The Lambda-the-Ultimate discussion yielded a couple new answers. One is about Mezzo/ATS, and there are various others which might be relevant.

The other one says that this patent is a copy of work done in prior art in BitC:

As far as I can tell, this work is a direct transcription of explanations I made to people at Microsoft about BitC immutability. The particular approach to immutability that they have applied to patent has been discussed multiple times on the BitC programming language list, not as something that we had any doubts or difficulties with, but as something that we took for granted as obviously doable. We even discussed the escape analysis necessary to ensure constructor safety.

This is the second case of a patent application by someone on the Midori group since my departure that appears to be directly based on my own work and/or my discussions at Microsoft regarding my prior work and the prior work of others. I do know that Duffy has done a bunch of work on resolving some issues in C# that preclude proper implementation of readonly, but he is not the inventor of either the notion of transitive immutability in a programming language nor of immutability permitting construction. Both were discussed on the BitC list prior to my arrival at Microsoft, including a much more general form of immutable initialization relying on confinement. I discussed this work with Duffy while I was at Microsoft. Heck, I've done a Ph.D. dissertation and two formal verification efforts on this topic; it's hardly new.

Given this, I think there is a problem insofar as the patent fails to credit an inventor at Microsoft (me), but more to the point, the patent application fails to cite prior art about which they knew: BitC, EROS, and KeyKOS. Given the prior work, I would have refused to support this filing on the basis of prior art.

Many people at Microsoft hold the view that outsiders can't do anything interesting. They are, in my experience, appallingly unaware of prior art in the field, and sincerely believe that they have invented many things that have existed for some time.