Introduce associateWith and associateWithTo functions

#KT-13814

libraries/stdlib/samples/test/samples/collections/collections.kt

@@ -300,6 +300,14 @@ class Collections {
 
     class Transformations {
 
+        @Sample
+        fun associateWith() {
+            val words = listOf("a", "abc", "ab", "def", "abcd")
+            val withLength = words.associateWith { it.length }
+            assertPrints(withLength.keys, "[a, abc, ab, def, abcd]")
+            assertPrints(withLength.values, "[1, 3, 2, 3, 4]")
+        }
+
         @Sample
         fun groupBy() {
             val words = listOf("a", "abc", "ab", "def", "abcd")

libraries/stdlib/samples/test/samples/text/strings.kt

@@ -84,6 +84,15 @@ class Strings {
         assertPrints(result, "[az, by, cx]")
     }
 
+    @Sample
+    fun associateWith() {
+        val string = "bonne journée"
+        // associate each character with its code
+        val result = string.associateWith { char -> char.toInt() }
+        // notice each letter occurs only once
+        assertPrints(result, "{b=98, o=111, n=110, e=101,  =32, j=106, u=117, r=114, é=233}")
+    }
+
     @Sample
     fun stringToByteArray() {
         val charset = Charsets.UTF_8