On Tue, Dec 10, 2013 at 6:09 PM, Glen Mailer <glenja...@gmail.com> wrote:
> I was recently working on some toy recursion problems, when I ran into a > function that I can express simply using normaly recursion, but I can't > seem to convert it into a form that works nicely with loop/recur. > > It's certainly not the right way to solve this problem, but I'm intrigued > to see what this pattern looks like with explicit tail calls: > > Problem: > Extract a slice from a list > (slice [ 3 4 5 6 7 8 9 ] 2 4) > ;=> [ 5 6 7 8 ] > > Normal Recursive Solution: > (defn slice [[h & tail] s n] > (cond > (zero? n) nil > (zero? s) (cons h (slice tail s (dec n))) > :else (slice tail (dec s) n))) > > What would the tail recursive version of this look like? can it retain the > nice readability of this form? > What about the accumulator pattern? (defn slice ([h s n] (slice h s n nil)) ([[h & tail] s n acc] (cond (zero? n) acc (zero? s) (recur tail s (dec n) (cons h acc)) :else (recur tail (dec s) n acc)))) -- -- 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.