CLJ-1872 Extend empty? to counted? colls that arent seqable, such as transients

Author: puredanger

src/clj/clojure/core.clj

@@ -6244,13 +6244,6 @@ fails, attempts to require sym's namespace and retries."
   ([m k f x y z & more]
    (assoc m k (apply f (get m k) x y z more))))
 
-(defn empty?
-  "Returns true if coll has no items - same as (not (seq coll)).
-  Please use the idiom (seq x) rather than (not (empty? x))"
-  {:added "1.0"
-   :static true}
-  [coll] (not (seq coll)))
-
 (defn coll?
   "Returns true if x implements IPersistentCollection"
   {:added "1.0"
@@ -6306,6 +6299,16 @@ fails, attempts to require sym's namespace and retries."
    :static true}
   [coll] (instance? clojure.lang.Counted coll))
 
+(defn empty?
+  "Returns true if coll has no items. To check the emptiness of a seq,
+  please use the idiom (seq x) rather than (not (empty? x))"
+  {:added "1.0"
+   :static true}
+  [coll]
+  (if (counted? coll)
+    (zero? (count coll))
+    (not (seq coll))))
+
 (defn reversible?
  "Returns true if coll implements Reversible"
  {:added "1.0"

test/clojure/test_clojure/sequences.clj

@@ -1136,7 +1136,10 @@
     {}
     #{}
     ""
-    (into-array []) )
+    (into-array [])
+    (transient [])
+    (transient #{})
+    (transient {}))
 
   (are [x] (not (empty? x))
     '(1 2)
@@ -1145,7 +1148,10 @@
     {:a 1 :b 2}
     #{1 2}
     "abc"
-    (into-array [1 2]) ))
+    (into-array [1 2])
+    (transient [1])
+    (transient #{1})
+    (transient {1 2})))
 
 
 (deftest test-every?