(learning Clojure) So I need a function that walks a set of directories and recursively gets the files paths contained in them. Here is my attempt.

dir-walk.clj

;
; Still learning Clojure... 
;
; Walk a directory or a series of directories and return a map of their files paths
;
; I initially started with the directory walk example here:
; 
; http://rosettacode.org/wiki/Walk_a_directory/Recursively#Clojure
;
(defn walk [dirpaths pattern]
  (let [get-files (fn [dirpath] 
                    (doall 
                     (filter #(re-matches pattern %)
                             (map #(.getAbsolutePath %) 
                                  (filter #(.isFile %) (file-seq (file dirpath)))))))] 
    (apply concat (map #(get-files %) dirpaths))))