On Tue, Oct 27, 2009 at 9:50 PM, Josh Daghlian <daghl...@gmail.com> wrote:
> The docs could use clarification, but it looks like take-nth is doing > what's advertised. > I don't see anything odd about the behavior of take-nth in regards to indexing: user=> (take 10 (take-nth 1 (range 100))) (0 1 2 3 4 5 6 7 8 9) user=> (take 10 (take-nth 2 (range 100))) (0 2 4 6 8 10 12 14 16 18) user=> (take 10 (take-nth 3 (range 100))) (0 3 6 9 12 15 18 21 24 27) It always starts with the zeroth item and skips ahead however many elements were specified. The second argument is the n in "every nth item". (You can think of it as the index of the SECOND item to take, so (take-nth 3 foo) takes index 0 of foo, then index 3, and so on.) Is there ever a case (I can't think of one) where a programmer really > wants to feed this function a non-positive n? That is, should take-nth > crap out if (< n 1)? Probably. Right now, it just seems to fail to advance through the sequence (interestingly, not just with n=0) so it never terminates. Even with an explicitly finite sequence input: user=> (take 10 (take-nth 0 [1 2 3 4 5])) (1 1 1 1 1 1 1 1 1 1) Perhaps it should just return a length-1 sequence of just the first element of the input, for zero, and bomb for negative? Or retain its current behavior for zero and bomb for negative. I'd recommend it just bombing for both. The correct interpretation of taking every zeroth item until the end IS to return an infinite sequence of just the first element (the one at index 0), but it's also perturbing to have an operation that normally produces a no-longer sequence produce an infinite one from a finite one. --~--~---------~--~----~------------~-------~--~----~ 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 -~----------~----~----~----~------~----~------~--~---
