How to remove array from array using ecto

array_substract_macro.ex

defmodule MyProject.Macro do

  @doc """
  
  @doc """
  ##  Examples:

    iex> query |> update([t], set: [unread_message_ids: array_substract(t.unread_message_ids, ^message_ids)])
  """
  defmacro array_substract(first, second) do
    quote do
      fragment(
        """
        COALESCE((
          SELECT array_agg(elem)
          FROM unnest(?) elem
          WHERE elem <> all(?)), ?
        )
        """,
        unquote(first),
        type(unquote(second), unquote(first)),
        type(unquote(second), [])
      )
    end
  end
end

This query just didn't work for me somehow so I've created the same function with another query which I think looks better.
https://gist.github.com/andreyuhai/cdff6e6b8791d6c8f510c8b15fcfd4c9