From mboxrd@z Thu Jan 1 00:00:00 1970 Path: news.gmane.io!.POSTED.blaine.gmane.org!not-for-mail From: Michael Heerdegen Newsgroups: gmane.emacs.bugs Subject: bug#61281: =?UTF-8?Q?=E2=80=9C`?=(a \, b)=?UTF-8?Q?=E2=80=9D?= equals to =?UTF-8?Q?=E2=80=9C`?=(a . , b)=?UTF-8?Q?=E2=80=9D?= Date: Mon, 06 Feb 2023 00:56:00 +0100 Message-ID: <87fsbju0of.fsf@web.de> References: <87a61tgdkx.fsf@web.de> <875ycghgv1.fsf@web.de> <871qn4hfte.fsf@web.de> Mime-Version: 1.0 Content-Type: text/plain Injection-Info: ciao.gmane.io; posting-host="blaine.gmane.org:116.202.254.214"; logging-data="26840"; mail-complaints-to="usenet@ciao.gmane.io" User-Agent: Gnus/5.13 (Gnus v5.13) Cc: Xie Shynur , "61281@debbugs.gnu.org" <61281@debbugs.gnu.org> To: Drew Adams Original-X-From: bug-gnu-emacs-bounces+geb-bug-gnu-emacs=m.gmane-mx.org@gnu.org Mon Feb 06 00:57:28 2023 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 1pOosx-0006pN-Ts for geb-bug-gnu-emacs@m.gmane-mx.org; 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Mon, 06 Feb 2023 00:56:01 +0100 In-Reply-To: (Drew Adams's message of "Sun, 5 Feb 2023 15:53:58 +0000") X-Provags-ID: V03:K1:S+ex5Kjaqj4UciDlzuMne+q395AfM/In5P2Hg4IYLQWAhJVn7Zx ZQRMZ3z5NEuhIknLVfRvdXfSKtcC54ZZZsIzQYrUGI2XZpTkxhlrtY60dufqhCn8lrnW9dG EU7Bj/c+RDFljL7b6syYXgoJVNZaOJWWk/x2RGbmjFqkQKZkIUU4IVWCCtxtu17iWE43f5Q /ANeYUlQt1gT55C0G9KVg== UI-OutboundReport: notjunk:1;M01:P0:c7RTP891OA0=;ShtVBZp+UAdNkkr8F3QquRNC+Ld +l5Z0SfSlYu/zusYpBkaQZomqp546SbxG4E/UXiSXFmxp+iMO2VbokPov5NkjQSof1Nw0j5aW iUfVDSe9W8Oo0MODjLzAdNnbrLXHRIf1qnsOemJqr0gLKR2+8EGlgl/k8kYmC42JvEmgKeG02 Puw2A2m2rnB/oMRZ8wCWlgMkZBWtBDOe/bNAODT/NbW8C+JQmb30CMUFwkZXjXBPMU6EK4jCJ 9hN3qkAbunBKKH7UZ4cw27AE5yRyqhhFe2XKomes75F3o3i5utG1R6TTnEbfuOJkNYXUT40En /Na2W44c8EYzzHb0e2SM9F/XpADEPWwzkZkcEoH8XV9GWjU7yxIfEzdIetIrUZg2niiDBINgk 2bq35HoALyxfRl/XhAF8t2ERaoxDkRcbJZlklmE8SNmin9uxoJ0OgPBYGu8ydl7prxuTNygeO MQR2YWaWQ2hCfZJ1m0iFEwO1TGDEBfcxWPUBDWv+2pkSdhR560EuKYEPT8GQbMQ9H25WWmUxI gmoM26TRk01iLx5akknpWSj0vo6cD8EvnSXM7mWNymmtQyK0ufKXYCAIV7BYAaQ+W3o3SiL1H eA8m+S5b6knrFCDagOqoJh2pn+HTWmEis/GVSiMEE38LJYiI5M6H8ssnchnPEHwLELFC+PKCu KsF7e9jjCWvWLEvpISi+4klef8hloEdYoIk3QodFtZkMKF2h/rwuxHldEbPec/RHRvOPEqrP9 dH9eTlHBnc/NYes8R2KOSssYGZfRvHOq+REYk/gpkpkgGrWVx/6y+Muak3X01VT37OCvRRLS 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-bounces+geb-bug-gnu-emacs=m.gmane-mx.org@gnu.org Xref: news.gmane.io gmane.emacs.bugs:254908 Archived-At: Drew Adams writes: > Dunno. (read ",foo") and (read ", foo" return > (\, foo). Why? (Just because the current > implementation of backquote depends on that?) As I said: any other format would lead to the same "problem", no? Unless ",X" is something "meta" that has no reader-construct-less expansion at all. > (read "'foo") returns just 'foo - it doesn't > return (quote foo). (read "`foo") returns > `foo, not (backquote foo). (read "`,foo") > returns `,foo. You forget that the printer is able to produce this format. Try `car'. > Notice the error msg from (eval ',foo): > > Debugger entered--Lisp error: (void-function \,) > ,foo > eval(,foo) > (progn (eval ',foo)) > > Nothing in (normal) Lisp syntax shows the use > of comma as a function. ,foo doesn't look > like function-call syntax, does it? Another side effect of ,X being equivalent to (\, X.). That's the only thing you need to remember. When you eval that, you should not be surprised that it's evaluated like ... Lisp evaluates things. > And here's the error from either (read ",") > or (eval (read ",")): > > End of file during parsing > > Yes, an error should be reported in each case, > but I think it should just say that comma is > undefined outside of backquote. S-exps are defined recursively. ",X" is read syntax of a valid s-exp, and I don't think we want to make the reader raise an error for it. But the reader expects an expression following the ",". And a single "," is _not_the read syntax of the symbol with the name "," (that is "\,": (symbol-name (read "\\,")) --> ","). So "End of file during parsing" is an appropriate message: no complete expression could be read, but something that looks like the start of an expression. Ok, so everything is about that you don't want that ,X and (\, X) are equivalent. All your arguments were of the kind "the implications are surprising". But you never answered the core question: what should ,X expand to instead that would not have any of these implications? Else all you say is that it's surprising when you lack knowledge. OTOH it seems not easy to find the information ,X == (\, X) somewhere. Is there a place where there is said something about the kind of expression the reader construct ,X produces? I didn't find anything in a rush. It should be explained, else this thing indeed can lead to surprises, as the one reported here. Michael.