From: "Pascal J. Bourguignon" <pjb@informatimago.com>
To: help-gnu-emacs@gnu.org
Subject: Re: no empty (zero) string predicate in Elisp
Date: Sun, 26 Apr 2015 17:03:01 +0200 [thread overview]
Message-ID: <87oambhqze.fsf@kuiper.lan.informatimago.com> (raw)
In-Reply-To: 87wq0zkqxa.fsf@debian.uxu
Emanuel Berg <embe8573@student.uu.se> writes:
>> not higher-level either
>
> I don't know the scientific definition of "high-level"
> - or how it applies to these three Elisp functions.
>
> The reason I want a binary operator is that it is more
> intuitive: it refects my way of thinking - "is the
> string empty?" vs. "is the string equal to another
> string that is empty?" - also, because a binary
> operator reduces the number of data items in the code
> (with one, the empty string).
The only problem with that, is that a binary operator has 2 arguments:
(binop a b)
therefore if you want a binary operator, you want:
(string= s "")
On the other hand, if you want only one argument, then you want a unary
operator:
(unary a)
and when this unary operator returns a boolean, you call it a predicate:
(emptyp s)
> In general, I don't want the same function to be
> spelled out over and over to do the same thing -
> instead, I want it factored out, named, and invoked
> with a "minimal", that is, sufficient, interface.
Definitely.
--
__Pascal Bourguignon__ http://www.informatimago.com/
“The factory of the future will have only two employees, a man and a
dog. The man will be there to feed the dog. The dog will be there to
keep the man from touching the equipment.” -- Carl Bass CEO Autodesk
next prev parent reply other threads:[~2015-04-26 15:03 UTC|newest]
Thread overview: 28+ messages / expand[flat|nested] mbox.gz Atom feed top
2015-04-25 3:44 no empty (zero) string predicate in Elisp Emanuel Berg
2015-04-25 9:26 ` Nicolas Petton
2015-05-16 9:23 ` Nicolas Petton
2015-05-16 13:22 ` Bozhidar Batsov
2015-05-16 13:28 ` Bozhidar Batsov
2015-05-16 13:36 ` Bozhidar Batsov
2015-05-16 13:46 ` Eli Zaretskii
2015-05-16 16:17 ` Bozhidar Batsov
2015-05-16 13:43 ` Stefan Monnier
2015-05-16 15:27 ` Drew Adams
[not found] ` <mailman.1583.1429954907.904.help-gnu-emacs@gnu.org>
2015-04-25 11:22 ` Emanuel Berg
2015-04-25 13:30 ` Stefan Monnier
[not found] ` <mailman.1591.1429968677.904.help-gnu-emacs@gnu.org>
2015-04-25 14:48 ` Pascal J. Bourguignon
2015-04-26 2:52 ` Stefan Monnier
2015-04-27 10:28 ` zerop: compiler macro vs defsubst (was: no empty (zero) string predicate in Elisp) Nicolas Richard
2015-04-27 12:19 ` zerop: compiler macro vs defsubst Stefan Monnier
[not found] ` <mailman.1626.1430016741.904.help-gnu-emacs@gnu.org>
2015-04-26 4:06 ` no empty (zero) string predicate in Elisp Pascal J. Bourguignon
2015-04-26 21:25 ` Stefan Monnier
2015-04-26 4:26 ` Rusi
2015-04-26 12:36 ` Emanuel Berg
2015-04-26 15:03 ` Pascal J. Bourguignon [this message]
2015-04-26 18:34 ` Emanuel Berg
2015-04-26 18:59 ` Marcin Borkowski
[not found] ` <mailman.1658.1430074770.904.help-gnu-emacs@gnu.org>
2015-04-26 19:06 ` Emanuel Berg
2015-04-26 20:11 ` Marcin Borkowski
[not found] ` <mailman.1662.1430079142.904.help-gnu-emacs@gnu.org>
2015-04-27 1:00 ` Emanuel Berg
2015-04-26 17:28 ` Rusi
2015-04-26 18:39 ` Emanuel Berg
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