Awesome! This speaks to something, which I've been thinking (and wishing) for a long time.
I've already done probabilistic programming in a scientific context (Python) and classical software engineering for web development (TypeScript, Python, Rust), and I've always wondered why I couldn't have the real-world modelling capacity of the former with the static type assurances of the latter. Love that you (and Microsoft) are thinking along the same lines!
Do you perhaps know of any Python implementations for this? There are plenty of dynamic stats programming libraries, but none offer typing solutions AFAIK.