Clojure directory tree builder

gistfile1.clj

(defn buildMap [fl]
  (cond
   (.isDirectory fl)
     (let [subfiles  (filter (complement nil?) (map buildMap (.listFiles fl)))]
       (list (.getAbsolutePath fl) subfiles (reduce + (map last subfiles)))
       )
   (.isFile fl)
     (list (.getAbsolutePath fl) (.length fl))
     )
  )

(pprint (buildMap (clojure.java.io/file "/Users/jason/Code/grades")))