Middleware can now be supplied as a vector (containing nils, which are ignored). This is going to make generating middleware much easier.

For example, Debug middleware can now more easily be conditionally added and removed.

src/re_frame/core.cljs

@@ -37,19 +37,4 @@
     (register-handler id [pure middleware] handler)))
 
 
-(defn comp-middleware
-  "Given a vector of middleware, filter out any nils, and use comp to compose.
-  v can  be vectors of vectors and will be flattended before use.
-  For convienience, if v turns out to already be a function, just return it."
-  [v]
-  (if (ifn? v)     ;; noop if v is a fucntion
-    v
-    (do
-      (assert  (or (vector? v) (list v))
-               (str "re-frame:  compose expects a vector, got: " v))
-      (let [v (remove nil? (flatten v))]
-        (cond
-          (empty? v)       noop
-          (= 1 (count v))  (first v)
-          :else            (apply comp v))))))
 

src/re_frame/handlers.cljs

@@ -7,6 +7,25 @@
             [cljs.core.async  :refer [chan put! <! timeout]]))
 
 
+
+;; -- composing middleware  -----------------------------------------------------------------------
+
+(defn comp-middleware
+  "Given a vector of middleware, filter out any nils, and use \"comp\" to compose them.
+  v can have nested vectors, and will be flattended before \"comp\" is applied.
+  For convienience, if v turns out to already be a function (assumed to be
+  middleware), just return it."
+  [v]
+  (cond
+    (ifn? v)      v  ;; assumed to be existing middleware
+    (vector? v)   (let [v (remove nil? (flatten v))]
+                    (cond
+                      (empty? v)       noop
+                      (= 1 (count v))  (first v)
+                      :else            (apply comp v)))
+    :else         (assert  (vector? v)
+                           (str "re-frame:  compose expects a vector, got: " v))))
+
 ;; -- the register of event handlers --------------------------------------------------------------
 
 (def ^:private id->fn  (atom {}))
@@ -19,9 +38,7 @@
     (swap! id->fn assoc event-id handler-fn))
 
   ([event-id middleware handler-fn]
-    (let  [mware  (if (vector? middleware)
-                    (apply comp middleware)   ;; compose the vector of middleware
-                    middleware)
+    (let  [mware     (comp-middleware middleware)
            hander-fn (mware handler-fn)]
       (register event-id hander-fn))))