Re: [GSoC] Parameter protocols in CL

[Charles Turner <chturne at gmail dot com>]

Thanks for the explanations Helmut.

On 18 July 2012 21:29, Helmut Eller <eller.helmut@gmail.com> wrote:
> One idea is to rewrite
>
> (lambda (&optional (var init-form supplied-p))
>   body)
>
> to
>
> (lambda (#!optional (tmp-var <unbound-marker>))
>   (let ((var (if (eq tmp-var <unbound-marker)
>                  init-form
>                  tmp-var)))
>     body))
>
> where <unbound-marker> is some special value that the user can usually
> not create, e.g. some of those in gnu.expr.Special.

Why not to:

(lambda (#!optional (tmp-var <unbound-marker>))
   (let* ((supplied-p (if (eq tmp-var <unbound-marker>) nil t))
             (var (if supplied-p tmp-var init-form)))
     body))

It seems like your translation ignores the supplied-p parameter.

> You mean SBCL's DESTRUCTURING-BIND generates
> something like ((lambda (&optional (a 2) &rest x) (list a x))) ?

Sorry, I mean't it uses that as part of it's destructuring implementation:

(defun parse-defmacro (lambda-list whole-var body name context
                       &key
                       (anonymousp nil)
                       (doc-string-allowed t)
                       ((:environment env-arg-name))        ; can't I
just pick another name for now?
                       ((:default-default *default-default*))
                       (error-fun 'error)
                       (wrap-block t))

> Without some small test case it's pretty hard to say what is going on.

Anything involving DEFUN's seems to cause it. As nobody has a copy of
my code, it's going to remain hard to see what's going on. I'm fairly
sure it's bootstrapping. I've got an unwiedly boot procedure for now
as editing make files pretty much guarantees I'll have nasty merge
conflicts when I svn update (aclocal && automake produces quite a lot
of diff I find).

Thanks,
Charlie.