On Fri, 26 Dec 2008 14:43:23 -0600 "Mark Volkmann" <r.mark.volkm...@gmail.com> wrote:
> >Why does > >(for [x (range 3)] (println x)) > >output > >(0 >nil 1 >nil 2 >nil) > >when run in the REPL instead of > >0 >1 >2 > >and nothing at all when run from a script? > The seq of nils is the return value of `(for ...)'. It is printed because the REPL shows return values and interpersed with println's output, because `for' is lazy and the printlns are executed while the seq is printed. When run from a script (as a top level form, I assume), the return value of the form is not used, therefore the tail-functions of the lazy sequence aren't evaluated and nothing at all is printed. This can be remedied by surrounding the `(for ...)' form with a `doall' or `dorun' form, which both evaluate the whole sequence (they differ in their return values). In this case `doseq' should be used instead of `for'. --~--~---------~--~----~------------~-------~--~----~ 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 -~----------~----~----~----~------~----~------~--~---
