Subject: bug#37849: composable character alternatives in rx

From: Mattias Engdegård <[email-masked]>
Date: Sun, 27 Oct 2019 10:17:40 +0100

Expansion inside (not ...) should be uncontroversial; now pushed (cbd439e785).

Character set operators (union, intersection, difference) would be useful. Consider:

(rx-define ident-chars (any "a-zA-Z0-9"))
(rx-define operator-chars (any ?+ ?- ?* ?/ ?< ?> ?=))

There is then currently no way to form the set of characters that excludes both the above sets.