(defn vec-abs
  [[x y]]
  (+ (* x x)
     (* y y)))

(defn vec-add
  [x y]
  (map + x y))

(defn vec-sq
  [[x y]]
  (vector (- (* x x)
             (* y y))
          (* 2 x y)))

(defn mandel
  [coord max-iterations]
  (count
   (filter #(> (vec-abs %) 4)
           (take max-iterations
                 (iterate #(vec (vec-add (vec-sq %)
                                         coord))
                          [0 0])))))

(defn build-square
  [x]
  (map #(vector (int (/ % x)) (mod % x))
       (range (* x x))))

(defn mand-set
  [size]
  (map #(cond (= 0 (mandel % 250)) "#"
              :else " ")
       (map (fn [x]
              (map #(/ (- %
                          (/ size 2.0))
                       (/ size 3.0))
                   x))
            (build-square size))))


(defn print-square
  [size square]
  (pprint (map #(apply str
                       (apply vector %))
               (partition size square))))