MapView<K,V> and MapRef<K,V> implementation?

[jiawen]

Chandler Carruth gave a presentation at C++Now 2019 on MapView and MapRef - map analogues of std::string_view and absl::Span. I'm wondering if there might eventually be an implementation, within Abseil or otherwise. It seems like such a useful tool and is well within Abseil's wheelhouse.

The only reference I can find is Arthur O'Dwyer's blog post about it.

[jiawen]

Arthur pointed me to an implementation in the Carbon repo.