Does this mean that keywords don't have any efficiency advantages over strings when used as map keys?
On 12 October 2014 02:25, David Nolen <dnolen.li...@gmail.com> wrote: > As already mentioned use identical? In ClojureScript you must use > keyword-identical? for fast comparisons. > > > On Friday, October 10, 2014, Jony Hudson <jonyepsi...@gmail.com> wrote: > >> Hi All, >> >> I've been optimising a piece of code lately, and have come to wonder >> about the performance of keyword comparison. Specifically, I'm not sure >> whether the performance I'm seeing is what is expected. The data structures >> page on clojure.org [1] indicates that keywords "provide very fast >> equality tests". If I micro-benchmark with criterium, then I find the >> following: >> >> As a baseline, comparing integers with `(= 0 1)` takes around 4ns. >> >> Comparing keywords with `(= :plus :minus)` takes around 30ns. >> >> This is about the same amount of time it takes to compare strings, `(= >> "plus" "minus")`, which comes in at about 25ns. >> >> This surprised me, as I would have guessed that "fast" would have been >> closer to the integer performance than the string performance. It's worth >> saying that I don't know a lot about benchmarking, but I do have some >> "real" code that's performance depends heavily on comparisons, and it seems >> to line up performance-wise with these micro-benchmarks. >> >> So, am I doing something silly (like I don't know about the fast = for >> keywords)? Or, are my expectations wrong, and this is about how long "fast" >> should be? Or is there a performance bug lurking? >> >> I'm using Clojure 1.6.0 (but have tried 1.5.0 and 1.7.0-alpha1 with >> similar results). >> x86_64 Mac OS X 10.9.5 4 cpu(s) >> >> Java HotSpot(TM) 64-Bit Server VM 25.5-b02 >> >> Thanks in advance for any input, >> >> >> Jony >> >> [1] http://clojure.org/data%5Fstructures >> >> -- >> 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 >> --- >> You received this message because you are subscribed to the Google Groups >> "Clojure" group. >> To unsubscribe from this group and stop receiving emails from it, send an >> email to clojure+unsubscr...@googlegroups.com. >> For more options, visit https://groups.google.com/d/optout. >> > -- > 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 > --- > You received this message because you are subscribed to the Google Groups > "Clojure" group. > To unsubscribe from this group and stop receiving emails from it, send an > email to clojure+unsubscr...@googlegroups.com. > For more options, visit https://groups.google.com/d/optout. > -- 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 --- You received this message because you are subscribed to the Google Groups "Clojure" group. To unsubscribe from this group and stop receiving emails from it, send an email to clojure+unsubscr...@googlegroups.com. For more options, visit https://groups.google.com/d/optout.
