def slope(p1=(0,0), p2=(1,1)): return (float(p2[1] - p1[1])) / (p2[0] - p1[0])
(defn slope [& {:keys [p1 p2] :or {p1 [0 0] p2 [1 1]}}] (float (/ (- (p2 1) (p1 1)) (- (p2 0) (p1 0)))))