Pascal Bourguignon wrote:

> ;; Smartass solution, using Common Lisp reduce:
>
> (defun group (list)
> (reduce (lambda (item result)
> (cond
> ((endp result) (list (list item)))
> ((eql (first (first result)) item) (cons (cons item (first result))
> (rest result)))
> (t (cons (list item) result))))
> list
> :from-end t
> :initial-value '()))

Shorter.

Gauche Scheme and Racket:

;; for Racket only
(require srfi/1) ;; fold-right

(define (kons x accum)
(if (or (null? accum) (not (equal? x (caar accum))))
(cons (list x) accum)
(cons (cons x (car accum)) (cdr accum))))

(define (group lst)
(fold-right
kons
'()
lst))