It would be pretty ugly to make this more introspective in C++.
For example, if you had to match patterns to distinguish between these three possibilities when looking at a tree: (val), (val (tree left) (tree right)), (val (tree subtree)). Here, the possibilities are not really separate types, but rather different ways of constructing a type. This sort of pattern shows up in general purpose programming (even meat and potato imperative programming) pretty often.
For example, if you had to match patterns to distinguish between these three possibilities when looking at a tree: (val), (val (tree left) (tree right)), (val (tree subtree)). Here, the possibilities are not really separate types, but rather different ways of constructing a type. This sort of pattern shows up in general purpose programming (even meat and potato imperative programming) pretty often.
There was a proposal for this championed by Stroustrup over ten years ago, but it went nowhere IIRC. https://www.stroustrup.com/pattern-matching-November-2014.pd...