Haskell has a pretty good story about how to use different dialects in the front end of the language, as long as the backend is still the same. Well, when I sa

Haskell has a pretty good story about how to use different dialects in the front end of the language, as long as the backend is still the same. Well, when I say Haskell, I mean ghc. Alas, C++ still mostly does its libraries via conceptual copy-and-paste (#include). So that would need to be fixed, if you wanted to mix-and-match dialects. You could probably keep '#include' syntax, but subtly change its meaning.