Re: master ea93326: Add `union' and `intersection' to rx (bug#37849)

[Mattias Engdegård]

10 dec. 2019 kl. 22.52 skrev Stefan Monnier <address@hidden>:

> Why not (re)use `or` instead of `union`?  IOW make it an optimization?

It probably could, but having to explain the restrictions to the user felt a 
bit messy, so I went with a neatly closed collection of set operations (union, 
intersection and complement). Still, some concessions had to be made: 
operations on character classes are limited, and 'not' allows some types of 
arguments that cannot be used in set operations at all.

For 'or' to work as argument to 'not' and 'intersection', its arguments would 
have to be restricted in similar ways. I'll see what can be done.