It makes me think of Lem's `watch` that displays s-expr results in an overlay, much like CIDER's Enlighten, somewhat like LightTable: https://lem-project.github.io/usage/common_lisp/#watch

There's sly-overlay too: https://git.sr.ht/~fosskers/sly-overlay (a couple function changes away to have it on Slime)

but those are not inside the stepper. (edit) oh, there's Sly-stickers: https://joaotavora.github.io/sly/#Stickers

LispWorks has a more graphical stepper / debugger so we might look into it.

There might be sthg on the newer CLOG?

I'm not certain, but Clojure supports this through CIDER's Enlighten mode: https://docs.cider.mx/cider/debugging/enlighten.html

It would be even better if larger values were inspectable, as it becomes challenging to view more complex data types beyond numbers and short strings.

The "inline" thingy can be seen as a popup/tooltip, could span many lines.

For those like me who have never heard of it, I think OP is referring to this: http://lighttable.com

Last touched three years ago. Interesting that someone came a long to give it a coat of paint (Electron update, ClojureScript update... etc.).