100% interoperability with C++ wouldn’t be my priority. I mean, everyone’s going to decide for themselves what creek they want to paddle up, but there are a lot of languages with other attractive features and not that one, and you don’t really need it. I mean, I’ve used the Be API with Python, Haskell and Ocaml, and they sure aren’t C++ interoperable.
Swift seems nice, but to me not really a typical open source project. The things we bring on board to Haiku are typically sort of guerilla projects for a while, that is, back at headquarters they may not know about the existence of a Haiku port right away, until it becomes a real thing that’s worth upstreaming patches etc. That seems somewhat foreign to Swift world, and I wonder how easy it will be to get Haiku on the list.