CLJS-2934: Enhanced delay printing

Author: mfikes

src/main/cljs/cljs/core.cljs

@@ -10395,7 +10395,13 @@ reduces them without incurring seq initialization"
 
   IPending
   (-realized? [x]
-    (not f)))
+    (not f))
+
+  IPrintWithWriter
+  (-pr-writer [x writer opts]
+    (-write writer "#object[cljs.core.Delay ")
+    (pr-writer {:status (if (nil? f) :ready :pending), :val value} writer opts)
+    (-write writer "]")))
 
 (defn ^boolean delay?
   "returns true if x is a Delay created with delay"

src/test/cljs/cljs/core_test.cljs

@@ -1633,6 +1633,12 @@
   (is (= "xyzzy" (str "x" "y" "z" "z" "y")))
   (is (= "a1b2c3" (str "a" 1 "b" 2 "c" 3))))
 
+(deftest test-cljs-2934
+  (let [x (delay 1)]
+    (is (= "#object[cljs.core.Delay {:status :pending, :val nil}]" (pr-str x)))
+    (force x)
+    (is (= "#object[cljs.core.Delay {:status :ready, :val 1}]" (pr-str x)))))
+
 (deftest test-cljs-2943
   (let [m1 {:a 2, :b 3, :c 5}
         m2 {:a 7, :b 11, :d 13, :e 17}