Hi, On Tue 20 Oct 2009 10:38, l...@gnu.org (Ludovic Courtès) writes:
> Andy Wingo <wi...@pobox.com> writes: > >> (sort '((a . 1) (b . -2) (c . 3)) < cdr) >> => ((b . -2) (a . 1) (c . 3)) > > FWIW I find: > > (sort '((a . 1) (b . -2) (c . 3)) > (lambda (x y) > (< (cdr x) (cdr y)))) > > more in the spirit of not “piling feature on top of feature”. (sort l < #:key cdr) is a bit contrived. But if your key takes time to compute, you need to use the decorate-sort-undecorate idiom, otherwise you compute the sort key O(n log n) times instead of O(n) times. It's part of our old Lisp tradition :) Plus.. it's for occupational safety. Less typing for the win! :) Andy -- http://wingolog.org/
