From: Marcin Borkowski <mbork@mbork.pl>
To: Alan Mackenzie <acm@muc.de>
Cc: emacs-devel@gnu.org
Subject: Re: 7 logical-xor implementations in source tree
Date: Wed, 31 Jul 2019 19:12:34 +0200 [thread overview]
Message-ID: <87y30eqgal.fsf@mbork.pl> (raw)
In-Reply-To: <20190730093651.GA5427@ACM>
On 2019-07-30, at 11:36, Alan Mackenzie <acm@muc.de> wrote:
> Hello, Marcin.
>
> On Sun, Jul 28, 2019 at 21:43:19 +0200, Marcin Borkowski wrote:
>
>> On 2019-07-28, at 10:04, Alan Mackenzie <acm@muc.de> wrote:
>
>> > Hello, Philippe.
>
>> > On Sun, Jul 28, 2019 at 09:09:01 +0200, Philippe Schnoebelen wrote:
>> >> On 2019/07/25 14:07, Mattias Engdegård wrote:
>> >> > 25 juli 2019 kl. 01.44 skrev Basil L. Contovounesios <contovob@tcd.ie>:
>
>
>> >> > bool-equal, bool-equiv, bool=, bool-eq are all fine as far as I'm concerned. `xnor' and `nxor', not so much.
>> >> > Racket has `boolean=?', but presumably it only copes with #t/#f.
>> >> > I'll be using `equiv' as placeholder below for brevity.
>
>> >> I like the name `iff' for this function.
>
>> > No, please don't use the name `iff' here. In mathematical circles, iff
>> > means "if and only if", and has done for many decades/several centuries.
>> > Introducing it into Emacs with a radically different meaning will be
>> > jarring in the extreme to anybody with a maths background.
>
>> Out of curiosity: how is that a "radically different meaning"? I assume
>> that we are talking about a function `iff' such that
>> (iff nil nil) evaluates to t
>> (iff nil <non-nil>) evaluates to nil
>> (iff <non-nil> nil) evaluates to nil
>> (iff <non-nil> <non-nil>) evaluates to t (or perhaps the latter
>> <non-nil>)
>
> Er, it's not radically different. My brain seems to have been switched
> off when I wrote my last post. Apologies.
No worry.
> Less importantly, I don't like iff being used in this way. I'm not sure
> why. Maybe it's because I've been used to iff applying solely to TRUE
> and FALSE. Maybe it's that I've been used to iff declaring a
> proposition, rather than being something to be calculated.
Well, these are subjective points, but there are much stronger arguments
against `iff' raised by others...
Best,
--
Marcin Borkowski
http://mbork.pl
next prev parent reply other threads:[~2019-07-31 17:12 UTC|newest]
Thread overview: 51+ messages / expand[flat|nested] mbox.gz Atom feed top
2019-07-22 18:48 7 logical-xor implementations in source tree Oleh Krehel
2019-07-22 21:47 ` Basil L. Contovounesios
2019-07-24 22:17 ` Basil L. Contovounesios
2019-07-24 23:15 ` Stefan Monnier
2019-07-24 23:44 ` Basil L. Contovounesios
2019-07-25 12:07 ` Mattias Engdegård
2019-07-25 17:28 ` Paul Eggert
2019-07-25 17:46 ` Mattias Engdegård
2019-07-28 7:09 ` Philippe Schnoebelen
2019-07-28 8:04 ` Alan Mackenzie
2019-07-28 19:43 ` Marcin Borkowski
2019-07-30 9:36 ` Alan Mackenzie
2019-07-30 10:57 ` Philippe Schnoebelen
2019-07-30 11:28 ` Andy Moreton
2019-07-30 12:34 ` Stefan Monnier
2019-07-30 14:25 ` Barry Fishman
2019-07-31 3:16 ` Richard Stallman
2019-07-31 15:20 ` Barry Fishman
2019-07-31 15:42 ` Stefan Monnier
2019-07-31 20:22 ` Basil L. Contovounesios
2019-07-31 21:15 ` Michael Heerdegen
2019-07-31 22:28 ` Mattias Engdegård
2019-07-31 23:39 ` Basil L. Contovounesios
2019-08-02 10:29 ` Mattias Engdegård
2019-08-02 10:59 ` Basil L. Contovounesios
2019-08-06 11:58 ` Mattias Engdegård
2019-07-31 20:31 ` Michael Heerdegen
2019-07-31 21:38 ` Drew Adams
2019-07-31 22:03 ` Drew Adams
2019-07-31 22:05 ` Basil L. Contovounesios
2019-07-31 23:20 ` Drew Adams
2019-08-01 0:09 ` Basil L. Contovounesios
2019-07-31 17:12 ` Marcin Borkowski [this message]
2019-07-23 8:39 ` Andy Moreton
2019-07-23 9:08 ` Basil L. Contovounesios
2019-07-23 9:14 ` Mattias Engdegård
2019-07-23 10:26 ` Andy Moreton
2019-07-23 10:40 ` Andreas Schwab
2019-07-23 12:11 ` Andy Moreton
2019-07-23 13:20 ` Basil L. Contovounesios
2019-07-23 13:54 ` Andy Moreton
2019-07-24 22:21 ` Basil L. Contovounesios
2019-07-23 10:44 ` Basil L. Contovounesios
2019-07-23 11:01 ` Yuri Khan
2019-07-25 21:46 ` Juri Linkov
2019-07-23 11:24 ` Noam Postavsky
2019-07-23 12:38 ` Stefan Monnier
2019-07-23 16:41 ` Mattias Engdegård
2019-07-23 17:12 ` Eli Zaretskii
2019-07-23 17:48 ` Paul Eggert
2019-07-23 19:45 ` Stefan Monnier
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