list of keys in ets tables

ets_keys.ex

defmodule EtsKeys do
  def keys(table_name) do
    first_key = :ets.first(table_name)
        keys(table_name, first_key, [first_key])
  end

 def keys(_table_name, '$end_of_table', ['$end_of_table'|acc]) do
    acc
 end
 def keys(table_name, current_key, acc) do
    next_key = :ets.next(table_name, current_key)
    keys(table_name, next_key, [next_key|acc])
 end
end

ets_keys.exs

defmodule EtsKeys do
  defp get_ets_keys_lazy(table_name) when is_atom(table_name) do
    eot = :"$end_of_table"

    Stream.resource(
        fn -> [] end,

        fn acc ->
            case acc do
                [] -> 
                    case :ets.first(table_name) do
                        ^eot -> {:halt, acc}
                        first_key -> {[first_key], first_key}                       
                    end

                acc -> 
                    case :ets.next(table_name, acc) do  
                        ^eot -> {:halt, acc}
                        next_key -> {[next_key], next_key}
                    end
            end
        end,

        fn _acc -> :ok end
    )
end
end