How do I make this work in a defenum macro?

  defenum EmailStatus, :email_status, @email_states

Right now, I’m getting:

warning: undefined module attribute @email_states, please remove access to @email_states or explicitly set it before access

It’s making no difference whether I’m using Macro.expand/2 or not:

values: {:@, [line: 122], [{:email_states, [line: 122], nil}]}
values-expanded: {{:., [],
  [
    {:__aliases__, [counter: {MyApp.Enum, 9}, alias: false],
     [:Module]},
    :get_attribute
  ]}, [],
 [
   {:__MODULE__, [counter: {MyApp.Enum, 9}], Kernel},
   :email_states,
   122
 ]}

I actually want to pass in a value that’s closer to:

  @a ~w(a b c d)
  @b ~w(e f g h)
  @c ~w(I j k l)
  defenum EmailStatus, :email_status, @a ++ @b ++ @c

The macro in question is complex, and may eventually be released as a fork of an already existing package. But for the purposes of this test, I believe that this will do:

  defmacro defenum(module, type, values) do
    quote location: :keep do
      defmodule unquote(module) do
        @enum_type unquote(type)
        @values Enum.map(unquote(values), &to_string/1)

        def type, do: @enum_type
        def values, do: @values
      end
    end
  end

Ideas?

-a