CLJS-3200: reduce code generated by destructure macro for maps

Author: thheller

src/main/cljs/cljs/core.cljs

@@ -3986,6 +3986,11 @@ reduces them without incurring seq initialization"
 
 (set! *unchecked-if* false)
 
+;; CLJS-3200: used by destructure macro for maps to reduce amount of repeated code
+;; placed here because it needs apply and hash-map (only declared at this point)
+(defn --destructure-map [x]
+  (if (implements? ISeq x) (apply cljs.core/hash-map x) x))
+
 (defn vary-meta
  "Returns an object of the same type and value as obj, with
   (apply f (meta obj) args) as its metadata."

src/main/clojure/cljs/core.cljc

@@ -666,7 +666,7 @@
                                (core/let [gmap (gensym "map__")
                                           defaults (:or b)]
                                  (core/loop [ret (core/-> bvec (conj gmap) (conj v)
-                                                          (conj gmap) (conj `(if (implements? ISeq ~gmap) (apply cljs.core/hash-map ~gmap) ~gmap))
+                                                          (conj gmap) (conj `(--destructure-map ~gmap))
                                                      ((core/fn [ret]
                                                         (if (:as b)
                                                           (conj ret (:as b) gmap)