> (b) has the advantage of adding translation and removal in one fell swoop --
> but if you only want to remove, then you have to make a translation table of
> 1:1 mappings = not hard, but a annoying:
Exactly that is the proposal. And for same exact reason that you point out,
I also can't give a comment what would be better. It would be indeed
quite strange from syntactical POV if I just want to remove "all except"
and must call translate(). So ideally both should exist I think.