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Re: no empty (zero) string predicate in Elisp
From: |
Pascal J. Bourguignon |
Subject: |
Re: no empty (zero) string predicate in Elisp |
Date: |
Sun, 26 Apr 2015 17:03:01 +0200 |
User-agent: |
Gnus/5.13 (Gnus v5.13) Emacs/24.3 (gnu/linux) |
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
- Re: no empty (zero) string predicate in Elisp, (continued)
Re: no empty (zero) string predicate in Elisp, Stefan Monnier, 2015/04/25
Message not available
Message not availableRe: no empty (zero) string predicate in Elisp, Pascal J. Bourguignon, 2015/04/26
Re: no empty (zero) string predicate in Elisp, Stefan Monnier, 2015/04/26
Message not availableRe: no empty (zero) string predicate in Elisp, Rusi, 2015/04/26
Message not available
- Re: no empty (zero) string predicate in Elisp, Emanuel Berg, 2015/04/26
- Re: no empty (zero) string predicate in Elisp,
Pascal J. Bourguignon <=
- Re: no empty (zero) string predicate in Elisp, Emanuel Berg, 2015/04/26
- Re: no empty (zero) string predicate in Elisp, Marcin Borkowski, 2015/04/26
- Message not available
- Re: no empty (zero) string predicate in Elisp, Emanuel Berg, 2015/04/26
- Re: no empty (zero) string predicate in Elisp, Marcin Borkowski, 2015/04/26
- Message not available
- Re: no empty (zero) string predicate in Elisp, Emanuel Berg, 2015/04/26
Re: no empty (zero) string predicate in Elisp, Rusi, 2015/04/26
Re: no empty (zero) string predicate in Elisp, Emanuel Berg, 2015/04/26