stuff.ex

  defmacro whitelist_literals(literals) do
    quote do
      for literal <- unquote(literals) do
        case literal do
          :boolean -> defp allow(exp) when is_boolean(exp), do: exp
          :number  -> defp allow(exp) when is_number(exp),  do: exp
          :integer -> defp allow(exp) when is_integer(exp), do: exp
          :float   -> defp allow(exp) when is_float(exp),   do: exp
          :tuple   -> defp allow(exp) when is_tuple(exp),   do: exp
          :list    -> defp allow(exp) when is_list(exp),    do: exp
          :map     -> defp allow(exp) when is_map(exp),     do: exp
          unknown  -> raise "Unknown literal #{inspect unknown}"
        end
      end
    end
  end