# Get the number of occurences of elements in a set

(defn frequencies
 "Get the number of occurences of each value in a sequence."
 [s]
 (let [freqs @{}
       fop (fn [x] 
         (let [n (get freqs x)]
          (put freqs x (if n (+ 1 n) 1))))
       _ (domap fop s)]
  freqs))