Mostly I'd say "no". At least, not much better than Cap'n Proto supports now. If you could convince multiple languages to share the same notion of a heap (incl

Mostly I'd say "no". At least, not much better than Cap'n Proto supports now. If you could convince multiple languages to share the same notion of a heap (including how to malloc() and free() memory), you might be able to get closer, allowing for truly mutable objects without the caveats Cap'n Proto has. However, memory allocation is a major place where languages tend to differ wildly.