Is it possible to define an extractor that is composed such that a sub-pattern depends on a previously matched sub-pattern?
Consider matching a date pattern, where valid "days" depends on the matched "month".
This is to avoid a guard to compare values bound by the sub-patterns, and also to avoid providing an overly-customized extractor.
Sample syntax:
case r"\d{4}-$month\d{2}-${day filter month.allows}\d{2}" => s"$month $day"
