Get all nested File objects from a directory | Clojure

get-nested-files.clj

;; Lovingly stolen from: https://gist.github.com/adambard/2217871
(require '[clojure.java.io :as io])

(defn is-file? [f] (.isFile f))
(defn is-dir? [f] (.isDirectory f))
(defn get-name [f] (.getName f))
(defn get-path [f] (.getPath f))

(def dir-path "/Users/<username>/Downloads/data")
(def dir (io/file dir-path))

(defn get-nested-files [d]
  (let [ls (if (is-dir? d) (.listFiles d) nil)
        files (filter is-file? ls)
        dirs (filter is-dir? ls)]
    (if (nil? ls)
      nil
      (flatten (concat
                files
                (map get-nested-files dirs))))))


(get-nested-files dir)