This is, of course, just a part of a larger whole - the fact that your Common Lisp program ships with a compiler it can access and effectively always runs in an edit-and-go debugger. Embracing this fact fully leads to a different workflow of software development.
Having done a bit of that, I found plenty of drawbacks of this approach, too - mostly various consequences of breaking the assumption that code that a program is running is the same as the code it was compiled from or that it started with. The aspect that annoyed me the most day-to-day was, basically, that whenever I fixed something on the fly through conditions and restarts and eval-ing code in a REPL, I never had a nice way to go back to that solution and port it to code. It was too easy to forget about a quick fix you did without thinking.
I now realized this should be easily fixable with external tooling - i.e. in Emacs/SLIME. What I think they need is a better way of keeping an audit trail. Capturing and persisting as much of the transient interactions you did as possible, letting you revisit them after and easily transfer into code or tests.
To some extent, undotree on neovim allows this because it offers a drastically different view on what "undo" means. But I agree with you, the lack of a git-like system is annoying. I even think this might be THE reason CL didn't catch on—companies want to keep track of things (hence all the dashboards and ticketing systems...).
What I meant though isn't collaborative/historical tracking, I meant day-to-day ergonomics; closer to "drastically different view on what 'undo' means", except it doesn't even have to be 'undo' - I don't need the ability to rollback every single thing; I just want to know whatever the hell I actually did an hour ago when I quickly SET-VALUE and IGNOREd my way through a few random condition popups and evaluated some code in between. Being careful and keeping track of this as I go slows me down and is kind of the opposite of REPL-driven interactive development ideas; nah, I should be able to go fast now, and later be able to review all the random surgery I did on a live image.
EDIT:
> undotree on neovim allows this because it offers a drastically different view on what "undo" means
As I understand it, this "different view" is treating undo history as a tree? If so, I know this from Emacs via similarly named `undo-tree' package. But honestly, the moment I saw this I thought this is brain-dead stupid most obvious way of treating undos. It's very unfortunate that almost no software embraces this approach, instead opting for a linear history that gets trimmed the moment you undo a few steps and make a change.
If you want to see a truly different view of undo, check out what Emacs does by default. I don't even understand it fully, but best I can tell after studying the explainer in undo-tree's documentation, is that Emacs is using a linear history like everyone else, but instead of moving back through the history and discarding "the future" when you branch out, `undo' itself is an undoable operation that gets appended to undo history, so when you type some things, undo it, type something else, and keep pressing undo, you'll erase the last text, then "undo the undo" and end up with the first thing you typed...
I am still waiting for a non-Lisp language with a half-decent restart system. Even compiled languages should be able to implement it (except dealing with a possible allocation failure when saving the register context to return to)
