[samatman]

I realized I didn't address one of the main things you said, which was about image-based tools. That's better as its own reply I reckon.

Depends on what you mean by "image-based". Julia doesn't support reloading core dumps, but it has pre-compilation, and it has Revise, which will do everything it can to keep the REPL state up-to-date with changes to the source code. My experience is that it always updates state (silently) or fails and tells you, and when it fails can be predicted: if you modify the layout of a struct, or change an enum, it can't track that, so the prompt will turn yellow and you'll have to restart. You get the same yellow prompt (instead of green, and this is configurable to use textual cues btw) if there's a syntax error, but in that case, you fix the code and press enter and it goes green again.

Revise evals the minimum amount of code to update the program state, this is instantaneous for all practical purposes.

The Julia REPL is a massive improvement over any of the REPLs which ship with open-source Common Lisps, and head and shoulders above what comes with most other languages. It is not yet up to the standard of a commercial Lisp, or of the Emacs SLIME-mode approach, but the community lives in the REPL (and notebooks), so I expect to see the polishing process continue.