From: Dmitry Gutov <dgutov@yandex.ru>
To: "Stephen J. Turnbull" <stephen@xemacs.org>
Cc: 'xfq' <xfq.free@gmail.com>, Drew Adams <drew.adams@oracle.com>,
emacs-devel@gnu.org
Subject: Re: /srv/bzr/emacs/trunk r112347: *doc/lispintro/emacs-lisp-intro.texi (defcustom, defun, simplified-beginning-of-buffer, defvar, Building Robots, Review, save-excursion): `defun' and `defcustom' are now macros rather thanspecial forms. (Bug#13853)
Date: Mon, 22 Apr 2013 05:47:36 +0400 [thread overview]
Message-ID: <87y5cb2v5z.fsf@yandex.ru> (raw)
In-Reply-To: <8738uj22gl.fsf@uwakimon.sk.tsukuba.ac.jp> (Stephen J. Turnbull's message of "Mon, 22 Apr 2013 02:55:22 +0900")
"Stephen J. Turnbull" <stephen@xemacs.org> writes:
> Dmitry Gutov writes:
>
> > http://www.nhplace.com/kent/Papers/Special-Forms.html starts with:
> >
> > "Special forms are those expressions in the Lisp language which do not
> > follow normal rules for evaluation.
>
> This is much broader than common usage, though, since it explicitly
> includes macros.
>
> In Commmon Lisp, which has a very narrow (extensional) definition of
> "special form"[1], it seems to me the intent of the definition is to
> describe those features of the language which are "unfunctional".
Ah, I see now. The definition is on the separate page, and there it says
that a special form != macro form, and the car of a special form must be
a special operator (from the predefined list):
http://www.lispworks.com/documentation/HyperSpec/Body/26_glo_s.htm#special_form
So at least that spec agrees with the narrow definition, as well as
with `special-form-p' implementation (like Drew mentioned).
CLTL 2nd Edition, though, allows implementing special forms as macros:
http://www.cs.cmu.edu/Groups/AI/html/cltl/clm/node59.html
and that's what happened to `defun' between Emacs 24.2 and 24.3, when
its implementation moved from C to Elisp. I think it would make sense to
still consider `defun' a special form, despite the implementation change.
> > I dunno, calling anything that can be used as a car of an evaluatable
> > sexp a "function" makes sense in general context.
>
> But there's a reason to avoid that usage where possible. In Lisp,
> functions are "funcall-able", while special operators and macros are
> not. This makes functions "first class" objects in a way that special
> operators and macros are not.
Sure, I just meant that the usage of "function" in the introduction
makes enough sense, despite the lack of precision.
> Footnotes:
> [1] http://www.lispworks.com/documentation/HyperSpec/Body/03_ababa.htm#clspecialops
next prev parent reply other threads:[~2013-04-22 1:47 UTC|newest]
Thread overview: 25+ messages / expand[flat|nested] mbox.gz Atom feed top
[not found] <E1UTtCq-0003Tj-Lr@vcs.savannah.gnu.org>
2013-04-21 12:39 ` /srv/bzr/emacs/trunk r112347: * doc/lispintro/emacs-lisp-intro.texi (defcustom, defun, simplified-beginning-of-buffer, defvar, Building Robots, Review, save-excursion): `defun' and `defcustom' are now macros rather than special forms. (Bug#13853) Leo Liu
2013-04-21 13:00 ` xfq
2013-04-21 14:00 ` Dmitry Gutov
2013-04-21 16:55 ` /srv/bzr/emacs/trunk r112347: *doc/lispintro/emacs-lisp-intro.texi (defcustom, defun, simplified-beginning-of-buffer, defvar, Building Robots, Review, save-excursion): `defun' and `defcustom' are now macros rather thanspecial " Drew Adams
2013-04-21 17:14 ` Dmitry Gutov
2013-04-21 17:55 ` Stephen J. Turnbull
2013-04-22 1:47 ` Dmitry Gutov [this message]
2013-04-21 18:04 ` Drew Adams
2013-04-21 18:57 ` Stephen J. Turnbull
2013-04-21 19:40 ` /srv/bzr/emacs/trunk r112347:*doc/lispintro/emacs-lisp-intro.texi (defcustom, defun, simplified-beginning-of-buffer, defvar, Building Robots, Review, save-excursion): `defun' and `defcustom' are now macros ratherthanspecial " Drew Adams
2013-04-22 1:21 ` Stephen J. Turnbull
2013-04-22 1:35 ` /srv/bzr/emacs/trunk r112347:*doc/lispintro/emacs-lisp-intro.texi(defcustom, defun, simplified-beginning-of-buffer, defvar, Building Robots, Review, save-excursion): `defun' and `defcustom' are now macrosratherthanspecial " Drew Adams
2013-04-22 2:00 ` /srv/bzr/emacs/trunk r112347: *doc/lispintro/emacs-lisp-intro.texi (defcustom, defun, simplified-beginning-of-buffer, defvar, Building Robots, Review, save-excursion): `defun' and `defcustom' are now macros rather thanspecial " Dmitry Gutov
2013-04-21 18:07 ` /srv/bzr/emacs/trunk r112347: * doc/lispintro/emacs-lisp-intro.texi (defcustom, defun, simplified-beginning-of-buffer, defvar, Building Robots, Review, save-excursion): `defun' and `defcustom' are now macros rather than special " Glenn Morris
2013-04-21 22:54 ` xfq
2013-04-22 17:02 ` Glenn Morris
2013-04-23 0:47 ` Xue Fuqiao
2013-04-23 16:42 ` Glenn Morris
2013-04-23 22:28 ` Xue Fuqiao
2013-04-22 3:17 ` Leo Liu
2013-04-22 10:31 ` xfq
2013-04-22 14:11 ` Leo Liu
2013-04-22 14:19 ` Dmitry Gutov
2013-04-22 15:37 ` Leo Liu
2013-04-22 14:47 ` Stefan Monnier
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