From mboxrd@z Thu Jan 1 00:00:00 1970 Path: news.gmane.io!.POSTED.blaine.gmane.org!not-for-mail From: Philip Kaludercic Newsgroups: gmane.emacs.devel Subject: Re: cond* vs pcase Date: Tue, 06 Feb 2024 16:50:02 +0000 Message-ID: <87o7cttu4l.fsf@posteo.net> References: <87il32iwmm.fsf@posteo.net> Mime-Version: 1.0 Content-Type: text/plain Injection-Info: ciao.gmane.io; posting-host="blaine.gmane.org:116.202.254.214"; logging-data="6714"; mail-complaints-to="usenet@ciao.gmane.io" Cc: arthur.miller@live.com, emacs-devel@gnu.org To: "Alfred M. 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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:315933 Archived-At: "Alfred M. Szmidt" writes: > "Alfred M. Szmidt" writes: > > > I use pcase often; but I use it just as a better cond. For example I find this > > handy: > > > > (defvar foo nil) <-- foo is some symbol > > > > (pcase foo > > ('bar (do-some-bar-stuff)) > > ('baz (do-some-baz-fluff))) > > > > cl-case seems more appropriate here (wish cl-case was just case ...) > > Why more appropriate? > > Because your not doing pattern matching, you're comparing against a > set of strings/symbols/numbers/.... Simply because pattern matching is a more powerful generalisation, capable of expressing case-distinction; in the end it compiles down to almost the same code anyway. > I always think of pcase as Elisp's case. In > addition, pcase avoids the danger of naively writing > > (cl-case foo > ('bar (do-some-bar-stuff)) > ('baz (do-some-baz-fluff))) > > and then getting surprised when foo evaluates to `quote'. > > Suprises will happy, you will get suprises with pcase and cond* too -- > I find it suprising that to match over symbols requires pattern > matching. One might also question why you (well, no you specifically) > are comparing against (quote bar) etc? That is a suprise in it self... I don't understand your point here. If one expects the cases to be evaluated, then quoting makes sense if you want to match a symbol. It is not true, but common enough that the byte compiler emits a warning. > > or this: > > > > (setq foo "some-string") > > > > (pcase foo > > ("foo" (do-foo-case)) > > ("bar" (do-bar-case))) > > > > Same here, with (intern foo) ... > > Being able to do equal instead of eql is also something that speaks in > favour of pcase... > > It speaks more in favor of having CASE where you can change the > comparison operator or a CASE-STRING or similar, not something much > more generic pcase (or even cond*!) -- i.e. why use pcase/cond* when > you're not using any of the features that are the main point of those > two macros. I am sorry, but I don't follow your point here either. Is the general claim, that one should only use whatever exactly and at most satisfies the needs at hand?