While not production ready, I’ve been happily surprised at this functionality when building with it. I love my interpreters to be deterministic, or when random to be explicitly seeded. It makes debugging much easier when I can rerun the same program multiple times and expect identical results.
Interestingly I think things that should not be deterministic should actually forced not to be.
Swift for instance will explicitly make iterating on a dictionary not deterministic (by randomizing the iteration), in order to catch weird bugs early if a client relies (knowingly or not) on the specific order the elements of the dictionary are ordered.