Elixirで作る最高のゲームエンジン ref: https://qiita.com/ryo33/items/7288f5cdfde1c298e1f7

defobject

defmacro defobject(definition) do
  quote do
    json = unquote(definition) |> Poison.encode! |> Poison.decode!
    case ExJsonSchema.Validator.validate(Zpids.Display.Object.schema, json) do
      {:error, x} ->
        raise inspect x
      _ -> :ok
    end
    def definition, do: unquote(definition)
  end
end

x-axis

move_x = case {left, right} do
  {true, false} -> -1
  {false, true} -> 1
  _ -> 0
end