[Top][All Lists]

[Date Prev][Date Next][Thread Prev][Thread Next][Date Index][Thread Index]

Re: alist and multiple values for one key

From: Oliver Scholz
Subject: Re: alist and multiple values for one key
Date: Tue, 21 Jan 2003 11:53:10 +0100
User-agent: Gnus/5.090008 (Oort Gnus v0.08) Emacs/21.3.50 (i386-mingw-nt5.1.2600)

address@hidden (Norbert C.) writes:

> Hi,
>        I would lile to find the "good way" to retrieve multiple values
> for a given key in an alist.
>        But I didn't find a natural way to do it. For example :
> (setq trees '((pine . cones) (pine . acorns) (oak . acorns) (maple .
> seeds)))
> ==> ((pine . cones) (pine . acorns) (oak . acorns) (maple . seeds))
> (assoc 'pine trees)
> ==> (pine . cones)
> What I'd like is something that returns each value associated with
> 'pine.

If I don't want to `(require 'cl)' I use something like this:

(delq nil
      (mapcar (lambda (elt)
                (if (eq (car elt) 'pine) elt nil))

You see this (delq nil (mapcar ... in Emacs' sources at some places,

2 Pluviôse an 211 de la Révolution
Liberté, Egalité, Fraternité!

reply via email to

[Prev in Thread] Current Thread [Next in Thread]