I didn't know reduce could be short circuited! I assume from the code below this is done calling the function reduced? Is this in Clojure 1.5 only and is where is this documented?
On Wednesday, February 27, 2013 4:59:33 AM UTC-5, Christophe Grand wrote: > > > On Wed, Feb 27, 2013 at 10:21 AM, Marko Topolnik > <marko.t...@gmail.com<javascript:> > > wrote: > >> >> (defn blank? [s] (every? #(Character/isWhitespace %) s)) >>> >>> Have you ever wondered about its performance? Here you go: >>> >>> user> (time (dotimes [_ 10000] (blank? " >>> "))) >>> "Elapsed time: 3887.578 msecs" >>> >> >> To give a more complete picture, this version >> >> (defn blank? [s] (every? #(Character/isWhitespace ^char %) s)) >> >> is only six times slower than the expanded version, and keeping an eye on >> reflection warnings is not such a drag. So, if it could be demonstrated >> that in general the properly type-hinted, but otherwise idiomatic Clojure >> is not more than 10 times slower than idiomatic Java, I'd consider that at >> least a good starting point. >> > > Now that reduce can be short-circuited, redifining every?, some and al on > top of it would yield some interesting gains: > > (defn revery? [pred coll] > (reduce (fn [t x] > (if (pred x) > t > (reduced false))) true coll)) > > (defn rblank? [s] (revery? #(Character/isWhitespace ^char %) s)) > (defn blank? [s] (every? #(Character/isWhitespace ^char %) s)) > > => (dotimes [_ 10] > (time (dotimes [_ 100000] (blank? " > ")))) > "Elapsed time: 515.371 msecs" > "Elapsed time: 500.408 msecs" > "Elapsed time: 507.646 msecs" > "Elapsed time: 644.074 msecs" > "Elapsed time: 529.717 msecs" > "Elapsed time: 482.813 msecs" > "Elapsed time: 557.563 msecs" > "Elapsed time: 486.573 msecs" > "Elapsed time: 493.636 msecs" > "Elapsed time: 481.357 msecs" > nil > => (dotimes [_ 10] > (time (dotimes [_ 100000] (rblank? " > ")))) > "Elapsed time: 227.692 msecs" > "Elapsed time: 99.937 msecs" > "Elapsed time: 95.922 msecs" > "Elapsed time: 91.193 msecs" > "Elapsed time: 90.794 msecs" > "Elapsed time: 94.765 msecs" > "Elapsed time: 89.842 msecs" > "Elapsed time: 120.551 msecs" > "Elapsed time: 90.843 msecs" > "Elapsed time: 93.523 msecs" > nil > > Christophe > -- -- 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/groups/opt_out.
