(defn insert [v at el] (flatten (assoc v at [el (v at)])) You get a lazy seq back, so further operations are probably not as performant as they should be. But that would be as performant as a regular assoc for just that one operation. What you do from then on.....
Mark On Aug 26, 10:33 am, Chouser <chou...@gmail.com> wrote: > On Thu, Aug 26, 2010 at 12:43 PM, David Nolen <dnolen.li...@gmail.com> wrote: > > On Thu, Aug 26, 2010 at 11:53 AM, Chouser <chou...@gmail.com> wrote: > > >> On Thu, Aug 26, 2010 at 9:44 AM, Jon Seltzer <seltzer1...@gmail.com> > >> wrote: > >> > I know what assoc does: > > >> > user=> (assoc [\a \b \c] 0 \d) ;please extend to much larger vector > >> > with index somewhere in the middle > >> > [\d \b \c] > > >> > but what if I want: > > >> > user=> (assoc-x [\a \b \c] 0 \d) ;is there an assoc-x > >> > [\a \d \b \c] > > >> > I don't see a function that does this. I'm sure I'm missing it. I, > >> > of course, know this could be done with a combination of other > >> > functions like subvec and/or into but it seems fundamental enough to > >> > have its function. > > >> The internal structure of vectors is such that this cannot be > >> done efficiently, which is why no function to do it is included > >> in clojure.core. You can do it inefficiently like this: > > >> (let [v '[a b c d e f] > >> i 3] > >> (into (subvec v 0 i) (cons 'X (subvec v i)))) > >> ;=> [a b c X d e f] > > >> That's about as good as you're going to get with vectors, O(n) > >> where n is (- (count v) i). > > >> --Chouser > >>http://joyofclojure.com/ > > > How is the performance of your FingerTrees looking? ;) > > David > > I'm actually working on it again, now that the book is requiring less > time. When it's ready, I won't be shy about announcing it. :-) > > --Chouserhttp://joyofclojure.com/ -- 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
