[slime-devel] Re: ABCL patches for SLIME HEAD

[Scott L. Burson]

On Sep 4, 2007, at 5:17 AM, Helmut Eller wrote:

> * Tobias C. Rittweiler [2007-09-03 19:32+0200] writes:
>
>> Just a guess, but what I could imagine that
>> `parse-first-valid-form-spec' in swank-arglist.lisp could possibly be
>> the culprit, as it uses the "mapping on several lists, one being
>> circular" trick:
>>
>>   (mapcar #'+ '(1 2 3 4) '#1=(10 . #1#))
>>
>> I'd expect this one to return (11 12 13 14), but closely rereading  
>> the
>> CLHS entry for the mapping functions, reveals that those are actually
>> only defined for /proper lists/.
>
> Never heard of this trick.
>

I think it's fair to consider it archaic, but it was once well known  
in Maclisp and early Lisp Machine Lisp.
IIRC, the latter even had a builtin function `circular-list' to  
simplify the construction of such lists.

-- Scott