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RE: I'd like to marry while and mapcar...
From: |
Doug Lewan |
Subject: |
RE: I'd like to marry while and mapcar... |
Date: |
Fri, 6 Feb 2015 13:44:29 +0000 |
There are already a few small programming paradigms for such things.
(dolist (VAR LIST [RESULT]) BODY...) might do the right kind of thing for you,
but it never feels lisp-ish to me. And on a long list you might not get the
efficiency you expect.
(while (and magic-condition the-list) ... (setq the-list (cdr the-list)) seems
closer.
(throw) and (catch) provide another style:
(catch 'foo
(mapcar (lambda (e)
...
(if (not (magic-test e))
(throw 'foo t)))))
I hope this helps.
--
,Doug
Douglas Lewan
Shubert Ticketing
(201) 489-8600 ext 224 or ext 4335
The human brain is the most complex thing known to man, according to the human
brain.
> -----Original Message-----
> From: help-gnu-emacs-bounces+dougl=shubertticketing.com@gnu.org
> [mailto:help-gnu-emacs-bounces+dougl=shubertticketing.com@gnu.org] On
> Behalf Of Marcin Borkowski
> Sent: Friday, 2015 February 06 07:57
> To: Help Gnu Emacs mailing list
> Subject: I'd like to marry while and mapcar...
>
> Hello Emacsers and Elispers!
>
> What I'd need is kind of a marriage of while and mapcar: I'd like to
> run
> some function until it returns nil and make a list of all results it
> gives back until then.
>
> Mu use case is that I'm getting some info from a LaTeX file. For
> instance, assume that I want to make a list of all files \include'd by
> a LaTeX document. I've written a function `get-TeX-macro-arguments'
> which finds the next occurence of a given TeX command, moves point past
> it and returns its arguments; if it does not find any such occurrence,
> it returns nil. So I can say something like this:
>
> (let (current-include (list-of-includes ()))
> (while (setq current-include (get-TeX-macro-arguments "include"))
> (setq list-of-includes (append list-of-includes current-include)))
> list-of-includes)
>
> This, however, looks a bit, let's say, Fortran-ish;-); I'm after a more
> Lispy way. (Of course, one step would be to use anaphoric while, but
> that doesn't help my main problem of ditching list-of-includes.)
>
> Yes, I know, I have too much time on my hands, and I bother about
> style.
> But I'm also curious whether there is any "standard" way, or whether
> I should indeed wrap something like the above code in a macro, or
> something. (Or maybe just don't care...)
>
> TIA,
>
> --
> Marcin Borkowski This email was proudly sent
> http://mbork.pl from my Emacs.