Test user-defined AST nodes.

test.txt

@@ -320,6 +320,21 @@ print("call testfun\n");
 
 testfun();
 
+// used-defined AST nodes are evaluated the same way as built-in types
+
+MakeSeven = Object.subtype(#MakeSeven);
+
+MakeSeven.__eval__(exp, env) {
+    print("MakeSeven.__eval__ invoked\n");
+    7;
+}
+
+myNode = MakeSeven.new();
+
+ast = (`6 * @myNode;); // user-defined node in AST
+
+print("AST eval => ", eval(ast), "\n");
+
 for (i from 0 to 10) 		     print(i, " ");  print("\n");
 for (i from 10 to 0) 		     print(i, " ");  print("\n");
 for (i in 10)        		     print(i, " ");  print("\n");