From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: from mp12.migadu.com ([2001:41d0:2:4a6f::]) (using TLSv1.3 with cipher TLS_AES_256_GCM_SHA384 (256/256 bits)) by ms5.migadu.com with LMTPS id YJY2I54wymJ5tAAAbAwnHQ (envelope-from ) for ; Sun, 10 Jul 2022 03:51:26 +0200 Received: from aspmx1.migadu.com ([2001:41d0:2:4a6f::]) (using TLSv1.3 with cipher TLS_AES_256_GCM_SHA384 (256/256 bits)) by mp12.migadu.com with LMTPS id l6cgI54wymLepQAAauVa8A (envelope-from ) for ; Sun, 10 Jul 2022 03:51:26 +0200 Received: from lists.gnu.org (lists.gnu.org [209.51.188.17]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by aspmx1.migadu.com (Postfix) with ESMTPS id 11EE211F2 for ; Sun, 10 Jul 2022 03:51:25 +0200 (CEST) Received: from localhost ([::1]:35854 helo=lists1p.gnu.org) by lists.gnu.org with esmtp (Exim 4.90_1) (envelope-from ) id 1oAM6V-0007Nu-MI for larch@yhetil.org; Sat, 09 Jul 2022 21:51:23 -0400 Received: from eggs.gnu.org ([2001:470:142:3::10]:42060) by lists.gnu.org with esmtps (TLS1.2:ECDHE_RSA_AES_256_GCM_SHA384:256) (Exim 4.90_1) (envelope-from ) id 1oAM6I-0007Nk-59 for help-guix@gnu.org; Sat, 09 Jul 2022 21:51:10 -0400 Received: from mx1.dismail.de ([78.46.223.134]:26174) by eggs.gnu.org with esmtps (TLS1.2:ECDHE_RSA_AES_256_GCM_SHA384:256) (Exim 4.90_1) (envelope-from ) id 1oAM6D-0000LJ-Pz; Sat, 09 Jul 2022 21:51:09 -0400 Received: from mx1.dismail.de (localhost [127.0.0.1]) by mx1.dismail.de (OpenSMTPD) with ESMTP id 6f6f82dd; Sun, 10 Jul 2022 03:51:01 +0200 (CEST) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed; d=dismail.de; h=date :message-id:from:to:subject:references:mime-version:content-type :content-transfer-encoding; s=20190914; bh=FN21deJoeKZHsA/yrWiRE OuJ554h/y3XPS0ZFhQUiL8=; b=P602fFU3qPPnmlfrvpVCjEu3VqS5GUrA/xIt5 KXVYa8r1NWAk3mpmIbBIUWIxOTXFR8CLeFE3D3VOG8pwFOlkaSkYcwfJU5HPfBp2 YSvXT34LciCqztSDDYy64DoaA+r+2QVxd9hmsnMOkn+x1Ll1CypA+1q6xF+jbfgw agCVv7+WI2ByK4zuDc0jGdxFluUI5JtHUjtYIsV3D15xVfzArByNaYB4agk/qKZA KsnmjZjn3CUx89A73OPpSH6SFjFapEuwZOFIJd9QULByyIH1fOZVjMSskVOBHJax v9qnsxHcGOkMe+nmhtf+jE4HZ1Be5hLnps+t4BZJ1G2ZGp7jA== Received: from smtp2.dismail.de ( [10.240.26.12]) by mx1.dismail.de (OpenSMTPD) with ESMTP id 7c52db9d; Sun, 10 Jul 2022 03:51:00 +0200 (CEST) Received: from smtp2.dismail.de (localhost [127.0.0.1]) by smtp2.dismail.de (OpenSMTPD) with ESMTP id 9c390393; Sun, 10 Jul 2022 03:51:00 +0200 (CEST) Received: by dismail.de (OpenSMTPD) with ESMTPSA id 6338a65d (TLSv1.3:TLS_AES_256_GCM_SHA384:256:NO); Sun, 10 Jul 2022 03:50:59 +0200 (CEST) Date: Sat, 9 Jul 2022 20:51:06 -0500 Message-ID: <20220709205106.GB24308@gac> From: jgart To: Guix Help Subject: Why do we force the lazy python? References: MIME-Version: 1.0 Content-Type: text/plain; charset=utf-8 Content-Disposition: inline Content-Transfer-Encoding: 8bit Received-SPF: pass client-ip=78.46.223.134; envelope-from=jgart@dismail.de; helo=mx1.dismail.de X-Spam_score_int: -27 X-Spam_score: -2.8 X-Spam_bar: -- X-Spam_report: (-2.8 / 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, RCVD_IN_DNSWL_LOW=-0.7, SPF_HELO_NONE=0.001, SPF_PASS=-0.001, T_SCC_BODY_TEXT_LINE=-0.01 autolearn=ham autolearn_force=no X-Spam_action: no action X-BeenThere: help-guix@gnu.org X-Mailman-Version: 2.1.29 Precedence: list List-Id: List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Errors-To: help-guix-bounces+larch=yhetil.org@gnu.org Sender: "Help-Guix" X-Migadu-Flow: FLOW_IN X-Migadu-To: larch@yhetil.org X-Migadu-Country: US ARC-Message-Signature: i=1; a=rsa-sha256; c=relaxed/relaxed; d=yhetil.org; s=key1; t=1657417885; h=from:from:sender:sender:reply-to:subject:subject:date:date: message-id:message-id:to:to:cc:mime-version:mime-version: content-type:content-type: content-transfer-encoding:content-transfer-encoding: references:references:list-id:list-help:list-unsubscribe: list-subscribe:list-post:dkim-signature; bh=FLUwc4Ak0g/tVmJ2fj+zmTebbw9G7lmlvfZ+32RVw90=; b=Z9QInb9YmS3mKN1yJ87d+YtqSiWhwOjPKhwhmzZDY39AmLgb5iXU/FWPeXZftjhZcnMuKi YoG9Q0ygmbB1eeh1DhGbKtyPLIm3+3vmHn1rDcGy+7EC+F5n4LtdNaqrGPRbhEzxbLsFN3 g2xOF6z6+TNUV29iKmzFt0NwvExBouPKwv42cAKgKFw0mG6PbJsKvsUTVrHDCFHm2AQWoV 3bJOMN7/gYXVxWEQqJ4Ko5HhiA4wuiniytoCn2f9g7tinMMjU0eA9WFa1QA+JAPft/s4TU MPzwtC7VeNBqgRisPe3Od0/poqPKozyXpC1BNHvqfaQ8bhahrTkJgmU1cBEJ/A== ARC-Seal: i=1; s=key1; d=yhetil.org; t=1657417885; a=rsa-sha256; cv=none; b=e33Fre+SZK29hXlJ6g7alMkbmWxM+SDFOxwIBLXQz3yfI2jWOSitHkK3D2rAjv3ffz0ZeR ErAtmAb4/9LYmpdt1t2nznQJA40Ccz4Ci7WzgE1jvA60UWXSROUJ17k78fZthBKW8y5rww ijIKQteuu1zRsKsKe/zJ+irAWP7qS8jzssxJaKOtAf+ZVwgkhEULJIxjpD7Y4Jq9fxihL8 1zRA5E3P/SUsqp7pUAZc4U0Dx0qAQmHCqJ3inQVg+Sda3zzUU0PqJuhQIy0UQ4geYbP6bq KDjlMTRS8dpznYOM8ylwpalKpXuYkRwRDHZKWqN5ly0L1iy6kp+nDZyhIr1fiQ== ARC-Authentication-Results: i=1; aspmx1.migadu.com; dkim=pass header.d=dismail.de header.s=20190914 header.b=P602fFU3; dmarc=pass (policy=reject) header.from=dismail.de; spf=pass (aspmx1.migadu.com: domain of "help-guix-bounces+larch=yhetil.org@gnu.org" designates 209.51.188.17 as permitted sender) smtp.mailfrom="help-guix-bounces+larch=yhetil.org@gnu.org" X-Migadu-Spam-Score: -2.05 Authentication-Results: aspmx1.migadu.com; dkim=pass header.d=dismail.de header.s=20190914 header.b=P602fFU3; dmarc=pass (policy=reject) header.from=dismail.de; spf=pass (aspmx1.migadu.com: domain of "help-guix-bounces+larch=yhetil.org@gnu.org" designates 209.51.188.17 as permitted sender) smtp.mailfrom="help-guix-bounces+larch=yhetil.org@gnu.org" X-Migadu-Queue-Id: 11EE211F2 X-Spam-Score: -2.05 X-Migadu-Scanner: scn1.migadu.com X-TUID: c1aiMh6AA9RB Hi Guixers, Why do we check if python is a promise and then "force" it? I'm just trying to understand the thinking for doing that since I didn't write this code. ``` (let ((python (if (promise? python) (force python) python))) ... ``` I understand that force makes a promise evaluate (laziness). That's about as much as I know. guix/build-system/python.scm:119 all best, jgart