(defn compress-string [s]
  (let [compressed ""]
    (loop [compressed compressed
           uncompressed (map char s)
           current-char (first uncompressed)
           current-count 1]
      (if (or (not (seq uncompressed)) (= (count s) < 3))
        compressed
        (if (= (second uncompressed) current-char)
            (recur compressed
                   (drop 1 uncompressed)
                   current-char
                   (+ current-count 1))
            (recur (str compressed current-char current-count)
                   (drop 1 uncompressed)
                   (first uncompressed)
                   1))))))

(compress-string "aaabddcejkkeddddddd")
; should output: a3b1d2c1e1j1k2e1d7
=> "a3a1b1d1d1c1e1j1k1k1e1d6"
(compress-string "aaaaa")
; should output: a5
=> "a5"
(compress-string "ababab")
; should output: a1b1a1b1a1b1
=> "a1a2a2a1"