diff --git a/ASTPlayground/ASTPlayground.dpr b/ASTPlayground/ASTPlayground.dpr
index 313f622..17e46a3 100644
--- a/ASTPlayground/ASTPlayground.dpr
+++ b/ASTPlayground/ASTPlayground.dpr
@@ -19,7 +19,8 @@ uses
     Myc.Fmx.AstEditor.Workspace in 'Myc.Fmx.AstEditor.Workspace.pas',
     Myc.Fmx.AstEditor.Text in 'Myc.Fmx.AstEditor.Text.pas',
     Myc.Utils in '..\Src\Myc.Utils.pas',
-    Myc.Ast.Script in '..\Src\AST\Myc.Ast.Script.pas';
+    Myc.Ast.Script in '..\Src\AST\Myc.Ast.Script.pas',
+    Myc.Ast.MacroExpander in '..\Src\AST\Myc.Ast.MacroExpander.pas';
 
 {$R *.res}
 
diff --git a/ASTPlayground/ASTPlayground.dproj b/ASTPlayground/ASTPlayground.dproj
index 0b40ffb..9476190 100644
--- a/ASTPlayground/ASTPlayground.dproj
+++ b/ASTPlayground/ASTPlayground.dproj
@@ -105,6 +105,7 @@
         <DCC_RemoteDebug>true</DCC_RemoteDebug>
         <DCC_IntegerOverflowCheck>true</DCC_IntegerOverflowCheck>
         <DCC_RangeChecking>true</DCC_RangeChecking>
+        <DCC_Inlining>off</DCC_Inlining>
     </PropertyGroup>
     <PropertyGroup Condition="'$(Cfg_1_Win32)'!=''">
         <DCC_RemoteDebug>false</DCC_RemoteDebug>
@@ -151,6 +152,7 @@
         <DCCReference Include="Myc.Fmx.AstEditor.Text.pas"/>
         <DCCReference Include="..\Src\Myc.Utils.pas"/>
         <DCCReference Include="..\Src\AST\Myc.Ast.Script.pas"/>
+        <DCCReference Include="..\Src\AST\Myc.Ast.MacroExpander.pas"/>
         <BuildConfiguration Include="Base">
             <Key>Base</Key>
         </BuildConfiguration>
diff --git a/ASTPlayground/MainForm.pas b/ASTPlayground/MainForm.pas
index 1a6a38a..b94b893 100644
--- a/ASTPlayground/MainForm.pas
+++ b/ASTPlayground/MainForm.pas
@@ -33,6 +33,7 @@ uses
     Myc.Ast.Binding,
     Myc.Ast.RTL,
     Myc.Ast.Script,
+    Myc.Ast.MacroExpander,
     FMX.Layouts,
     FMX.Objects,
     Myc.Ast.Debugger,
@@ -214,8 +215,24 @@ var
     scriptScope: IExecutionScope;
     visitor: IEvaluatorVisitor;
 begin
+    var macroExpander :=
+        TMacroExpander.Create(
+                function(const ANode: IAstNode): TDataValue
+                begin
+                    var binder := TAstBinder.Create(AParentScope) as IAstBinder;
+
+                    var descriptor: IScopeDescriptor;
+                    var boundAst := binder.Execute(ANode, descriptor);
+
+                    var evalScope := descriptor.CreateScope(AParentScope);
+                    var evaluator := CreateEvaluator(evalScope);
+
+                    Result := evaluator.Execute(boundAst);
+                end)
+            as IMacroExpander;
+
     binder := TAstBinder.Create(AParentScope);
-    FCurrAst := binder.Execute(ANode, FCurrDesc);
+    FCurrAst := binder.Execute(macroExpander.Execute(ANode), FCurrDesc);
 
     scriptScope := FCurrDesc.CreateScope(AParentScope);
     visitor := CreateEvaluator(scriptScope);
diff --git a/ASTPlayground/Myc.Fmx.AstEditor.Text.pas b/ASTPlayground/Myc.Fmx.AstEditor.Text.pas
index e093905..3c16c24 100644
--- a/ASTPlayground/Myc.Fmx.AstEditor.Text.pas
+++ b/ASTPlayground/Myc.Fmx.AstEditor.Text.pas
@@ -27,6 +27,9 @@ type
         function VisitAssignment(const Node: IAssignmentNode): TDataValue; override;
         function VisitIndexer(const Node: IIndexerNode): TDataValue; override;
         function VisitMemberAccess(const Node: IMemberAccessNode): TDataValue; override;
+        function VisitQuasiquote(const Node: IQuasiquoteNode): TDataValue; override;
+        function VisitUnquote(const Node: IUnquoteNode): TDataValue; override;
+        function VisitUnquoteSplicing(const Node: IUnquoteSplicingNode): TDataValue; override;
         function VisitCreateSeries(const Node: ICreateSeriesNode): TDataValue; override;
         function VisitAddSeriesItem(const Node: IAddSeriesItemNode): TDataValue; override;
         function VisitSeriesLength(const Node: ISeriesLengthNode): TDataValue; override;
@@ -200,6 +203,21 @@ begin
     Result := Format('%s.%s', [baseStr, Node.Member.Name]);
 end;
 
+function TAstToTextVisitor.VisitQuasiquote(const Node: IQuasiquoteNode): TDataValue;
+begin
+    Result := '`' + Node.Expression.Accept(Self).AsText;
+end;
+
+function TAstToTextVisitor.VisitUnquote(const Node: IUnquoteNode): TDataValue;
+begin
+    Result := '~' + Node.Expression.Accept(Self).AsText;
+end;
+
+function TAstToTextVisitor.VisitUnquoteSplicing(const Node: IUnquoteSplicingNode): TDataValue;
+begin
+    Result := '~@' + Node.Expression.Accept(Self).AsText;
+end;
+
 function TAstToTextVisitor.VisitSeriesLength(const Node: ISeriesLengthNode): TDataValue;
 var
     seriesStr: string;
diff --git a/ASTPlayground/Myc.Fmx.AstEditor.pas b/ASTPlayground/Myc.Fmx.AstEditor.pas
index 0e8f66d..84ab62d 100644
--- a/ASTPlayground/Myc.Fmx.AstEditor.pas
+++ b/ASTPlayground/Myc.Fmx.AstEditor.pas
@@ -115,6 +115,9 @@ type
         function VisitVariableDeclaration(const Node: IVariableDeclarationNode): TDataValue; override;
         function VisitAssignment(const Node: IAssignmentNode): TDataValue; override;
         function VisitMacroDefinition(const Node: IMacroDefinitionNode): TDataValue; override;
+        function VisitQuasiquote(const Node: IQuasiquoteNode): TDataValue; override;
+        function VisitUnquote(const Node: IUnquoteNode): TDataValue; override;
+        function VisitUnquoteSplicing(const Node: IUnquoteSplicingNode): TDataValue; override;
         function VisitIndexer(const Node: IIndexerNode): TDataValue; override;
         function VisitMemberAccess(const Node: IMemberAccessNode): TDataValue; override;
         function VisitCreateSeries(const Node: ICreateSeriesNode): TDataValue; override;
@@ -1245,6 +1248,75 @@ begin
     Result := TDataValue.Void;
 end;
 
+function TAstToAuraNodeVisitor.VisitQuasiquote(const Node: IQuasiquoteNode): TDataValue;
+begin
+    VisitOperatorNode(
+        [Node.Expression],
+        function(const InputResults: TAuraNodeResultList): TAuraNodeResult
+        var
+            qqNode: TAuraNode;
+            inputPin, outPin: TControl;
+        begin
+            qqNode := BuildNodeControl('`', '');
+            qqNode.TitleFont.Size := 20;
+            inputPin := CreateInput(qqNode, '');
+            outPin := CreateOutput(qqNode);
+            if Assigned(InputResults[0].OutputPin) then
+                FConnections.Add(TPinConnection.Create(InputResults[0].OutputPin, inputPin));
+            FinalizeNodeLayout(qqNode);
+            Result.LayoutNode := qqNode;
+            Result.OutputPin := outPin;
+        end
+    );
+    Result := TDataValue.Void;
+end;
+
+function TAstToAuraNodeVisitor.VisitUnquote(const Node: IUnquoteNode): TDataValue;
+begin
+    VisitOperatorNode(
+        [Node.Expression],
+        function(const InputResults: TAuraNodeResultList): TAuraNodeResult
+        var
+            uqNode: TAuraNode;
+            inputPin, outPin: TControl;
+        begin
+            uqNode := BuildNodeControl('~', '');
+            uqNode.TitleFont.Size := 20;
+            inputPin := CreateInput(uqNode, '');
+            outPin := CreateOutput(uqNode);
+            if Assigned(InputResults[0].OutputPin) then
+                FConnections.Add(TPinConnection.Create(InputResults[0].OutputPin, inputPin));
+            FinalizeNodeLayout(uqNode);
+            Result.LayoutNode := uqNode;
+            Result.OutputPin := outPin;
+        end
+    );
+    Result := TDataValue.Void;
+end;
+
+function TAstToAuraNodeVisitor.VisitUnquoteSplicing(const Node: IUnquoteSplicingNode): TDataValue;
+begin
+    VisitOperatorNode(
+        [Node.Expression],
+        function(const InputResults: TAuraNodeResultList): TAuraNodeResult
+        var
+            uqsNode: TAuraNode;
+            inputPin, outPin: TControl;
+        begin
+            uqsNode := BuildNodeControl('~@', '');
+            uqsNode.TitleFont.Size := 20;
+            inputPin := CreateInput(uqsNode, '');
+            outPin := CreateOutput(uqsNode);
+            if Assigned(InputResults[0].OutputPin) then
+                FConnections.Add(TPinConnection.Create(InputResults[0].OutputPin, inputPin));
+            FinalizeNodeLayout(uqsNode);
+            Result.LayoutNode := uqsNode;
+            Result.OutputPin := outPin;
+        end
+    );
+    Result := TDataValue.Void;
+end;
+
 function TAstToAuraNodeVisitor.VisitVariableDeclaration(const Node: IVariableDeclarationNode): TDataValue;
 var
     details: string;
diff --git a/Src/AST/Myc.Ast.Analyzer.pas b/Src/AST/Myc.Ast.Analyzer.pas
index ba5adcc..9357871 100644
--- a/Src/AST/Myc.Ast.Analyzer.pas
+++ b/Src/AST/Myc.Ast.Analyzer.pas
@@ -8,21 +8,23 @@ uses
     System.Generics.Collections,
     Myc.Ast.Nodes,
     Myc.Ast.Visitor,
-    Myc.Ast.Scope;
+    Myc.Ast.Scope,
+    Myc.Data.Value;
 
 type
     // This visitor analyzes the AST to find all variables that need to be "lifted" or "boxed"
     // because they are captured by a nested lambda.
-    TUpvalueAnalyzer = class(TAstTraverser)
+    TUpvalueAnalyzer = class(TAstTransformer)
     private
         FBoxedDeclarations: THashSet<IVariableDeclarationNode>;
         FCurrentScope: IScopeDescriptor;
         FDeclarationMap: TDictionary<IScopeDescriptor, TDictionary<string, IVariableDeclarationNode>>;
         procedure MarkDeclarationForBoxing(const AName: string);
     protected
-        function TransformLambdaExpression(const Node: ILambdaExpressionNode): ILambdaExpressionNode; override;
-        function TransformIdentifier(const Node: IIdentifierNode): IIdentifierNode; override;
-        function TransformVariableDeclaration(const Node: IVariableDeclarationNode): IVariableDeclarationNode; override;
+        // Overridden Visit methods to perform analysis during traversal.
+        function VisitLambdaExpression(const Node: ILambdaExpressionNode): TDataValue; override;
+        function VisitIdentifier(const Node: IIdentifierNode): TDataValue; override;
+        function VisitVariableDeclaration(const Node: IVariableDeclarationNode): TDataValue; override;
     public
         constructor Create(const AParent: IScopeDescriptor);
         destructor Destroy; override;
@@ -96,24 +98,26 @@ begin
     end;
 end;
 
-function TUpvalueAnalyzer.TransformIdentifier(const Node: IIdentifierNode): IIdentifierNode;
+function TUpvalueAnalyzer.VisitIdentifier(const Node: IIdentifierNode): TDataValue;
 var
     address: TResolvedAddress;
 begin
-    Result := Node;
-    if not Assigned(FCurrentScope) then
-        exit;
-
-    address := FCurrentScope.FindSymbol(Node.Name);
-
-    if (address.Kind = akLocalOrParent) and (address.ScopeDepth > 0) then
+    if Assigned(FCurrentScope) then
     begin
-        // This is an upvalue. Mark its original declaration for boxing.
-        MarkDeclarationForBoxing(Node.Name);
+        address := FCurrentScope.FindSymbol(Node.Name);
+
+        if (address.Kind = akLocalOrParent) and (address.ScopeDepth > 0) then
+        begin
+            // This is an upvalue. Mark its original declaration for boxing.
+            MarkDeclarationForBoxing(Node.Name);
+        end;
     end;
+
+    // As a traverser, return the original node wrapped in a TDataValue.
+    Result := TDataValue.FromIntf<IIdentifierNode>(Node);
 end;
 
-function TUpvalueAnalyzer.TransformLambdaExpression(const Node: ILambdaExpressionNode): ILambdaExpressionNode;
+function TUpvalueAnalyzer.VisitLambdaExpression(const Node: ILambdaExpressionNode): TDataValue;
 begin
     // A lambda creates a new lexical scope, inheriting from the current one.
     FCurrentScope := TScope.CreateDescriptor(FCurrentScope);
@@ -124,19 +128,21 @@ begin
 
         // Traverse the lambda body within the new scope context.
         Node.Body.Accept(Self);
-        Result := Node; // We do not transform, just analyze.
+
+        // We do not transform, just analyze. Return the original node wrapped.
+        Result := TDataValue.FromIntf<ILambdaExpressionNode>(Node);
     finally
         // Restore the parent scope after leaving the lambda.
         FCurrentScope := FCurrentScope.Parent;
     end;
 end;
 
-function TUpvalueAnalyzer.TransformVariableDeclaration(const Node: IVariableDeclarationNode): IVariableDeclarationNode;
+function TUpvalueAnalyzer.VisitVariableDeclaration(const Node: IVariableDeclarationNode): TDataValue;
 var
     scopeDeclarations: TDictionary<string, IVariableDeclarationNode>;
 begin
-    Result := Node;
-
+    // Traverse the initializer first. It's evaluated in the current scope
+    // before the new variable is defined.
     if Assigned(Node.Initializer) then
         Node.Initializer.Accept(Self);
 
@@ -150,6 +156,9 @@ begin
         FDeclarationMap.Add(FCurrentScope, scopeDeclarations);
     end;
     scopeDeclarations.Add(Node.Identifier.Name, Node);
+
+    // As a traverser, return the original node wrapped in a TDataValue.
+    Result := TDataValue.FromIntf<IVariableDeclarationNode>(Node);
 end;
 
 end.
diff --git a/Src/AST/Myc.Ast.Binding.pas b/Src/AST/Myc.Ast.Binding.pas
index 3a3d599..0b2965d 100644
--- a/Src/AST/Myc.Ast.Binding.pas
+++ b/Src/AST/Myc.Ast.Binding.pas
@@ -49,25 +49,24 @@ type
         // Stack management for tail-call state is centralized here.
         function Accept(const Node: IAstNode): TDataValue; override;
 
+        // The binder overrides specific visit methods to enrich the AST.
+        function VisitIdentifier(const Node: IIdentifierNode): TDataValue; override;
+        function VisitVariableDeclaration(const Node: IVariableDeclarationNode): TDataValue; override;
+        function VisitAssignment(const Node: IAssignmentNode): TDataValue; override;
+        function VisitLambdaExpression(const Node: ILambdaExpressionNode): TDataValue; override;
+        function VisitMacroDefinition(const Node: IMacroDefinitionNode): TDataValue; override;
+        function VisitFunctionCall(const Node: IFunctionCallNode): TDataValue; override;
+        function VisitRecurNode(const Node: IRecurNode): TDataValue; override;
+        function VisitBlockExpression(const Node: IBlockExpressionNode): TDataValue; override;
+        function VisitIfExpression(const Node: IIfExpressionNode): TDataValue; override;
+        function VisitTernaryExpression(const Node: ITernaryExpressionNode): TDataValue; override;
+        function VisitBinaryExpression(const Node: IBinaryExpressionNode): TDataValue; override;
+        function VisitUnaryExpression(const Node: IUnaryExpressionNode): TDataValue; override;
     public
         constructor Create(const AInitialScope: IExecutionScope);
         destructor Destroy; override;
 
         function Execute(const RootNode: IAstNode; out Descriptor: IScopeDescriptor): IAstNode;
-
-        // The binder overrides specific transform methods to enrich the AST.
-        function TransformIdentifier(const Node: IIdentifierNode): IIdentifierNode; override;
-        function TransformVariableDeclaration(const Node: IVariableDeclarationNode): IVariableDeclarationNode; override;
-        function TransformAssignment(const Node: IAssignmentNode): IAssignmentNode; override;
-        function TransformLambdaExpression(const Node: ILambdaExpressionNode): ILambdaExpressionNode; override;
-        function TransformMacroDefinition(const Node: IMacroDefinitionNode): IMacroDefinitionNode; override;
-        function TransformFunctionCall(const Node: IFunctionCallNode): IFunctionCallNode; override;
-        function TransformRecur(const Node: IRecurNode): IRecurNode; override;
-        function TransformBlockExpression(const Node: IBlockExpressionNode): IBlockExpressionNode; override;
-        function TransformIfExpression(const Node: IIfExpressionNode): IIfExpressionNode; override;
-        function TransformTernaryExpression(const Node: ITernaryExpressionNode): ITernaryExpressionNode; override;
-        function TransformBinaryExpression(const Node: IBinaryExpressionNode): IBinaryExpressionNode; override;
-        function TransformUnaryExpression(const Node: IUnaryExpressionNode): IUnaryExpressionNode; override;
     end;
 
     TBoundIdentifierNode = class(TIdentifierNode)
@@ -285,9 +284,10 @@ begin
     Result := True;
 end;
 
-function TAstBinder.TransformIdentifier(const Node: IIdentifierNode): IIdentifierNode;
+function TAstBinder.VisitIdentifier(const Node: IIdentifierNode): TDataValue;
 var
     adr: TResolvedAddress;
+    boundNode: IIdentifierNode;
 begin
     adr := FCurrentDescriptor.FindSymbol(Node.Name);
     if adr.Kind = akLocalOrParent then
@@ -306,22 +306,24 @@ begin
                 upvalue.Map.Add(adr, upvalueIndex);
             end;
 
-            Result := TBoundIdentifierNode.Create(Node, TResolvedAddress.Create(akUpvalue, 0, upvalueIndex));
+            boundNode := TBoundIdentifierNode.Create(Node, TResolvedAddress.Create(akUpvalue, 0, upvalueIndex));
         end
         else
-            Result := TBoundIdentifierNode.Create(Node, adr);
+            boundNode := TBoundIdentifierNode.Create(Node, adr);
+        Result := TDataValue.FromIntf<IIdentifierNode>(boundNode);
     end
     else
         raise Exception.CreateFmt('Undefined identifier: "%s"', [Node.Name]);
 end;
 
-function TAstBinder.TransformVariableDeclaration(const Node: IVariableDeclarationNode): IVariableDeclarationNode;
+function TAstBinder.VisitVariableDeclaration(const Node: IVariableDeclarationNode): TDataValue;
 var
     initializer: IAstNode;
     slotIndex: Integer;
     address: TResolvedAddress;
     boundIdentifier: IIdentifierNode;
     isBoxed: Boolean;
+    boundDecl: IVariableDeclarationNode;
 begin
     if not IsValidIdentifier(Node.Identifier.Name) then
         raise Exception.CreateFmt('Invalid identifier name: "%s".', [Node.Identifier.Name]);
@@ -340,28 +342,29 @@ begin
     isBoxed := (FBoxedDeclarations <> nil) and FBoxedDeclarations.Contains(Node);
 
     // Always create a bound declaration node, passing the IsBoxed flag.
-    Result := TBoundVariableDeclarationNode.Create(boundIdentifier, initializer, isBoxed);
+    boundDecl := TBoundVariableDeclarationNode.Create(boundIdentifier, initializer, isBoxed);
+    Result := TDataValue.FromIntf<IVariableDeclarationNode>(boundDecl);
 end;
 
-function TAstBinder.TransformAssignment(const Node: IAssignmentNode): IAssignmentNode;
+function TAstBinder.VisitAssignment(const Node: IAssignmentNode): TDataValue;
 begin
     FNextIsTail := False;
-    Result := inherited TransformAssignment(Node);
+    Result := inherited VisitAssignment(Node);
 end;
 
-function TAstBinder.TransformBinaryExpression(const Node: IBinaryExpressionNode): IBinaryExpressionNode;
+function TAstBinder.VisitBinaryExpression(const Node: IBinaryExpressionNode): TDataValue;
 begin
     FNextIsTail := False;
-    Result := inherited TransformBinaryExpression(Node);
+    Result := inherited VisitBinaryExpression(Node);
 end;
 
-function TAstBinder.TransformUnaryExpression(const Node: IUnaryExpressionNode): IUnaryExpressionNode;
+function TAstBinder.VisitUnaryExpression(const Node: IUnaryExpressionNode): TDataValue;
 begin
     FNextIsTail := False;
-    Result := inherited TransformUnaryExpression(Node);
+    Result := inherited VisitUnaryExpression(Node);
 end;
 
-function TAstBinder.TransformLambdaExpression(const Node: ILambdaExpressionNode): ILambdaExpressionNode;
+function TAstBinder.VisitLambdaExpression(const Node: ILambdaExpressionNode): TDataValue;
 var
     i: integer;
     boundParams: TArray<IIdentifierNode>;
@@ -370,6 +373,7 @@ var
     upvalues: TArray<TResolvedAddress>;
     hasNestedLambdas: Boolean;
     lastNestedLambdaCount: Integer;
+    boundLambda: ILambdaExpressionNode;
 begin
     FUpvalueStack.Push(TUpvalueMapping.Create);
     try
@@ -415,14 +419,16 @@ begin
     end;
 
     inc(FNestedLambdaCount);
-    Result := TBoundLambdaExpressionNode.Create(Node, boundBody, boundParams, lambdaScope, upvalues, hasNestedLambdas);
+    boundLambda := TBoundLambdaExpressionNode.Create(Node, boundBody, boundParams, lambdaScope, upvalues, hasNestedLambdas);
+    Result := TDataValue.FromIntf<ILambdaExpressionNode>(boundLambda);
 end;
 
-function TAstBinder.TransformFunctionCall(const Node: IFunctionCallNode): IFunctionCallNode;
+function TAstBinder.VisitFunctionCall(const Node: IFunctionCallNode): TDataValue;
 var
     isTailCall: Boolean;
     callee: IAstNode;
     args: TArray<IAstNode>;
+    boundCall: IFunctionCallNode;
 begin
     isTailCall := FIsTailStack.Peek;
 
@@ -430,19 +436,20 @@ begin
     callee := Accept(Node.Callee).AsIntf<IAstNode>;
     args := TransformNodes<IAstNode>(Node.Arguments);
 
-    Result := TBoundFunctionCallNode.Create(Node, callee, args, isTailCall);
+    boundCall := TBoundFunctionCallNode.Create(Node, callee, args, isTailCall);
+    Result := TDataValue.FromIntf<IFunctionCallNode>(boundCall);
 end;
 
-function TAstBinder.TransformRecur(const Node: IRecurNode): IRecurNode;
+function TAstBinder.VisitRecurNode(const Node: IRecurNode): TDataValue;
 begin
     if not FIsTailStack.Peek then
         raise Exception.Create('''recur'' can only be used in a tail position.');
 
     FNextIsTail := False;
-    Result := inherited TransformRecur(Node);
+    Result := inherited VisitRecurNode(Node);
 end;
 
-function TAstBinder.TransformBlockExpression(const Node: IBlockExpressionNode): IBlockExpressionNode;
+function TAstBinder.VisitBlockExpression(const Node: IBlockExpressionNode): TDataValue;
 var
     exprs: TArray<IAstNode>;
     i: Integer;
@@ -450,16 +457,16 @@ var
 begin
     isContextTail := FIsTailStack.Peek;
 
-    SetLength(exprs, Node.Expressions.Count);
-    for i := 0 to Node.Expressions.Count - 1 do
+    SetLength(exprs, Length(Node.Expressions));
+    for i := 0 to High(exprs) do
     begin
-        FNextIsTail := isContextTail and (i = Node.Expressions.Count - 1);
+        FNextIsTail := isContextTail and (i = High(exprs));
         exprs[i] := Accept(Node.Expressions[i]).AsIntf<IAstNode>;
     end;
-    Result := TAst.Block(exprs);
+    Result := TDataValue.FromIntf<IBlockExpressionNode>(TAst.Block(exprs));
 end;
 
-function TAstBinder.TransformIfExpression(const Node: IIfExpressionNode): IIfExpressionNode;
+function TAstBinder.VisitIfExpression(const Node: IIfExpressionNode): TDataValue;
 var
     isContextTail: Boolean;
     condition, thenBranch, elseBranch: IAstNode;
@@ -474,18 +481,18 @@ begin
     elseBranch := Accept(Node.ElseBranch).AsIntf<IAstNode>;
 
     if (condition <> Node.Condition) or (thenBranch <> Node.ThenBranch) or (elseBranch <> Node.ElseBranch) then
-        Result := TAst.IfExpr(condition, thenBranch, elseBranch)
+        Result := TDataValue.FromIntf<IIfExpressionNode>(TAst.IfExpr(condition, thenBranch, elseBranch))
     else
-        Result := Node;
+        Result := TDataValue.FromIntf<IIfExpressionNode>(Node);
 end;
 
-function TAstBinder.TransformMacroDefinition(const Node: IMacroDefinitionNode): IMacroDefinitionNode;
+function TAstBinder.VisitMacroDefinition(const Node: IMacroDefinitionNode): TDataValue;
 begin
     // The binder runs after the macro expander. It should never see a macro definition.
     raise Exception.Create('IMacroDefinitionNode found in AST after macro expansion phase.');
 end;
 
-function TAstBinder.TransformTernaryExpression(const Node: ITernaryExpressionNode): ITernaryExpressionNode;
+function TAstBinder.VisitTernaryExpression(const Node: ITernaryExpressionNode): TDataValue;
 var
     isContextTail: Boolean;
     condition, thenBranch, elseBranch: IAstNode;
@@ -500,9 +507,9 @@ begin
     elseBranch := Accept(Node.ElseBranch).AsIntf<IAstNode>;
 
     if (condition <> Node.Condition) or (thenBranch <> Node.ThenBranch) or (elseBranch <> Node.ElseBranch) then
-        Result := TAst.TernaryExpr(condition, thenBranch, elseBranch)
+        Result := TDataValue.FromIntf<ITernaryExpressionNode>(TAst.TernaryExpr(condition, thenBranch, elseBranch))
     else
-        Result := Node;
+        Result := TDataValue.FromIntf<ITernaryExpressionNode>(Node);
 end;
 
 end.
diff --git a/Src/AST/Myc.Ast.Debugger.pas b/Src/AST/Myc.Ast.Debugger.pas
index a9450af..0f318c7 100644
--- a/Src/AST/Myc.Ast.Debugger.pas
+++ b/Src/AST/Myc.Ast.Debugger.pas
@@ -26,7 +26,7 @@ type
 
     protected
         // Overridden to provide the debug-specific visitor factory.
-        function CreateVisitorFactory: TVisitorFactory; override;
+        function CreateVisitorFactory: TEvaluatorFactory; override;
 
     public
         constructor Create(const AScope: IExecutionScope; ALog: TStrings; AShowScope: Boolean; AInitialIndent: Integer = 0);
@@ -66,13 +66,13 @@ begin
     ShowScope;
 end;
 
-function TDebugEvaluatorVisitor.CreateVisitorFactory: TVisitorFactory;
+function TDebugEvaluatorVisitor.CreateVisitorFactory: TEvaluatorFactory;
 begin
     // Return a closure that creates a new Debug visitor, using the current context
 
-    var callingVisitor := Self as IAstVisitor;
+    var callingVisitor := Self as IEvaluatorVisitor;
     Result :=
-        function(const AScope: IExecutionScope): IAstVisitor
+        function(const AScope: IExecutionScope): IEvaluatorVisitor
         begin
             var visitor := callingVisitor as TDebugEvaluatorVisitor;
             Result := TDebugEvaluatorVisitor.Create(AScope, visitor.FLog, visitor.FShowScope, visitor.FIndentLevel);
diff --git a/Src/AST/Myc.Ast.Dumper.pas b/Src/AST/Myc.Ast.Dumper.pas
index 6c989f2..7a4d007 100644
--- a/Src/AST/Myc.Ast.Dumper.pas
+++ b/Src/AST/Myc.Ast.Dumper.pas
@@ -42,6 +42,9 @@ type
         function VisitVariableDeclaration(const Node: IVariableDeclarationNode): TDataValue; override;
         function VisitAssignment(const Node: IAssignmentNode): TDataValue; override;
         function VisitMacroDefinition(const Node: IMacroDefinitionNode): TDataValue; override;
+        function VisitQuasiquote(const Node: IQuasiquoteNode): TDataValue; override;
+        function VisitUnquote(const Node: IUnquoteNode): TDataValue; override;
+        function VisitUnquoteSplicing(const Node: IUnquoteSplicingNode): TDataValue; override;
         function VisitIndexer(const Node: IIndexerNode): TDataValue; override;
         function VisitMemberAccess(const Node: IMemberAccessNode): TDataValue; override;
         function VisitCreateSeries(const Node: ICreateSeriesNode): TDataValue; override;
@@ -350,6 +353,33 @@ begin
     Result := TDataValue.Void;
 end;
 
+function TAstDumper.VisitQuasiquote(const Node: IQuasiquoteNode): TDataValue;
+begin
+    Log('Quasiquote');
+    Indent;
+    Node.Expression.Accept(Self);
+    Unindent;
+    Result := TDataValue.Void;
+end;
+
+function TAstDumper.VisitUnquote(const Node: IUnquoteNode): TDataValue;
+begin
+    Log('Unquote');
+    Indent;
+    Node.Expression.Accept(Self);
+    Unindent;
+    Result := TDataValue.Void;
+end;
+
+function TAstDumper.VisitUnquoteSplicing(const Node: IUnquoteSplicingNode): TDataValue;
+begin
+    Log('UnquoteSplicing');
+    Indent;
+    Node.Expression.Accept(Self);
+    Unindent;
+    Result := TDataValue.Void;
+end;
+
 function TAstDumper.VisitIndexer(const Node: IIndexerNode): TDataValue;
 begin
     Log('Indexer');
diff --git a/Src/AST/Myc.Ast.Evaluator.pas b/Src/AST/Myc.Ast.Evaluator.pas
index 22db272..8c235b3 100644
--- a/Src/AST/Myc.Ast.Evaluator.pas
+++ b/Src/AST/Myc.Ast.Evaluator.pas
@@ -14,13 +14,13 @@ uses
     Myc.Ast.Scope;
 
 type
-    // A factory for creating visitors, primarily used by the debugger subsystem.
-    TVisitorFactory = reference to function(const Scope: IExecutionScope): IAstVisitor;
-
     IEvaluatorVisitor = interface(IAstVisitor)
         function Execute(const RootNode: IAstNode): TDataValue;
     end;
 
+    // A factory for creating visitors, primarily used by the debugger subsystem.
+    TEvaluatorFactory = reference to function(const Scope: IExecutionScope): IEvaluatorVisitor;
+
     // The standard AST evaluator for production use.
     TEvaluatorVisitor = class(TAstVisitor, IEvaluatorVisitor)
     private
@@ -36,6 +36,9 @@ type
         function VisitTernaryExpression(const Node: ITernaryExpressionNode): TDataValue; override;
         function VisitLambdaExpression(const Node: ILambdaExpressionNode): TDataValue; override;
         function VisitMacroDefinition(const Node: IMacroDefinitionNode): TDataValue; override;
+        function VisitQuasiquote(const Node: IQuasiquoteNode): TDataValue; override;
+        function VisitUnquote(const Node: IUnquoteNode): TDataValue; override;
+        function VisitUnquoteSplicing(const Node: IUnquoteSplicingNode): TDataValue; override;
         function VisitFunctionCall(const Node: IFunctionCallNode): TDataValue; override;
         function VisitBlockExpression(const Node: IBlockExpressionNode): TDataValue; override;
         function VisitVariableDeclaration(const Node: IVariableDeclarationNode): TDataValue; override;
@@ -50,7 +53,7 @@ type
         function IsTruthy(const AValue: TDataValue): Boolean; inline;
 
         // Returns a closure that can create the correct type of visitor for a lambda's body.
-        function CreateVisitorFactory: TVisitorFactory; virtual;
+        function CreateVisitorFactory: TEvaluatorFactory; virtual;
 
         property Scope: IExecutionScope read FScope;
     public
@@ -132,10 +135,10 @@ begin
     HandleTCO(Result);
 end;
 
-function TEvaluatorVisitor.CreateVisitorFactory: TVisitorFactory;
+function TEvaluatorVisitor.CreateVisitorFactory: TEvaluatorFactory;
 begin
     // The production visitor returns a factory that creates another production visitor.
-    Result := function(const AScope: IExecutionScope): IAstVisitor begin Result := TEvaluatorVisitor.Create(AScope); end;
+    Result := function(const AScope: IExecutionScope): IEvaluatorVisitor begin Result := TEvaluatorVisitor.Create(AScope); end;
 end;
 
 procedure TEvaluatorVisitor.HandleTCO(var ResultValue: TDataValue);
@@ -173,7 +176,7 @@ var
     i: Integer;
     sourceAddresses: TArray<TResolvedAddress>;
     closureScope: IExecutionScope;
-    visitorFactory: TVisitorFactory;
+    visitorFactory: TEvaluatorFactory;
 begin
     // Cast to the bound node to access binder-specific information.
     boundNode := Node as TBoundLambdaExpressionNode;
@@ -249,6 +252,21 @@ begin
     raise Exception.Create('Macro definitions cannot be evaluated at runtime.');
 end;
 
+function TEvaluatorVisitor.VisitQuasiquote(const Node: IQuasiquoteNode): TDataValue;
+begin
+    raise Exception.Create('Quasiquote nodes are a compile-time construct and cannot be evaluated at runtime.');
+end;
+
+function TEvaluatorVisitor.VisitUnquote(const Node: IUnquoteNode): TDataValue;
+begin
+    raise Exception.Create('Unquote nodes are a compile-time construct and cannot be evaluated at runtime.');
+end;
+
+function TEvaluatorVisitor.VisitUnquoteSplicing(const Node: IUnquoteSplicingNode): TDataValue;
+begin
+    raise Exception.Create('Unquote-splicing nodes are a compile-time construct and cannot be evaluated at runtime.');
+end;
+
 function TEvaluatorVisitor.VisitFunctionCall(const Node: IFunctionCallNode): TDataValue;
 var
     calleeValue: TDataValue;
diff --git a/Src/AST/Myc.Ast.JSON.pas b/Src/AST/Myc.Ast.JSON.pas
index 477258f..6e045a0 100644
--- a/Src/AST/Myc.Ast.JSON.pas
+++ b/Src/AST/Myc.Ast.JSON.pas
@@ -35,6 +35,9 @@ type
         function JsonToTernaryExprNode(const AObj: TJSONObject): ITernaryExpressionNode;
         function JsonToLambdaExprNode(const AObj: TJSONObject): ILambdaExpressionNode;
         function JsonToMacroDefNode(const AObj: TJSONObject): IMacroDefinitionNode;
+        function JsonToQuasiquoteNode(const AObj: TJSONObject): IQuasiquoteNode;
+        function JsonToUnquoteNode(const AObj: TJSONObject): IUnquoteNode;
+        function JsonToUnquoteSplicingNode(const AObj: TJSONObject): IUnquoteSplicingNode;
         function JsonToFunctionCallNode(const AObj: TJSONObject): IFunctionCallNode;
         function JsonToRecurNode(const AObj: TJSONObject): IRecurNode;
         function JsonToBlockNode(const AObj: TJSONObject): IBlockExpressionNode;
@@ -55,6 +58,9 @@ type
         function VisitTernaryExpression(const Node: ITernaryExpressionNode): TDataValue; override;
         function VisitLambdaExpression(const Node: ILambdaExpressionNode): TDataValue; override;
         function VisitMacroDefinition(const Node: IMacroDefinitionNode): TDataValue; override;
+        function VisitQuasiquote(const Node: IQuasiquoteNode): TDataValue; override;
+        function VisitUnquote(const Node: IUnquoteNode): TDataValue; override;
+        function VisitUnquoteSplicing(const Node: IUnquoteSplicingNode): TDataValue; override;
         function VisitFunctionCall(const Node: IFunctionCallNode): TDataValue; override;
         function VisitRecurNode(const Node: IRecurNode): TDataValue; override;
         function VisitBlockExpression(const Node: IBlockExpressionNode): TDataValue; override;
@@ -295,6 +301,21 @@ begin
     Result := TDataValue.Void;
 end;
 
+function TJsonAstConverter.JsonToQuasiquoteNode(const AObj: TJSONObject): IQuasiquoteNode;
+begin
+    Result := TAst.Quasiquote(JsonToNode(AObj.GetValue('Expression')));
+end;
+
+function TJsonAstConverter.JsonToUnquoteNode(const AObj: TJSONObject): IUnquoteNode;
+begin
+    Result := TAst.Unquote(JsonToNode(AObj.GetValue('Expression')));
+end;
+
+function TJsonAstConverter.JsonToUnquoteSplicingNode(const AObj: TJSONObject): IUnquoteSplicingNode;
+begin
+    Result := TAst.UnquoteSplicing(JsonToNode(AObj.GetValue('Expression')));
+end;
+
 function TJsonAstConverter.VisitFunctionCall(const Node: IFunctionCallNode): TDataValue;
 var
     obj, calleeObj: TJSONObject;
@@ -362,7 +383,7 @@ begin
     for expr in Node.Expressions do
         expr.Accept(Self);
 
-    SetLength(tempExprs, Node.Expressions.Count);
+    SetLength(tempExprs, Length(Node.Expressions));
     for i := High(tempExprs) downto 0 do
         tempExprs[i] := FJsonObjectStack.Pop;
 
@@ -646,6 +667,48 @@ begin
     Result := TAst.MacroDef(name, params, body);
 end;
 
+function TJsonAstConverter.VisitQuasiquote(const Node: IQuasiquoteNode): TDataValue;
+var
+    obj, exprObj: TJSONObject;
+begin
+    Node.Expression.Accept(Self);
+    exprObj := FJsonObjectStack.Pop;
+
+    obj := TJSONObject.Create;
+    obj.AddPair('NodeType', TJSONString.Create('Quasiquote'));
+    obj.AddPair('Expression', exprObj);
+    FJsonObjectStack.Push(obj);
+    Result := TDataValue.Void;
+end;
+
+function TJsonAstConverter.VisitUnquote(const Node: IUnquoteNode): TDataValue;
+var
+    obj, exprObj: TJSONObject;
+begin
+    Node.Expression.Accept(Self);
+    exprObj := FJsonObjectStack.Pop;
+
+    obj := TJSONObject.Create;
+    obj.AddPair('NodeType', TJSONString.Create('Unquote'));
+    obj.AddPair('Expression', exprObj);
+    FJsonObjectStack.Push(obj);
+    Result := TDataValue.Void;
+end;
+
+function TJsonAstConverter.VisitUnquoteSplicing(const Node: IUnquoteSplicingNode): TDataValue;
+var
+    obj, exprObj: TJSONObject;
+begin
+    Node.Expression.Accept(Self);
+    exprObj := FJsonObjectStack.Pop;
+
+    obj := TJSONObject.Create;
+    obj.AddPair('NodeType', TJSONString.Create('UnquoteSplicing'));
+    obj.AddPair('Expression', exprObj);
+    FJsonObjectStack.Push(obj);
+    Result := TDataValue.Void;
+end;
+
 function TJsonAstConverter.JsonToFunctionCallNode(const AObj: TJSONObject): IFunctionCallNode;
 var
     callee: IAstNode;
@@ -774,6 +837,12 @@ begin
         Result := JsonToLambdaExprNode(obj)
     else if nodeType = 'MacroDef' then
         Result := JsonToMacroDefNode(obj)
+    else if nodeType = 'Quasiquote' then
+        Result := JsonToQuasiquoteNode(obj)
+    else if nodeType = 'Unquote' then
+        Result := JsonToUnquoteNode(obj)
+    else if nodeType = 'UnquoteSplicing' then
+        Result := JsonToUnquoteSplicingNode(obj)
     else if nodeType = 'FunctionCall' then
         Result := JsonToFunctionCallNode(obj)
     else if nodeType = 'Recur' then
diff --git a/Src/AST/Myc.Ast.MacroExpander.pas b/Src/AST/Myc.Ast.MacroExpander.pas
new file mode 100644
index 0000000..8a34aeb
--- /dev/null
+++ b/Src/AST/Myc.Ast.MacroExpander.pas
@@ -0,0 +1,269 @@
+unit Myc.Ast.MacroExpander;
+
+interface
+
+uses
+    System.SysUtils,
+    System.Classes,
+    System.Generics.Collections,
+    Myc.Data.Value,
+    Myc.Ast.Nodes,
+    Myc.Ast.Scope,
+    Myc.Ast.Visitor;
+
+type
+    // Defines the strategy for compiling and evaluating an AST node at compile time.
+    TCompileTimeExecutor = reference to function(const ANode: IAstNode): TDataValue;
+
+    IMacroExpander = interface(IAstVisitor)
+        function Execute(const RootNode: IAstNode): IAstNode;
+    end;
+
+    // The macro expander is now a pure AST transformation engine.
+    TMacroExpander = class(TAstTransformer, IMacroExpander)
+    private
+        FMacros: TDictionary<string, IMacroDefinitionNode>;
+        FExecutor: TCompileTimeExecutor;
+        function ExpandNode(const ANode: IAstNode): IAstNode;
+    protected
+        function VisitMacroDefinition(const Node: IMacroDefinitionNode): TDataValue; override;
+        function VisitFunctionCall(const Node: IFunctionCallNode): TDataValue; override;
+    public
+        constructor Create(const AExecutor: TCompileTimeExecutor);
+        destructor Destroy; override;
+        function Execute(const RootNode: IAstNode): IAstNode;
+    end;
+
+implementation
+
+uses
+    Myc.Ast;
+
+type
+    TExpansionHelper = class(TAstTransformer)
+    private
+        FExpansionScope: IExecutionScope;
+        FExpander: TMacroExpander;
+        FExecutor: TCompileTimeExecutor;
+    protected
+        function VisitUnquote(const Node: IUnquoteNode): TDataValue; override;
+        function VisitUnquoteSplicing(const Node: IUnquoteSplicingNode): TDataValue; override;
+        function VisitFunctionCall(const Node: IFunctionCallNode): TDataValue; override;
+    public
+        constructor Create(AExpansionScope: IExecutionScope; AExpander: TMacroExpander; AExecutor: TCompileTimeExecutor);
+        class function Expand(
+            Node: IAstNode;
+            ExpansionScope: IExecutionScope;
+            Expander: TMacroExpander;
+            Executor: TCompileTimeExecutor
+        ): IAstNode; static;
+    end;
+
+    TSubstitutor = class(TAstTransformer)
+    private
+        FParamScope: IExecutionScope;
+    protected
+        function VisitIdentifier(const Node: IIdentifierNode): TDataValue; override;
+    public
+        constructor Create(AParamScope: IExecutionScope);
+    end;
+
+{ TMacroExpander }
+
+constructor TMacroExpander.Create(const AExecutor: TCompileTimeExecutor);
+begin
+    inherited Create;
+    Assert(Assigned(AExecutor), 'A TCompileTimeExecutor must be provided.');
+    FMacros := TDictionary<string, IMacroDefinitionNode>.Create;
+    FExecutor := AExecutor;
+end;
+
+destructor TMacroExpander.Destroy;
+begin
+    FMacros.Free;
+    inherited;
+end;
+
+function TMacroExpander.ExpandNode(const ANode: IAstNode): IAstNode;
+var
+    lastNode: IAstNode;
+begin
+    Result := ANode;
+    if not Assigned(Result) then
+        exit;
+    repeat
+        lastNode := Result;
+        Result := Self.Accept(lastNode).AsIntf<IAstNode>;
+    until Result = lastNode;
+end;
+
+function TMacroExpander.Execute(const RootNode: IAstNode): IAstNode;
+begin
+    FMacros.Clear;
+    Result := ExpandNode(RootNode);
+end;
+
+function TMacroExpander.VisitFunctionCall(const Node: IFunctionCallNode): TDataValue;
+var
+    macroDef: IMacroDefinitionNode;
+    expandedNode: IAstNode;
+    i: Integer;
+begin
+    if not (Node.Callee is TIdentifierNode) then
+    begin
+        Result := inherited VisitFunctionCall(Node);
+        exit;
+    end;
+
+    var calleeIdentifier := Node.Callee as TIdentifierNode;
+
+    if FMacros.TryGetValue(calleeIdentifier.Name, macroDef) then
+    begin
+        var expansionScope := TAst.CreateScope(nil); // Temporary scope for parameters, no parent needed.
+
+        if Length(Node.Arguments) <> Length(macroDef.Parameters) then
+            raise Exception.CreateFmt(
+                'Macro %s expects %d arguments, but got %d',
+                [macroDef.Name.Name, Length(macroDef.Parameters), Length(Node.Arguments)]);
+
+        for i := 0 to High(macroDef.Parameters) do
+            expansionScope.Define(macroDef.Parameters[i].Name, TDataValue.FromIntf<IAstNode>(Node.Arguments[i]));
+
+        if not (macroDef.Body is TQuasiquoteNode) then
+            raise Exception.CreateFmt('Macro body for "%s" must be a quasiquoted expression.', [macroDef.Name.Name]);
+
+        expandedNode := TExpansionHelper.Expand(IQuasiquoteNode(macroDef.Body).Expression, expansionScope, Self, FExecutor);
+
+        Result := Self.Accept(expandedNode);
+    end
+    else
+    begin
+        Result := inherited VisitFunctionCall(Node);
+    end;
+end;
+
+function TMacroExpander.VisitMacroDefinition(const Node: IMacroDefinitionNode): TDataValue;
+begin
+    FMacros.AddOrSetValue(Node.Name.Name, Node);
+    Result := TDataValue.FromIntf<IBlockExpressionNode>(TBlockExpressionNode.Create([]));
+end;
+
+{ TExpansionHelper }
+
+constructor TExpansionHelper.Create(AExpansionScope: IExecutionScope; AExpander: TMacroExpander; AExecutor: TCompileTimeExecutor);
+begin
+    inherited Create;
+    FExpansionScope := AExpansionScope;
+    FExpander := AExpander;
+    FExecutor := AExecutor;
+end;
+
+class function TExpansionHelper.Expand(
+    Node: IAstNode;
+    ExpansionScope: IExecutionScope;
+    Expander: TMacroExpander;
+    Executor: TCompileTimeExecutor
+): IAstNode;
+var
+    helper: TExpansionHelper;
+begin
+    helper := TExpansionHelper.Create(ExpansionScope, Expander, Executor);
+    try
+        Result := helper.Accept(Node).AsIntf<IAstNode>;
+    finally
+        helper.Free;
+    end;
+end;
+
+function TExpansionHelper.VisitFunctionCall(const Node: IFunctionCallNode): TDataValue;
+var
+    newArgs: TList<IAstNode>;
+    transformedArgValue: TDataValue;
+    transformedArgNode: IAstNode;
+    transformedCallee: IAstNode;
+begin
+    newArgs := TList<IAstNode>.Create;
+    try
+        for var arg in Node.Arguments do
+        begin
+            transformedArgValue := Self.Accept(arg);
+            if transformedArgValue.IsVoid then
+                continue;
+            transformedArgNode := transformedArgValue.AsIntf<IAstNode>;
+            if (transformedArgNode is TBlockExpressionNode) then
+                newArgs.AddRange((transformedArgNode as TBlockExpressionNode).Expressions)
+            else
+                newArgs.Add(transformedArgNode);
+        end;
+        transformedCallee := Self.Accept(Node.Callee).AsIntf<IAstNode>;
+        Result := TDataValue.FromIntf<IAstNode>(TAst.FunctionCall(transformedCallee, newArgs.ToArray));
+    finally
+        newArgs.Free;
+    end;
+end;
+
+function TExpansionHelper.VisitUnquote(const Node: IUnquoteNode): TDataValue;
+var
+    substitutor: TSubstitutor;
+    substitutedAst, expandedAst: IAstNode;
+    value: TDataValue;
+begin
+    // Step 1: Substitute macro parameters with their AST node values.
+    substitutor := TSubstitutor.Create(FExpansionScope);
+    try
+        substitutedAst := substitutor.Execute(Node.Expression);
+    finally
+        substitutor.Free;
+    end;
+
+    // Step 2: Recursively expand any macros within the substituted expression.
+    expandedAst := FExpander.ExpandNode(substitutedAst);
+
+    // Step 3: Call the injected executor strategy to bind and evaluate the AST.
+    value := FExecutor(expandedAst);
+
+    // Step 4: Wrap the resulting value for insertion into the template.
+    if value.Kind in [vkScalar, vkText] then
+        Result := TDataValue.FromIntf<IAstNode>(TAst.Constant(value))
+    else
+        Result := value;
+end;
+
+function TExpansionHelper.VisitUnquoteSplicing(const Node: IUnquoteSplicingNode): TDataValue;
+var
+    unquotedValue: TDataValue;
+    unquotedNode: IAstNode;
+begin
+    unquotedValue := Self.VisitUnquote(TAst.Unquote(Node.Expression));
+    if unquotedValue.Kind = vkInterface then
+        unquotedNode := unquotedValue.AsIntf<IAstNode>
+    else
+        unquotedNode := nil;
+    if not (unquotedNode is TBlockExpressionNode) then
+        raise Exception.Create('Expression inside unquote-splicing (`~@`) must evaluate to a list of nodes (a block).');
+    Result := unquotedValue;
+end;
+
+{ TSubstitutor }
+constructor TSubstitutor.Create(AParamScope: IExecutionScope);
+begin
+    inherited Create;
+    FParamScope := AParamScope;
+end;
+
+function TSubstitutor.VisitIdentifier(const Node: IIdentifierNode): TDataValue;
+var
+    addr: TResolvedAddress;
+    nodeValue: TDataValue;
+begin
+    addr := FParamScope.CreateDescriptor.FindSymbol(Node.Name);
+    if (addr.Kind = akLocalOrParent) and (addr.ScopeDepth = 0) then
+    begin
+        nodeValue := FParamScope.Values[addr];
+        Result := nodeValue;
+        exit;
+    end;
+    Result := inherited VisitIdentifier(Node);
+end;
+
+end.
diff --git a/Src/AST/Myc.Ast.Nodes.pas b/Src/AST/Myc.Ast.Nodes.pas
index 1a56ec2..e96f439 100644
--- a/Src/AST/Myc.Ast.Nodes.pas
+++ b/Src/AST/Myc.Ast.Nodes.pas
@@ -162,9 +162,9 @@ type
 
     IBlockExpressionNode = interface(IAstNode)
         {$region 'private'}
-        function GetExpressions: TList<IAstNode>;
+        function GetExpressions: TArray<IAstNode>;
         {$endregion}
-        property Expressions: TList<IAstNode> read GetExpressions;
+        property Expressions: TArray<IAstNode> read GetExpressions;
     end;
 
     IVariableDeclarationNode = interface(IAstNode)
diff --git a/Src/AST/Myc.Ast.Script.pas b/Src/AST/Myc.Ast.Script.pas
index 557062c..430595d 100644
--- a/Src/AST/Myc.Ast.Script.pas
+++ b/Src/AST/Myc.Ast.Script.pas
@@ -386,11 +386,11 @@ begin
                 // (defmacro name [params] body)
                 if (Length(tailNodes) <> 3) or (tailTokens[0].Kind <> tkIdentifier) then
                     raise Exception.Create('Syntax Error: ''defmacro'' requires a name, a parameter list, and a body.');
-                if elements[1].Node <> nil then
+                if elements[2].Params = nil then
                     raise Exception.Create('Syntax Error: Expected a parameter list [...] after macro name.');
 
                 var macroName := IIdentifierNode(tailNodes[0]);
-                var macroParams := elements[1].Params;
+                var macroParams := elements[2].Params;
                 var macroBody := tailNodes[2];
 
                 Result := TAst.MacroDef(macroName, macroParams, macroBody);
@@ -405,7 +405,7 @@ begin
             begin
                 if Length(tailNodes) <> 2 then
                     raise Exception.Create('Syntax Error: ''fn'' requires a parameter list and a body.');
-                if elements[1].Node <> nil then
+                if elements[1].Params = nil then
                     raise Exception.Create('Syntax Error: Expected a parameter list [...] after ''fn''.');
                 Result := TAst.LambdaExpr(elements[1].Params, tailNodes[1]);
             end
diff --git a/Src/AST/Myc.Ast.Visitor.pas b/Src/AST/Myc.Ast.Visitor.pas
index bbc2cda..dc2ba36 100644
--- a/Src/AST/Myc.Ast.Visitor.pas
+++ b/Src/AST/Myc.Ast.Visitor.pas
@@ -41,59 +41,34 @@ type
     end;
 
     // A base visitor that walks the AST and rebuilds it node by node.
-    // This class uses the Template Method pattern:
-    // - The Visit... methods are the template and should not be overridden.
-    // - The virtual Transform... methods are the hooks for derived classes to customize behavior.
+    // Derived classes can override the virtual Visit... methods to customize behavior.
     TAstTransformer = class abstract(TAstVisitor, IAstTransformer)
     private
         FDone: Boolean;
 
     protected
-        // Final Visit methods - these should not be overridden. They call the virtual Transform methods.
-        function VisitConstant(const Node: IConstantNode): TDataValue; override; final;
-        function VisitIdentifier(const Node: IIdentifierNode): TDataValue; override; final;
-        function VisitBinaryExpression(const Node: IBinaryExpressionNode): TDataValue; override; final;
-        function VisitUnaryExpression(const Node: IUnaryExpressionNode): TDataValue; override; final;
-        function VisitIfExpression(const Node: IIfExpressionNode): TDataValue; override; final;
-        function VisitTernaryExpression(const Node: ITernaryExpressionNode): TDataValue; override; final;
-        function VisitLambdaExpression(const Node: ILambdaExpressionNode): TDataValue; override; final;
-        function VisitFunctionCall(const Node: IFunctionCallNode): TDataValue; override; final;
-        function VisitBlockExpression(const Node: IBlockExpressionNode): TDataValue; override; final;
-        function VisitVariableDeclaration(const Node: IVariableDeclarationNode): TDataValue; override; final;
-        function VisitAssignment(const Node: IAssignmentNode): TDataValue; override; final;
-        function VisitMacroDefinition(const Node: IMacroDefinitionNode): TDataValue; override; final;
-        function VisitQuasiquote(const Node: IQuasiquoteNode): TDataValue; override; final;
-        function VisitUnquote(const Node: IUnquoteNode): TDataValue; override; final;
-        function VisitUnquoteSplicing(const Node: IUnquoteSplicingNode): TDataValue; override; final;
-        function VisitIndexer(const Node: IIndexerNode): TDataValue; override; final;
-        function VisitMemberAccess(const Node: IMemberAccessNode): TDataValue; override; final;
-        function VisitCreateSeries(const Node: ICreateSeriesNode): TDataValue; override; final;
-        function VisitAddSeriesItem(const Node: IAddSeriesItemNode): TDataValue; override; final;
-        function VisitSeriesLength(const Node: ISeriesLengthNode): TDataValue; override; final;
-        function VisitRecurNode(const Node: IRecurNode): TDataValue; override; final;
-
-        // Dispatch methods for each node type. Derived classes override these to change the transformation.
-        function TransformConstant(const Node: IConstantNode): IConstantNode; virtual;
-        function TransformIdentifier(const Node: IIdentifierNode): IIdentifierNode; virtual;
-        function TransformBinaryExpression(const Node: IBinaryExpressionNode): IBinaryExpressionNode; virtual;
-        function TransformUnaryExpression(const Node: IUnaryExpressionNode): IUnaryExpressionNode; virtual;
-        function TransformIfExpression(const Node: IIfExpressionNode): IIfExpressionNode; virtual;
-        function TransformTernaryExpression(const Node: ITernaryExpressionNode): ITernaryExpressionNode; virtual;
-        function TransformLambdaExpression(const Node: ILambdaExpressionNode): ILambdaExpressionNode; virtual;
-        function TransformFunctionCall(const Node: IFunctionCallNode): IFunctionCallNode; virtual;
-        function TransformBlockExpression(const Node: IBlockExpressionNode): IBlockExpressionNode; virtual;
-        function TransformVariableDeclaration(const Node: IVariableDeclarationNode): IVariableDeclarationNode; virtual;
-        function TransformAssignment(const Node: IAssignmentNode): IAssignmentNode; virtual;
-        function TransformMacroDefinition(const Node: IMacroDefinitionNode): IMacroDefinitionNode; virtual;
-        function TransformQuasiquote(const Node: IQuasiquoteNode): IQuasiquoteNode; virtual;
-        function TransformUnquote(const Node: IUnquoteNode): IUnquoteNode; virtual;
-        function TransformUnquoteSplicing(const Node: IUnquoteSplicingNode): IUnquoteSplicingNode; virtual;
-        function TransformIndexer(const Node: IIndexerNode): IIndexerNode; virtual;
-        function TransformMemberAccess(const Node: IMemberAccessNode): IMemberAccessNode; virtual;
-        function TransformCreateSeries(const Node: ICreateSeriesNode): ICreateSeriesNode; virtual;
-        function TransformAddSeriesItem(const Node: IAddSeriesItemNode): IAddSeriesItemNode; virtual;
-        function TransformSeriesLength(const Node: ISeriesLengthNode): ISeriesLengthNode; virtual;
-        function TransformRecur(const Node: IRecurNode): IRecurNode; virtual;
+        // These virtual methods implement the default identity-transformation (cloning) behavior.
+        function VisitConstant(const Node: IConstantNode): TDataValue; override;
+        function VisitIdentifier(const Node: IIdentifierNode): TDataValue; override;
+        function VisitBinaryExpression(const Node: IBinaryExpressionNode): TDataValue; override;
+        function VisitUnaryExpression(const Node: IUnaryExpressionNode): TDataValue; override;
+        function VisitIfExpression(const Node: IIfExpressionNode): TDataValue; override;
+        function VisitTernaryExpression(const Node: ITernaryExpressionNode): TDataValue; override;
+        function VisitLambdaExpression(const Node: ILambdaExpressionNode): TDataValue; override;
+        function VisitFunctionCall(const Node: IFunctionCallNode): TDataValue; override;
+        function VisitBlockExpression(const Node: IBlockExpressionNode): TDataValue; override;
+        function VisitVariableDeclaration(const Node: IVariableDeclarationNode): TDataValue; override;
+        function VisitAssignment(const Node: IAssignmentNode): TDataValue; override;
+        function VisitMacroDefinition(const Node: IMacroDefinitionNode): TDataValue; override;
+        function VisitQuasiquote(const Node: IQuasiquoteNode): TDataValue; override;
+        function VisitUnquote(const Node: IUnquoteNode): TDataValue; override;
+        function VisitUnquoteSplicing(const Node: IUnquoteSplicingNode): TDataValue; override;
+        function VisitIndexer(const Node: IIndexerNode): TDataValue; override;
+        function VisitMemberAccess(const Node: IMemberAccessNode): TDataValue; override;
+        function VisitCreateSeries(const Node: ICreateSeriesNode): TDataValue; override;
+        function VisitAddSeriesItem(const Node: IAddSeriesItemNode): TDataValue; override;
+        function VisitSeriesLength(const Node: ISeriesLengthNode): TDataValue; override;
+        function VisitRecurNode(const Node: IRecurNode): TDataValue; override;
 
         // Helper to transform an array of nodes.
         function TransformNodes<T: IAstNode>(const Nodes: TArray<T>): TArray<T>;
@@ -106,11 +81,8 @@ type
         function Execute(const RootNode: IAstNode): IAstNode;
     end;
 
-    // TAstTraverser simply inherits the identity-transform (cloning) behavior from TAstTransformer.
-    TAstTraverser = class(TAstTransformer);
-
     // Generic traverser for managing state during AST walks.
-    TAstTraverser<T> = class(TAstTraverser)
+    TAstTraverser<T> = class(TAstTransformer)
     private
         FData: TStack<T>;
     protected
@@ -141,202 +113,210 @@ begin
     Result := Accept(RootNode).AsIntf<IAstNode>;
 end;
 
-// --- Default implementations for Transform... methods (Identity Transformation / Cloning) ---
-
-function TAstTransformer.TransformConstant(const Node: IConstantNode): IConstantNode;
+function TAstTransformer.VisitConstant(const Node: IConstantNode): TDataValue;
 begin
     // The node itself is immutable, return it directly.
-    Result := Node;
+    Result := TDataValue.FromIntf<IConstantNode>(Node);
 end;
 
-function TAstTransformer.TransformIdentifier(const Node: IIdentifierNode): IIdentifierNode;
+function TAstTransformer.VisitIdentifier(const Node: IIdentifierNode): TDataValue;
 begin
-    Result := Node;
+    Result := TDataValue.FromIntf<IIdentifierNode>(Node);
 end;
 
-function TAstTransformer.TransformBinaryExpression(const Node: IBinaryExpressionNode): IBinaryExpressionNode;
+function TAstTransformer.VisitBinaryExpression(const Node: IBinaryExpressionNode): TDataValue;
 begin
     var left := Accept(Node.Left).AsIntf<IAstNode>;
     var right := Accept(Node.Right).AsIntf<IAstNode>;
     if (left = Node.Left) and (right = Node.Right) then
-        Result := Node
+        Result := TDataValue.FromIntf<IBinaryExpressionNode>(Node)
     else
-        Result := TAst.BinaryExpr(left, Node.Operator, right);
+        Result := TDataValue.FromIntf<IBinaryExpressionNode>(TAst.BinaryExpr(left, Node.Operator, right));
 end;
 
-function TAstTransformer.TransformUnaryExpression(const Node: IUnaryExpressionNode): IUnaryExpressionNode;
+function TAstTransformer.VisitUnaryExpression(const Node: IUnaryExpressionNode): TDataValue;
 begin
     var right := Accept(Node.Right).AsIntf<IAstNode>;
     if right = Node.Right then
-        Result := Node
+        Result := TDataValue.FromIntf<IUnaryExpressionNode>(Node)
     else
-        Result := TAst.UnaryExpr(Node.Operator, right);
+        Result := TDataValue.FromIntf<IUnaryExpressionNode>(TAst.UnaryExpr(Node.Operator, right));
 end;
 
-function TAstTransformer.TransformIfExpression(const Node: IIfExpressionNode): IIfExpressionNode;
+function TAstTransformer.VisitIfExpression(const Node: IIfExpressionNode): TDataValue;
 begin
     var condition := Accept(Node.Condition).AsIntf<IAstNode>;
     var thenBranch := Accept(Node.ThenBranch).AsIntf<IAstNode>;
     var elseBranch := Accept(Node.ElseBranch).AsIntf<IAstNode>;
     if (condition = Node.Condition) and (thenBranch = Node.ThenBranch) and (elseBranch = Node.ElseBranch) then
-        Result := Node
+        Result := TDataValue.FromIntf<IIfExpressionNode>(Node)
     else
-        Result := TAst.IfExpr(condition, thenBranch, elseBranch);
+        Result := TDataValue.FromIntf<IIfExpressionNode>(TAst.IfExpr(condition, thenBranch, elseBranch));
 end;
 
-function TAstTransformer.TransformTernaryExpression(const Node: ITernaryExpressionNode): ITernaryExpressionNode;
+function TAstTransformer.VisitTernaryExpression(const Node: ITernaryExpressionNode): TDataValue;
 begin
     var condition := Accept(Node.Condition).AsIntf<IAstNode>;
     var thenBranch := Accept(Node.ThenBranch).AsIntf<IAstNode>;
     var elseBranch := Accept(Node.ElseBranch).AsIntf<IAstNode>;
     if (condition = Node.Condition) and (thenBranch = Node.ThenBranch) and (elseBranch = Node.ElseBranch) then
-        Result := Node
+        Result := TDataValue.FromIntf<ITernaryExpressionNode>(Node)
     else
-        Result := TAst.TernaryExpr(condition, thenBranch, elseBranch);
+        Result := TDataValue.FromIntf<ITernaryExpressionNode>(TAst.TernaryExpr(condition, thenBranch, elseBranch));
 end;
 
-function TAstTransformer.TransformLambdaExpression(const Node: ILambdaExpressionNode): ILambdaExpressionNode;
+function TAstTransformer.VisitLambdaExpression(const Node: ILambdaExpressionNode): TDataValue;
 begin
     var parameters := TransformNodes<IIdentifierNode>(Node.Parameters);
     var body := Accept(Node.Body).AsIntf<IAstNode>;
     if (parameters = Node.Parameters) and (body = Node.Body) then
-        Result := Node
+        Result := TDataValue.FromIntf<ILambdaExpressionNode>(Node)
     else
-        Result := TAst.LambdaExpr(parameters, body);
+        Result := TDataValue.FromIntf<ILambdaExpressionNode>(TAst.LambdaExpr(parameters, body));
 end;
 
-function TAstTransformer.TransformFunctionCall(const Node: IFunctionCallNode): IFunctionCallNode;
+function TAstTransformer.VisitFunctionCall(const Node: IFunctionCallNode): TDataValue;
 begin
     var callee := Accept(Node.Callee).AsIntf<IAstNode>;
     var args := TransformNodes<IAstNode>(Node.Arguments);
     if (callee = Node.Callee) and (args = Node.Arguments) then
-        Result := Node
+        Result := TDataValue.FromIntf<IFunctionCallNode>(Node)
     else
-        Result := TAst.FunctionCall(callee, args);
+        Result := TDataValue.FromIntf<IFunctionCallNode>(TAst.FunctionCall(callee, args));
 end;
 
-function TAstTransformer.TransformBlockExpression(const Node: IBlockExpressionNode): IBlockExpressionNode;
+function TAstTransformer.VisitBlockExpression(const Node: IBlockExpressionNode): TDataValue;
+var
+    expressions: TArray<IAstNode>;
+    i: Integer;
+    hasChanged: Boolean;
 begin
-    // TList is mutable, so we always transform.
-    var exprs: TArray<IAstNode>;
-    var i: Integer;
-    SetLength(exprs, Node.Expressions.Count);
-    for i := 0 to Node.Expressions.Count - 1 do
-        exprs[i] := Accept(Node.Expressions[i]).AsIntf<IAstNode>;
-    Result := TAst.Block(exprs);
+    // Check if any child expression has changed before creating a new node.
+    hasChanged := false;
+    SetLength(expressions, Length(Node.Expressions));
+    for i := 0 to High(Node.Expressions) do
+    begin
+        expressions[i] := Accept(Node.Expressions[i]).AsIntf<IAstNode>;
+        if expressions[i] <> Node.Expressions[i] then
+            hasChanged := true;
+    end;
+
+    if hasChanged then
+        Result := TDataValue.FromIntf<IBlockExpressionNode>(TAst.Block(expressions))
+    else
+        Result := TDataValue.FromIntf<IBlockExpressionNode>(Node);
 end;
 
-function TAstTransformer.TransformVariableDeclaration(const Node: IVariableDeclarationNode): IVariableDeclarationNode;
+function TAstTransformer.VisitVariableDeclaration(const Node: IVariableDeclarationNode): TDataValue;
 begin
     var identifier := Accept(Node.Identifier).AsIntf<IIdentifierNode>;
     var initializer := Accept(Node.Initializer).AsIntf<IAstNode>;
     if (identifier = Node.Identifier) and (initializer = Node.Initializer) then
-        Result := Node
+        Result := TDataValue.FromIntf<IVariableDeclarationNode>(Node)
     else
-        Result := TAst.VarDecl(identifier, initializer);
+        Result := TDataValue.FromIntf<IVariableDeclarationNode>(TAst.VarDecl(identifier, initializer));
 end;
 
-function TAstTransformer.TransformAssignment(const Node: IAssignmentNode): IAssignmentNode;
+function TAstTransformer.VisitAssignment(const Node: IAssignmentNode): TDataValue;
 begin
     var identifier := Accept(Node.Identifier).AsIntf<IIdentifierNode>;
     var value := Accept(Node.Value).AsIntf<IAstNode>;
     if (identifier = Node.Identifier) and (value = Node.Value) then
-        Result := Node
+        Result := TDataValue.FromIntf<IAssignmentNode>(Node)
     else
-        Result := TAst.Assign(identifier, value);
+        Result := TDataValue.FromIntf<IAssignmentNode>(TAst.Assign(identifier, value));
 end;
 
-function TAstTransformer.TransformMacroDefinition(const Node: IMacroDefinitionNode): IMacroDefinitionNode;
+function TAstTransformer.VisitMacroDefinition(const Node: IMacroDefinitionNode): TDataValue;
 begin
-    // Added identity transform for macro definitions.
     var name := Accept(Node.Name).AsIntf<IIdentifierNode>;
     var parameters := TransformNodes<IIdentifierNode>(Node.Parameters);
     var body := Accept(Node.Body).AsIntf<IAstNode>;
     if (name = Node.Name) and (parameters = Node.Parameters) and (body = Node.Body) then
-        Result := Node
+        Result := TDataValue.FromIntf<IMacroDefinitionNode>(Node)
     else
-        Result := TAst.MacroDef(name, parameters, body);
+        Result := TDataValue.FromIntf<IMacroDefinitionNode>(TAst.MacroDef(name, parameters, body));
 end;
 
-function TAstTransformer.TransformQuasiquote(const Node: IQuasiquoteNode): IQuasiquoteNode;
+function TAstTransformer.VisitQuasiquote(const Node: IQuasiquoteNode): TDataValue;
 begin
     var expr := Accept(Node.Expression).AsIntf<IAstNode>;
     if expr = Node.Expression then
-        Result := Node
+        Result := TDataValue.FromIntf<IQuasiquoteNode>(Node)
     else
-        Result := TAst.Quasiquote(expr);
+        Result := TDataValue.FromIntf<IQuasiquoteNode>(TAst.Quasiquote(expr));
 end;
 
-function TAstTransformer.TransformUnquote(const Node: IUnquoteNode): IUnquoteNode;
+function TAstTransformer.VisitUnquote(const Node: IUnquoteNode): TDataValue;
 begin
     var expr := Accept(Node.Expression).AsIntf<IAstNode>;
     if expr = Node.Expression then
-        Result := Node
+        Result := TDataValue.FromIntf<IUnquoteNode>(Node)
     else
-        Result := TAst.Unquote(expr);
+        Result := TDataValue.FromIntf<IUnquoteNode>(TAst.Unquote(expr));
 end;
 
-function TAstTransformer.TransformUnquoteSplicing(const Node: IUnquoteSplicingNode): IUnquoteSplicingNode;
+function TAstTransformer.VisitUnquoteSplicing(const Node: IUnquoteSplicingNode): TDataValue;
 begin
     var expr := Accept(Node.Expression).AsIntf<IAstNode>;
     if expr = Node.Expression then
-        Result := Node
+        Result := TDataValue.FromIntf<IUnquoteSplicingNode>(Node)
     else
-        Result := TAst.UnquoteSplicing(expr);
+        Result := TDataValue.FromIntf<IUnquoteSplicingNode>(TAst.UnquoteSplicing(expr));
 end;
 
-function TAstTransformer.TransformIndexer(const Node: IIndexerNode): IIndexerNode;
+function TAstTransformer.VisitIndexer(const Node: IIndexerNode): TDataValue;
 begin
     var base := Accept(Node.Base).AsIntf<IAstNode>;
     var index := Accept(Node.Index).AsIntf<IAstNode>;
     if (base = Node.Base) and (index = Node.Index) then
-        Result := Node
+        Result := TDataValue.FromIntf<IIndexerNode>(Node)
     else
-        Result := TAst.Indexer(base, index);
+        Result := TDataValue.FromIntf<IIndexerNode>(TAst.Indexer(base, index));
 end;
 
-function TAstTransformer.TransformMemberAccess(const Node: IMemberAccessNode): IMemberAccessNode;
+function TAstTransformer.VisitMemberAccess(const Node: IMemberAccessNode): TDataValue;
 begin
     var base := Accept(Node.Base).AsIntf<IAstNode>;
     var member := Node.Member;
     if (base = Node.Base) and (member = Node.Member) then
-        Result := Node
+        Result := TDataValue.FromIntf<IMemberAccessNode>(Node)
     else
-        Result := TAst.MemberAccess(base, member);
+        Result := TDataValue.FromIntf<IMemberAccessNode>(TAst.MemberAccess(base, member));
 end;
 
-function TAstTransformer.TransformCreateSeries(const Node: ICreateSeriesNode): ICreateSeriesNode;
+function TAstTransformer.VisitCreateSeries(const Node: ICreateSeriesNode): TDataValue;
 begin
-    Result := Node;
+    Result := TDataValue.FromIntf<ICreateSeriesNode>(Node);
 end;
 
-function TAstTransformer.TransformAddSeriesItem(const Node: IAddSeriesItemNode): IAddSeriesItemNode;
+function TAstTransformer.VisitAddSeriesItem(const Node: IAddSeriesItemNode): TDataValue;
 begin
     var series := Accept(Node.Series).AsIntf<IIdentifierNode>;
     var value := Accept(Node.Value).AsIntf<IAstNode>;
     var lookback := Accept(Node.Lookback).AsIntf<IAstNode>;
     if (series = Node.Series) and (value = Node.Value) and (lookback = Node.Lookback) then
-        Result := Node
+        Result := TDataValue.FromIntf<IAddSeriesItemNode>(Node)
     else
-        Result := TAst.AddSeriesItem(series, value, lookback);
+        Result := TDataValue.FromIntf<IAddSeriesItemNode>(TAst.AddSeriesItem(series, value, lookback));
 end;
 
-function TAstTransformer.TransformSeriesLength(const Node: ISeriesLengthNode): ISeriesLengthNode;
+function TAstTransformer.VisitSeriesLength(const Node: ISeriesLengthNode): TDataValue;
 begin
     var series := Accept(Node.Series).AsIntf<IIdentifierNode>;
     if series = Node.Series then
-        Result := Node
+        Result := TDataValue.FromIntf<ISeriesLengthNode>(Node)
     else
-        Result := TAst.SeriesLength(series);
+        Result := TDataValue.FromIntf<ISeriesLengthNode>(TAst.SeriesLength(series));
 end;
 
-function TAstTransformer.TransformRecur(const Node: IRecurNode): IRecurNode;
+function TAstTransformer.VisitRecurNode(const Node: IRecurNode): TDataValue;
 begin
     var args := TransformNodes<IAstNode>(Node.Arguments);
     if args = Node.Arguments then
-        Result := Node
+        Result := TDataValue.FromIntf<IRecurNode>(Node)
     else
-        Result := TAst.Recur(args);
+        Result := TDataValue.FromIntf<IRecurNode>(TAst.Recur(args));
 end;
 
 function TAstTransformer.TransformNodes<T>(const Nodes: TArray<T>): TArray<T>;
@@ -356,111 +336,6 @@ begin
         Result := Nodes;
 end;
 
-function TAstTransformer.VisitConstant(const Node: IConstantNode): TDataValue;
-begin
-    Result := TDataValue.FromIntf<IConstantNode>(TransformConstant(Node));
-end;
-
-function TAstTransformer.VisitIdentifier(const Node: IIdentifierNode): TDataValue;
-begin
-    Result := TDataValue.FromIntf<IIdentifierNode>(TransformIdentifier(Node));
-end;
-
-function TAstTransformer.VisitBinaryExpression(const Node: IBinaryExpressionNode): TDataValue;
-begin
-    Result := TDataValue.FromIntf<IBinaryExpressionNode>(TransformBinaryExpression(Node));
-end;
-
-function TAstTransformer.VisitUnaryExpression(const Node: IUnaryExpressionNode): TDataValue;
-begin
-    Result := TDataValue.FromIntf<IUnaryExpressionNode>(TransformUnaryExpression(Node));
-end;
-
-function TAstTransformer.VisitIfExpression(const Node: IIfExpressionNode): TDataValue;
-begin
-    Result := TDataValue.FromIntf<IIfExpressionNode>(TransformIfExpression(Node));
-end;
-
-function TAstTransformer.VisitTernaryExpression(const Node: ITernaryExpressionNode): TDataValue;
-begin
-    Result := TDataValue.FromIntf<ITernaryExpressionNode>(TransformTernaryExpression(Node));
-end;
-
-function TAstTransformer.VisitLambdaExpression(const Node: ILambdaExpressionNode): TDataValue;
-begin
-    Result := TDataValue.FromIntf<ILambdaExpressionNode>(TransformLambdaExpression(Node));
-end;
-
-function TAstTransformer.VisitFunctionCall(const Node: IFunctionCallNode): TDataValue;
-begin
-    Result := TDataValue.FromIntf<IFunctionCallNode>(TransformFunctionCall(Node));
-end;
-
-function TAstTransformer.VisitBlockExpression(const Node: IBlockExpressionNode): TDataValue;
-begin
-    Result := TDataValue.FromIntf<IBlockExpressionNode>(TransformBlockExpression(Node));
-end;
-
-function TAstTransformer.VisitVariableDeclaration(const Node: IVariableDeclarationNode): TDataValue;
-begin
-    Result := TDataValue.FromIntf<IVariableDeclarationNode>(TransformVariableDeclaration(Node));
-end;
-
-function TAstTransformer.VisitAssignment(const Node: IAssignmentNode): TDataValue;
-begin
-    Result := TDataValue.FromIntf<IAssignmentNode>(TransformAssignment(Node));
-end;
-
-function TAstTransformer.VisitMacroDefinition(const Node: IMacroDefinitionNode): TDataValue;
-begin
-    Result := TDataValue.FromIntf<IMacroDefinitionNode>(TransformMacroDefinition(Node));
-end;
-
-function TAstTransformer.VisitQuasiquote(const Node: IQuasiquoteNode): TDataValue;
-begin
-    Result := TDataValue.FromIntf<IQuasiquoteNode>(TransformQuasiquote(Node));
-end;
-
-function TAstTransformer.VisitUnquote(const Node: IUnquoteNode): TDataValue;
-begin
-    Result := TDataValue.FromIntf<IUnquoteNode>(TransformUnquote(Node));
-end;
-
-function TAstTransformer.VisitUnquoteSplicing(const Node: IUnquoteSplicingNode): TDataValue;
-begin
-    Result := TDataValue.FromIntf<IUnquoteSplicingNode>(TransformUnquoteSplicing(Node));
-end;
-
-function TAstTransformer.VisitIndexer(const Node: IIndexerNode): TDataValue;
-begin
-    Result := TDataValue.FromIntf<IIndexerNode>(TransformIndexer(Node));
-end;
-
-function TAstTransformer.VisitMemberAccess(const Node: IMemberAccessNode): TDataValue;
-begin
-    Result := TDataValue.FromIntf<IMemberAccessNode>(TransformMemberAccess(Node));
-end;
-
-function TAstTransformer.VisitCreateSeries(const Node: ICreateSeriesNode): TDataValue;
-begin
-    Result := TDataValue.FromIntf<ICreateSeriesNode>(TransformCreateSeries(Node));
-end;
-
-function TAstTransformer.VisitAddSeriesItem(const Node: IAddSeriesItemNode): TDataValue;
-begin
-    Result := TDataValue.FromIntf<IAddSeriesItemNode>(TransformAddSeriesItem(Node));
-end;
-
-function TAstTransformer.VisitSeriesLength(const Node: ISeriesLengthNode): TDataValue;
-begin
-    Result := TDataValue.FromIntf<ISeriesLengthNode>(TransformSeriesLength(Node));
-end;
-
-function TAstTransformer.VisitRecurNode(const Node: IRecurNode): TDataValue;
-begin
-    Result := TDataValue.FromIntf<IRecurNode>(TransformRecur(Node));
-end;
-
 { TAstTraverser<T> }
 
 constructor TAstTraverser<T>.Create;
diff --git a/Src/AST/Myc.Ast.pas b/Src/AST/Myc.Ast.pas
index 9189cb0..ab0aef7 100644
--- a/Src/AST/Myc.Ast.pas
+++ b/Src/AST/Myc.Ast.pas
@@ -211,13 +211,12 @@ type
 
     TBlockExpressionNode = class(TAstNode, IBlockExpressionNode)
     private
-        FExpressions: TList<IAstNode>;
-        function GetExpressions: TList<IAstNode>;
+        FExpressions: TArray<IAstNode>;
+        function GetExpressions: TArray<IAstNode>;
     public
         constructor Create(const AExpressions: array of IAstNode);
-        destructor Destroy; override;
         function Accept(const Visitor: IAstVisitor): TDataValue; override;
-        property Expressions: TList<IAstNode> read FExpressions;
+        property Expressions: TArray<IAstNode> read FExpressions;
     end;
 
     TVariableDeclarationNode = class(TAstNode, IVariableDeclarationNode)
@@ -605,19 +604,10 @@ end;
 { TBlockExpressionNode }
 
 constructor TBlockExpressionNode.Create(const AExpressions: array of IAstNode);
-var
-    expr: IAstNode;
 begin
     inherited Create;
-    FExpressions := TList<IAstNode>.Create;
-    for expr in AExpressions do
-        FExpressions.Add(expr);
-end;
-
-destructor TBlockExpressionNode.Destroy;
-begin
-    FExpressions.Free;
-    inherited;
+    SetLength(FExpressions, Length(AExpressions));
+    TArray.Copy<IAstNode>(AExpressions, FExpressions, 0, 0, Length(AExpressions));
 end;
 
 function TBlockExpressionNode.Accept(const Visitor: IAstVisitor): TDataValue;
@@ -625,7 +615,7 @@ begin
     Result := Visitor.VisitBlockExpression(Self);
 end;
 
-function TBlockExpressionNode.GetExpressions: TList<IAstNode>;
+function TBlockExpressionNode.GetExpressions: TArray<IAstNode>;
 begin
     Result := FExpressions;
 end;