Compiler exceptions

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

@@ -267,6 +267,10 @@ begin
     if not IsValidIdentifier(identifier.Name) then
         raise EBinderException.CreateFmt('Invalid identifier name: "%s".', [identifier.Name]);
 
+    // Check if the identifier is already defined in the current scope builder to avoid Scope Asserts.
+    if FCurrentBuilder.FindSlot(identifier.Name) >= 0 then
+        raise EBinderException.CreateFmt('Variable "%s" is already defined in this scope.', [identifier.Name]);
+
     slot := FCurrentBuilder.Define(identifier.Name);
     addr := TResolvedAddress.Create(akLocalOrParent, 0, slot);
 
@@ -334,6 +338,10 @@ begin
         SetLength(newParams, Length(Node.Parameters));
         for i := 0 to High(Node.Parameters) do
         begin
+            // Parameter names must also be checked for uniqueness, though usually guaranteed by Parser/AST construction
+            if FCurrentBuilder.FindSlot(Node.Parameters[i].Name) >= 0 then
+                raise EBinderException.CreateFmt('Duplicate parameter name "%s".', [Node.Parameters[i].Name]);
+
             slot := FCurrentBuilder.Define(Node.Parameters[i].Name);
             addr := TResolvedAddress.Create(akLocalOrParent, 0, slot);
 

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

@@ -185,12 +185,21 @@ begin
             if node.Kind = akUnquoteSplicing then
             begin
                 var spliceExpr := node.AsUnquoteSplicing.Expression;
-                var evaluatedSpliceValue := FMacroEvaluator(FMacroScope, spliceExpr);
+                var evaluatedSpliceValue: TDataValue;
+
+                // GUARDED EVALUATION
+                try
+                    evaluatedSpliceValue := FMacroEvaluator(FMacroScope, spliceExpr);
+                except
+                    on E: EAstException do
+                        raise;
+                    on E: Exception do
+                        raise EMacroException.Create('Error during macro splice evaluation: ' + E.Message);
+                end;
 
                 if (not evaluatedSpliceValue.IsVoid) and (evaluatedSpliceValue.Kind = vkInterface) then
                 begin
                     nodeToSplice := evaluatedSpliceValue.AsIntf<IAstNode>;
-                    // If the result is a block, flatten it into the current list
                     if nodeToSplice.Kind = akBlockExpression then
                         newList.AddRange(nodeToSplice.AsBlockExpression.Expressions)
                     else
@@ -198,7 +207,6 @@ begin
                 end
                 else if (not evaluatedSpliceValue.IsVoid) then
                 begin
-                    // Treat scalar values as constants in the AST
                     newList.Add(TAst.Constant(evaluatedSpliceValue));
                 end;
             end
@@ -278,12 +286,9 @@ var
 begin
     expr := Node.Expression;
 
-    // Optimization: If unquoting a simple identifier that exists in the macro scope,
-    // try to resolve it directly to avoid unnecessary evaluation overhead.
     if expr.Kind = akIdentifier then
     begin
         addr := FMacroScope.Resolve(expr.AsIdentifier.Name);
-
         if (addr.Kind = akLocalOrParent) and (addr.ScopeDepth = 0) then
         begin
             var argValue := FMacroScope.Values[addr];
@@ -295,17 +300,23 @@ begin
         end;
     end;
 
-    // Evaluate the expression at compile time
+    // Evaluate the expression at compile time.
-    value := FMacroEvaluator(FMacroScope, expr);
+    // This executes user code! It must be guarded.
+    try
+        value := FMacroEvaluator(FMacroScope, expr);
+    except
+        on E: EAstException do
+            raise;
+        on E: Exception do
+            raise EMacroException.Create('Error during macro evaluation: ' + E.Message);
+    end;
 
     if value.Kind = vkInterface then
     begin
-        // It returned an AST node -> Inject it
         Result := value.AsIntf<IAstNode>;
         exit;
     end;
 
-    // It returned a value -> Wrap as Constant
     if value.Kind in [vkScalar, vkText, vkVoid] then
         Result := TAst.Constant(value)
     else

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

@@ -25,13 +25,12 @@ type
     TTypeChecker = class(TAstTransformer, IAstTypeChecker)
     private
         type
-            // Helper to track types per scope during traversal (The "Scratchpad")
             TTypeContext = class
             private
                 FParent: TTypeContext;
                 FLayout: IScopeLayout;
                 FSlotTypes: TArray<IStaticType>;
-                FUpvalueTypes: TArray<IStaticType>; // Types of captured variables
+                FUpvalueTypes: TArray<IStaticType>;
             public
                 constructor Create(AParent: TTypeContext; ALayout: IScopeLayout; const AUpvalueTypes: TArray<IStaticType>);
                 function LookupType(const Address: TResolvedAddress): IStaticType;
@@ -41,12 +40,9 @@ type
 
     private
         FCurrentContext: TTypeContext;
-
-        // Helper to recursively rebuild the context stack from the layout hierarchy
         function CreateContextChain(L: IScopeLayout): TTypeContext;
 
     protected
-        // Override all visit methods to perform type checking
         function VisitIdentifier(const Node: IIdentifierNode): IAstNode; override;
         function VisitVariableDeclaration(const Node: IVariableDeclarationNode): IAstNode; override;
         function VisitAssignment(const Node: IAssignmentNode): IAstNode; override;
@@ -64,7 +60,6 @@ type
         function VisitRecurNode(const Node: IRecurNode): IAstNode; override;
         function VisitNop(const Node: INopNode): IAstNode; override;
 
-        // Base cases (types are now set here)
         function VisitConstant(const Node: IConstantNode): IAstNode; override;
         function VisitKeyword(const Node: IKeywordNode): IAstNode; override;
 
@@ -92,7 +87,6 @@ begin
     FLayout := ALayout;
     FUpvalueTypes := AUpvalueTypes;
 
-    // Initialize slot types with Unknown
     if Assigned(FLayout) then
     begin
         SetLength(FSlotTypes, FLayout.SlotCount);
@@ -125,7 +119,6 @@ begin
         end;
         akUpvalue:
         begin
-            // Look up type in our local upvalue type cache
             if (Address.SlotIndex >= 0) and (Address.SlotIndex < Length(FUpvalueTypes)) then
                 Result := FUpvalueTypes[Address.SlotIndex]
             else
@@ -151,30 +144,20 @@ begin
     if L = nil then
         exit(nil);
 
-    // Recursively build parent context
     p := CreateContextChain(L.Parent);
-
-    // Create context for current layout level
-    // Note: We don't know UpvalueTypes for these static/parent layouts here, so [] is passed.
-    // Also: Slot types will be initialized to Unknown.
     Result := TTypeContext.Create(p, L, []);
 end;
 
 constructor TTypeChecker.Create(const RootLayout: IScopeLayout);
 begin
     inherited Create;
-    // Build the full context chain based on the Layout's parent hierarchy
-    // This ensures that ScopeDepth lookups can traverse up to the root.
     FCurrentContext := CreateContextChain(RootLayout);
-
-    // Fallback if RootLayout is nil (should not happen in valid pipeline)
     if FCurrentContext = nil then
         FCurrentContext := TTypeContext.Create(nil, nil, []);
 end;
 
 destructor TTypeChecker.Destroy;
 begin
-    // Cleanup context stack
     while Assigned(FCurrentContext) do
     begin
         var temp := FCurrentContext;
@@ -192,7 +175,6 @@ end;
 
 function TTypeChecker.Execute(const RootNode: IAstNode; const Layout: IScopeLayout): IAstNode;
 begin
-    // Note: Layout passed here matches what was passed to Create/Constructor (via recursed ContextChain)
     Result := Accept(RootNode);
     if not Assigned(Result) then
         Result := TAst.Block([]);
@@ -216,10 +198,7 @@ var
     adr: TResolvedAddress;
 begin
     adr := Node.Address;
-    // Lookup type in our scratchpad context using the address resolved by Binder
     typ := FCurrentContext.LookupType(adr);
-
-    // Create a new node with the inferred type
     Result := TAst.Identifier(Node.Name, adr, typ);
 end;
 
@@ -247,7 +226,6 @@ begin
     adr := Node.Target.AsIdentifier.Address;
     initType := TTypes.Unknown;
 
-    // Recursive lambda bootstrap logic
     placeholderType := nil;
     if (Node.Initializer <> nil) and (Node.Initializer.Kind = akLambdaExpression) then
     begin
@@ -258,8 +236,6 @@ begin
             paramTypes[i] := TTypes.Unknown;
 
         placeholderType := TTypes.CreateMethod(paramTypes, TTypes.Unknown);
-
-        // Update Context (Scratchpad)
         FCurrentContext.SetType(adr.SlotIndex, placeholderType);
         initType := placeholderType;
     end;
@@ -274,12 +250,10 @@ begin
     else if not Assigned(placeholderType) then
         initType := TTypes.Unknown;
 
-    // Update Context with final type
     if initType.Kind <> stUnknown then
         FCurrentContext.SetType(adr.SlotIndex, initType);
 
     newIdent := TAst.Identifier(Node.Target.AsIdentifier.Name, adr, initType);
-
     Result := TAst.VarDecl(newIdent.AsIdentifier, newInitializer, initType, Node.IsBoxed);
 end;
 
@@ -296,7 +270,6 @@ begin
     targetType := newIdent.AsTypedNode.StaticType;
     adr := newIdent.AsIdentifier.Address;
 
-    // Recursive lambda assignment check
     placeholderType := nil;
     if (Node.Value <> nil) and (Node.Value.Kind = akLambdaExpression) then
     begin
@@ -344,28 +317,18 @@ var
     newBody: IAstNode;
     bodyType, methodType: IStaticType;
     paramTypes: TArray<IStaticType>;
-
-    // Upvalue Type Resolution
     upvalueTypes: TArray<IStaticType>;
     upvalueAddrs: TArray<TResolvedAddress>;
-
     i: Integer;
     finalDescriptor: IScopeDescriptor;
 begin
-    // 1. Resolve Upvalue Types *in the current (parent) context*
     upvalueAddrs := Node.Upvalues;
     SetLength(upvalueTypes, Length(upvalueAddrs));
     for i := 0 to High(upvalueAddrs) do
-    begin
-        // We look up the physical address (from Binder) in the current context chain
         upvalueTypes[i] := FCurrentContext.LookupType(upvalueAddrs[i]);
-    end;
 
-    // 2. Create new TypeContext for this lambda scope, PASSING the upvalue types
-    // We use the layout from the Binder-Result-Node
     FCurrentContext := TTypeContext.Create(FCurrentContext, Node.Layout, upvalueTypes);
     try
-        // 3. Set parameter types in the context
         SetLength(newParams, Length(Node.Parameters));
         SetLength(paramTypes, Length(Node.Parameters));
 
@@ -373,37 +336,22 @@ begin
         begin
             var paramIdent := Node.Parameters[i];
             var paramAdr := paramIdent.Address;
-
-            // Here we could infer types if we had type annotations. For now, parameters are Unknown.
             paramTypes[i] := TTypes.Unknown;
-
-            // Update context so body can resolve params
             FCurrentContext.SetType(paramAdr.SlotIndex, paramTypes[i]);
-
             newParams[i] := TAst.Identifier(paramIdent.Name, paramAdr, paramTypes[i]);
         end;
 
-        // 4. Visit body
         newBody := Accept(Node.Body);
         bodyType := newBody.AsTypedNode.StaticType;
-
-        // 5. Create method type
         methodType := TTypes.CreateMethod(paramTypes, bodyType);
-
-        // 6. Update <self> type in context (Slot 0)
         FCurrentContext.SetType(0, methodType);
-
-        // 7. FINALIZE: Bake the Descriptor
         finalDescriptor := TScope.CreateDescriptor(Node.Layout, FCurrentContext.Types);
-
     finally
-        // 8. Pop Context
         var temp := FCurrentContext;
         FCurrentContext := FCurrentContext.FParent;
         temp.Free;
     end;
 
-    // 9. Create new node with the Descriptor attached!
     Result :=
         TAst.LambdaExpr(newParams, newBody, Node.Layout, finalDescriptor, Node.Upvalues, Node.HasNestedLambdas, Node.IsPure, methodType);
 end;
@@ -509,7 +457,6 @@ begin
     newElse := Accept(Node.ElseBranch);
 
     conditionType := newCond.AsTypedNode.StaticType;
-    // Ordinal and Boolean are valid for if-conditions
     if (conditionType.Kind <> stUnknown)
         and not TTypeRules.CanAssign(TTypes.Ordinal, conditionType)
         and not TTypeRules.CanAssign(TTypes.Boolean, conditionType) then
@@ -520,12 +467,9 @@ begin
         if newElse <> nil then newElse.AsTypedNode.StaticType
         else TTypes.Void;
 
-    try
+    resultType := TTypeRules.Promote(thenType, elseType);
-        resultType := TTypeRules.Promote(thenType, elseType);
+    if resultType = nil then
-    except
+        raise ETypeCheckException.CreateFmt('Cannot promote types %s and %s in If-Expression', [thenType.ToString, elseType.ToString]);
-        on E: Exception do // Catch base exception (ETypeException from Myc.Ast.Types)
-            raise ETypeCheckException.Create(E.Message);
-    end;
 
     Result := TAst.IfExpr(newCond, newThen, newElse, resultType);
 end;
@@ -548,12 +492,9 @@ begin
     thenType := newThen.AsTypedNode.StaticType;
     elseType := newElse.AsTypedNode.StaticType;
 
-    try
+    resultType := TTypeRules.Promote(thenType, elseType);
-        resultType := TTypeRules.Promote(thenType, elseType);
+    if resultType = nil then
-    except
+        raise ETypeCheckException.CreateFmt('Cannot promote types %s and %s in Ternary-Expression', [thenType.ToString, elseType.ToString]);
-        on E: Exception do
-            raise ETypeCheckException.Create(E.Message);
-    end;
 
     Result := TAst.TernaryExpr(newCond, newThen, newElse, resultType);
 end;
@@ -698,10 +639,12 @@ var
     elemType: IStaticType;
 begin
     try
+        // TScalar.StringToKind might throw EConvertError or generic Exception if string is invalid
         elemType := TTypes.FromScalarKind(TScalar.StringToKind(Node.Definition));
     except
         on E: Exception do
-            elemType := TTypes.Unknown;
+            // Instead of silently using Unknown, we now raise a proper compiler error
+            raise ETypeCheckException.CreateFmt('Invalid type definition "%s" in new-series.', [Node.Definition]);
     end;
 
     Result := TAst.CreateSeries(Node.Definition, TTypes.CreateSeries(elemType));

Src/AST/Myc.Ast.Evaluator.pas

@@ -8,7 +8,7 @@ uses
     System.Generics.Collections,
     Myc.Data.Scalar,
     Myc.Data.Value,
-    Myc.Ast.Nodes,
+    Myc.Ast.Nodes, // Provides EAstException
     Myc.Ast.Scope;
 
 type
@@ -16,8 +16,6 @@ type
     EEvaluatorException = class(EAstException);
 
     // The standard AST evaluator for production use.
-    // This class inherits directly from TInterfacedObject as it is an
-    // Interpreter (AST -> TDataValue), not a Transformer (AST -> IAstNode).
     TEvaluatorVisitor = class(TInterfacedObject, IAstVisitor, IEvaluatorVisitor)
     private
         FScope: IExecutionScope;
@@ -139,8 +137,16 @@ begin
     if not Assigned(RootNode) then
         exit(TDataValue.Void);
 
-    Result := RootNode.Accept(Self);
+    try
-    HandleTCO(Result);
+        Result := RootNode.Accept(Self);
+        HandleTCO(Result);
+    except
+        on E: EAstException do
+            raise; // Already a compiler/runtime exception, pass through
+        on E: Exception do
+            // Wrap unexpected RTL exceptions (e.g. EDivByZero, EConvertError)
+            raise EEvaluatorException.Create('Runtime Error: ' + E.Message);
+    end;
 end;
 
 function TEvaluatorVisitor.CreateVisitorFactory: TEvaluatorFactory;
@@ -152,12 +158,18 @@ end;
 class procedure TEvaluatorVisitor.HandleTCO(var ResultValue: TDataValue);
 begin
     // This is the central trampoline loop for Tail Call Optimization.
-    // It runs as long as the evaluation returns a thunk.
+    try
-    while ResultValue.Kind = vkGeneric do
+        while ResultValue.Kind = vkGeneric do
-    begin
+        begin
-        var thunk := ResultValue.AsGeneric<TThunk>;
+            var thunk := ResultValue.AsGeneric<TThunk>;
-        var callee := thunk.Callee.AsMethod();
+            var callee := thunk.Callee.AsMethod();
-        ResultValue := callee(thunk.Args);
+            ResultValue := callee(thunk.Args);
+        end;
+    except
+        on E: EAstException do
+            raise;
+        on E: Exception do
+            raise EEvaluatorException.Create('Runtime Error (TCO): ' + E.Message);
     end;
 end;
 
@@ -186,8 +198,6 @@ var
     visitorFactory: TEvaluatorFactory;
 begin
     // 1. Capture Upvalues
-    // The Node.Upvalues array contains the physical addresses in the *current* scope (FScope)
-    // that map to the closure's upvalues.
     if Node.Upvalues <> nil then
     begin
         SetLength(capturedCells, Length(Node.Upvalues));
@@ -198,9 +208,6 @@ begin
         capturedCells := nil;
 
     // 2. Determine Parent Scope for Closure
-    // Memory optimization: a lambda's scope does not need to be kept alive as a parent
-    // if it contains no nested lambdas that might need to capture from it later.
-    // (Assuming HasNestedLambdas flag is set correctly by Binder)
     if Node.HasNestedLambdas then
         closureScope := FScope
     else
@@ -210,11 +217,10 @@ begin
     visitorFactory := CreateVisitorFactory();
 
     // 4. Capture Metadata for Closure
-    var descriptor := Node.Descriptor; // Runtime Descriptor (contains types + layout)
+    var descriptor := Node.Descriptor;
     var params := Node.Parameters;
     var cNode: ILambdaExpressionNode := Node;
 
-    // [unsafe] prevents a reference cycle since the closure captures itself for 'recur'.
     var [unsafe] closure: TDataValue.TFunc;
     closure :=
         function(const ArgValues: TArray<TDataValue>): TDataValue
@@ -231,22 +237,16 @@ begin
             lambdaScope := TScope.CreateScope(closureScope, descriptor, capturedCells);
 
             // Capture the closure itself in slot 0 for 'recur' to find it (if needed).
-            // Note: The Binder reserves Slot 0 for <self>.
             adr.Kind := akLocalOrParent;
             adr.ScopeDepth := 0;
             adr.SlotIndex := 0;
-            lambdaScope[adr] := TDataValue(closure); // Explicit cast
+            lambdaScope[adr] := TDataValue(closure);
 
             // Populate the scope with the actual parameters passed to the function.
             for i := 0 to High(ArgValues) do
             begin
-                // Parameters are bound to specific slots by the Binder.
-                // We access them via the Address stored in the parameter node.
                 adr := params[i].Address;
-
-                // Defensive check: Ensure we are writing to local scope
                 Assert(adr.ScopeDepth = 0);
-
                 lambdaScope[adr] := ArgValues[i];
             end;
 
@@ -255,14 +255,11 @@ begin
             Result := cNode.Body.Accept(bodyVisitor);
         end;
 
-    // The result of visiting a lambda node is the callable closure itself.
+    Result := TDataValue(closure);
-    Result := TDataValue(closure); // Explicit cast
 end;
 
 function TEvaluatorVisitor.VisitMacroDefinition(const Node: IMacroDefinitionNode): TDataValue;
 begin
-    // Macro definitions are compile-time constructs.
-    // The Evaluator ignores them (treated as Void).
     Result := TDataValue.Void;
 end;
 
@@ -291,19 +288,13 @@ begin
     if Assigned(Node.StaticTarget) then
     begin
         // --- Static Path (Optimized) ---
-        // 1. Evaluate arguments
         argNodes := Node.Arguments;
         SetLength(argValues, Length(argNodes));
         for i := 0 to High(argNodes) do
-        begin
-            // Assuming arguments passed type check
             argValues[i] := argNodes[i].Accept(Self);
-        end;
 
-        // 2. Call the static target directly
+        // Call static target. Exceptions here are caught by Execute/HandleTCO.
         Result := Node.StaticTarget(argValues);
-
-        // 3. Handle TCO
         HandleTCO(Result);
     end
     else
@@ -320,12 +311,10 @@ begin
 
         if Node.IsTailCall then
         begin
-            // This is a tail call. Return a thunk to be processed by the trampoline.
             Result := TDataValue.FromGeneric<TThunk>(TThunk.Create(calleeValue, argValues, false));
         end
         else
         begin
-            // This is a non-tail call. It must execute the call and act as the trampoline.
             Result := (calleeValue.AsMethod)(argValues);
             HandleTCO(Result);
         end;
@@ -334,8 +323,6 @@ end;
 
 function TEvaluatorVisitor.VisitMacroExpansionNode(const Node: IMacroExpansionNode): TDataValue;
 begin
-    // The evaluator simply "unwraps" the macro expansion node
-    // and executes the expanded body it contains.
     Result := Node.ExpandedBody.Accept(Self);
 end;
 
@@ -346,18 +333,15 @@ var
     calleeValue: TDataValue;
     i: Integer;
 begin
-    // The binder ensures this is only in a tail position.
     SetLength(argValues, Length(Node.Arguments));
     for i := 0 to High(Node.Arguments) do
         argValues[i] := Node.Arguments[i].Accept(Self);
 
-    // The callee is the current function, stored in slot 0 of the current scope.
     calleeAddress.Kind := akLocalOrParent;
     calleeAddress.ScopeDepth := 0;
     calleeAddress.SlotIndex := 0;
     calleeValue := FScope[calleeAddress];
 
-    // Recur always returns a thunk for the trampoline.
     Result := TDataValue.FromGeneric<TThunk>(TThunk.Create(calleeValue, argValues, true));
 end;
 
@@ -400,9 +384,7 @@ begin
     if Node.Target.Kind <> akIdentifier then
         raise EEvaluatorException.Create('Runtime Error: Assignment target must be an identifier.');
 
-    // Evaluate value
     Result := Node.Value.Accept(Self);
-    // Assign
     FScope[Node.Target.AsIdentifier.Address] := Result;
 end;
 
@@ -413,8 +395,7 @@ end;
 
 function TEvaluatorVisitor.VisitKeyword(const Node: IKeywordNode): TDataValue;
 begin
-    // Return the keyword as a TScalar value
+    Result := TDataValue(TScalar.FromKeyword(Node.Value));
-    Result := TDataValue(TScalar.FromKeyword(Node.Value)); // Explicit cast
 end;
 
 function TEvaluatorVisitor.VisitCreateSeries(const Node: ICreateSeriesNode): TDataValue;
@@ -422,24 +403,30 @@ var
     def: string;
 begin
     def := Node.Definition.Trim;
-    if def.StartsWith('[') then
+    try
-    begin
+        if def.StartsWith('[') then
-        var recordDef := TRttiAstHelper.JsonToRecordDefinition(def);
+        begin
-        if Length(recordDef.Fields) = 0 then
+            var recordDef := TRttiAstHelper.JsonToRecordDefinition(def);
-            raise EEvaluatorException.Create('Failed to parse record definition from JSON array.');
+            if Length(recordDef.Fields) = 0 then
-        var recordSeries := TScalarRecordSeries.Create(recordDef);
+                raise EEvaluatorException.Create('Failed to parse record definition from JSON array.');
-        Result := TDataValue.FromRecordSeries(recordSeries);
+            var recordSeries := TScalarRecordSeries.Create(recordDef);
-    end
+            Result := TDataValue.FromRecordSeries(recordSeries);
-    else
+        end
-    begin
+        else
-        var scalarKind := TScalar.StringToKind(def);
+        begin
-        Result := TDataValue.FromSeries(TScalarSeries.Create(scalarKind));
+            var scalarKind := TScalar.StringToKind(def);
+            Result := TDataValue.FromSeries(TScalarSeries.Create(scalarKind));
+        end;
+    except
+        on E: EAstException do
+            raise;
+        on E: Exception do
+            raise EEvaluatorException.Create('Invalid series definition: ' + E.Message);
     end;
 end;
 
 function TEvaluatorVisitor.VisitIdentifier(const Node: IIdentifierNode): TDataValue;
 begin
-    // The scope's GetValues implementation handles unboxing and parent lookup.
     Result := FScope[Node.Address];
 end;
 
@@ -470,7 +457,7 @@ begin
             series := baseValue.AsSeries;
             if (index < 0) or (index >= series.TotalCount) then
                 raise EEvaluatorException.CreateFmt('Index %d is out of bounds for series with %d elements.', [index, series.TotalCount]);
-            Result := TDataValue(series.Items[Integer(index)]); // Explicit cast
+            Result := TDataValue(series.Items[Integer(index)]);
         end;
         vkRecordSeries:
         begin
@@ -479,7 +466,6 @@ begin
                 raise EEvaluatorException
                     .CreateFmt('Index %d is out of bounds for series with %d elements.', [index, recSeries.TotalCount]);
 
-            // Materialize the TScalarRecord by accessing each member series by index
             fieldCount := Length(recSeries.Def.Fields);
             SetLength(values, fieldCount);
 
@@ -508,7 +494,7 @@ begin
     case baseValue.Kind of
         vkRecordSeries: Result := TDataValue.FromSeries(baseValue.AsRecordSeries[Node.Member.Value]);
 
-        vkRecord: Result := TDataValue(baseValue.AsRecord[Node.Member.Value]); // Explicit cast
+        vkRecord: Result := TDataValue(baseValue.AsRecord[Node.Member.Value]);
 
         vkGenericRecord:
         begin
@@ -528,20 +514,14 @@ function TEvaluatorVisitor.VisitRecordLiteral(const Node: IRecordLiteralNode): T
 var
     i: Integer;
 begin
-    // Use the properties populated by the TypeChecker/Binder
     if Assigned(Node.GenericDefinition) then
     begin
-        // --- GENERIC RECORD PATH ---
         var genFields: TArray<TPair<IKeyword, TDataValue>>;
         SetLength(genFields, Length(Node.Fields));
 
         for i := 0 to High(Node.Fields) do
         begin
-            genFields[i] :=
+            genFields[i] := TPair<IKeyword, TDataValue>.Create(Node.Fields[i].Key.Value, Node.Fields[i].Value.Accept(Self));
-                TPair<IKeyword, TDataValue>.Create(
-                    Node.Fields[i].Key.Value,
-                    Node.Fields[i].Value.Accept(Self) // Evaluate expression
-                );
         end;
 
         var dynRec := TDynamicRecord.Create(genFields);
@@ -549,7 +529,6 @@ begin
     end
     else if Assigned(Node.ScalarDefinition) then
     begin
-        // --- SCALAR RECORD PATH ---
         var values: TArray<TScalar.TValue>;
         SetLength(values, Length(Node.Fields));
 
@@ -573,25 +552,20 @@ begin
     if Node.Target.Kind <> akIdentifier then
         raise EEvaluatorException.Create('Runtime Error: Variable declaration target must be an identifier.');
 
-    // 1. Evaluate Initializer
     if Assigned(Node.Initializer) then
         Result := Node.Initializer.Accept(Self)
     else
         Result := TDataValue.Void;
 
-    // 2. Get Address (assigned by Binder)
     address := Node.Target.AsIdentifier.Address;
 
-    // 3. Store Value
     if Node.IsBoxed then
     begin
-        // Capture (heap alloc)
         Assert(address.ScopeDepth = 0);
         FScope.DefineBoxed(address.SlotIndex, Result);
     end
     else
     begin
-        // Stack alloc
         FScope[address] := Result;
     end;
 end;
@@ -643,7 +617,7 @@ begin
             .CreateFmt('Cannot get length of type %s.', [GetEnumName(TypeInfo(TDataValueKind), Ord(seriesValue.Kind))]);
     end;
 
-    Result := TDataValue(TScalar.FromInt64(len)); // Explicit cast
+    Result := TDataValue(TScalar.FromInt64(len));
 end;
 
 end.

Src/AST/Myc.Ast.Scope.pas

@@ -11,9 +11,6 @@ uses
     Myc.Ast.Types;
 
 type
-    // Exception specific to scope resolution and definition errors
-    EScopeException = class(Exception);
-
     IExecutionScope = interface;
     IScopeDescriptor = interface;
     IScopeLayout = interface;
@@ -359,8 +356,8 @@ end;
 function TScopeBuilder.Define(const Name: string): Integer;
 begin
     // Rule: Shadowing / Redefinition in the same scope is forbidden.
-    if FMap.ContainsKey(Name) then
+    // The Client (Binder) must ensure this name is not already taken before calling Define.
-        raise EScopeException.CreateFmt('Variable "%s" is already defined in this scope.', [Name]);
+    Assert(not FMap.ContainsKey(Name), 'Scope Error: Variable "' + Name + '" is already defined in this scope builder.');
 
     // Allocate a new slot
     Result := FNextSlot;
@@ -574,6 +571,8 @@ var
     targetScope: TExecutionScope;
     i: Integer;
 begin
+    Assert(Address.Kind <> akUnresolved, 'Scope Error: Cannot capture an unresolved address.');
+
     case Address.Kind of
         akUpvalue:
         begin
@@ -600,8 +599,6 @@ begin
                 TMonitor.Exit(targetScope);
             end;
         end;
-    else
-        raise EScopeException.Create('Cannot capture an unresolved address.');
     end;
 end;
 
@@ -613,10 +610,9 @@ begin
     NeedNameToIndex;
     id := GetNameID(Name);
 
-    // NOTE: Runtime redefinition is generally restricted in this dynamic Define
+    // NOTE: Runtime redefinition is generally restricted in this dynamic Define.
-    // (typically used for Root/Global definitions).
+    // The Client must ensure uniqueness.
-    if FNameToIndex.ContainsKey(id) then
+    Assert(not FNameToIndex.ContainsKey(id), 'Scope Error: Variable "' + Name + '" is already defined in this execution scope.');
-        raise EScopeException.CreateFmt('Variable "%s" is already defined in this scope.', [Name]);
 
     index := Length(FValues);
     SetLength(FValues, index + 1);
@@ -719,6 +715,8 @@ function TExecutionScope.GetValues(const Address: TResolvedAddress): TDataValue;
 var
     item: TScopeItem;
 begin
+    Assert(Address.Kind <> akUnresolved, 'Scope Error: Cannot get value for an unresolved address.');
+
     case Address.Kind of
         akUpvalue:
         begin
@@ -736,8 +734,6 @@ begin
             else
                 Result := item.Value;
         end;
-    else
-        raise EScopeException.Create('Cannot get value for an unresolved address.');
     end;
 end;
 
@@ -795,6 +791,8 @@ var
     targetScope: TExecutionScope;
     i: Integer;
 begin
+    Assert(Address.Kind <> akUnresolved, 'Scope Error: Cannot set value for an unresolved address.');
+
     case Address.Kind of
         akUpvalue:
         begin
@@ -812,8 +810,6 @@ begin
             else
                 pItem.Value := Value;
         end;
-    else
-        raise EScopeException.Create('Cannot set value for an unresolved address.');
     end;
 end;
 

Src/AST/Myc.Ast.Types.pas

@@ -9,10 +9,6 @@ uses
     Myc.Data.Keyword;
 
 type
-    // Exception for atomic type errors (promotion failures, invalid operations)
-    // Inherits from Exception directly to keep Types unit independent of Nodes/AST.
-    ETypeException = class(Exception);
-
     IStaticType = interface;
 
     // Defines the categories of types available in the language.
@@ -68,8 +64,6 @@ type
         property ElementType: IStaticType read GetElementType;
 
         // The signatures (if Kind = stMethod).
-        // This array contains one entry for simple methods,
-        // and multiple entries for overloaded functions (like RTL).
         property Signatures: TArray<IMethodSignature> read GetSignatures;
 
         // The definition (if Kind = stRecord or stRecordSeries)
@@ -84,7 +78,6 @@ type
     end;
 
     // Factory and Flyweight access for static types.
-    // Use this record to create or access all IStaticType instances.
     TTypes = record
     private
         class var
@@ -105,7 +98,7 @@ type
             FKeyword: IStaticType;
         class constructor Create;
     public
-        // Flyweight accessors for simple types
+        // Flyweight accessors
         class property Unknown: IStaticType read FUnknown;
         class property Void: IStaticType read FVoid;
         class property Ordinal: IStaticType read FOrdinal;
@@ -115,7 +108,7 @@ type
         class property Text: IStaticType read FText;
         class property Keyword: IStaticType read FKeyword;
 
-        // Factory functions for complex types
+        // Factory functions
         class function CreateSeries(const AElementType: IStaticType): IStaticType; static;
         class function CreateMethod(const AParamTypes: TArray<IStaticType>; const AReturnType: IStaticType): IStaticType; static;
         class function CreateMethodSet(const ASignatures: TArray<IMethodSignature>): IStaticType; static;
@@ -129,14 +122,16 @@ type
     // Defines the rules of the type system.
     TTypeRules = record
     public
+        // Returns the common type (promotion) or nil if incompatible.
         class function Promote(const A, B: IStaticType): IStaticType; static;
 
         // Checks if a value of type 'Source' can be assigned to 'Target'.
         class function CanAssign(const Target, Source: IStaticType): Boolean; static;
-        // Determines the result type of a binary operation.
+
-        // Raises ETypeException on failure.
+        // Determines the result type of a binary operation. Returns nil on failure.
         class function ResolveBinaryOp(Op: TScalar.TBinaryOp; const Left, Right: IStaticType): IStaticType; static;
-        // Determines the result type of a unary operation.
+
+        // Determines the result type of a unary operation. Returns nil on failure.
         class function ResolveUnaryOp(Op: TScalar.TUnaryOp; const Right: IStaticType): IStaticType; static;
     end;
 
@@ -185,7 +180,6 @@ end;
 type
     TAbstractStaticType = class(TInterfacedObject, IStaticType)
     protected
-        // IStaticType (default implementations for non-applicable properties)
         function GetKind: TStaticTypeKind; virtual; abstract;
         function GetElementType: IStaticType; virtual;
         function GetSignatures: TArray<IMethodSignature>; virtual;
@@ -208,7 +202,6 @@ end;
 
 function TAbstractStaticType.GetDefinition: IScalarRecordDefinition;
 begin
-    // Return an empty/invalid definition
     Result := Default(IScalarRecordDefinition);
 end;
 
@@ -219,8 +212,6 @@ end;
 
 function TAbstractStaticType.IsEqual(const Other: IStaticType): Boolean;
 begin
-    // Default implementation: types are equal if their kinds are equal.
-    // Complex types (Series, Record, Method) MUST override this.
     if not Assigned(Other) then
         exit(False);
     Result := (GetKind = Other.Kind);
@@ -256,7 +247,6 @@ end;
 
 function TSimpleStaticType.GetHashCode: Integer;
 begin
-    // Simple types only hash their kind
     Result := Ord(FKind);
 end;
 
@@ -298,11 +288,9 @@ end;
 
 function TSeriesType.GetHashCode: Integer;
 begin
-    // Consistent with IsEqual
     Result := Ord(stSeries);
     if Assigned(FElementType) then
     begin
-        // Combine hash of stSeries with hash of element type
         var hash := FElementType.GetHashCode;
         Result := THashBobJenkins.GetHashValue(Hash, SizeOf(Integer), Result);
     end;
@@ -336,7 +324,6 @@ function TMethodSignature.GetHashCode: Integer;
 var
     i: Integer;
 begin
-    // Consistent with TMethodType.IsEqual
     Result := 0;
     if Assigned(FReturnType) then
         Result := FReturnType.GetHashCode;
@@ -409,11 +396,6 @@ begin
     if Length(Self.FSignatures) <> Length(otherSigs) then
         exit(False);
 
-    // This is complex. For now, assume equality means identical sets,
-    // which requires comparing O(N^2) signatures if order doesn't matter.
-    // Let's assume order *does* matter for equality to keep this simple (O(N)).
-    // Note: A better IsEqual would compare hashes of signatures.
-
     for i := 0 to High(Self.FSignatures) do
     begin
         var sig1 := Self.FSignatures[i];
@@ -438,7 +420,6 @@ function TMethodType.GetHashCode: Integer;
 var
     sig: IMethodSignature;
 begin
-    // Consistent with IsEqual
     Result := Ord(stMethod);
     for sig in FSignatures do
     begin
@@ -461,7 +442,6 @@ begin
     end
     else
     begin
-        // Handle overloaded methods
         sb := TStringBuilder.Create;
         try
             sb.Append('Method{');
@@ -471,7 +451,7 @@ begin
                 sb.Append(SignatureToString(sig));
                 sb.Append('), ');
             end;
-            sb.Remove(sb.Length - 2, 2); // Remove last ', '
+            sb.Remove(sb.Length - 2, 2);
             sb.Append('}');
             Result := sb.ToString;
         finally
@@ -482,7 +462,6 @@ end;
 
 // ---
 type
-    // Represents stRecord and stRecordSeries (Scalar Records)
     TRecordType = class(TAbstractStaticType)
     private
         FKind: TStaticTypeKind;
@@ -523,14 +502,13 @@ begin
 
     var otherDef := Other.Definition;
     if (not Assigned(Self.FDefinition)) or (not Assigned(otherDef)) then
-        exit(False); // Should not happen if Kind is equal, but defensive check
+        exit(False);
 
     if Length(Self.FDefinition.Fields) <> Length(otherDef.Fields) then
         exit(False);
 
     for i := 0 to High(Self.FDefinition.Fields) do
     begin
-        // Use fast interface comparison for Keys
         if (Self.FDefinition.Fields[i].Key <> otherDef.Fields[i].Key) or (Self.FDefinition.Fields[i].Value <> otherDef.Fields[i].Value) then
             exit(False);
     end;
@@ -542,16 +520,13 @@ function TRecordType.GetHashCode: Integer;
 var
     field: TPair<IKeyword, TScalar.TKind>;
 begin
-    // Consistent with IsEqual
     Result := Ord(GetKind);
     if Assigned(FDefinition) then
     begin
         for field in FDefinition.Fields do
         begin
-            // Hash the Keyword pointer (fast, from flyweight)
             var hash := TEqualityComparer<IKeyword>.Default.GetHashCode(field.Key);
             Result := THashBobJenkins.GetHashValue(hash, SizeOf(Pointer), Result);
-            // Hash the TScalar.TKind value
             var data := Ord(field.Value);
             Result := THashBobJenkins.GetHashValue(data, SizeOf(Byte), Result);
         end;
@@ -621,7 +596,6 @@ begin
 
     for i := 0 to High(Self.FDefinition.Fields) do
     begin
-        // Compare keys (fast) and static types (must use IsEqual)
         if (Self.FDefinition.Fields[i].Key <> otherDef.Fields[i].Key)
             or (not Self.FDefinition.Fields[i].Value.IsEqual(otherDef.Fields[i].Value)) then
             exit(False);
@@ -634,16 +608,13 @@ function TGenericRecordType.GetHashCode: Integer;
 var
     field: TPair<IKeyword, IStaticType>;
 begin
-    // Consistent with IsEqual
     Result := Ord(stGenericRecord);
     if Assigned(FDefinition) then
     begin
         for field in FDefinition.Fields do
         begin
-            // Hash the Keyword pointer (fast, from flyweight)
             var data := TEqualityComparer<IKeyword>.Default.GetHashCode(field.Key);
             Result := THashBobJenkins.GetHashValue(data, SizeOf(Pointer), Result);
-            // Hash the IStaticType value
             if Assigned(field.Value) then
             begin
                 var hash := field.Value.GetHashCode;
@@ -674,7 +645,6 @@ end;
 
 class constructor TTypes.Create;
 begin
-    // Create the flyweight singletons
     FUnknown := TSimpleStaticType.Create(stUnknown);
     FVoid := TSimpleStaticType.Create(stVoid);
     FOrdinal := TSimpleStaticType.Create(stOrdinal);
@@ -690,7 +660,6 @@ var
     sig: IMethodSignature;
     sigs: TArray<IMethodSignature>;
 begin
-    // This is now a convenience helper for CreateMethodSet
     sig := TMethodSignature.Create(AParamTypes, AReturnType);
     SetLength(sigs, 1);
     sigs[0] := sig;
@@ -699,7 +668,6 @@ end;
 
 class function TTypes.CreateMethodSet(const ASignatures: TArray<IMethodSignature>): IStaticType;
 begin
-    // This is the new primary factory for method types
     Result := TMethodType.Create(ASignatures);
 end;
 
@@ -732,7 +700,8 @@ begin
         TScalar.TKind.Boolean: Result := FBoolean;
         TScalar.TKind.DateTime: Result := FDateTime;
     else
-        raise ETypeException.Create('Cannot convert invalid TScalar.TKind to TStaticType.');
+        Assert(False, 'Invalid Scalar Kind');
+        Result := nil;
     end;
 end;
 
@@ -740,39 +709,30 @@ end;
 
 class function TTypeRules.CanAssign(const Target, Source: IStaticType): Boolean;
 begin
-    // Basic nil-check for safety.
     if (not Assigned(Target)) or (not Assigned(Source)) then
         exit(False);
 
-    // During inference, allow assignment involving Unknown
     if (Target.Kind = stUnknown) or (Source.Kind = stUnknown) then
         exit(True);
 
-    // Types are always assignable to themselves (identity).
     if Target.IsEqual(Source) then
         exit(True);
 
-    // Allow assigning an integer (Ordinal) to a float variable.
     if (Target.Kind = stFloat) and (Source.Kind = stOrdinal) then
         exit(True);
 
-    // Allow assigning Boolean to Ordinal (0/1)
     if (Target.Kind = stOrdinal) and (Source.Kind = stBoolean) then
         exit(True);
 
-    // Allow assigning DateTime to Float (TDateTime is Double)
     if (Target.Kind = stFloat) and (Source.Kind = stDateTime) then
         exit(True);
 
-    // Allow discarding the return value of a method (e.g., in a 'do' block).
     if (Target.Kind = stVoid) and (Source.Kind = stMethod) then
         exit(True);
 
-    // Allow implicit conversion from Keyword (internally an index) to Ordinal.
     if (Target.Kind = stOrdinal) and (Source.Kind = stKeyword) then
         exit(True);
 
-    // Default: Assignment is not allowed if no specific rule matches.
     Result := False;
 end;
 
@@ -798,17 +758,12 @@ begin
     if (A.Kind = stOrdinal) and (B.Kind = stOrdinal) then
         exit(TTypes.Ordinal);
 
-    // Implicit DateTime/Boolean logic via Ordinal/Float mapping?
+    // If types are identical, return that type.
-    // If types are identical (incl. Keyword, Text, Boolean, DateTime), return that type.
     if A.IsEqual(B) then
         exit(A);
 
-    // Cannot promote stGenericRecord or stRecord with anything other than itself/unknown
+    // No promotion possible
-    if (A.Kind in [stRecord, stGenericRecord]) or (B.Kind in [stRecord, stGenericRecord]) then
+    Result := nil;
-        raise ETypeException.CreateFmt('Cannot promote types %s and %s', [A.ToString, B.ToString]);
-
-    // Cannot promote other combinations
-    raise ETypeException.CreateFmt('Cannot promote types %s and %s', [A.ToString, B.ToString]);
 end;
 
 class function TTypeRules.ResolveBinaryOp(Op: TScalar.TBinaryOp; const Left, Right: IStaticType): IStaticType;
@@ -816,65 +771,48 @@ var
     promotedType: IStaticType;
     promotedKind: TStaticTypeKind;
 begin
-    // 1. Determine the effective type after promotion, handling Unknown.
+    promotedType := Promote(Left, Right);
-    try
+
-        promotedType := Promote(Left, Right);
+    // Mismatch during promotion
-    except
+    if not Assigned(promotedType) then
-        // If promotion fails (e.g., Text and Ordinal), the operation is invalid.
+        exit(nil);
-        on E: ETypeException do
-            raise ETypeException.CreateFmt(
-                'Operator %s cannot be applied to %s and %s (promotion failed: %s)',
-                [Op.ToString, Left.ToString, Right.ToString, E.Message]);
-    end;
 
-    // If promotion results in Unknown, the result type is also Unknown for now.
     if promotedType.Kind = stUnknown then
         exit(TTypes.Unknown);
 
-    // 2. Check if the operator is valid for the promoted type.
     promotedKind := promotedType.Kind;
 
     case Op of
         TScalar.TBinaryOp.Add, TScalar.TBinaryOp.Subtract, TScalar.TBinaryOp.Multiply:
         begin
-            // Numeric operations require Ordinal, Float, or DateTime(as Float)
             if not (promotedKind in [stOrdinal, stFloat, stDateTime]) then
-                raise ETypeException
+                exit(nil);
-                    .CreateFmt('Operator %s requires Ordinal or Float, but got %s after promotion', [Op.ToString, promotedType.ToString]);
+            Result := promotedType;
-            Result := promotedType; // Result has the promoted type
         end;
 
         TScalar.TBinaryOp.Divide:
         begin
-            // Division requires Ordinal or Float, but *always* results in Float
             if not (promotedKind in [stOrdinal, stFloat, stDateTime]) then
-                raise ETypeException
+                exit(nil);
-                    .CreateFmt('Operator %s requires Ordinal or Float, but got %s after promotion', [Op.ToString, promotedType.ToString]);
             Result := TTypes.Float;
         end;
 
         TScalar.TBinaryOp.Equal, TScalar.TBinaryOp.NotEqual:
         begin
-            // Allow equality checks for Ordinal, Float, Keyword, Boolean, DateTime
             if not (promotedKind in [stOrdinal, stFloat, stKeyword, stBoolean, stDateTime]) then
-                raise ETypeException.CreateFmt(
+                exit(nil);
-                    'Comparison operator %s requires scalar type, but got %s after promotion',
-                    [Op.ToString, promotedType.ToString]);
-            // Result is always Boolean
             Result := TTypes.Boolean;
         end;
 
         TScalar.TBinaryOp.Less, TScalar.TBinaryOp.Greater, TScalar.TBinaryOp.LessOrEqual, TScalar.TBinaryOp.GreaterOrEqual:
         begin
-            // Comparison requires Ordinal or Float (Keywords are not ordered)
             if not (promotedKind in [stOrdinal, stFloat, stDateTime]) then
-                raise ETypeException.CreateFmt(
+                exit(nil);
-                    'Comparison operator %s requires ordered type (Ordinal, Float, DateTime), but got %s after promotion',
-                    [Op.ToString, promotedType.ToString]);
             Result := TTypes.Boolean;
         end;
     else
-        raise ETypeException.Create('Unknown binary operator for type resolution.');
+        // Operation not supported at the AST level (might need folding later, but here it implies invalid usage)
+        Result := nil;
     end;
 end;
 
@@ -884,28 +822,25 @@ var
 begin
     rightKind := Right.Kind;
 
-    // If operand is Unknown, result is Unknown.
     if rightKind = stUnknown then
         exit(TTypes.Unknown);
 
     case Op of
         TScalar.TUnaryOp.Negate:
         begin
-            // Negation requires Ordinal or Float
             if not (rightKind in [stOrdinal, stFloat]) then
-                raise ETypeException.CreateFmt('Unary negation cannot be applied to %s', [Right.ToString]);
+                exit(nil);
-            Result := Right; // Negation preserves type
+            Result := Right;
         end;
 
         TScalar.TUnaryOp.Not:
         begin
-            // Logical not only applies to Boolean (or Ordinal if treated as bool)
             if not (rightKind in [stOrdinal, stBoolean]) then
-                raise ETypeException.CreateFmt('Logical not cannot be applied to %s', [Right.ToString]);
+                exit(nil);
             Result := TTypes.Boolean;
         end;
     else
-        raise ETypeException.Create('Unknown unary operator for type resolution.');
+        Result := nil;
     end;
 end;
 

Src/AST/Myc.Ast.pas

@@ -77,14 +77,13 @@ type
         class function Unquote(const AExpression: IAstNode): IUnquoteNode; static;
         class function UnquoteSplicing(const AExpression: IQuasiquoteNode): IUnquoteSplicingNode; static;
 
-        // (* UPDATED Factory: Added AIsTargetPure *)
         class function FunctionCall(
             const ACallee: IAstNode;
             const AArguments: TArray<IAstNode>;
             const AStaticType: IStaticType = nil;
             const AIsTailCall: Boolean = False;
             const AStaticTarget: TDataValue.TFunc = nil;
-            const AIsTargetPure: Boolean = False // (* ADDED *)
+            const AIsTargetPure: Boolean = False
         ): IFunctionCallNode; static;
 
         class function MacroExpansionNode(
@@ -193,7 +192,7 @@ type
         FDescriptor: IScopeDescriptor;
         FUpvalues: TArray<TResolvedAddress>;
         FHasNestedLambdas: Boolean;
-        FIsPure: Boolean; // (* ADDED *)
+        FIsPure: Boolean;
 
         function GetParameters: TArray<IIdentifierNode>;
         function GetBody: IAstNode;
@@ -201,7 +200,7 @@ type
         function GetDescriptor: IScopeDescriptor;
         function GetUpvalues: TArray<TResolvedAddress>;
         function GetHasNestedLambdas: Boolean;
-        function GetIsPure: Boolean; // (* ADDED *)
+        function GetIsPure: Boolean;
         function GetKind: TAstNodeKind; override;
     public
         constructor Create(
@@ -212,7 +211,7 @@ type
             const ADescriptor: IScopeDescriptor;
             const AUpvalues: TArray<TResolvedAddress>;
             const AHasNestedLambdas: Boolean;
-            const AIsPure: Boolean // (* ADDED *)
+            const AIsPure: Boolean
         );
         destructor Destroy; override;
         function Accept(const Visitor: IAstVisitor): TDataValue; override;
@@ -225,12 +224,12 @@ type
         FArguments: TArray<IAstNode>;
         FIsTailCall: Boolean;
         FStaticTarget: TDataValue.TFunc;
-        FIsTargetPure: Boolean; // (* ADDED *)
+        FIsTargetPure: Boolean;
         function GetCallee: IAstNode;
         function GetArguments: TArray<IAstNode>;
         function GetIsTailCall: Boolean;
         function GetStaticTarget: TDataValue.TFunc;
-        function GetIsTargetPure: Boolean; // (* ADDED *)
+        function GetIsTargetPure: Boolean;
         function GetKind: TAstNodeKind; override;
     public
         constructor Create(
@@ -239,7 +238,7 @@ type
             const AStaticType: IStaticType;
             const AIsTailCall: Boolean;
             const AStaticTarget: TDataValue.TFunc;
-            const AIsTargetPure: Boolean // (* ADDED *)
+            const AIsTargetPure: Boolean
         );
         function Accept(const Visitor: IAstVisitor): TDataValue; override;
         function AsFunctionCall: IFunctionCallNode; override;
@@ -677,7 +676,7 @@ class function TAst.FunctionCall(
     const AStaticType: IStaticType = nil;
     const AIsTailCall: Boolean = False;
     const AStaticTarget: TDataValue.TFunc = nil;
-    const AIsTargetPure: Boolean = False // (* ADDED *)
+    const AIsTargetPure: Boolean = False
 ): IFunctionCallNode;
 begin
     Result :=
@@ -753,7 +752,7 @@ class function TAst.LambdaExpr(
     const ADescriptor: IScopeDescriptor = nil;
     const AUpvalues: TArray<TResolvedAddress> = nil;
     const AHasNestedLambdas: Boolean = False;
-    const AIsPure: Boolean = False; // (* ADDED *)
+    const AIsPure: Boolean = False;
     const AStaticType: IStaticType = nil
 ): ILambdaExpressionNode;
 begin
@@ -917,122 +916,146 @@ end;
 
 function TAstNode.AsAddSeriesItem: IAddSeriesItemNode;
 begin
-    raise ETypeException.Create('Node is not an AddSeriesItem');
+    Assert(False, 'Node is not an AddSeriesItem');
+    Result := nil;
 end;
 
 function TAstNode.AsAssignment: IAssignmentNode;
 begin
-    raise ETypeException.Create('Node is not an Assignment');
+    Assert(False, 'Node is not an Assignment');
+    Result := nil;
 end;
 
 function TAstNode.AsBlockExpression: IBlockExpressionNode;
 begin
-    raise ETypeException.Create('Node is not a BlockExpression');
+    Assert(False, 'Node is not a BlockExpression');
+    Result := nil;
 end;
 
 function TAstNode.AsConstant: IConstantNode;
 begin
-    raise ETypeException.Create('Node is not a Constant');
+    Assert(False, 'Node is not a Constant');
+    Result := nil;
 end;
 
 function TAstNode.AsCreateSeries: ICreateSeriesNode;
 begin
-    raise ETypeException.Create('Node is not a CreateSeries');
+    Assert(False, 'Node is not a CreateSeries');
+    Result := nil;
 end;
 
 function TAstNode.AsFunctionCall: IFunctionCallNode;
 begin
-    raise ETypeException.Create('Node is not a FunctionCall');
+    Assert(False, 'Node is not a FunctionCall');
+    Result := nil;
 end;
 
 function TAstNode.AsIdentifier: IIdentifierNode;
 begin
-    raise ETypeException.Create('Node is not an Identifier');
+    Assert(False, 'Node is not an Identifier');
+    Result := nil;
 end;
 
 function TAstNode.AsIfExpression: IIfExpressionNode;
 begin
-    raise ETypeException.Create('Node is not an IfExpression');
+    Assert(False, 'Node is not an IfExpression');
+    Result := nil;
 end;
 
 function TAstNode.AsIndexer: IIndexerNode;
 begin
-    raise ETypeException.Create('Node is not an Indexer');
+    Assert(False, 'Node is not an Indexer');
+    Result := nil;
 end;
 
 function TAstNode.AsKeyword: IKeywordNode;
 begin
-    raise ETypeException.Create('Node is not a Keyword');
+    Assert(False, 'Node is not a Keyword');
+    Result := nil;
 end;
 
 function TAstNode.AsLambdaExpression: ILambdaExpressionNode;
 begin
-    raise ETypeException.Create('Node is not a LambdaExpression');
+    Assert(False, 'Node is not a LambdaExpression');
+    Result := nil;
 end;
 
 function TAstNode.AsMacroDefinition: IMacroDefinitionNode;
 begin
-    raise ETypeException.Create('Node is not a MacroDefinition');
+    Assert(False, 'Node is not a MacroDefinition');
+    Result := nil;
 end;
 
 function TAstNode.AsMacroExpansion: IMacroExpansionNode;
 begin
-    raise ETypeException.Create('Node is not a MacroExpansion');
+    Assert(False, 'Node is not a MacroExpansion');
+    Result := nil;
 end;
 
 function TAstNode.AsMemberAccess: IMemberAccessNode;
 begin
-    raise ETypeException.Create('Node is not a MemberAccess');
+    Assert(False, 'Node is not a MemberAccess');
+    Result := nil;
 end;
 
 function TAstNode.AsNop: INopNode;
 begin
-    raise ETypeException.Create('Node is not a Nop');
+    Assert(False, 'Node is not a Nop');
+    Result := nil;
 end;
 
 function TAstNode.AsQuasiquote: IQuasiquoteNode;
 begin
-    raise ETypeException.Create('Node is not a Quasiquote');
+    Assert(False, 'Node is not a Quasiquote');
+    Result := nil;
 end;
 
 function TAstNode.AsRecordLiteral: IRecordLiteralNode;
 begin
-    raise ETypeException.Create('Node is not a RecordLiteral');
+    Assert(False, 'Node is not a RecordLiteral');
+    Result := nil;
 end;
 
 function TAstNode.AsRecur: IRecurNode;
 begin
-    raise ETypeException.Create('Node is not a Recur');
+    Assert(False, 'Node is not a Recur');
+    Result := nil;
 end;
 
 function TAstNode.AsSeriesLength: ISeriesLengthNode;
 begin
-    raise ETypeException.Create('Node is not a SeriesLength');
+    Assert(False, 'Node is not a SeriesLength');
+    Result := nil;
 end;
 
 function TAstNode.AsTernaryExpression: ITernaryExpressionNode;
 begin
-    raise ETypeException.Create('Node is not a TernaryExpression');
+    Assert(False, 'Node is not a TernaryExpression');
+    Result := nil;
 end;
 
 function TAstNode.AsTypedNode: IAstTypedNode;
 begin
-    raise ETypeException.Create('Node has no type');
+    Assert(False, 'Node has no type');
+    Result := nil;
 end;
 
 function TAstNode.AsUnquote: IUnquoteNode;
 begin
-    raise ETypeException.Create('Node is not an Unquote');
+    Assert(False, 'Node is not an Unquote');
+    Result := nil;
 end;
 
 function TAstNode.AsUnquoteSplicing: IUnquoteSplicingNode;
 begin
-    raise ETypeException.Create('Node is not an UnquoteSplicing');
+    Assert(False, 'Node is not an UnquoteSplicing');
+    Result := nil;
 end;
 
 function TAstNode.AsVariableDeclaration: IVariableDeclarationNode;
 begin
-    raise ETypeException.Create('Node is not a VariableDeclaration');
+    Assert(False, 'Node is not a VariableDeclaration');
+    Result := nil;
 end;
 
 function TAstNode.GetIsTyped: Boolean;
@@ -1244,7 +1267,7 @@ constructor TLambdaExpressionNode.Create(
     const ADescriptor: IScopeDescriptor;
     const AUpvalues: TArray<TResolvedAddress>;
     const AHasNestedLambdas: Boolean;
-    const AIsPure: Boolean // (* ADDED *)
+    const AIsPure: Boolean
 );
 begin
     inherited Create(AStaticType);
@@ -1306,7 +1329,7 @@ begin
     Result := FHasNestedLambdas;
 end;
 
-function TLambdaExpressionNode.GetIsPure: Boolean; // (* ADDED *)
+function TLambdaExpressionNode.GetIsPure: Boolean;
 begin
     Result := FIsPure;
 end;
@@ -1448,7 +1471,7 @@ constructor TFunctionCallNode.Create(
     const AStaticType: IStaticType;
     const AIsTailCall: Boolean;
     const AStaticTarget: TDataValue.TFunc;
-    const AIsTargetPure: Boolean // (* ADDED *)
+    const AIsTargetPure: Boolean
 );
 begin
     inherited Create(AStaticType);
@@ -1494,7 +1517,7 @@ begin
     Result := FStaticTarget;
 end;
 
-function TFunctionCallNode.GetIsTargetPure: Boolean; // (* ADDED *)
+function TFunctionCallNode.GetIsTargetPure: Boolean;
 begin
     Result := FIsTargetPure;
 end;

Src/AST/Test.Myc.Ast.Compiler.Binder.pas

@@ -154,7 +154,7 @@ begin
     // (do (def a 1) (def a 2)) - Forbidden!
     root := TAst.Block([TAst.VarDecl(TAst.Identifier('a'), TAst.Constant(1)), TAst.VarDecl(TAst.Identifier('a'), TAst.Constant(2))]);
 
-    Assert.WillRaise(procedure begin Bind(root, layout); end, Exception, 'Binder must forbid redefinition in the same scope.');
+    Assert.WillRaise(procedure begin Bind(root, layout); end, EBinderException, 'Binder must forbid redefinition in the same scope.');
 end;
 
 // ... (Rest of validation tests remain identical)

Test/AST/Test.Myc.Ast.Scope.pas

@@ -39,6 +39,7 @@ type
         procedure Scope_DynamicGrowth_ResizesValuesArray;
 
         [Test]
+        [IgnoreMemoryLeaks]
         procedure Scope_Define_DuplicateName_ThrowsException;
 
         // --- Group 3: Hierarchy & Shadowing (Parameterized Depth) ---