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From: "B. Pym" <Nobody447095@here-nor-there.org>
Newsgroups: comp.lang.lisp
Subject: Re: shootout: implementing an interpreter
Date: Wed, 7 Aug 2024 17:28:34 -0000 (UTC)
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Kent M. Pitman wrote:

> (defun shrug (list)
>   (loop for (x . sublist-and-more) on list
>         for more = (member x sublist-and-more)
>         when more
>          collect `(g ,x ,(ldiff sublist-and-more more))))
> => SHRUG
> 
> (shrug '(a b c a d b d))
> => ((G A (B C)) (G B (C A D)) (G D (B)))


newLISP

(define (shrug xs  (x (pop xs)))
  (and xs
    (if (match (list '* x '*) xs)
      (cons (list 'g x ($it 0)) (shrug xs))
      (shrug xs))))

(shrug '(a b c a d b d))

((g a (b c)) (g b (c a d)) (g d (b)))