More general use of who in definitions

[usaoc]

This is to record an initial thought about more general use of who (in the sense of define/who that binds a who syntax parameter to a defined name) in Rhombus. There seems to be many cases where existing Racket functions expect symbolic names, for example, in make-parameter (see racket/racket#4810). Maybe providing and encouraging the use of who will be a good idea? Ideas are welcome.

[usaoc]

I think a check-like macro (as used internally in Racket) can also be a good idea, and relates to who because both are inspired by Racket-internal macros.

[mflatt]

Functions now support a ~who option.

I haven't found much need for a check-like macro, though, because argument annotations perform those checks.

[usaoc]

I guess ~who is still missing in def, but the usefulness of that is more doubtful than in fun and alike. For things like parameters, we may be better served with a separate definition form; for other things, we may not necessarily want to use the exact variable name for the debugging name (say, prompt tags). But I’ll leave this open just in case someone has more thoughts on the topic.