4clojure GoL problem http://www.4clojure.com/problem/94

gol.clj

(defn gol
  "Returns the next generation for a given game of life board"
  [b]
  (let [cells (for [x (range (count (first b)))
                    y (range (count b))]
                [x y])
        is-alive? (fn [[x y]]
                    (= \# (get-in b [x y])))
        find-surrounding-live (fn [[cellx celly]] 
                                (for [x (range (dec cellx) (+ 2 cellx)) 
                                      y (range (dec celly) (+ 2 celly))
                                      :when (is-alive? [x y])
                                      :when (not (and (= x cellx) (= y celly)))]
                                  [x y]))
        count-surrounding-live (comp count find-surrounding-live)
        empty-board (->> (repeat (count b)
                                 (vec (repeat (count (first b)) " ")))
                         vec)]
    (->> cells
         (filter #(or 
                   (and (is-alive? %) (<= 2 (count-surrounding-live %) 3))
                   (and (complement (is-alive? %)) (= 3 (count-surrounding-live %)))))
         (reduce #(assoc-in %1 %2 "#")
                 empty-board)
         (map (partial apply str)))))