[slime-devel] Re: Patch for stepper support in SBCL and (sort of) CLISP

Svein Ove Aas sveina at gmail.com
Wed Oct 5 19:09:45 UTC 2005

On 10/5/05, Bill Clementson <billclem at gmail.com> wrote:
> Hi Svein,
> > Due to a few requests lately, I thought I should mention something:
> > This code is obsolete.
> >
> > It only ever really worked on SBCL, and even there not perfectly. I'm
> > rewriting it as something that should work everywhere, but meanwhile
> > any non-fatal bugs are going to go unfixed - sorry about that."
> Any progress in getting the SBCL stepper working yet?

It always pretty much worked in SBCL, so I assume you're referring to
my new implementation. Progress? Some.

The basic design is a Lisp evaluator that communicates with the
stepper UI by way of the condition system - pretty much the same setup
as my last attempt, except that I'm writing said evaluator myself. I'm
about halfway done with the evaluator, and haven't really tried doing
anything about the UI yet; Slime's debugger works fairly well for the
development bit.

*IF* I had nothing else to do, I could probably get a workable stepper
(sans UI) in a week. As I do, in fact, have other things to do, I'm
aiming to complete it by christmas. Partials will be unpredictable,
but feel free to pull patches from
darcs://brage.info/~svein/repos/slime/, which will contain semi-stable
code once I've got such a thing. (At the moment it's practically
empty. You could still use it as a CVS gateway, I suppose.)

I'll also announce it to slime-dev once I feel confident about letting
the ravening hordes at my code. As has been mentioned, all good things
come to those who wait - for a tidbit, I've got a framework for
step-backwards in place.

> Also, what were the problems that you had getting it to work with OpenMCL?

(defmacro step (&body body) , at body)

That about summarizes it. I'd been using that macro as a starting
point for figuring out how the implementations did it. OpenMCL
apparently didn't, but maybe I didn't dig deep enough.

I'd appreciate pointers to whitepapers on Lisp evaluation and such, if
you have some handy.

- Svein Ove Aas

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