From mboxrd@z Thu Jan 1 00:00:00 1970 Path: news.gmane.io!.POSTED.blaine.gmane.org!not-for-mail From: Zelphir Kaltstahl Newsgroups: gmane.lisp.guile.user Subject: Surprising behavior of eq? Date: Sun, 20 Sep 2020 14:16:07 +0200 Message-ID: Mime-Version: 1.0 Content-Type: text/plain; charset=utf-8 Content-Transfer-Encoding: 8bit Injection-Info: ciao.gmane.io; posting-host="blaine.gmane.org:116.202.254.214"; logging-data="33231"; mail-complaints-to="usenet@ciao.gmane.io" User-Agent: Mozilla/5.0 (X11; Linux x86_64; rv:68.0) Gecko/20100101 Icedove/68.10.0 To: Guile User Original-X-From: guile-user-bounces+guile-user=m.gmane-mx.org@gnu.org Sun Sep 20 14:16:36 2020 Return-path: Envelope-to: guile-user@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 1kJyGh-0008Xb-SS for guile-user@m.gmane-mx.org; Sun, 20 Sep 2020 14:16:35 +0200 Original-Received: from localhost ([::1]:39128 helo=lists1p.gnu.org) by lists.gnu.org with esmtp (Exim 4.90_1) (envelope-from ) id 1kJyGg-00031j-QT for guile-user@m.gmane-mx.org; Sun, 20 Sep 2020 08:16:34 -0400 Original-Received: from eggs.gnu.org ([2001:470:142:3::10]:51064) by lists.gnu.org with esmtps (TLS1.2:ECDHE_RSA_AES_256_GCM_SHA384:256) (Exim 4.90_1) (envelope-from ) id 1kJyGO-00031Z-5G for guile-user@gnu.org; Sun, 20 Sep 2020 08:16:16 -0400 Original-Received: from mout02.posteo.de ([185.67.36.66]:36629) by eggs.gnu.org with esmtps (TLS1.2:ECDHE_RSA_AES_256_GCM_SHA384:256) (Exim 4.90_1) (envelope-from ) id 1kJyGK-0003ke-Vo for guile-user@gnu.org; Sun, 20 Sep 2020 08:16:15 -0400 Original-Received: from submission (posteo.de [89.146.220.130]) by mout02.posteo.de (Postfix) with ESMTPS id 53FAE2400FB for ; Sun, 20 Sep 2020 14:16:09 +0200 (CEST) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=posteo.de; s=2017; t=1600604169; bh=hHATM81B34AieyeuMkfw3yziZ2OeD45PIBz3kUaYLyM=; h=To:From:Subject:Date:From; b=ip7We+MAMYG9IrsWpuwr246QTDsP/dicxSHB19gr4JpDasr/Ve2blLPryIVGtRd18 hq2hmzrvm4qQpBHgnzfCU7eJ30kR/5yl6LPw9fGHiggCPEePuKVjRwujzS+591eOjd mjli1YzVLc3ql7AbunBEeOuu8ajcVIz9ECDGGA0Chf6L1g+3CsjZYh+REhDCqVrXWw 3L3r1YC2UK+dYYz/iQHwp5R9xUkV4KV4dVVdrRfGZ/ag8HuyKtYWbINmA/SY4DIH5E 2lbufP0G5uMadShbhHp7+msL5fojEBAtHEjYs39BD/Lx0ux+gPozmtf30mMcKoK7ww puTyhlUdzCT+w== Original-Received: from customer (localhost [127.0.0.1]) by submission (posteo.de) with ESMTPSA id 4BvRPN5DPFz9rxM for ; Sun, 20 Sep 2020 14:16:08 +0200 (CEST) Content-Language: en-US Received-SPF: pass client-ip=185.67.36.66; envelope-from=zelphirkaltstahl@posteo.de; helo=mout02.posteo.de X-detected-operating-system: by eggs.gnu.org: First seen = 2020/09/20 08:16:09 X-ACL-Warn: Detected OS = Linux 3.11 and newer [fuzzy] X-Spam_score_int: -20 X-Spam_score: -2.1 X-Spam_bar: -- X-Spam_report: (-2.1 / 5.0 requ) BAYES_00=-1.9, DKIM_SIGNED=0.1, DKIM_VALID=-0.1, DKIM_VALID_AU=-0.1, DKIM_VALID_EF=-0.1, HTML_MESSAGE=0.001, RCVD_IN_DNSWL_NONE=-0.0001, RCVD_IN_MSPIKE_H3=-0.01, RCVD_IN_MSPIKE_WL=-0.01, SPF_HELO_NONE=0.001, SPF_PASS=-0.001 autolearn=ham autolearn_force=no X-Spam_action: no action X-Content-Filtered-By: Mailman/MimeDel 2.1.23 X-BeenThere: guile-user@gnu.org X-Mailman-Version: 2.1.23 Precedence: list List-Id: General Guile related discussions List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Errors-To: guile-user-bounces+guile-user=m.gmane-mx.org@gnu.org Original-Sender: "guile-user" Xref: news.gmane.io gmane.lisp.guile.user:16930 Archived-At: Hello Guile users, I just noticed something weird about eq?. My Guile version is: I get the different results, depending on whether I define some bindings in a let or using define: (In Emacs Geiser:) ~~~~ (define x '(10 9)) (define y '(10 9)) (eq? x y) $2 = #f (let ([x '(10 9)] [y '(10 9)]) (eq? x y)) $3 = #t ~~~~ Is this intentional or a bug? I first noticed something strange when writing the following code: ~~~~DEFINITION~~~~ (define make-multiple-list-remover (λ (equal-proc) (λ (lst unwanted) (let loop ([remaining-list lst]) (cond [(null? remaining-list) '()] [(equal-proc (car remaining-list) unwanted) (loop (cdr remaining-list))] [else (cons (car remaining-list) (loop (cdr remaining-list)))]))))) ~~~~ ~~~~TEST~~~~ (let ([a '(9 10)] [b '(9 10)]) (test-equal "make-multiple-list-remover-03" `(1 2 (3) (4) ,a) ((make-multiple-list-remover eq?) `(a b (c) (d) ,a) b))) ~~~~ I was wondering, why the test fails. I think (eq? ...) should not be able to see the equivalence of both lists a and b, just like when defined using (define ...). I can also run it in the REPL and see the difference: ~~~~ (define a '(9 10)) (define b '(9 10)) ((make-multiple-list-remover eq?) `(a b (c) (d) ,a) b) $4 = (a b (c) (d) (9 10)) (let ([a '(9 10)] [b '(9 10)]) ((make-multiple-list-remover eq?) `(a b (c) (d) ,a) b)) $5 = (a b (c) (d)) ~~~~ Somehow the bindings of let seem to be different from the bindings created using define. What about using define inside let? ~~~~ ~~~~ -- repositories: https://notabug.org/ZelphirKaltstahl