Yep, you're right on this one! We went with Rust because we wanted to make it embeddable in other languages.

And on the policy language. Polar is indeed a prolog variant. You can see pretty early we took the decision to diverge from a more familiar prolog syntax [1] because we wanted to make it a little more accessible.

1: https://docs.osohq.com/changelogs/0.2.0.html