feat: update structure

cs2030s/labs/Lab6/Test2.java

@@ -0,0 +1,42 @@
+import cs2030s.fp.Constant;
+import cs2030s.fp.Memo;
+
+public class Test2 {
+  public static void main(String[] args) {
+    CS2030STest we = new CS2030STest();
+    
+    Memo<Integer> mod1 = Memo.from(2030);
+    we.expect(
+      "Memo<Integer> mod1 = Memo.from(2030)",
+      mod1.toString(),
+      "2030"
+    );
+    
+    Memo<String> mod2 = Memo.from(() -> "CS2030S");
+    we.expect(
+      "Memo<String> mod2 = Memo.from(\"CS2030S\")",
+      mod2.toString(),
+      "?"
+    );
+    we.expect(
+      "mod2.get()",
+      mod2.get().toString(),
+      "CS2030S"
+    );
+    
+    Memo<String> hello = Memo.from(() -> {
+      System.out.println("world!");
+      return "hello";
+    });
+    we.expect(
+      "hello.get() // warning: we do not check print output",
+      hello.get(),
+      "hello"
+    );
+    we.expect(
+      "hello.get() // warning: we do not check print output",
+      hello.get(),
+      "hello"
+    );
+  }
+}