Here's a pass using reduce, keeping both collections in the return value, conj-ing to one and taking from the other as necessary...
(defn nil-coalesce [coll subs] (first (reduce (fn [[a b] x] (if x [(conj a x) b] [(conj a (first b)) (rest b)])) [[] subs] coll))) user> (nil-coalesce [nil 1 2 3 nil nil] [4 5]) [4 1 2 3 5 nil] -- 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