Re: the sort function in lisp (destructive)

RJ> Another alternative would be a SORT that does not reorder the CONS
RJ> cells, but the CARs of the CONS cells. SORT the list into another
RJ> data structure and then set the list's CARs from there.

and if implementation uses bubble-sort algorithm it doesn't even need any
additional storage!

but i think we can confuse Xah without introducing any significant
runtime/space overhead:

(defun pseudo-nice-sort (list pred)
(when list
(let ((beheaded-list (cons (first list) (rest list))))
(setf beheaded-list (sort beheaded-list pred))
(setf (car list) (car beheaded-list)
(cdr list) (cdr beheaded-list))
list)))

it will not "destroy variable" because it preserves the first CONS:

CL-USER> (let ((l1 (list 'd 'e 'a 'f 'x 'h)))
(let ((l2 (pseudo-nice-sort l1 #'string<)))
(values l1 l2)))
(A D E F H X)
(A D E F H X)

however it's still destructive, so in some cases it can bring more than a
few hours of happy debugging


.

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