bug#6596: 23.2; cl.texi docs loop destructuring for alist

[Kevin Ryde]

I didn't immediately realize the cl `loop' macro destructuring could be
used to crunch an alist.  Perhaps an example in the manual per below.
If you're not a cl programmer you need lots of examples to understand
that huge `loop' thing :-).

2010-07-10  Kevin Ryde  <user42@zip.com.au>

        * cl.texi (For Clauses): Add destructuring example processing an
        alist.

--- cl.texi.orig        2010-07-10 09:37:14.000000000 +1000
+++ cl.texi     2010-07-10 09:38:54.000000000 +1000
@@ -2599,7 +2599,14 @@
 than values the trailing variables get the value @code{nil}.
 If @code{nil} is used as a variable name, the corresponding
 values are ignored.  Destructuring may be nested, and dotted
-lists of variables like @code{(x . y)} are allowed.
+lists of variables like @code{(x . y)} are allowed, so for example
+to process an alist
+
+@example
+(loop for (key . value) in '((a . 1) (b . 2))
+      collect value)
+     @result{} (1 2)
+@end example
 
 @node Iteration Clauses, Accumulation Clauses, For Clauses, Loop Facility
 @subsection Iteration Clauses


In GNU Emacs 23.2.1 (i486-pc-linux-gnu, GTK+ Version 2.20.0)
 of 2010-05-16 on raven, modified by Debian
configured using `configure  '--build' 'i486-linux-gnu' '--build' 
'i486-linux-gnu' '--prefix=/usr' '--sharedstatedir=/var/lib' 
'--libexecdir=/usr/lib' '--localstatedir=/var/lib' '--infodir=/usr/share/info' 
'--mandir=/usr/share/man' '--with-pop=yes' 
'--enable-locallisppath=/etc/emacs23:/etc/emacs:/usr/local/share/emacs/23.2/site-lisp:/usr/local/share/emacs/site-lisp:/usr/share/emacs/23.2/site-lisp:/usr/share/emacs/site-lisp:/usr/share/emacs/23.2/leim'
 '--with-x=yes' '--with-x-toolkit=gtk' '--with-toolkit-scroll-bars' 
'build_alias=i486-linux-gnu' 'CFLAGS=-DDEBIAN -g -O2' 'LDFLAGS=-g' 'CPPFLAGS=''

Important settings:
  value of $LC_ALL: nil
  value of $LC_COLLATE: nil
  value of $LC_CTYPE: nil
  value of $LC_MESSAGES: nil
  value of $LC_MONETARY: nil
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  value of $LANG: en_AU
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  locale-coding-system: iso-latin-1-unix
  default enable-multibyte-characters: t