Add missing sum() on Streams.

libraries/stdlib/src/generated/_Numeric.kt

@@ -19,6 +19,18 @@ public fun Iterable<Int>.sum(): Int {
     return sum
 }
 
+/**
+ * Returns the sum of all elements in the collection
+ */
+public fun Stream<Int>.sum(): Int {
+    val iterator = iterator()
+    var sum: Int = 0
+    while (iterator.hasNext()) {
+        sum += iterator.next()
+    }
+    return sum
+}
+
 /**
  * Returns the sum of all elements in the collection
  */
@@ -31,6 +43,18 @@ public fun Iterable<Long>.sum(): Long {
     return sum
 }
 
+/**
+ * Returns the sum of all elements in the collection
+ */
+public fun Stream<Long>.sum(): Long {
+    val iterator = iterator()
+    var sum: Long = 0
+    while (iterator.hasNext()) {
+        sum += iterator.next()
+    }
+    return sum
+}
+
 /**
  * Returns the sum of all elements in the collection
  */
@@ -43,6 +67,18 @@ public fun Iterable<Double>.sum(): Double {
     return sum
 }
 
+/**
+ * Returns the sum of all elements in the collection
+ */
+public fun Stream<Double>.sum(): Double {
+    val iterator = iterator()
+    var sum: Double = 0.0
+    while (iterator.hasNext()) {
+        sum += iterator.next()
+    }
+    return sum
+}
+
 /**
  * Returns the sum of all elements in the collection
  */
@@ -55,6 +91,18 @@ public fun Iterable<Float>.sum(): Float {
     return sum
 }
 
+/**
+ * Returns the sum of all elements in the collection
+ */
+public fun Stream<Float>.sum(): Float {
+    val iterator = iterator()
+    var sum: Float = 0.0f
+    while (iterator.hasNext()) {
+        sum += iterator.next()
+    }
+    return sum
+}
+
 /**
  * Returns the sum of all elements in the collection
  */

libraries/stdlib/test/collections/CollectionTest.kt

@@ -435,6 +435,7 @@ class CollectionTest {
         expect(3.0) { arrayListOf(1.0, 2.0).sum() }
         expect(3000000000000) { arrayListOf<Long>(1000000000000, 2000000000000).sum() }
         expect(3.0.toFloat()) { arrayListOf<Float>(1.0.toFloat(), 2.0.toFloat()).sum() }
+        expect(3.0.toFloat()) { streamOf<Float>(1.0.toFloat(), 2.0.toFloat()).sum() }
     }
 
     test fun takeReturnsFirstNElements() {

libraries/tools/kotlin-stdlib-gen/src/generators/GenerateCollections.kt

@@ -25,6 +25,7 @@ fun generateCollectionsAPI(outDir: File) {
         // TODO: decide if sum for byte and short is needed and how to make it work
         for (numeric in listOf(Int, Long, /*Byte, Short, */ Double, Float)) {
             build(builder, Iterables, numeric)
+            build(builder, Streams, numeric)
         }
 
         for (numeric in listOf(Int, Long, Byte, Short, Double, Float)) {