Hello All, I encountered the following behavior in Clojure 1.6 and wanted to check if it should be considered a bug or not. I would say yes but wanted to double check on the list first.
Here's a minimal test case that elicited the error: (defn f [xs acc] (if (nil? xs) acc (recur (next xs) (+ (first xs) acc)))) (f [1 2 3 4] 0) => 10 Now, if I want to add pre/post conditions, the following happens: (defn g [xs acc] {:pre [(or (nil? xs) (sequential? xs)) (number? acc)] :post [number?]} (if (nil? xs) acc (recur (next xs) (+ (first xs) acc)))) => this fails to compile with "CompilerException java.lang.UnsupportedOperationException: Can only recur from tail position" In fact, it is only the post-condition that triggers the issue. My guess would be that the recur statement is being knocked out of tail position by the mechanism for handling the post-condition assertion. It can be fixed in the code by adding an explicit loop: (defn g2 [xs acc] {:pre [(or (nil? xs) (sequential? xs)) (number? acc)] :post [number?]} (loop [xs xs acc acc] (if (nil? xs) acc (recur (next xs) (+ (first xs) acc))))) Thanks, Michael O'Keefe -- 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 --- You received this message because you are subscribed to the Google Groups "Clojure" group. To unsubscribe from this group and stop receiving emails from it, send an email to clojure+unsubscr...@googlegroups.com. For more options, visit https://groups.google.com/d/optout.