Coincidentally, cling (wrapped by xeus-cling) is also a product from CERN.

Many of the CERN researchers are pretty deep into C++.

It was there that I got my template meta-programming baptism, back in 2002, when gcc was still trying to cope with template heavy code.

And curiously, also where I got my first safety heavy code reviews of C++ best practices.

I don't believe those a coincidences, but more collaborations and the right people working together :-)