[brabel]

The example you posted is very interesting as it used both a visitor and ADTs. It seems the need for the Visitor comes from the generics in this case? Probably a Rust specific limitation. I don’t understand why you mention exhaustiveness though, it’s obviously easy have comprehensive or partial matching with ADT.

[cyberax]

No. The code can be rewritten without visitors using iterators for traversal, for example). But it'll look badly.

Visitors in the linked example are real classic visitors. The code _within_ the visitor methods, of course, uses pattern matching, but the pattern itself is not materially different from C++.

Exhaustiveness checking for pattern matching is also "best effort" for complex matching.