From mboxrd@z Thu Jan 1 00:00:00 1970 Path: news.gmane.org!not-for-mail From: Oleh Krehel Newsgroups: gmane.emacs.devel Subject: Re: Would seq-range and seq-mapcat be useful? Date: Fri, 30 Jan 2015 16:38:24 +0100 Message-ID: References: <878uglwmra.fsf@petton.fr> <874mr9w8at.fsf@petton.fr> <87lhkkefhn.fsf@petton.fr> NNTP-Posting-Host: plane.gmane.org Mime-Version: 1.0 Content-Type: text/plain; charset=UTF-8 X-Trace: ger.gmane.org 1422632322 12746 80.91.229.3 (30 Jan 2015 15:38:42 GMT) X-Complaints-To: usenet@ger.gmane.org NNTP-Posting-Date: Fri, 30 Jan 2015 15:38:42 +0000 (UTC) Cc: Stefan Monnier , emacs-devel To: Nicolas Petton Original-X-From: emacs-devel-bounces+ged-emacs-devel=m.gmane.org@gnu.org Fri Jan 30 16:38:42 2015 Return-path: Envelope-to: ged-emacs-devel@m.gmane.org Original-Received: from lists.gnu.org ([208.118.235.17]) by plane.gmane.org with esmtp (Exim 4.69) (envelope-from ) id 1YHDeZ-00070f-Rf for ged-emacs-devel@m.gmane.org; Fri, 30 Jan 2015 16:38:39 +0100 Original-Received: from localhost ([::1]:37400 helo=lists.gnu.org) by lists.gnu.org with esmtp (Exim 4.71) (envelope-from ) id 1YHDeZ-0005Mg-26 for ged-emacs-devel@m.gmane.org; Fri, 30 Jan 2015 10:38:39 -0500 Original-Received: from eggs.gnu.org ([2001:4830:134:3::10]:35707) by lists.gnu.org with esmtp (Exim 4.71) (envelope-from ) id 1YHDeM-0005Ma-Jz for emacs-devel@gnu.org; Fri, 30 Jan 2015 10:38:27 -0500 Original-Received: from Debian-exim by eggs.gnu.org with spam-scanned (Exim 4.71) (envelope-from ) id 1YHDeL-0002iq-Hm for emacs-devel@gnu.org; Fri, 30 Jan 2015 10:38:26 -0500 Original-Received: from mail-we0-x233.google.com ([2a00:1450:400c:c03::233]:43414) by eggs.gnu.org with esmtp (Exim 4.71) (envelope-from ) id 1YHDeL-0002ie-7T for emacs-devel@gnu.org; Fri, 30 Jan 2015 10:38:25 -0500 Original-Received: by mail-we0-f179.google.com with SMTP id q59so27816349wes.10 for ; Fri, 30 Jan 2015 07:38:24 -0800 (PST) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=gmail.com; s=20120113; h=mime-version:in-reply-to:references:date:message-id:subject:from:to :cc:content-type; bh=fe+bJGkDhemGa8HIjw/wLl50HfgqENzgm0WG+TIkVr8=; b=xPoQ2TTzPR0Y9nM9HnTBn/sTpG6Kx9WMDiRdB9tz/6RSx2ySJx5Laj7bDaB6QYmZUE wZP4fNjcTjRIOqTJo+i2E7d/yPUlErM3a31tOmaHIUqYrS+setyOrwYXvoN0Z/ZvWIbI uyyKVPScRZv3WtUoGpq7H3mrENUmgabqW/3Lgcz5iJcwkX0BTU67mgjk03LYm+hNTZ+f 5vL0/BLhWRkNU5oSlZ+GuD5KvPAaoJwUU71VnUUn1z+eAlYzjgsOoYi//lbe4BVSVMNo VcDP6v+SKQAe5/fLkTeWzBwwht4tF6nimLitdu463vZct7C+rjuG3lZhQ4RS2qGb6lNc Mg7Q== X-Received: by 10.194.234.2 with SMTP id ua2mr12987940wjc.40.1422632304511; Fri, 30 Jan 2015 07:38:24 -0800 (PST) Original-Received: by 10.27.137.137 with HTTP; Fri, 30 Jan 2015 07:38:24 -0800 (PST) In-Reply-To: <87lhkkefhn.fsf@petton.fr> X-detected-operating-system: by eggs.gnu.org: Error: Malformed IPv6 address (bad octet value). X-Received-From: 2a00:1450:400c:c03::233 X-BeenThere: emacs-devel@gnu.org X-Mailman-Version: 2.1.14 Precedence: list List-Id: "Emacs development discussions." List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Errors-To: emacs-devel-bounces+ged-emacs-devel=m.gmane.org@gnu.org Original-Sender: emacs-devel-bounces+ged-emacs-devel=m.gmane.org@gnu.org Xref: news.gmane.org gmane.emacs.devel:182063 Archived-At: On Fri, Jan 30, 2015 at 11:21 AM, Nicolas Petton wrote: > > Oleh Krehel writes: > >> Hi Nicolas, >> >> On Thu, Jan 29, 2015 at 11:06 PM, Nicolas Petton wrote: >> >>> Sure, `seq-range' would be a convenient way to create a sequence of >>> numbers. A simple implementation could be: >>> >>> (defun seq-range (start end) >>> (let ((lst nil)) >>> (while (< start end) >>> (push end lst) >>> (setq end (1- end))) >>> lst)) >> >> This is just `number-sequence' from subr.el. > > Indeed :) > > Nico > -- > Nicolas Petton > http://nicolas-petton.fr > I'd like to have this: (defun seq-group-by (fn lst) (nreverse (cl-reduce (lambda (acc it) (let* ((key (funcall fn it)) (cell (assoc key acc))) (if cell (setcdr cell (push it (cdr cell))) (push (list key it) acc)) acc)) lst :initial-value nil))) (seq-group-by #'car '(("a" 1) ("b" 2) ("b" 5) ("c" 1))) ;; (("a" ("a" 1)) ;; ("b" ("b" 5) ;; ("b" 2)) ;; ("c" ("c" 1))) (seq-group-by #'cadr '(("a" 1) ("b" 2) ("b" 5) ("c" 1))) ;; ((1 ("c" 1) ;; ("a" 1)) ;; (2 ("b" 2)) ;; (5 ("b" 5))) Is this already somewhere? Oleh