[Chabs]

std::visit mostly allows you to do that already:

https://coliru.stacked-crooked.com/a/be5c44281eea8bc4

Then only unfortunate missing piece of the puzzle is that there's no trivial way to create a closure out of this, so it requires a bit more manual work to propagate local state to the visitor.

[ddalcino]

If you build your visitor out of lambdas, instead of a struct, you can propagate local state to the visitor easily by using lambda captures. There are good examples of this approach at https://en.cppreference.com/w/cpp/utility/variant/visit

[Chabs]

Unfortunately, you can't leverage template substitution rules with the lambda approach. And that's really necessary if you want to have actual powerful match expressions.

[pjmlp]

For those working with C++ an answer might come in C++23.

http://open-std.org/jtc1/sc22/wg21/docs/papers/2019/p1371r0....