Really good stuff. Here I am waiting to see what Leroy et al will deliver on mini-ML compiler or more from Habit team when Klein et al deliver a systems-oriented, certified compiler. Heck yeah! Interesting, too, in that it splits the supporting argument between the functional language and stuff in C. Its focus on being essentially an executable spec with verified translations will help in high assurance where spec to implementation correspondence is quite important. Could be a shortcut when this produces acceptable implementations.