I haven't used it in production (yet!), but I do follow the evolution of the language and observe its implementation from the Computer Scientist's point of view.
C3 is feature stable now, but still pre-1.0, that shouldn't stop you using it in production though. That said you'll want to be engaged with the community for updates, and if you encounter any issues.
Basically anything that can be done in C++ should be written in C3 and enjoy the thought process. I can't stand the current situation with C++ where you start writing your code and if you don't have written down what you want to achieve, you immediately get lost in the `attempting to decipher the cryptic error messages` procedure, only to realize you have lost track of what you were supposed to do in the first place.
> What potential uses did you have in mind?
That's interesting question; hmm...pretty much anything I could have written it in a static typed programming language, in a sane way without losing my mind? lol