From mboxrd@z Thu Jan 1 00:00:00 1970 Path: news.gmane.io!.POSTED.blaine.gmane.org!not-for-mail From: Mattias =?UTF-8?Q?Engdeg=C3=A5rd?= Newsgroups: gmane.emacs.bugs Subject: bug#42147: 28.0.50; pure vs side-effect-free, missing optimizations? Date: Sat, 25 Jul 2020 23:00:33 +0200 Message-ID: <51FE77F3-CA05-459A-9601-9E1EEBC1E2FE@acm.org> References: <3A9CC2A3-8307-47B2-8D80-795C0AF020E1@acm.org> <0433A879-C98D-4B1A-B85C-A15DA9289099@acm.org> <1621669100.2102667.1593639091621@mail.yahoo.com> <33C2E2C8-16A6-47A9-B3A4-8A5F43648E04@acm.org> Mime-Version: 1.0 (Mac OS X Mail 12.4 \(3445.104.15\)) Content-Type: text/plain; charset=utf-8 Content-Transfer-Encoding: quoted-printable Injection-Info: ciao.gmane.io; posting-host="blaine.gmane.org:116.202.254.214"; logging-data="9857"; mail-complaints-to="usenet@ciao.gmane.io" Cc: Paul Eggert , Stefan Monnier , Andrea Corallo , 42147@debbugs.gnu.org To: Philipp Stephani Original-X-From: bug-gnu-emacs-bounces+geb-bug-gnu-emacs=m.gmane-mx.org@gnu.org Sat Jul 25 23:01:19 2020 Return-path: Envelope-to: geb-bug-gnu-emacs@m.gmane-mx.org Original-Received: from lists.gnu.org ([209.51.188.17]) by ciao.gmane.io with esmtps (TLS1.2:ECDHE_RSA_AES_256_GCM_SHA384:256) (Exim 4.92) (envelope-from ) id 1jzRIE-0002UL-Vd for geb-bug-gnu-emacs@m.gmane-mx.org; Sat, 25 Jul 2020 23:01:19 +0200 Original-Received: from localhost ([::1]:38382 helo=lists1p.gnu.org) by lists.gnu.org with esmtp (Exim 4.90_1) (envelope-from ) id 1jzRIE-0007RE-1A for geb-bug-gnu-emacs@m.gmane-mx.org; Sat, 25 Jul 2020 17:01:18 -0400 Original-Received: from eggs.gnu.org ([2001:470:142:3::10]:56602) by lists.gnu.org with esmtps (TLS1.2:ECDHE_RSA_AES_256_GCM_SHA384:256) (Exim 4.90_1) (envelope-from ) id 1jzRHy-0007Qz-Jj for bug-gnu-emacs@gnu.org; Sat, 25 Jul 2020 17:01:03 -0400 Original-Received: from debbugs.gnu.org ([209.51.188.43]:39706) by eggs.gnu.org with esmtps (TLS1.2:ECDHE_RSA_AES_128_GCM_SHA256:128) (Exim 4.90_1) (envelope-from ) id 1jzRHx-0005Cb-UU for bug-gnu-emacs@gnu.org; Sat, 25 Jul 2020 17:01:02 -0400 Original-Received: from Debian-debbugs by debbugs.gnu.org with local (Exim 4.84_2) (envelope-from ) id 1jzRHx-0003Zy-Rs for bug-gnu-emacs@gnu.org; Sat, 25 Jul 2020 17:01:01 -0400 X-Loop: help-debbugs@gnu.org Resent-From: Mattias =?UTF-8?Q?Engdeg=C3=A5rd?= Original-Sender: "Debbugs-submit" Resent-CC: bug-gnu-emacs@gnu.org Resent-Date: Sat, 25 Jul 2020 21:01:01 +0000 Resent-Message-ID: Resent-Sender: help-debbugs@gnu.org X-GNU-PR-Message: followup 42147 X-GNU-PR-Package: emacs Original-Received: via spool by 42147-submit@debbugs.gnu.org id=B42147.159571085613729 (code B ref 42147); Sat, 25 Jul 2020 21:01:01 +0000 Original-Received: (at 42147) by debbugs.gnu.org; 25 Jul 2020 21:00:56 +0000 Original-Received: from localhost ([127.0.0.1]:51250 helo=debbugs.gnu.org) by debbugs.gnu.org with esmtp (Exim 4.84_2) (envelope-from ) id 1jzRHs-0003ZM-Fd for submit@debbugs.gnu.org; Sat, 25 Jul 2020 17:00:56 -0400 Original-Received: from mail1480c50.megamailservers.eu ([91.136.14.80]:38032 helo=mail118c50.megamailservers.eu) by debbugs.gnu.org with esmtp (Exim 4.84_2) (envelope-from ) id 1jzRHp-0003Yu-An for 42147@debbugs.gnu.org; Sat, 25 Jul 2020 17:00:55 -0400 X-Authenticated-User: mattiase@bredband.net DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=megamailservers.eu; s=maildub; t=1595710837; bh=Sr4g8fKQQQwm16Yo/E5uOHZuZvgydZlS1hHx9QmC4z0=; h=Subject:From:In-Reply-To:Date:Cc:References:To:From; b=sDk0gu8CpLZ8gW8UlsMVdnPhdua7RcS8qRPigKGMYmOWbNi8nLhhSxvoDVAdyLEnP VwjxXShBgE1hBlN1vzHcCHWDMNH+/x+G5MelTrNF8aBLBFrSOLiZQ+PjAaykzzIx5B g8Tyg+m73T+IB5Z4Ru9RqjylojygbxUO1Yuy/p/E= Feedback-ID: mattiase@acm.or Original-Received: from stanniol.lan (c-4e4ae655.032-75-73746f71.bbcust.telenor.se [85.230.74.78]) (authenticated bits=0) by mail118c50.megamailservers.eu (8.14.9/8.13.1) with ESMTP id 06PL0YUP007872; Sat, 25 Jul 2020 21:00:35 +0000 In-Reply-To: X-Mailer: Apple Mail (2.3445.104.15) X-CTCH-RefID: str=0001.0A782F1B.5F1C9D75.0015:SCFSTAT68638221, ss=1, re=-4.000, recu=0.000, reip=0.000, cl=1, cld=1, fgs=0 X-CTCH-VOD: Unknown X-CTCH-Spam: Unknown X-CTCH-Score: -4.000 X-CTCH-Flags: 0 X-CTCH-ScoreCust: 0.000 X-CSC: 0 X-CHA: v=2.3 cv=KaGsTjQD c=1 sm=1 tr=0 a=klNLuyVZdLUgl+K5Uafb2A==:117 a=klNLuyVZdLUgl+K5Uafb2A==:17 a=IkcTkHD0fZMA:10 a=M51BFTxLslgA:10 a=pGLkceISAAAA:8 a=vfDNckH_IXM4D5rU_z8A:9 a=QEXdDO2ut3YA:10 X-BeenThere: debbugs-submit@debbugs.gnu.org X-Mailman-Version: 2.1.18 Precedence: list X-BeenThere: bug-gnu-emacs@gnu.org List-Id: "Bug reports for GNU Emacs, the Swiss army knife of text editors" List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Errors-To: bug-gnu-emacs-bounces+geb-bug-gnu-emacs=m.gmane-mx.org@gnu.org Original-Sender: "bug-gnu-emacs" Xref: news.gmane.io gmane.emacs.bugs:183551 Archived-At: 25 juli 2020 kl. 22.11 skrev Philipp Stephani : > The manual states that > "This function [concat] always constructs a new string that is not > =E2=80=98eq=E2=80=99 to any existing string" so I don't see how it = could ever be pure. Actually that part of the manual was corrected fairly recently, as that = statement hasn't been true for decades. More to the point, the current set of functions marked as 'pure' are = really the superset 'pure-absent-mutation': functions that are pure when = it can be assumed that the arguments are not modified. This assumption = can be based on physical immutability (integers), by convention (string = constants), or anything else the compiler can prove such as control = flow. There is also the question of what equality to use and here the answer = is probably 'equal' since we are only dealing with immutables. (The = return values of these functions cannot be considered mutable for = obvious reasons, so make-string is out.) If you want to rename the property accordingly then I won't object. In = any case, it is certainly a good idea to be precise about what the = various sets really mean. There are also some functions declared 'pure' that appear to have side = effects: kbd, package-get-version