From mboxrd@z Thu Jan 1 00:00:00 1970 Path: news.gmane.io!.POSTED.blaine.gmane.org!not-for-mail From: Stefan Monnier Newsgroups: gmane.emacs.devel Subject: Re: Declaring Lisp function types Date: Sun, 03 Mar 2024 09:52:23 -0500 Message-ID: References: Mime-Version: 1.0 Content-Type: text/plain Injection-Info: ciao.gmane.io; posting-host="blaine.gmane.org:116.202.254.214"; logging-data="22473"; mail-complaints-to="usenet@ciao.gmane.io" User-Agent: Gnus/5.13 (Gnus v5.13) Cc: Stefan Monnier via "Emacs development discussions." To: Andrea Corallo Original-X-From: emacs-devel-bounces+ged-emacs-devel=m.gmane-mx.org@gnu.org Sun Mar 03 15:52:55 2024 Return-path: Envelope-to: ged-emacs-devel@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 1rgnCx-0005co-KP for ged-emacs-devel@m.gmane-mx.org; Sun, 03 Mar 2024 15:52:55 +0100 Original-Received: from localhost ([::1] helo=lists1p.gnu.org) by lists.gnu.org with esmtp (Exim 4.90_1) (envelope-from ) id 1rgnCZ-00029d-4w; Sun, 03 Mar 2024 09:52:31 -0500 Original-Received: from eggs.gnu.org ([2001:470:142:3::10]) by lists.gnu.org with esmtps (TLS1.2:ECDHE_RSA_AES_256_GCM_SHA384:256) (Exim 4.90_1) (envelope-from ) id 1rgnCX-00029R-IS for emacs-devel@gnu.org; Sun, 03 Mar 2024 09:52:29 -0500 Original-Received: from mailscanner.iro.umontreal.ca ([132.204.25.50]) by eggs.gnu.org with esmtps (TLS1.2:ECDHE_RSA_AES_256_GCM_SHA384:256) (Exim 4.90_1) (envelope-from ) id 1rgnCV-0005k0-Sj; Sun, 03 Mar 2024 09:52:29 -0500 Original-Received: from pmg3.iro.umontreal.ca (localhost [127.0.0.1]) by pmg3.iro.umontreal.ca (Proxmox) with ESMTP id B01A744169D; Sun, 3 Mar 2024 09:52:25 -0500 (EST) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=iro.umontreal.ca; s=mail; t=1709477544; bh=X3phmyT31y/xLQig9UPuwRs4rjtGeL+Z98bhYzewF0o=; h=From:To:Cc:Subject:In-Reply-To:References:Date:From; b=dYwfzPZlGpoHijFyOwGfIaYNzxLHEwK4gInZAv0VhZ4PzyiMWWpy9aaiDMGmJ+a3s U6v5ITn91HoJ6KD4c/PSUMd6BQusYPqvqGY0VOlbeHFJvcY6lqWhaenFJD+u1Vf6q8 AQ4wiet7hflJsCm6w0tG7ZCyOWR4HcTo/ijNC2TyG6z29S6uwNRgGvsuhdQHEgww1w TKrJx2qDf8aYI9+y7v/jgLyKMwV7NtsnGkP3hzZs1g1cC4CbEoeBRUfcfDpHlEI7Ny z2AFewGsJ1pRiLy8Tx+tcnKpluyxf/hGN4sCsgVPMFINVrHIltcrST/yoAa/qHlGE4 R4lNa8Afd4WzQ== Original-Received: from mail01.iro.umontreal.ca (unknown [172.31.2.1]) by pmg3.iro.umontreal.ca (Proxmox) with ESMTP id 4040B441625; Sun, 3 Mar 2024 09:52:24 -0500 (EST) Original-Received: from pastel (unknown [216.154.1.84]) by mail01.iro.umontreal.ca (Postfix) with ESMTPSA id 1D1C41202C7; Sun, 3 Mar 2024 09:52:24 -0500 (EST) In-Reply-To: (Andrea Corallo's message of "Sun, 03 Mar 2024 04:52:52 -0500") Received-SPF: pass client-ip=132.204.25.50; envelope-from=monnier@iro.umontreal.ca; helo=mailscanner.iro.umontreal.ca X-Spam_score_int: -42 X-Spam_score: -4.3 X-Spam_bar: ---- X-Spam_report: (-4.3 / 5.0 requ) BAYES_00=-1.9, DKIM_SIGNED=0.1, DKIM_VALID=-0.1, DKIM_VALID_AU=-0.1, RCVD_IN_DNSWL_MED=-2.3, 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: emacs-devel@gnu.org X-Mailman-Version: 2.1.29 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-mx.org@gnu.org Original-Sender: emacs-devel-bounces+ged-emacs-devel=m.gmane-mx.org@gnu.org Xref: news.gmane.io gmane.emacs.devel:316755 Archived-At: >> so I see no semantic issue with using `ftype` or `type` here, unless >> there are functions whose type could take another form than (function >> )? Are you thinking of types like >> (or (function (int) int) (function (float) float))? > > That's a good example why it would be good to be able to accept the type > specifier as a declaration with no tricks. Then I'd go with (declare (type (function ..))) This may be a bit more verbose, but it's simple and clear. And to the extent that people are worried that it could become pervasive and even mandatory, I think verbose is good. > On the specific case I'm not sure we want to support this in the inner > machinery (at least for now). +1 >> More important I think is to document what such annotations mean and >> what they should look like (currently, this is not super important, >> because the annotations live together with the code that uses them, but >> if we move them outside of `comp.el`, the "contract" needs to be made >> more explicit). >> - How they interact with `&optional` and `&rest` (or even `&key` for >> `c-defun`). > ATM we already support in type specifiers `&optional` and `&rest`: I know, but it needs to be documented. > Not sure we want to handle &key as well as it looks to me not very > native to the elisp machinery. OTOH cl-defun just expands to the > native elisp call convention. FWIW, I agree. >> - What will/could happen if one of the arguments does not have the >> specified type? > I think if ones does a declaration has to declare the type of all > arguments (rest should be optional). I mean, what happens (both at compile-time and at run-time) when `my-fun` says (function (number) number) but we call it with a string? >> - What will/could happen if the result does not have the >> specified type? > I think we want to complete it with the inferred return type if we have > it or t otherwise. Same here: I meant what happens when `my-fun` actually returns nil even though its own type declaration claims it returns a number? Maybe we should also give a hint about the potential benefits (how it influences the generated code), so coders can have a better idea about when a type annotation is worthwhile and when it's not. Stefan