oops... I am just learning the language right now.... and just quickly looked at what you did... Would the use of "recur" instead of self-calls potentially help consuming stack space?
http://clojure.org/special_forms#toc10 On Dec 4, 5:37 pm, Daniel Eklund <[EMAIL PROTECTED]> wrote: > I > > On Dec 4, 2:55 pm, PeterB <[EMAIL PROTECTED]> wrote: > > > Hi, > > > I downloaded clojure_20080916.zip and had a go with a simple tree > > benchmark (cut-down version of the one in the computer language > > shootout http://shootout.alioth.debian.org/). > > > The Java version is pretty simple and runs in about 2s on my laptop: > > > public class Main > > { > > public static void main(String[] args) > > { > > System.out.println("result: " + sumTrees(10000, 10)); > > } > > > public static int sumTrees(int iterations, int depth) > > { > > int i; > > int sum = 0; > > > for (i = 1; i <= iterations; i++) > > sum += TreeNode.bottomUpTree(i, depth).itemCheck() + > > TreeNode.bottomUpTree(-i, depth).itemCheck(); > > return sum; > > } > > > public static class TreeNode > > { > > private TreeNode left, right; > > private int item; > > > TreeNode(int item) > > { > > this.item = item; > > } > > > TreeNode(int item, TreeNode left, TreeNode right) > > { > > this.left = left; > > this.right = right; > > this.item = item; > > } > > > private static TreeNode bottomUpTree(int item, int depth) > > { > > if (depth > 0) > > return new TreeNode(item, > > bottomUpTree(2*item-1, > > depth-1), > > bottomUpTree(2*item, > > depth-1)); > > else > > return new TreeNode(item); > > } > > > int itemCheck() > > { > > if (left == null) > > return item; > > else > > return item + left.itemCheck() - right.itemCheck(); > > } > > } > > > } > > > The Clojure version is considerably more compact and elegant: > > > (defn make-tree [item depth] > > (if (zero? depth) > > (list item nil nil) > > (let [item2 (* 2 item) depth-1 (dec depth)] > > (list item (make-tree (dec item2) depth-1) (make-tree item2 > > depth-1))))) > > > (defn check-tree [tree] > > (if (nil? tree) > > 0 > > (let [[i l r] tree] (- (+ i (check-tree l)) (check-tree r))))) > > > (defn sum-trees [iterations depth] > > (let [sum #(+ (check-tree (make-tree % depth)) > > (check-tree (make-tree (- %) depth)))] > > (reduce #(+ %1 %2) 0 (map sum (range 1 (inc iterations)))))) > > > (time (println "result:" (sum-trees 10000 10))) > > > However, there is a heavy price to be paid for this elegance: > > 'Elapsed time: 100730.161515 msecs' > > > Ouch! That's rather disappointing :-( > > Any suggestions for improving the performance? --~--~---------~--~----~------------~-------~--~----~ 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 To unsubscribe from this group, send email to [EMAIL PROTECTED] For more options, visit this group at http://groups.google.com/group/clojure?hl=en -~----------~----~----~----~------~----~------~--~---
