On Sun, Nov 14, 2010 at 9:36 PM, Eric Kobrin <erl...@gmail.com> wrote:
> This brought to mind the general case of detecting emptiness. The > current practice of using `seq` to check for non-emptiness wastes > resources. It depends: in many cases you need to call seq anyway in the non-empty branch so seq+if-let is both expressive and efficient. However from time to time you really need to check for emptiness quickly. (zero? (count x)) is one way, (.isEmpty ^java.util.Collection x) is another. This limits the use of nice abstractions like `reduce` in > performance critical environments where a sentinel could be used. Not > everyone will be able to use a sentinel value to solve their > particular problem. What can be done to make `empty` faster? > However if your [] is really a sentinel, what about creating a real sentinel with (Object.) or (gensym) and checking it with identical? hth, Christophe -- Professional: http://cgrand.net/ (fr) On Clojure: http://clj-me.cgrand.net/ (en) -- 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
