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From: Drew Adams <drew.adams@oracle.com>
To: Eric Abrahamsen <eric@ericabrahamsen.net>, help-gnu-emacs@gnu.org
Subject: RE: replace element in list
Date: Wed, 21 Nov 2018 21:39:11 -0800 (PST)	[thread overview]
Message-ID: <45a3b5b6-2985-4eab-bb2c-2ad9b4459018@default> (raw)
In-Reply-To: <87zhu1y9k1.fsf@ericabrahamsen.net>

> > (defun my-list-replace (obj orig new)
> >     "Replaces an element in a list with something else"
> >     (let* ((pos (cl-position orig obj :test 'equal))
> >            (pos (if pos pos 0))
> >            (objlen (length obj))
> >            (head (butlast obj (- objlen pos)))
> >            (trail (nthcdr (+ 1 pos) obj)))
> >       (append head (append new trail))))
> 
> (let ((orig '(("a" . "b") ("c" "d")))
>       (obj  '("c" "d"))
>       (new '(":)")))
>   (setf (nth (cl-position obj orig :test #'equal) orig) new)
>   orig)

(defun toto (xs old new)
  (let ((ms  (member old xs)))
    (unless ms (error "%S is not in %S" old xs))
    (setcar ms new)
    xs))



  reply	other threads:[~2018-11-22  5:39 UTC|newest]

Thread overview: 23+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2018-11-22  4:42 replace element in list edgar
2018-11-22  5:18 ` Eric Abrahamsen
2018-11-22  5:39   ` Drew Adams [this message]
2018-11-22  6:04     ` Eric Abrahamsen
2018-11-22 13:19 ` Stefan Monnier
     [not found] ` <mailman.4442.1542892802.1284.help-gnu-emacs@gnu.org>
2018-11-23 12:05   ` Robert Munyer
2018-11-24  3:01 ` edgar
2018-11-24  5:27   ` Drew Adams
2018-11-24  7:22     ` edgar
  -- strict thread matches above, loose matches on Subject: below --
2019-09-02  9:44 Replace " Andreas Röhler
2019-09-02 10:37 ` tomas
2019-09-02 10:41   ` tomas
2019-09-02 10:46     ` tomas
2019-09-02 11:03       ` Michael Heerdegen
2019-09-02 11:05         ` tomas
2019-09-02 13:38           ` Andreas Röhler
2019-09-02 13:29 ` Stefan Monnier
2019-09-02 13:43   ` tomas
2019-09-02 14:00     ` Andreas Röhler
2019-09-02 14:57       ` Stefan Monnier
2019-09-02 20:29         ` Andreas Röhler
2019-09-02 21:32           ` Stefan Monnier
2019-09-03  5:37             ` Andreas Röhler

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