> Have you seen André van Tonder’s SRFI 57?
> <https://srfi.schemers.org/srfi-57/srfi-57.html>

> It provides ‘label polymorphism’ for records, which seems to be
> roughly what you’re aiming at.

Yes, but the problem with that SRFI (IIRC, it has been a while since I
tried it) is that the portable implementation is unusably slow. That's
probably fixable but I didn't look into it.

At Marc's suggestion, I ended up adding writing some helper functions on
top of the mappings SRFI, which provided most of the ML-like
functionality I was going for.

Thanks,
Antero