You could probably extend Racket's pattern matching to do the same stuff. It can already match against structurs you define yourself, but I don't think it can d

You could probably extend Racket's pattern matching to do the same stuff. It can already match against structurs you define yourself, but I don't think it can do things like "match anything with this pattern in this recursive data structure" unless "recursive data structure" is a list, and even then I don't think it will do any kind of complete search of the list other than the top-level elements (not sure though).