with the support of Futurice 💚.

Licensed under CC BY 4.0.

Editorial note