Function from hell

gistfile1.clj

; Given a string of comma separated integers, write a function which 
; returns a new comma separated string that only contains the numbers 
; which are perfect squares.

(fn [s]
  (apply str 
   (interpose \, 
     (filter #(= (Math/sqrt %) 
                 (Math/floor (Math/sqrt %))) 
             (map #(Integer/parseInt %) 
                  (re-seq #"\w+" s))))))