On 24 Jan., 16:50, wubbie <sunj...@gmail.com> wrote: > Hi, > > I wonder why self-call(filter) is used in one place and > recur is used in the other. > > (defn filter > "Returns a lazy seq of the items in coll for which > (pred item) returns true. pred must be free of side-effects." > [pred coll] > (when (seq coll) > (if (pred (first coll)) > (lazy-cons (first coll) (filter pred (rest coll))) ;; filter > * > (recur pred (rest coll))))) ;; recur **
As the self-call to filter happens inside a lazy-cons the stack is safe. One can’t use recur here, because this call is not in the tail position. It is a recursive non-tail call. --~--~---------~--~----~------------~-------~--~----~ 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 -~----------~----~----~----~------~----~------~--~---
