[kaba0]

What should happen when you remove an existing field, remove a method already used, change its initial value, etc? You will quickly get some incorrect state by blind hot swapping, and it is not trivial to do in a mutable object graph.

Clojure (and other lisps) can do it well because their scope of changes can be really small. Nonetheless, method hot-swap is well-defined and is implemented by OpenJDK.

[e67f70028a46fba]

Dcevm handles all those reasonably well. The current version doesn’t support changing super classes but the old version did. This is in dev mode so it doesn’t need to be perfect, just right enough most of the time.