Commit 2021-03-16 10:12 c0036af2

feat(category/is_iso): make is_iso a Prop (#6662) Perhaps long overdue, this makes is_iso into a Prop. It hasn't been a big deal, as it was always a subsingleton. Nevertheless this is probably safer than carrying data around in the typeclass inference system. As a side effect simple is now a Prop as well.