const does not imply pure. If applied to a member function, it makes this const; if applied to types it makes types const. You just demonstrated what I mean wh

const does not imply pure. If applied to a member function, it makes this const; if applied to types it makes types const. You just demonstrated what I mean when I comment that const is fraught. Purity is a different concept. Purity more easily maps more closely to an abstract concept and is easier to for people reason about.