2048 collapse row clojure

gistfile1.clj

(defn collapse-row [row]                                     
  (filterv (complement nil?)                                 
           (reduce (fn [acc elm]                             
                     (let [n (peek acc)]                     
                       (if (= n elm)                         
                         (conj (pop acc) (* n 2) nil)        
                         (conj acc elm))))                   
                  [nil]                                      
                  row)))