Except it isn't really a debugger. It is just a repl in the environment you have constructed. The difference is most debuggers don't let you do as much as these would let you do.
Kind of hard to fully explain. With a debugger, you can typically only analyze variables on the stack. You can, of course, step over lines and such. However, with the live coding languages, you can literally redefine the function that is causing grief. More, you can, on the fly, define a new helper function that it should call to handle the current input causing trouble and redefine the method to call over to that.
People have come closer than I give credit in Java land doing this. I've never seen anyone else come close, though.
I think most any dynamic language should be able to do this. Most can't, though, due to serious limitations on what can be redefined and what cannot.
> However, with the live coding languages, you can literally redefine the function that is causing grief. More, you can, on the fly, define a new helper function that it should call to handle the current input causing trouble and redefine the method to call over to that.
"This is basically how Lisp and Smalltalk work.", as agentultra commented further up in this thread.
Well, a difference. There are others.