animated value in electric

animated.clj

(def timer*
  (->> e/<clock ;; produce time
       (y/sample e/-get-system-time-ms) ;; label time
       (y/reductions (fn([] {:t (e/-get-system-time-ms) :dt 0})
                       ([acc next] ;; produce difference
		        {:t (e/-get-system-time-ms)
			 :dt (- next (:t acc))})))))
       
(defn pid [<setpoint {:keys [<force error-threshold k <clock]
                      :or {<force (y/watch (atom 10))
                           <clock (y/eduction (map :dt) timer*)      
                           k 0.0005
                           error-threshold 0.2}}]
  (y/cp
   (let [!curr (atom 0)
	 !gate (atom true)]
     (y/?< <setpoint)
     (reset! !gate true)
     (let [<gated-clock (if (y/?< (y/watch !gate)) <clock (y/ap))
	   [setpoint force curr dt]
           (y/?< (y/sample vector
			   <setpoint <force (y/watch !curr) <gated-clock
			   <gated-clock))
           err (- setpoint curr)]
       (if (< (Math/abs err) error-threshold)
	 (do (reset! !gate false) setpoint)
	 (swap! !curr + (* err dt k force)))))))

(defmacro animated-value [setpoint & {:as args}]
  `(let [!v# (atom 0)]
     (reset! !v# ~setpoint)
     (new (pid (y/watch !v#) ~args))))