The only ones I&#x27;ve seen that delivered [with caveats] were Concurrent Pascal, Ada&#x27;s Ravenscar, Eiffel&#x27;s SCOOP, and recently Rust. SCOOP got the most CompSci work with a Java port, one proving no deadlocks, one proving no livelocks, a formal verification in Maude that caught problems, and one modification to almost entirely eliminate performance penalty.<p>So, it can happen but does rarely enough to arouse strong skepticism. I usually don&#x27;t buy it.