added example of compiler issue; unable to create 'size' and 'empty' properties on Collection<T> and java.util.Map<T> it seems? wonder if its a qualified name issue - qualified names don't seem to be allowed on extension properties - will raise an issue...

stdlib/ktSrc/JavaUtil.kt

@@ -82,37 +82,3 @@ val <T> List<T>.last : T?
 
 
 
-// Map APIs
-/** Returns the size of the map */
-/* TODO get redeclaration errors
-val Map<*,*>.size : Int
-    get() = size()
-*/
-
-/** Returns true if this map is empty */
-/* TODO get redeclaration errors
-val Map<*,*>.empty : Boolean
-    get() = isEmpty()
-*/
-
-/** Returns the value for the given key or returns the result of the defaultValue function if there was no entry for the given key */
-inline fun <K,V> java.util.Map<K,V>.getOrElse(key: K, defaultValue: ()-> V) : V {
-  val current = this.get(key)
-  if (current != null) {
-    return current
-  } else {
-    return defaultValue()
-  }
-}
-
-/** Returns the value for the given key or the result of the defaultValue function is put into the map for the given value and returned */
-inline fun <K,V> java.util.Map<K,V>.getOrElseUpdate(key: K, defaultValue: ()-> V) : V {
-  val current = this.get(key)
-  if (current != null) {
-    return current
-  } else {
-    val answer = defaultValue()
-    this.put(key, answer)
-    return answer
-  }
-}

stdlib/ktSrc/JavaUtilMap.kt

@@ -0,0 +1,39 @@
+package std.util
+
+import java.util.*
+
+// Map APIs
+
+/** Returns the size of the map */
+/* TODO get redeclaration errors
+val Map<*,*>.size : Int
+    get() = size()
+*/
+
+/** Returns true if this map is empty */
+/* TODO get redeclaration errors
+val Map<*,*>.empty : Boolean
+    get() = isEmpty()
+*/
+
+/** Returns the value for the given key or returns the result of the defaultValue function if there was no entry for the given key */
+inline fun <K,V> java.util.Map<K,V>.getOrElse(key: K, defaultValue: ()-> V) : V {
+  val current = this.get(key)
+  if (current != null) {
+    return current
+  } else {
+    return defaultValue()
+  }
+}
+
+/** Returns the value for the given key or the result of the defaultValue function is put into the map for the given value and returned */
+inline fun <K,V> java.util.Map<K,V>.getOrElseUpdate(key: K, defaultValue: ()-> V) : V {
+  val current = this.get(key)
+  if (current != null) {
+    return current
+  } else {
+    val answer = defaultValue()
+    this.put(key, answer)
+    return answer
+  }
+}

testlib/test/MapTest.kt

@@ -32,4 +32,12 @@ class MapTest() : TestSupport() {
 
     assertEquals(1, data.size())
   }
+
+  /** TODO can't seem to define size/empty properties for Map
+  fun testSizeAndEmpty() {
+    assert{ data.empty }
+
+    assertEquals(data.size, 0)
+  }
+  */
 }