Data commit

Task/Null-object/Ecstasy/null-object.ecstasy

@@ -0,0 +1,25 @@
+module NullObject {
+    void run() {
+        @Inject Console console;
+        console.print($"Null value={Null}, Null.toString()={Null.toString()}");
+
+     // String s = Null;        // <-- compiler error: cannot assign Null to a String type
+        String? s = Null;       // "String?" is shorthand for the union "Nullable|String"
+        String s2 = "test";
+        console.print($"{s=}, {s2=}, {s==s2=}");
+
+     // Int len = s.size;       // <-- compiler error: String? does not have a "size" property
+        Int len = s?.size : 0;
+        console.print($"{len=}");
+
+        if (String test ?= s) {
+            // "s" is still Null in this test, we never get here
+        } else {
+            s = "a non-null value";
+        }
+
+     // if (String test ?= s){} // <-- compiler error: The expression type is not nullable
+        s2 = s;                 // at this point, s is known to be a non-null String
+        console.print($"{s=}, {s2=}, {s==s2=}");
+    }
+}