Node immutability improved

Src/AST/Myc.Ast.Compiler.TCO.pas

@@ -184,29 +184,23 @@ end;
 
 function TAstTCO.VisitLambdaExpression(const Node: ILambdaExpressionNode): IAstNode;
 var
-    N: TLambdaExpressionNode;
     newParams: TArray<IIdentifierNode>;
     newBody: IAstNode;
 begin
-    N := (Node as TLambdaExpressionNode);
-
     // Parameters are not in tail position (handled by AcceptParameters)
     FNextIsTail := False;
-    newParams := AcceptParameters(N.Parameters);
+    newParams := AcceptParameters(Node.Parameters);
 
     // The body of a lambda is *always* a tail position (relative to the lambda)
     FNextIsTail := True;
-    newBody := Accept(N.Body);
+    newBody := Accept(Node.Body);
 
-    if (newParams = N.Parameters) and (newBody = N.Body) then
+    if (newParams = Node.Parameters) and (newBody = Node.Body) then
         Result := Node
     else
     begin
-        Result := TLambdaExpressionNode.Create(newParams, newBody, N.StaticType);
-        // Copy runtime properties
-        (Result as TLambdaExpressionNode).ScopeDescriptor := N.ScopeDescriptor;
-        (Result as TLambdaExpressionNode).Upvalues := N.Upvalues;
-        (Result as TLambdaExpressionNode).HasNestedLambdas := N.HasNestedLambdas;
+        // Rebuild using factory and copy properties via interface
+        Result := TAst.LambdaExpr(newParams, newBody, Node.ScopeDescriptor, Node.Upvalues, Node.HasNestedLambdas, Node.StaticType);
     end;
 end;
 
@@ -245,26 +239,23 @@ end;
 function TAstTCO.VisitFunctionCall(const Node: IFunctionCallNode): IAstNode;
 var
     isTailCall: Boolean;
-    N: TFunctionCallNode;
     newCallee: IAstNode;
     newArgs: TArray<IAstNode>;
 begin
     isTailCall := FIsTailStack.Peek;
-    N := (Node as TFunctionCallNode);
 
     // Arguments are not in tail position
     FNextIsTail := False;
-    newCallee := Accept(N.Callee);
-    newArgs := AcceptNodes(N.Arguments);
+    newCallee := Accept(Node.Callee);
+    newArgs := AcceptNodes(Node.Arguments);
 
     // CoW check: Create a new node only if children changed OR IsTailCall needs update
-    if (newCallee = N.Callee) and (newArgs = N.Arguments) and (isTailCall = N.IsTailCall) then
+    if (newCallee = Node.Callee) and (newArgs = Node.Arguments) and (isTailCall = Node.IsTailCall) then
         Result := Node
     else
     begin
-        Result := TFunctionCallNode.Create(newCallee, newArgs, N.StaticType);
-        // Mutate the *new* node with the TCO status
-        (Result as TFunctionCallNode).IsTailCall := isTailCall;
+        // Use factory to create new node, passing the *new* TCO status
+        Result := TAst.FunctionCall(newCallee, newArgs, Node.StaticType, isTailCall);
     end;
 end;