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. :-) --Chouser http://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
