The PPAML project yielded a lot of cool work, I think that many people are still figuring out the most impact use case. I believe that the most mature new production language is Figaro, out of Charles River. They have some good example projects and a introductory text for their language.

https://www.cra.com/technical-expertise/probabilistic-modeli...

https://www.amazon.com/Practical-Probabilistic-Programming-A...

That being said, I'm very happy that Hakaru is getting attention.