On Nov 20, 2012, at 10:12 AM, Mark Engelberg wrote: > Clojure's sorted collections must be provided with a sorting function where > items "tie" if and only if they are equal. > > (sorted-set-by #(compare [(second %) %] [(second %2) %2]) [:a 1] [:b 1] [:c > 1]))
Mark, I like the brevity of this way of writing comparison functions with tie breakers, and see that it would extend well to multiple sort keys, and ascending or descending order on each key can be chosen independently. My question is perhaps of the is-the-number-of-angels-that-can-dance-on-the-head-of-a-pin-finite-or-infinite kind. Does Clojure promise anywhere in its documentation that it compares vectors and sequences in lexicographic order? I know the implementation does in fact do this today, and probably has since compare was implemented for vectors, and there is no good reason I know of that it might ever change. For most purposes, I'd say that is good enough to run with it and tell the whole world. The only nagging doubt is relying on undocumented behavior. I guess my real question is: "Would it be good for Clojure to document and promise this comparison behavior?" Andy -- You received this message because you are subscribed to the Google Groups "Clojure" group. To post to this group, send email to clojure@googlegroups.com Note that posts from new members are moderated - please be patient with your first post. To unsubscribe from this group, send email to clojure+unsubscr...@googlegroups.com For more options, visit this group at http://groups.google.com/group/clojure?hl=en
