On Mon, Aug 3, 2009 at 2:47 AM, Jonas<jonas.enl...@gmail.com> wrote: > > I find the :while modifier non intuitive > > user=> (for [x (range 1 10) y (range 1 10) :while (= y 2)] [x y]) > () > user=> (for [x (range 1 10) y (range 1 10) :while (= x 2)] [x y]) > ([2 1] [2 2] [2 3] [2 4] [2 5] [2 6] [2 7] [2 8] [2 9]) > > My (false) intuition told me that both expressions would have been > evaluated to an empty sequence. Could someone explain the rationale > behind the :while modifier?
:while only bails from the loop on which it is placed. In your examples that's the 'y' loop, so the 'x' loop is unaffected by your :while and proceeds through its entire range in both examples. In the first example, the 'y' loop never produces anything so the result is empty. The :while modifier for 'doseq' behaves the same way. This has come up before: http://clojure-log.n01se.net/date/2009-06-12.html#15:02a-15:33 --Chouser --~--~---------~--~----~------------~-------~--~----~ 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 -~----------~----~----~----~------~----~------~--~---
