;; Vector ops go like this:

(defn #^floats v [x y]
  [(float x) (float y)])

(defn #^Float vx [#^floats vec]
  (vec 0))

(defn #^Float vy [#^floats vec]
  (vec 1))

(defn #^floats v+ [#^floats a #^floats b]
  [(+ (a 0) (b 0))
   (+ (a 1) (b 1))])

(defn #^floats v- [#^floats a #^floats b]
  [(- (a 0) (b 0))
   (- (a 1) (b 1))])

(defn #^floats v* [#^floats vec #^Number m]
  [(* (vec 0) (float m))
   (* (vec 1) (float m))])



;; Main part

(defn update-point [p]
  [(v+ (first p) (second p))
   (v+ (v* (second p) 0.999) (v 0 0.1))])

(defn make-points [count pos]
  (map (fn [_] [pos (v (- (rand 10) 5) (- (rand 10) 8))])
       (range count)))

(defn main []
  (with-screen "Foo" 800 600 false []
    (with-update
      (clear-screen +black+))
    (loop [ps []]
      (with-update
        (clear-screen (color 0 0 0 32))
        (set-color +yellow+)
        (doseq p ps
          (draw-line (first p) (v- (first p) (v* (second p) 2.0))))
        (draw-fps)
        (if (key-pressed? (vk ESCAPE))
          (close-screen)))
      (when (screen-running?) (recur (concat (make-points 10 (v 400 300))
                                             (filter (fn [p]
                                                       (point-inside-rectangle? (first p)
                                                                                (v 0 -100) 800 700))
                                                     (map update-point ps))))))))