Macro expander integrated in binder

Src/AST/Myc.Ast.pas

@@ -74,6 +74,7 @@ type
     public
         constructor Create(const AValue: TDataValue);
         function Accept(const Visitor: IAstVisitor): TDataValue; override;
+        property Value: TDataValue read GetValue;
     end;
 
     TIdentifierNode = class(TAstNode, IIdentifierNode)
@@ -169,6 +170,7 @@ type
     public
         constructor Create(const AExpression: IAstNode);
         function Accept(const Visitor: IAstVisitor): TDataValue; override;
+        property Expression: IAstNode read GetExpression;
     end;
 
     TUnquoteNode = class(TAstNode, IUnquoteNode)
@@ -865,7 +867,13 @@ end;
 
 class function TAst.IfExpr(const ACondition: IAstNode; const AThenBranch, AElseBranch: IAstNode): IIfExpressionNode;
 begin
-    Result := TIfExpressionNode.Create(ACondition, AThenBranch, AElseBranch);
+    Result :=
+        TIfExpressionNode.Create(
+            ACondition,
+            AThenBranch,
+            if AElseBranch = nil then TBlockExpressionNode.Create([]) as IAstNode
+            else AElseBranch
+        );
 end;
 
 class function TAst.Indexer(const ABase: IAstNode; const AIndex: IAstNode): IIndexerNode;