I mean, the project that started this discussion is considered "not necessarily worth while" by most people, that's why they use systems that require restarts o

I mean, the project that started this discussion is considered "not necessarily worth while" by most people, that's why they use systems that require restarts on function redefinition instead of hot code reloading. But if you're going to the trouble of supporting hot code reloading, you ought to support (at least as an option) structure redefinition as well. Otherwise you've only gone halfway to making an actual interactive system.