west.clj

(ns genetic.core)

(def letters
  (conj (map (comp char
                   (partial + 97))
             (range 26))
        \space))

(defn random-string [source]
  (let [length (count source)]
    (apply str
           (repeatedly length
                       (fn []
                         (rand-nth source))))))

(def letter-val-map
  (into {}
        (map vector
             letters
             (range))))

(defn char-diff [x y]
  (Math/abs (- (letter-val-map x)
               (letter-val-map y))))

(defn string-distance [s1 s2]
  (reduce + (map char-diff s1 s2)))

(defn mutate-string [s]
  (let [n (rand-int (count s))
        [l [x & r]] (split-at n s)]
    (apply str (concat l [(rand-nth letters)] r))))

(defn genetic-iteration [target seed]
  (println seed)
  (first (first (sort-by last
                         (for [s (map mutate-string (repeat 50 seed))]
                           [s (string-distance s target)])))))

(defn guess-target [iterations target]
  (nth (iterate (partial genetic-iteration target) (random-string target))
       iterations))

(defn -main [target]
  (first (drop-while (fn [s]
                       (not= s target))
                     (iterate (partial genetic-iteration target) (random-string target)))))