kek.ex

  @control_keys ["$type"]

  def cast_args(args) when is_map(args) do
    {control, args} = Map.split(args, @control_keys)

    type = Map.get(control, "$type", "map")

    cast_arg(type, args, control)
  end
  def cast_args(args) when is_list(args), do: Enum.map(args, &cast_args/1)
  def cast_args(arg), do: arg

  defp cast_arg("$map", args, control) do
    args
    |> Enum.map(fn {k, v} ->
      {cast_key(k, control), cast_args(v)}
    end)
    |> Map.new
  end
  defp cast_arg("$list", args, control) do
    args
    |> Enum.map(fn {k, v} ->
      {cast_key(k, control), cast_args(v)}
    end)
  end
  defp cast_arg("$tuple", args, _control) do
    List.to_tuple(args["tuple"])
  end
  defp cast_arg(type, args, _control) do
    args =
      args
      |> Enum.map(fn {k, v} ->
        {String.to_existing_atom(k), v}
      end)

    Kernel.struct!(cast_type(type), args)
  end

  def cast_key(key, _control) do
    case key do
      ":" <> key ->
        String.to_existing_atom(key)
      key ->
        key
    end
  end

  def cast_type(type) do
    type
    |> String.split(".")
    |> Enum.reduce(fn (name, acc) -> Module.concat(acc, name) end)
  end