will-have-a-cell-refactoring.clj

; ...

(defn num-neighbors-being-a-cell [cell cells]
  (count (filter (neighbors cell) cells)))

(defn has-cell? [loc cells] 
  (= loc (some #{loc} cells)))

(defn will-have-a-cell? [loc cells]
  (let [num-neighbors (num-neighbors-being-a-cell loc cells)]
    (or (= num-neighbors 3)
        (and (= num-neighbors 2)
             (has-cell? loc cells)))))

;...