Easing Function in clojurescript

easings.cljs

(def ^:private easing-fns
  {:linear identity
   :sine-in #(- 1 (js/Math.cos (/ (* % (.-PI js/Math)) 2)))
   :sine-out #(js/Math.sin (/ (* % (.-PI js/Math)) 2))
   :sine-in-out #(/ (- (dec (js/Math.cos (* (.-PI js/Math) %)))) 2)
   :quad-in #(* % %)
   :quad-out #(* % (- 2 %))
   :quad-in-out #(if (< % 0.5) (* 2 % %)
                     (dec (* (- 4 (* 2 %)) %)))
   :cubic-out #(inc (apply * (map dec [% % %])))
   :cubic-in #(* % % %)
   :cubic-in-out #(if (< % 0.5) (* 4 % % %)
                      (inc (* (dec %) (- (* 2 %) 2) (- (* 2 %) 2))))})

Used in Voicelane to perform audio volume fade in/out

Input range: 0 <= x <= 1;

(comment
  ((easing-fns :sine-in) 0.3)
  ((easing-fns :sine-out) 0.3)
  ((easing-fns :sine-in-out) 0.3)
  ((easing-fns :cubic-in) 0.3)
  ((easing-fns :cubic-out) 0.3)
  ((easing-fns :cubic-in-out) 0.3)
  ((easing-fns :quad-in-out) 0.3)
  ((easing-fns :quad-in) 0.3)
  ((easing-fns :quad-out) 0.3))