On Wed, Dec 29, 2010 at 11:14 AM, Andreas Kostler <andreas.koestler.le...@gmail.com> wrote: > Hi all, > I've implemented a recursive version of insertion sort as a bit of an warm up > with clojure. For some reason it just doesn't "feel" right. The recursion > feels forced on poor old insertion sort. This might be inherent to insertion > sort. > My poor clojure skills are more likely to blame, though. > Can I please get some feedback on how to address the problem in a more > idiomatic way? > > ; Inserts element into a sorted vector > (defn insert-into [sorted-vec element] > (loop [i (count sorted-vec)] > (if (and (> i 0) (> (nth sorted-vec (dec i)) element)) > (recur (dec i)) > (into (conj (subvec sorted-vec 0 i) element) (subvec > sorted-vec i))))) > > > (defn insertion-sort [vector] > (loop [i 0 > _vec vector] > (if (< i (count _vec)) > (recur (inc i) > (into (insert-into (subvec _vec 0 i) (nth _vec i)) > (subvec _vec (inc i)))) > _vec))) > > Kind Regards > Andreas
Vectors are actually rather poorly designed for that sort of thing (insertion in the middle) and loop is generally to be resorted to only if there isn't a higher-order function that will do the job. How about: (defn insert-into [s x] (let [[low high] (split-with #(< % x) s)] (concat low [x] high))) (defn insertion-sort [s] (reduce insert-into [] s)) Here, split-with and reduce are the HOFs that obviate the need for loop. -- 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