added a sample experiment comparing Scala's use of Option[T] and how we can use T? in Kotlin today together with how we may support it in the future

libraries/stdlib/test/language/scala/OptionTest.kt

@@ -0,0 +1,142 @@
+package language.scala
+
+import kotlin. *
+import kotlin.test.assertEquals
+
+import junit.framework.TestCase
+import kotlin.util.arrayList
+
+/**
+ * This test case shows how we can use T?, the Kotlin nullable type instead of Option[T] in Scala
+ *
+ * Its worth saying that nullable types have 2 huge benefits over Option:
+ *
+ *   * Already works with any Java or JVM based API which can return nulls
+ *   * No extra object construction to wrap non-null values
+ *
+ * Examples taken from the [Scala API docs for Option](http://www.scala-lang.org/api/current/scala/Option.html)
+ *
+ * Note that currently the Kotlin library doesn't support the composition API of collections on T? like Scala's Option[T] does...
+ */
+class OptionTest: TestCase() {
+
+    fun testPatternMatching() {
+        fun foo(name: String?): String {
+
+            /* Scala:
+
+             val nameMaybe = request.getParameter("name")
+             nameMaybe match {
+               case Some(name) => {
+                 name.trim.toUppercase
+               }
+               case None => {
+                 "No name value"
+               }
+             }
+            */
+
+            // Kotlin version:
+            return when (name) {
+                is String -> {
+                    name.trim().toUpperCase()
+                }
+                else -> {
+                    "No name value"
+                }
+            }
+        }
+
+        assertEquals("No name value", foo(null))
+        assertEquals("BAR", foo("BAR"))
+        assertEquals("BAR", foo("  bar "))
+
+        println("foo(null) = ${foo(null)}")
+        println("foo(\"  bar   \") = ${foo("  bar   ")}")
+    }
+
+    fun testPatternMatchingUsingIf() {
+        fun foo2(name: String?): String {
+
+            /* Scala:
+
+             val nameMaybe = request.getParameter("name")
+             nameMaybe match {
+               case Some(name) => {
+                 name.trim.toUppercase
+               }
+               case None => {
+                 "No name value"
+               }
+             }
+            */
+
+            // Kotlin version
+            return if (name != null)  {
+                name.trim().toUpperCase()
+            } else {
+                "No name value"
+            }
+        }
+
+        assertEquals("No name value", foo2(null))
+        assertEquals("BAR", foo2("BAR"))
+        assertEquals("BAR", foo2("  bar "))
+
+        println("foo2(null) = ${foo2(null)}")
+        println("foo2(\"  bar   \") = ${foo2("  bar   ")}")
+    }
+
+
+    fun testFunctionComposition() {
+        /* Scala:
+
+        val name:Option[String] = request.getParameter("name")
+        val upper = name map { _.trim } filter { _.length != 0 } map { _.toUpperCase }
+        println(upper.getOrElse(""))
+
+        */
+
+        /** TODO
+            The following would work if we implemented the filter/map methods on T?
+
+        fun foo(name: String?): String {
+            val upper = name.map<String,String>{ it.trim() }.filter{ it.length != 0 }.map { it.toUpperCase() }
+            return upper ?: ""
+        }
+
+        assertEquals("", foo(null))
+        assertEquals("", foo("  "))
+        assertEquals("BAR", foo("  bar "))
+        */
+
+        // TODO...
+    }
+
+    fun testCompositionWithFor() {
+        fun foo3(name: String?): String {
+        /* Scala:
+
+        val upper = for {
+            name <- request.getParameter("name")
+            trimmed <- Some(name.trim)
+            upper <- Some(trimmed.toUpperCase) if trimmed.length != 0
+        } yield upper
+        println(upper.getOrElse(""))
+        */
+
+            // Kotlin version
+            // not as clean as we've no way to compose if statements so have
+            // to cheat and use returns
+            if (name != null) {
+                val trimmed = name.trim()
+                if (trimmed.length() != 0) {
+                    return trimmed.toUpperCase()
+                }
+            }
+            return ""
+        }
+    }
+
+
+}