What’s wrong with :
@impl true
def naive_datetime_to_string(year, month, day, hour, minute, second, microsecond) do
date_to_string(year, month, day) <> " " <> Calendar.ISO.time_to_string(hour, minute, second, microsecond)
end
and use that instead of Calendar.ISO.naive_datetime_to_string? i.e. provide the alternate implementation where desired and only use the original implementation where needed.
In a way you seem to be looking for dynamic dispatch of a polymorphic operation typically implemented in class-based languages.
