[Date Prev][Date Next][Thread Prev][Thread Next][Date Index][Thread Index]
Re: empty-line-p
From: |
Barry Margolin |
Subject: |
Re: empty-line-p |
Date: |
Fri, 30 Mar 2007 01:46:53 -0400 |
User-agent: |
MT-NewsWatcher/3.5.2 (PPC Mac OS X) |
In article <jwv648j70t5.fsf-monnier+gnu.emacs.help@gnu.org>,
Stefan Monnier <monnier@iro.umontreal.ca> wrote:
> > (if (looking-at "^[ \t\f\r]*$")
> > t
> > nil)))
>
> (if <foo> t nil)
>
> is an eta-regexp, which can be advantageously reduced to just <foo>.
>
>
> Stefan
>
>
> PS: The classical eta-regexp is (lambda (x) (<foo> x)), which is equivalent to
> just <foo>. Another variant is (cons (car <foo>) (cdr <foo>)), which
> eta-reduces to just <foo>.
That last one is different, because the new cons is not eq to the
original <foo>.
--
Barry Margolin, barmar@alum.mit.edu
Arlington, MA
*** PLEASE post questions in newsgroups, not directly to me ***
*** PLEASE don't copy me on replies, I'll read them in the group ***