Hello, On Wed 21 Oct 2009 18:06, l...@gnu.org (Ludovic Courtès) writes:
> Andy Wingo <wi...@pobox.com> writes: > >> 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. > > If you insist: > > (sort '((a . 1) (b . -2) (c . 3)) > (memoized-lambda > (lambda (x y) > (< (cdr x) (cdr y))))) This simply does not have the same characteristics. You have to memoize the keys, not the comparisons. And a hash table does not have quite the same characteristics. > :-) Sure, yes -- but it is somewhat distressing that we want different Schemes. > Also, it would be a departure from R5RS (and R6RS’ ‘list-sort’, FWIW). It's a compatible extension. Andy -- http://wingolog.org/
