diff --git a/src/performance.clj b/src/performance.clj
index 64ffaaa..d265d08 100644
--- a/src/performance.clj
+++ b/src/performance.clj
@@ -101,7 +101,7 @@
    :volume 50           ;; volume of performance
    :key [:C :major]})   ;; current key signature
 
-(defn merge-perfs  ;; TODO what if p1 and p2 are single notes?
+(defn merge-perfs
   "Merges two performances"
   [p1 p2]
   (if (nil? (seq p1))
@@ -119,26 +119,33 @@
 (defn perf
   "Implementation of perform, returns a tuple of (performance, duration)"
   [player-map context music]
-  (let [{:keys [player duration-t]} context]
+  (let [{:keys [player duration-t time]} context]
     (match music
           {:duration duration
-           :pitch pitch} [((:play-note player)
-                           context
-                           music)
+           :pitch pitch} [[((:play-note player)
+                            context
+                            music)]
                           (* duration duration-t)]
           {:duration duration} [[] (* duration duration-t)]
-          [:+ & ms] (reduce (fn [[events-acc dur-acc] m]
-                              (let [[events dur] (perf player-map
-                                                       context
-                                                       m)]
-                                [(concat events-acc events)
-                                 (+ dur-acc dur)])) 
-                            [[] 0]
-                            ms)
+          [:+ & ms] (let [[{events :events} dur]
+                          (reduce (fn [[{events-acc :events time-acc :time} dur-acc] m]
+                                    (let [[events dur]
+                                          (perf player-map
+                                                (assoc context
+                                                       :time
+                                                       (+ (:time context) time-acc))
+                                                m)]
+                                      [{:events (concat events-acc events)
+                                        :time (+ time-acc dur)}
+                                       (+ dur-acc dur)])) 
+                                  [{:events [] :time time} 0]
+                                  ms)]
+                      [events dur])
           [:= & ms] (reduce (fn [[merged-events max-dur] m]
                               (let [[events dur] (perf player-map
                                                        context
                                                        m)]
+                                (prn events)
                                 [(merge-perfs merged-events events)
                                  (max max-dur dur)]))
                             [[] 0]