They are image based, so you can just save your session and continue using it later in another day.
> I think the author alluded to that. Of course I have no experience with Mesa/Cedar Oberon. I'll have to check those out.
On those systems, the unit of loaded code is a module and the whole OS only has dynamic libraries as executables.
So you can just reload a module and the next time you do module.proc on the repl, you will be referring to the newly loaded module.
For me an ideal REPL should be like the experience I used to have in Smalltalk.