It has occurred to me that it might be nice to have a datatype which represents a string of bits, where you don't have to have exactly multiples of 8 of them...and where positions were on a bit-level.
If there were such a type, it might be called BITS! to not conflict...but either way it does point out that BINARY! is kind of a misleading name.
Since today's BINARY! is a series managed in multiples of 8 bits, wouldn't it be better to call it BYTES! ?
I'll add that I'm kind of leaning toward saying that the representation be ${FFFF} or $"FFFF" as opposed to using & to replace #. This is more of a nod to historical $ sign for hex... leaves & free for other applications...and gives the ability to put characters in quoted strings cleanly, like:
rebElide("some-char: #{c}");
Although that particular case can be done without delimiters as #c ... but we need to work through what is and isn't legal to do without quotes or braces.