On May 18, 2009, at 11:58, Adrian Cuthbertson wrote: > I know I keep plugging this - sorry - but it just keeps surfacing > as a solution; > > (lcm 4 6) > 12 > (binding [clojure.contrib.math/gcd (fn [a b] 1)] (lcm 4 6)) > 24
Such a use of binding will lead to bad surprises as soon as you use it with lazy sequences: (map #(lcm % 6) (range 6)) -> (0 6 6 6 12 30) (binding [clojure.contrib.math/gcd (fn [a b] 1)] (map #(lcm % 6) (range 6))) -> (0 6 6 6 12 30) You have to use doall to get the result you expect: (binding [clojure.contrib.math/gcd (fn [a b] 1)] (doall (map #(lcm % 6) (range 6)))) -> (0 6 12 18 24 30) The reason is that the temporary binding remains active only while map creates the lazy sequence that it returns, but it is no longer active when the actual elements of the lazy sequence are evaluated. More details and examples in my blog post: http://onclojure.com/2009/05/06/simulating-dynamic-scoping/ Konrad. --~--~---------~--~----~------------~-------~--~----~ 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 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 -~----------~----~----~----~------~----~------~--~---
