From: "Pascal J. Bourguignon" <pjb@informatimago.com>
To: help-gnu-emacs@gnu.org
Subject: Re: plists, alists, and hashtables
Date: Sat, 08 Aug 2015 05:48:34 +0200 [thread overview]
Message-ID: <87r3nejv8t.fsf@kuiper.lan.informatimago.com> (raw)
In-Reply-To: mailman.7941.1438965165.904.help-gnu-emacs@gnu.org
Stefan Monnier <monnier@iro.umontreal.ca> writes:
> I think what you're getting at is that (core) Lisp is somewhat
> "untyped", so alists/plists can't be distinguished from other data built
> using cons-cells: only the user knows whether that cons cells is meant
> to be an alist or a plist or something else.
This is a strawman argument.
You can always wrap a-lists into a tagged type (a structure), and only
touch it thru checked functions. This is what my dictionary abstraction
does. Therefore you can prove that your a-list will never be
ill-formed.
This is useless, it's still more practical to use plain a-list, and not
for the syntax, but for the very reason that you can process a plain
a-list as if it wasn't an a-list and break the a-list invariant.
If your programming process require a formal approach where you have the
computer check your invariants, then be sure to wrap your a-lists in a
structure and a functional abstraction that let you control it.
Otherwise, you can use a-list directly, and syntactic suggar won't help,
but on the contrary detract you from writing good code.
--
__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:[~2015-08-08 3:48 UTC|newest]
Thread overview: 55+ messages / expand[flat|nested] mbox.gz Atom feed top
2015-07-31 21:42 How to iterate over properties in a plist? Marcin Borkowski
2015-07-31 22:18 ` Stefan Monnier
2015-07-31 22:29 ` Marcin Borkowski
2015-07-31 22:42 ` Dmitry Gutov
2015-08-01 13:34 ` Michael Heerdegen
[not found] ` <mailman.7705.1438381807.904.help-gnu-emacs@gnu.org>
2015-07-31 23:33 ` Pascal J. Bourguignon
2015-08-01 22:49 ` Stefan Monnier
[not found] ` <mailman.7750.1438469396.904.help-gnu-emacs@gnu.org>
2015-08-04 10:15 ` plists, alists, and hashtables (was: How to iterate over properties in a plist?) Ted Zlatanov
2015-08-04 10:29 ` Nicolas Petton
[not found] ` <mailman.7809.1438684158.904.help-gnu-emacs@gnu.org>
2015-08-04 11:23 ` plists, alists, and hashtables Ted Zlatanov
2015-08-05 4:36 ` plists, alists, and hashtables (was: How to iterate over properties in a plist?) Rusi
2015-08-05 6:12 ` plists, alists, and hashtables Pascal J. Bourguignon
2015-08-05 9:47 ` Ted Zlatanov
2015-08-05 12:20 ` Rusi
2015-08-06 19:16 ` Stefan Monnier
[not found] ` <mailman.7892.1438888819.904.help-gnu-emacs@gnu.org>
2015-08-07 16:33 ` Rusi
2015-08-05 17:24 ` Pascal J. Bourguignon
2015-08-05 18:31 ` Ted Zlatanov
2015-08-05 19:30 ` Barry Margolin
2015-08-05 19:40 ` Robert Thorpe
2015-08-05 21:11 ` Pascal J. Bourguignon
2015-08-06 15:17 ` Ted Zlatanov
2015-08-06 18:46 ` Pascal J. Bourguignon
2015-08-06 20:19 ` Drew Adams
2015-08-06 21:08 ` Ted Zlatanov
2015-08-07 0:23 ` Pascal J. Bourguignon
2015-08-06 19:35 ` Stefan Monnier
2015-08-05 13:48 ` Drew Adams
2015-08-06 19:12 ` Stefan Monnier
[not found] ` <mailman.7890.1438888393.904.help-gnu-emacs@gnu.org>
2015-08-06 20:00 ` Pascal J. Bourguignon
2015-08-06 20:57 ` Ted Zlatanov
2015-08-06 21:10 ` Drew Adams
[not found] ` <mailman.7902.1438895429.904.help-gnu-emacs@gnu.org>
2015-08-06 21:15 ` Ted Zlatanov
2015-08-06 21:31 ` Stefan Monnier
2015-08-07 1:53 ` Ted Zlatanov
2015-08-07 7:34 ` Pascal J. Bourguignon
2015-08-07 16:32 ` Stefan Monnier
[not found] ` <mailman.7941.1438965165.904.help-gnu-emacs@gnu.org>
2015-08-08 3:48 ` Pascal J. Bourguignon [this message]
2015-08-08 13:42 ` Stefan Monnier
2015-08-08 14:51 ` Rusi
2015-08-07 0:08 ` Pascal J. Bourguignon
2015-08-07 2:14 ` Ted Zlatanov
2015-08-07 7:53 ` Pascal J. Bourguignon
2015-08-07 11:21 ` Ted Zlatanov
2015-08-07 11:47 ` Pascal J. Bourguignon
2015-08-07 17:21 ` Ted Zlatanov
2015-08-07 19:21 ` Stefan Monnier
[not found] ` <mailman.7952.1438975314.904.help-gnu-emacs@gnu.org>
2015-08-08 3:52 ` Pascal J. Bourguignon
2015-08-07 16:35 ` Stefan Monnier
[not found] <mailman.7856.1438803631.904.help-gnu-emacs@gnu.org>
2015-08-05 20:08 ` Ted Zlatanov
2015-08-05 20:45 ` Stefan Monnier
2015-08-05 21:36 ` Drew Adams
2015-08-05 21:41 ` Pascal J. Bourguignon
[not found] ` <mailman.7860.1438807554.904.help-gnu-emacs@gnu.org>
2015-08-06 1:32 ` Ted Zlatanov
[not found] ` <mailman.7862.1438810623.904.help-gnu-emacs@gnu.org>
2015-08-06 1:36 ` Ted Zlatanov
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