I think I just solved a long-open issue in BOOL regarding conditional Lists. It’s something that’s been nagging me a long time. For one thing, it’s one place that’s line-sensitive, and BOOL tries to avoid that. (Actually BOOL is very line-sensitive, but not that way.)
The other thing is that it conflated two things into one, and that’s also to be avoided. Clarity is everything, and not overloading concepts is an important part of clarity. (Orthogonality is another clarity goal that BOOL considers important.)
The background for this goes back to a BOOL primary design goal and technique.