gistfile1.clj

(ns bpsmannschott
  (:import java.io.File)
  (:import java.io.FileNotFoundException))

(defn as-file [s]
  "Return whatever we have as a java.io.File object"
  (cond (instance? File s) s   ; already a file, return unchanged
        (string? s) (File. s)  ; return java.io.File for path s
        :else (throw (FileNotFoundException. (str s)))))

(defn walk [^File dir]
  (let [children (.listFiles dir)
        subdirs (filter #(.isDirectory %) children)
        files (filter #(.isFile %) children)]
    (concat files (mapcat walk subdirs))))

;; EXAMPLE
;; count the number of files in or below /tmp
;;
;; (count (walk (as-file "/tmp")))
;;
;; alternately:
;;
;; (-> "/tmp" as-file walk count)