I am wondering if this is correct, this should be a map of arbitrary size (could be 0, could be 1000) of integer keys.

@type quests() :: %{Integer => any()}

defmodule GameState do
    @type obj() :: %{0=> Integer, optional(1)=> Integer, optional(2)=> Integer}
    @type quest() :: %{id: Integer, step: Integer, obj: obj()}
    @type quests() :: %{Integer => quest()}

    @type gamestate() :: %{quests: quests()}

    @spec get_quests(gamestate()) :: quests()
    def get_quests(gs) do
        :erlang.map_get(:quests, gs)
    end

    @spec act(gamestate()) :: any()
    def act(gamestate) do
        quests = get_quests(gamestate)

        cur_quest_id = quests
        |> Map.keys()
        |> List.last()
        cur_quest = Map.fetch!(quests, cur_quest_id)

        cur_objs = Table.QuestStep.by_id_order(cur_quest.id, cur_quest.step)
        done_objs = Enum.filter(cur_objs, fn{idx,obj}->
            cur_quest.obj[idx].amount >= obj.amount
        end)
    end

    def go do
        quest = %{id: 10010, step: 2, obj: %{0=> 14}}
        quests = %{10010=> quest}
        gamestate = %{quests: quests}
        act(gamestate)
    end
end

The idea here is to trigger a error from dialyzer here cur_quest.obj[idx].amount that .amount is not a valid key for obj().

Instead I get this, but if I call this from the REPL it works just fine. The function call succeeds.

lib/game/gamestate.ex:28:call
The function call will not succeed.

Table.QuestStep.by_id_order(Integer, Integer)

will never return since it differs in arguments with
positions 1st and 2nd from the success typing arguments:

(pos_integer(), 1 | 2 | 3 | 4 | 5 | 6 | 7 | 8 | 9)

Can anyone advise please?