diff -r 0f1b97538ad4 -r 2f33c51cac48 cws/main_cw04.tex
--- a/cws/main_cw04.tex	Thu Nov 13 17:44:58 2025 +0000
+++ b/cws/main_cw04.tex	Thu Nov 13 21:53:20 2025 +0000
@@ -322,19 +322,20 @@
   as follows:
 
 {\small\begin{lstlisting}
-abstract class Move
-case object U extends Move    // up
-case object D extends Move    // down
-case object R extends Move    // right
-case object L extends Move    // left
-case object RU extends Move   // ...
-case object LU extends Move
-case object RD extends Move
-case object LD extends Move
-case object UR extends Move
-case object UL extends Move
-case object DR extends Move
-case object DL extends Move
+enum Move {
+  case U    // up
+  case D    // down
+  case R    // right
+  case L    // left
+  case RU   // ...
+  case LU 
+  case RD 
+  case LD 
+  case UR 
+  case UL 
+  case DR 
+  case DL 
+}
 \end{lstlisting}}
 
 You need to implement an \texttt{eval} function that takes a piece