AST function purity analysis

ASTPlayground/ASTPlayground.dpr

@@ -26,7 +26,8 @@ uses
     Myc.Ast.Compiler.Macros in '..\Src\AST\Myc.Ast.Compiler.Macros.pas',
     Myc.Ast.Compiler.Specializer in '..\Src\AST\Myc.Ast.Compiler.Specializer.pas',
     Myc.Ast.Environment in '..\Src\AST\Myc.Ast.Environment.pas',
-    Myc.Ast.Debugger in '..\Src\AST\Myc.Ast.Debugger.pas';
+    Myc.Ast.Debugger in '..\Src\AST\Myc.Ast.Debugger.pas',
+    Myc.Ast.Analysis.Purity in '..\Src\AST\Myc.Ast.Analysis.Purity.pas';
 
 {$R *.res}
 

ASTPlayground/ASTPlayground.dproj

@@ -157,6 +157,7 @@
         <DCCReference Include="..\Src\AST\Myc.Ast.Compiler.Specializer.pas"/>
         <DCCReference Include="..\Src\AST\Myc.Ast.Environment.pas"/>
         <DCCReference Include="..\Src\AST\Myc.Ast.Debugger.pas"/>
+        <DCCReference Include="..\Src\AST\Myc.Ast.Analysis.Purity.pas"/>
         <BuildConfiguration Include="Base">
             <Key>Base</Key>
         </BuildConfiguration>
@@ -212,6 +213,12 @@
                         <Overwrite>true</Overwrite>
                     </Platform>
                 </DeployFile>
+                <DeployFile LocalName="Win64\Debug\ASTPlayground.rsm" Configuration="Debug" Class="DebugSymbols">
+                    <Platform Name="Win64">
+                        <RemoteName>ASTPlayground.rsm</RemoteName>
+                        <Overwrite>true</Overwrite>
+                    </Platform>
+                </DeployFile>
                 <DeployFile LocalName="Win64\Release\ASTPlayground.exe" Configuration="Release" Class="ProjectOutput">
                     <Platform Name="Win64">
                         <RemoteName>ASTPlayground.exe</RemoteName>

ASTPlayground/MainForm.fmx

@@ -197,7 +197,7 @@ object Form1: TForm1
         'Expanded'
         'Bound'
         'Specialized')
-      ItemIndex = 0
+      ItemIndex = 3
       Position.X = 672.000000000000000000
       Position.Y = 576.000000000000000000
       Size.Width = 104.000000000000000000

ASTPlayground/MainForm.pas

@@ -110,7 +110,7 @@ type
         procedure RTLListViewChange(Sender: TObject);
     private
         FCurrUnboundAst: IAstNode;
-        FCurrExec: TDataValue.TFunc;
+        FCurrExec: TCompiledFunction;
         FEnvironment: TAstEnvironment;
         FWorkspace: TAuraWorkspace;
         FScriptUpdate: Boolean;
@@ -262,7 +262,7 @@ end;
 function TForm1.ExecuteAst(const ANode: IAstNode): TDataValue;
 begin
     FCurrUnboundAst := ANode;
-    FCurrExec := nil; // Clear previous
+    FCurrExec := Default(TCompiledFunction);
 
     // 1. Set strategy based on UI
     if DebugBox.IsChecked then
@@ -273,12 +273,21 @@ begin
     try
         // Wrap in Lambda to compile
         var funcDef := TAst.LambdaExpr([], ANode);
-        FCurrExec := FEnvironment.Compile(funcDef).Func;
+        FCurrExec := FEnvironment.Compile(funcDef);
-        Result := FCurrExec([]);
+
+        if Assigned(FCurrExec.Func) then
+        begin
+            Memo1.Lines.Add(
+                Format('Compiled. Signature: %s, IsPure=%s', [FCurrExec.StaticType.ToString, BoolToStr(FCurrExec.IsPure, true)])
+            );
+        end;
+
+        Result := FCurrExec.Func([]);
 
     except
         on E: Exception do
         begin
+            FCurrExec.Func := nil;
             Memo1.Lines.Add('--- ERROR ---');
             Memo1.Lines.Add(E.ClassName + ': ' + E.Message);
             Result := TDataValue.Void;
@@ -645,7 +654,7 @@ begin
                 FCurrUnboundAst := converter.Deserialize(jsonObj);
 
                 // Run the full pipeline via environment
-                FCurrExec := FEnvironment.Compile(FCurrUnboundAst).Func;
+                FCurrExec := FEnvironment.Compile(FCurrUnboundAst);
 
                 Memo1.Lines.Add('AST deserialized and bound successfully from JSON.');
                 Memo1.Lines.Add('You can now visualize it (Middle Mouse Click) or pretty-print it.');
@@ -655,7 +664,6 @@ begin
         except
             on E: Exception do
             begin
-                FCurrExec := nil;
                 Memo1.Lines.Add('Error deserializing AST from JSON:');
                 Memo1.Lines.Add(E.Message);
                 Memo1.Lines.Add('--- Original JSON ---');
@@ -675,7 +683,7 @@ var
 begin
     Memo1.Lines.Clear;
 
-    if not Assigned(FCurrExec) then
+    if not Assigned(FCurrExec.Func) then
     begin
         Memo1.Lines.Add('No AST available to serialize. Please generate one first.');
         exit;
@@ -703,7 +711,7 @@ begin
     Memo1.Lines.Clear;
     Memo1.Lines.Add('--- AST Dump ---');
 
-    if not Assigned(FCurrExec) then
+    if not Assigned(FCurrExec.Func) then
     begin
         Memo1.Lines.Add('No *compiled* AST has been generated yet. Click a test button first.');
         exit;

Src/AST/Myc.Ast.Analysis.Purity.pas

@@ -0,0 +1,250 @@
+unit Myc.Ast.Analysis.Purity;
+
+interface
+
+uses
+    System.SysUtils,
+    Myc.Data.Value,
+    Myc.Ast.Nodes,
+    Myc.Ast.Visitor,
+    Myc.Ast.Scope;
+
+type
+    /// <summary>
+    ///  Analyzes an AST to determine if it is referentially transparent and free of side effects.
+    /// </summary>
+    TPurityAnalyzer = class(TAstVisitor<Boolean>)
+    protected
+        // Default behavior: Visit children. If all children return True, then True.
+        // However, we must explicitly define what is allowed.
+        function Accept(const Node: IAstNode): Boolean; override;
+
+        // --- Safe Leaves / Constructs ---
+        function VisitConstant(const Node: IConstantNode): Boolean; override;
+        function VisitKeyword(const Node: IKeywordNode): Boolean; override;
+        function VisitIfExpression(const Node: IIfExpressionNode): Boolean; override;
+        function VisitTernaryExpression(const Node: ITernaryExpressionNode): Boolean; override;
+        function VisitBlockExpression(const Node: IBlockExpressionNode): Boolean; override;
+        function VisitRecordLiteral(const Node: IRecordLiteralNode): Boolean; override;
+        function VisitVariableDeclaration(const Node: IVariableDeclarationNode): Boolean; override;
+        function VisitSeriesLength(const Node: ISeriesLengthNode): Boolean; override;
+
+        // --- Critical Checks ---
+        function VisitIdentifier(const Node: IIdentifierNode): Boolean; override;
+        function VisitFunctionCall(const Node: IFunctionCallNode): Boolean; override;
+        function VisitRecurNode(const Node: IRecurNode): Boolean; override;
+
+        // --- Forbidden Constructs (Side Effects / Unsafe) ---
+        function VisitAssignment(const Node: IAssignmentNode): Boolean; override;
+        function VisitAddSeriesItem(const Node: IAddSeriesItemNode): Boolean; override;
+
+        // Allocation is considered pure in this context (it creates a new value, doesn't mutate existing world)
+        function VisitCreateSeries(const Node: ICreateSeriesNode): Boolean; override;
+
+        function VisitIndexer(const Node: IIndexerNode): Boolean; override;
+        function VisitMemberAccess(const Node: IMemberAccessNode): Boolean; override;
+
+        // Ignored / Irrelevant for Runtime Purity (Compile-time constructs or Definitions)
+        function VisitLambdaExpression(const Node: ILambdaExpressionNode): Boolean; override;
+        function VisitMacroDefinition(const Node: IMacroDefinitionNode): Boolean; override;
+        function VisitQuasiquote(const Node: IQuasiquoteNode): Boolean; override;
+        function VisitUnquote(const Node: IUnquoteNode): Boolean; override;
+        function VisitUnquoteSplicing(const Node: IUnquoteSplicingNode): Boolean; override;
+        function VisitMacroExpansionNode(const Node: IMacroExpansionNode): Boolean; override;
+        function VisitNop(const Node: INopNode): Boolean; override;
+
+    public
+        class function IsPure(const RootNode: IAstNode): Boolean;
+    end;
+
+implementation
+
+{ TPurityAnalyzer }
+
+class function TPurityAnalyzer.IsPure(const RootNode: IAstNode): Boolean;
+begin
+    var analyzer := TPurityAnalyzer.Create;
+    try
+        Result := analyzer.Accept(RootNode);
+    finally
+        analyzer.Free;
+    end;
+end;
+
+function TPurityAnalyzer.Accept(const Node: IAstNode): Boolean;
+begin
+    // If a node is nil (e.g. optional else-branch), it's "nothing", which is pure.
+    if not Assigned(Node) then
+        exit(True);
+
+    // Dispatch to specific Visit method via generic base
+    Result := Node.Accept(Self).AsGeneric<Boolean>;
+end;
+
+// --- Safe Leaves ---
+
+function TPurityAnalyzer.VisitConstant(const Node: IConstantNode): Boolean;
+begin
+    Result := True;
+end;
+
+function TPurityAnalyzer.VisitKeyword(const Node: IKeywordNode): Boolean;
+begin
+    Result := True;
+end;
+
+function TPurityAnalyzer.VisitNop(const Node: INopNode): Boolean;
+begin
+    Result := True;
+end;
+
+// --- Identifier: Only local variables are safe ---
+
+function TPurityAnalyzer.VisitIdentifier(const Node: IIdentifierNode): Boolean;
+begin
+    // We only allow access to local variables (ScopeDepth = 0).
+    // Accessing Parent/Upvalues (ScopeDepth > 0) makes the function state-dependent (closure state),
+    // effectively impure regarding referential transparency across different closure instances,
+    // unless we could prove the upvalue is constant (which we don't track yet).
+
+    // Note: Parameters are also ScopeDepth=0 in the Binder logic.
+    Result := (Node.Address.Kind = akLocalOrParent) and (Node.Address.ScopeDepth = 0);
+end;
+
+// --- Function Call: The Core Logic ---
+
+function TPurityAnalyzer.VisitFunctionCall(const Node: IFunctionCallNode): Boolean;
+begin
+    // 1. The target function MUST be marked as Pure (from RTL or previous inference).
+    if not Node.IsTargetPure then
+        exit(False);
+
+    // 2. All arguments must be pure expressions.
+    for var arg in Node.Arguments do
+        if not Accept(arg) then
+            exit(False);
+
+    Result := True;
+end;
+
+// --- Recursion ---
+
+function TPurityAnalyzer.VisitRecurNode(const Node: IRecurNode): Boolean;
+begin
+    // 'recur' is just control flow. It is pure if its arguments are pure.
+    for var arg in Node.Arguments do
+        if not Accept(arg) then
+            exit(False);
+    Result := True;
+end;
+
+// --- Structures: Recursive Checks ---
+
+function TPurityAnalyzer.VisitIfExpression(const Node: IIfExpressionNode): Boolean;
+begin
+    Result := Accept(Node.Condition) and Accept(Node.ThenBranch) and Accept(Node.ElseBranch);
+end;
+
+function TPurityAnalyzer.VisitTernaryExpression(const Node: ITernaryExpressionNode): Boolean;
+begin
+    Result := Accept(Node.Condition) and Accept(Node.ThenBranch) and Accept(Node.ElseBranch);
+end;
+
+function TPurityAnalyzer.VisitBlockExpression(const Node: IBlockExpressionNode): Boolean;
+begin
+    for var expr in Node.Expressions do
+        if not Accept(expr) then
+            exit(False);
+    Result := True;
+end;
+
+function TPurityAnalyzer.VisitVariableDeclaration(const Node: IVariableDeclarationNode): Boolean;
+begin
+    // 'def x = ...' is locally pure if the initializer is pure.
+    // It mutates the local scope (stack), but that is contained within the function execution.
+    Result := Accept(Node.Initializer);
+end;
+
+function TPurityAnalyzer.VisitRecordLiteral(const Node: IRecordLiteralNode): Boolean;
+begin
+    for var field in Node.Fields do
+        if not Accept(field.Value) then
+            exit(False);
+    Result := True;
+end;
+
+function TPurityAnalyzer.VisitIndexer(const Node: IIndexerNode): Boolean;
+begin
+    // Reading from a structure is pure if the indices/base are pure.
+    Result := Accept(Node.Base) and Accept(Node.Index);
+end;
+
+function TPurityAnalyzer.VisitMemberAccess(const Node: IMemberAccessNode): Boolean;
+begin
+    Result := Accept(Node.Base);
+end;
+
+function TPurityAnalyzer.VisitSeriesLength(const Node: ISeriesLengthNode): Boolean;
+begin
+    // Querying length is pure.
+    // The series identifier check happens in VisitIdentifier.
+    Result := True;
+end;
+
+// --- Forbidden (Impure) ---
+
+function TPurityAnalyzer.VisitAssignment(const Node: IAssignmentNode): Boolean;
+begin
+    // Mutation of variables is defined as impure.
+    Result := False;
+end;
+
+function TPurityAnalyzer.VisitAddSeriesItem(const Node: IAddSeriesItemNode): Boolean;
+begin
+    // Mutation of a series (side effect).
+    Result := False;
+end;
+
+function TPurityAnalyzer.VisitCreateSeries(const Node: ICreateSeriesNode): Boolean;
+begin
+    // Creating a NEW object is considered pure in this context,
+    // as it does not mutate existing global state.
+    Result := True;
+end;
+
+// --- Irrelevant / Nested (Definitions are pure, execution logic checked separately) ---
+
+function TPurityAnalyzer.VisitLambdaExpression(const Node: ILambdaExpressionNode): Boolean;
+begin
+    // Defining a function is a pure operation.
+    // Whether the function itself is pure when executed is determined when *that* function is compiled.
+    Result := True;
+end;
+
+function TPurityAnalyzer.VisitMacroDefinition(const Node: IMacroDefinitionNode): Boolean;
+begin
+    Result := True; // Compile-time construct
+end;
+
+function TPurityAnalyzer.VisitQuasiquote(const Node: IQuasiquoteNode): Boolean;
+begin
+    Result := True; // Structural construction
+end;
+
+function TPurityAnalyzer.VisitUnquote(const Node: IUnquoteNode): Boolean;
+begin
+    Result := Accept(Node.Expression);
+end;
+
+function TPurityAnalyzer.VisitUnquoteSplicing(const Node: IUnquoteSplicingNode): Boolean;
+begin
+    Result := Accept(Node.Expression);
+end;
+
+function TPurityAnalyzer.VisitMacroExpansionNode(const Node: IMacroExpansionNode): Boolean;
+begin
+    // We analyze the already expanded body.
+    Result := Accept(Node.ExpandedBody);
+end;
+
+end.

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

@@ -368,7 +368,7 @@ begin
     // If FLambdaCounter increased by more than just 1 (myself), children were visited.
     hasNested := FLambdaCounter > (startCount + 1);
 
-    Result := TAst.LambdaExpr(newParams, newBody, finalLayout, nil, upvaluesList, hasNested);
+    Result := TAst.LambdaExpr(newParams, newBody, finalLayout, nil, upvaluesList, hasNested, Node.IsPure);
 end;
 
 function TAstBinder.VisitFunctionCall(const Node: IFunctionCallNode): IAstNode;

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

@@ -219,7 +219,7 @@ begin
 
     newBody := Accept(Node.Body);
 
-    Result := TAst.LambdaExpr(newParams, newBody, nil, nil, nil, False, TTypes.Unknown);
+    Result := TAst.LambdaExpr(newParams, newBody, nil, nil, nil, False, Node.IsPure, TTypes.Unknown);
 end;
 
 function TExpansionVisitor.VisitUnquote(const Node: IUnquoteNode): IAstNode;

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

@@ -22,6 +22,7 @@ type
     // This transformer runs *after* TypeChecker.
     // It specializes all statically resolvable function calls (RTL and user-defined)
     // by replacing them with nodes that have a direct StaticTarget.
+    // It propagates Purity information but does NOT perform Constant Folding yet.
     TStaticSpecializer = class(TAstTransformer, IAstSpecializer)
     private
         FEnvironment: IEnvironment;
@@ -35,7 +36,6 @@ type
         constructor Create(const AEnvironment: IEnvironment);
         function Execute(const RootNode: IAstNode): IAstNode;
 
-        // Descriptor removed from signature as it is not needed for specialization
         class function Specialize(const AEnvironment: IEnvironment; const RootNode: IAstNode): IAstNode; static;
     end;
 
@@ -128,7 +128,16 @@ begin
     if FEnvironment.MonomorphCache.TryGetValue(key, specializedMethod) then
     begin
         // 4a. Cache Hit (Environment)
-        Result := TAst.FunctionCall(newCallee, newArgs, specializedMethod.ReturnType, Node.IsTailCall, specializedMethod.Target);
+        // Propagate IsPure flag from cache to AST node
+        Result :=
+            TAst.FunctionCall(
+                newCallee,
+                newArgs,
+                specializedMethod.ReturnType,
+                Node.IsTailCall,
+                specializedMethod.Target,
+                specializedMethod.IsPure
+            );
         exit;
     end;
 
@@ -139,7 +148,16 @@ begin
         // 5a. Cache Hit (RTL)
         FEnvironment.MonomorphCache.Add(key, specializedMethod);
 
-        Result := TAst.FunctionCall(newCallee, newArgs, specializedMethod.ReturnType, Node.IsTailCall, specializedMethod.Target);
+        // Propagate IsPure flag from RTL definition to AST node
+        Result :=
+            TAst.FunctionCall(
+                newCallee,
+                newArgs,
+                specializedMethod.ReturnType,
+                Node.IsTailCall,
+                specializedMethod.Target,
+                specializedMethod.IsPure
+            );
         exit;
     end;
 
@@ -148,7 +166,7 @@ begin
 
     if (funcDef <> nil) then
     begin
-        // Cannot specialize closures safely without more complex analysis
+        // Cannot specialize closures safely without more complex analysis if they have state
         if funcDef.Kind = akLambdaExpression then
         begin
             var lambdaDef := funcDef.AsLambdaExpression;
@@ -160,17 +178,18 @@ begin
         end;
 
         // 6a. Compile func with KNOWN TYPES
-        // This recursively triggers Bind -> Check -> Specialize for the callee body!
+        // This recursively triggers Bind -> Check -> Specialize -> Purity Inference for the callee body!
         var compiled := FEnvironment.Compile(funcDef, argTypes);
 
         // 6b. Store in cache
         // Get the return type from the *full function type* returned by Compile
         var returnType := compiled.StaticType.Signatures[0].ReturnType;
-        specializedMethod := TSpecializedMethod.Create(compiled.Func, returnType);
+        specializedMethod := TSpecializedMethod.Create(compiled.Func, returnType, compiled.IsPure);
         FEnvironment.MonomorphCache.Add(key, specializedMethod);
 
         // 6c. Return the new node
-        Result := TAst.FunctionCall(newCallee, newArgs, returnType, Node.IsTailCall, compiled.Func);
+        // Propagate the inferred IsPure flag to the AST node
+        Result := TAst.FunctionCall(newCallee, newArgs, returnType, Node.IsTailCall, compiled.Func, compiled.IsPure);
         exit;
     end;
 

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

@@ -180,7 +180,18 @@ begin
     begin
         // Rebuild using factory.
         // IMPORTANT: Pass Layout AND Descriptor (TCO runs after TypeChecker).
-        Result := TAst.LambdaExpr(newParams, newBody, Node.Layout, Node.Descriptor, Node.Upvalues, Node.HasNestedLambdas, Node.StaticType);
+        // (* FIX: Pass Node.IsPure to preserve it *)
+        Result :=
+            TAst.LambdaExpr(
+                newParams,
+                newBody,
+                Node.Layout,
+                Node.Descriptor,
+                Node.Upvalues,
+                Node.HasNestedLambdas,
+                Node.IsPure,
+                Node.StaticType
+            );
     end;
 end;
 
@@ -242,7 +253,8 @@ begin
             newArgs,
             Node.StaticType,
             isTailCall,
-            Node.StaticTarget // Preserve the static target from Specializer
+            Node.StaticTarget, // Preserve the static target from Specializer
+            Node.IsTargetPure // (* FIX: Preserve the purity flag from Specializer! *)
         );
 end;
 

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

@@ -400,7 +400,8 @@ begin
     end;
 
     // 9. Create new node with the Descriptor attached!
-    Result := TAst.LambdaExpr(newParams, newBody, Node.Layout, finalDescriptor, Node.Upvalues, Node.HasNestedLambdas, methodType);
+    Result :=
+        TAst.LambdaExpr(newParams, newBody, Node.Layout, finalDescriptor, Node.Upvalues, Node.HasNestedLambdas, Node.IsPure, methodType);
 end;
 
 function TTypeChecker.VisitFunctionCall(const Node: IFunctionCallNode): IAstNode;

Src/AST/Myc.Ast.Dumper.pas

@@ -201,7 +201,12 @@ var
     slot: Integer;
     typ: IStaticType;
 begin
-    LogFmt('LambdaExpression (HasNested: %s)', [Node.HasNestedLambdas.ToString(TUseBoolStrs.True)], Node);
+    // (* UPDATED: Added IsPure output *)
+    LogFmt(
+        'LambdaExpression (HasNested: %s, IsPure: %s)',
+        [Node.HasNestedLambdas.ToString(TUseBoolStrs.True), BoolToStr(Node.IsPure, True)],
+        Node
+    );
     Indent;
 
     // 1. Layout & Symbols
@@ -277,7 +282,12 @@ begin
     else
         staticStatus := 'nil';
 
-    LogFmt('FunctionCall (IsTailCall: %s, StaticTarget: %s%s)', [Node.IsTailCall.ToString(TUseBoolStrs.True), staticStatus, sigStr], Node);
+    // (* UPDATED: Added IsTargetPure output *)
+    LogFmt(
+        'FunctionCall (IsTailCall: %s, StaticTarget: %s%s, IsTargetPure: %s)',
+        [Node.IsTailCall.ToString(TUseBoolStrs.True), staticStatus, sigStr, BoolToStr(Node.IsTargetPure, True)],
+        Node
+    );
 
     Indent;
     Log('Callee:');

Src/AST/Myc.Ast.Environment.pas

@@ -41,7 +41,8 @@ type
     public
         Func: TDataValue.TFunc;
         StaticType: IStaticType;
-        constructor Create(const AFunc: TDataValue.TFunc; const AStaticType: IStaticType);
+        IsPure: Boolean;
+        constructor Create(const AFunc: TDataValue.TFunc; const AStaticType: IStaticType; AIsPure: Boolean);
     end;
 
     IExecutionStrategy = interface
@@ -143,7 +144,8 @@ uses
     Myc.Ast.Compiler.Binder,
     Myc.Ast.Compiler.TypeChecker,
     Myc.Ast.Compiler.Specializer,
-    Myc.Ast.Compiler.TCO;
+    Myc.Ast.Compiler.TCO,
+    Myc.Ast.Analysis.Purity;
 
 { TMonoCacheKey }
 
@@ -202,10 +204,11 @@ end;
 
 { TCompiledFunction }
 
-constructor TCompiledFunction.Create(const AFunc: TDataValue.TFunc; const AStaticType: IStaticType);
+constructor TCompiledFunction.Create(const AFunc: TDataValue.TFunc; const AStaticType: IStaticType; AIsPure: Boolean);
 begin
     Func := AFunc;
     StaticType := AStaticType;
+    IsPure := AIsPure;
 end;
 
 type
@@ -344,6 +347,8 @@ end;
 procedure TAstEnvironment.Define(const Name: String; const AScript: IAstNode);
 begin
     var compiled := Compile(AScript);
+    // Note: Define now potentially handles Pure flags internally via the Node metadata,
+    // but the runtime value is just the TDataValue.
     RootScope.Define(Name, compiled.Func([]), compiled.StaticType);
 end;
 
@@ -526,6 +531,7 @@ var
     typedNode: IAstNode;
     specialized: IAstNode;
     tcoOptimized: IAstNode;
+    isPure: Boolean;
 begin
     // 0. Wrap in Lambda to create an isolatable compilation unit (scope)
     var prg := TAst.LambdaExpr(Params, Node);
@@ -549,25 +555,27 @@ begin
     // 4. Optimize (TCO)
     tcoOptimized := TAstTCO.Optimize(specialized);
 
-    // 5. Create Evaluator
+    // 5. Purity Inference
-    // We create a scope based on the descriptor to run the lambda body.
+    // Check the body of the optimized lambda for purity.
-    // The lambda itself (as a node) is evaluated to produce a closure.
+    // Note: tcoOptimized is a LambdaExpressionNode. Its body is what we check.
-    // Since we wrapped the user code in a LambdaExpr, evaluating 'tcoOptimized'
+    isPure := TPurityAnalyzer.IsPure(tcoOptimized.AsLambdaExpression.Body);
-    // returns the closure (TFunc).
+
+    // 6. Create Evaluator
     var visitor := FExecutionStrategy.CreateVisitor(descriptor.CreateScope(FRootScope));
 
     // Execute the AST to get the TFunc (Closure)
-    var closure := tcoOptimized.Accept(visitor);
+    var closure := tcoOptimized.Accept(visitor).AsMethod();
 
     // Wrap TCO handling for the final result
     finalFunc :=
         function(const Args: TArray<TDataValue>): TDataValue
         begin
-            Result := closure.AsMethod()(Args);
+            Result := closure(Args);
             TEvaluatorVisitor.HandleTCO(Result);
         end;
 
-    Result := TCompiledFunction.Create(finalFunc, funcType);
+    // Pass IsPure flag to the compiled function record
+    Result := TCompiledFunction.Create(finalFunc, funcType, isPure);
 end;
 
 function TEnvironment.Compile(const Node: IFunctionDefinition; const ArgTypes: TArray<IStaticType>): TCompiledFunction;
@@ -578,6 +586,7 @@ var
     finalFunc: TDataValue.TFunc;
 
     typedNode, specialized, tcoOptimized: IAstNode;
+    isPure: Boolean;
 begin
     // Same steps as above, but Node is already a definition (Lambda)
     var expanded := ExpandMacros(Node);
@@ -590,6 +599,9 @@ begin
     specialized := Specialize(typedNode);
     tcoOptimized := TAstTCO.Optimize(specialized);
 
+    // Purity Inference
+    isPure := TPurityAnalyzer.IsPure(tcoOptimized.AsLambdaExpression.Body);
+
     var visitor := FExecutionStrategy.CreateVisitor(descriptor.CreateScope(FRootScope));
     var closure := tcoOptimized.Accept(visitor);
 
@@ -600,7 +612,7 @@ begin
             TEvaluatorVisitor.HandleTCO(Result);
         end;
 
-    Result := TCompiledFunction.Create(finalFunc, funcType);
+    Result := TCompiledFunction.Create(finalFunc, funcType, isPure);
 end;
 
 function TEnvironment.ExpandMacros(const Node: IAstNode): IAstNode;

Src/AST/Myc.Ast.Nodes.pas

@@ -158,9 +158,11 @@ type
         {$region 'private'}
         function GetBody: IAstNode;
         function GetParameters: TArray<IIdentifierNode>;
+        function GetIsPure: Boolean; // (* ADDED *)
         {$endregion}
         property Body: IAstNode read GetBody;
         property Parameters: TArray<IIdentifierNode> read GetParameters;
+        property IsPure: Boolean read GetIsPure; // (* ADDED *)
     end;
 
     INopNode = interface(IAstTypedNode)
@@ -228,6 +230,7 @@ type
 
         function GetUpvalues: TArray<TResolvedAddress>;
         function GetHasNestedLambdas: Boolean;
+        // GetIsPure is inherited from IFunctionDefinition
         {$endregion}
 
         property Parameters: TArray<IIdentifierNode> read GetParameters;
@@ -238,6 +241,7 @@ type
 
         property Upvalues: TArray<TResolvedAddress> read GetUpvalues;
         property HasNestedLambdas: Boolean read GetHasNestedLambdas;
+    // IsPure is inherited
     end;
 
     IFunctionCallNode = interface(IAstTypedNode)
@@ -246,11 +250,13 @@ type
         function GetArguments: TArray<IAstNode>;
         function GetIsTailCall: Boolean;
         function GetStaticTarget: TDataValue.TFunc;
+        function GetIsTargetPure: Boolean; // (* ADDED *)
         {$endregion}
         property Callee: IAstNode read GetCallee;
         property Arguments: TArray<IAstNode> read GetArguments;
         property IsTailCall: Boolean read GetIsTailCall;
         property StaticTarget: TDataValue.TFunc read GetStaticTarget;
+        property IsTargetPure: Boolean read GetIsTargetPure; // (* ADDED *)
     end;
 
     // A node representing a macro call.

Src/AST/Myc.Ast.RTL.pas

@@ -47,11 +47,11 @@ type
     public
         Target: TDataValue.TFunc;
         ReturnType: IStaticType;
-        constructor Create(const ATarget: TDataValue.TFunc; const AReturnType: IStaticType);
+        IsPure: Boolean; // (* ADDED *)
+        constructor Create(const ATarget: TDataValue.TFunc; const AReturnType: IStaticType; AIsPure: Boolean);
     end;
 
     // The cache holding TDataValue.TFunc wrappers for static native functions.
-    // Verwendet den generischen TSpecializedMethod-Record aus Myc.Ast.Types
     TStaticBootstrapCache = TDictionary<TStaticSignatureKey, TSpecializedMethod>;
 
     TRtlFunctionInfo = class
@@ -153,7 +153,7 @@ constructor TRtlExportAttribute.Create(const AName: string);
 begin
     inherited Create;
     Self.Name := AName;
-    Self.IsPure := False; // Default to impure
+    Self.IsPure := False; // Default to impure (safe)
 end;
 
 constructor TRtlExportAttribute.Create(const AName: string; AIsPure: Boolean);
@@ -230,6 +230,15 @@ begin
     inherited Destroy;
 end;
 
+{ TSpecializedMethod }
+
+constructor TSpecializedMethod.Create(const ATarget: TDataValue.TFunc; const AReturnType: IStaticType; AIsPure: Boolean);
+begin
+    Target := ATarget;
+    ReturnType := AReturnType;
+    IsPure := AIsPure;
+end;
+
 { TRtlRegistry }
 
 class constructor TRtlRegistry.Create;
@@ -252,7 +261,7 @@ begin
     FStaticBootstrap := TStaticBootstrapCache.Create(TStaticSignatureKeyComparer.Create);
     FStaticFuncMap := TRtlFunctionMap.Create;
 
-    // 2. Perform RTTI Scan (formerly Pass 1 of RegisterAll)
+    // 2. Perform RTTI Scan
     ctx := TRttiContext.Create;
     try
         rtlType := ctx.GetType(TypeInfo(TRtlFunctions));
@@ -292,7 +301,7 @@ begin
 
             if isDynamic then
             begin
-                if Assigned(funcInfo.DynamicWrapper) and Assigned(funcInfo.DynamicWrapper) then
+                if Assigned(funcInfo.DynamicWrapper) then
                     raise EInvalidOpException.CreateFmt('Duplicate dynamic fallback defined for %s', [rtlName]);
 
                 var wrapperFactory :=
@@ -323,8 +332,8 @@ begin
                 var wrapper := CreateStaticWrapper(method, retType, argTypes, rttiParams);
                 if Assigned(wrapper) then
                 begin
-                    methodRecord := TSpecializedMethod.Create(wrapper, retType);
+                    // (* UPDATED: Capture IsPure from attribute *)
-                    // Use renamed static helper
+                    methodRecord := TSpecializedMethod.Create(wrapper, retType, exportAttr.IsPure);
                     RegisterStaticSpecialization(rtlName, argTypes, methodRecord);
                 end
                 else
@@ -366,8 +375,6 @@ var
     key: TStaticSignatureKey;
 begin
     key := TStaticSignatureKey.Create(AName, AArgTypes);
-    // This allows multiple RTTI scans (e.g. in tests) without crashing,
-    // though only the class constructor should call this now.
     FStaticBootstrap.AddOrSetValue(key, AMethod);
 end;
 
@@ -724,12 +731,6 @@ begin
     TRtlRegistry.RegisterAll(AScope);
 end;
 
-constructor TSpecializedMethod.Create(const ATarget: TDataValue.TFunc; const AReturnType: IStaticType);
-begin
-    Target := ATarget;
-    ReturnType := AReturnType;
-end;
-
 initialization
     // Register this library's functions with the central AST factory.
     TAst.RegisterLibrary(RegisterRtlFunctions);

Src/AST/Myc.Ast.Visitor.pas

@@ -486,7 +486,17 @@ begin
     else
     begin
         // Use TAst factory and copy properties via interface getters
-        Result := TAst.LambdaExpr(newParams, newBody, Node.Layout, Node.Descriptor, Node.Upvalues, Node.HasNestedLambdas, Node.StaticType);
+        Result :=
+            TAst.LambdaExpr(
+                newParams,
+                newBody,
+                Node.Layout,
+                Node.Descriptor,
+                Node.Upvalues,
+                Node.HasNestedLambdas,
+                Node.IsPure,
+                Node.StaticType
+            );
     end;
 end;
 

Src/AST/Myc.Ast.pas

@@ -56,14 +56,15 @@ type
             const AStaticType: IStaticType = nil
         ): ITernaryExpressionNode; static;
 
-        // Factory Updated: Includes Layout (mandatory) and Descriptor (optional)
+        // (* UPDATED Factory: Added AIsPure *)
         class function LambdaExpr(
             const AParameters: TArray<IIdentifierNode>;
             const ABody: IAstNode;
-            const ALayout: IScopeLayout = nil; // Nil allowed only for raw AST construction (before Binder)
+            const ALayout: IScopeLayout = nil;
-            const ADescriptor: IScopeDescriptor = nil; // Nil allowed before TypeChecker
+            const ADescriptor: IScopeDescriptor = nil;
             const AUpvalues: TArray<TResolvedAddress> = nil;
             const AHasNestedLambdas: Boolean = False;
+            const AIsPure: Boolean = False; // (* ADDED *)
             const AStaticType: IStaticType = nil
         ): ILambdaExpressionNode; static;
 
@@ -76,12 +77,14 @@ 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 AStaticTarget: TDataValue.TFunc = nil;
+            const AIsTargetPure: Boolean = False // (* ADDED *)
         ): IFunctionCallNode; static;
 
         class function MacroExpansionNode(
@@ -194,6 +197,7 @@ type
         FDescriptor: IScopeDescriptor;
         FUpvalues: TArray<TResolvedAddress>;
         FHasNestedLambdas: Boolean;
+        FIsPure: Boolean; // (* ADDED *)
 
         function GetParameters: TArray<IIdentifierNode>;
         function GetBody: IAstNode;
@@ -201,6 +205,7 @@ type
         function GetDescriptor: IScopeDescriptor;
         function GetUpvalues: TArray<TResolvedAddress>;
         function GetHasNestedLambdas: Boolean;
+        function GetIsPure: Boolean; // (* ADDED *)
         function GetKind: TAstNodeKind; override;
     public
         constructor Create(
@@ -210,7 +215,8 @@ type
             const ALayout: IScopeLayout;
             const ADescriptor: IScopeDescriptor;
             const AUpvalues: TArray<TResolvedAddress>;
-            const AHasNestedLambdas: Boolean
+            const AHasNestedLambdas: Boolean;
+            const AIsPure: Boolean // (* ADDED *)
         );
         destructor Destroy; override;
         function Accept(const Visitor: IAstVisitor): TDataValue; override;
@@ -223,10 +229,12 @@ type
         FArguments: TArray<IAstNode>;
         FIsTailCall: Boolean;
         FStaticTarget: TDataValue.TFunc;
+        FIsTargetPure: Boolean; // (* ADDED *)
         function GetCallee: IAstNode;
         function GetArguments: TArray<IAstNode>;
         function GetIsTailCall: Boolean;
         function GetStaticTarget: TDataValue.TFunc;
+        function GetIsTargetPure: Boolean; // (* ADDED *)
         function GetKind: TAstNodeKind; override;
     public
         constructor Create(
@@ -234,12 +242,14 @@ type
             const AArguments: TArray<IAstNode>;
             const AStaticType: IStaticType;
             const AIsTailCall: Boolean;
-            const AStaticTarget: TDataValue.TFunc
+            const AStaticTarget: TDataValue.TFunc;
+            const AIsTargetPure: Boolean // (* ADDED *)
         );
         function Accept(const Visitor: IAstVisitor): TDataValue; override;
         function AsFunctionCall: IFunctionCallNode; override;
     end;
 
+    // ... (Other node definitions unchanged) ...
     TVariableDeclarationNode = class(TAstTypedNode, IVariableDeclarationNode)
     private
         FIdentifier: IIdentifierNode;
@@ -260,8 +270,6 @@ type
         function AsVariableDeclaration: IVariableDeclarationNode; override;
     end;
 
-    // --- Other internal node classes ---
-
     TConstantNode = class(TAstTypedNode, IConstantNode)
     private
         FValue: TDataValue;
@@ -644,7 +652,6 @@ end;
 class function TAst.Constant(const AValue: TDataValue; const AStaticType: IStaticType = nil): IConstantNode;
 begin
     var constType := AStaticType;
-
     if constType = nil then
     begin
         case AValue.Kind of
@@ -655,7 +662,6 @@ begin
             constType := TTypes.Unknown;
         end;
     end;
-
     Result := TConstantNode.Create(AValue, constType);
 end;
 
@@ -684,7 +690,8 @@ class function TAst.FunctionCall(
     const AArguments: TArray<IAstNode>;
     const AStaticType: IStaticType = nil;
     const AIsTailCall: Boolean = False;
-    const AStaticTarget: TDataValue.TFunc = nil
+    const AStaticTarget: TDataValue.TFunc = nil;
+    const AIsTargetPure: Boolean = False // (* ADDED *)
 ): IFunctionCallNode;
 begin
     Result :=
@@ -694,7 +701,8 @@ begin
             if AStaticType <> nil then AStaticType
             else TTypes.Unknown,
             AIsTailCall,
-            AStaticTarget
+            AStaticTarget,
+            AIsTargetPure
         );
 end;
 
@@ -759,6 +767,7 @@ class function TAst.LambdaExpr(
     const ADescriptor: IScopeDescriptor = nil;
     const AUpvalues: TArray<TResolvedAddress> = nil;
     const AHasNestedLambdas: Boolean = False;
+    const AIsPure: Boolean = False; // (* ADDED *)
     const AStaticType: IStaticType = nil
 ): ILambdaExpressionNode;
 begin
@@ -771,7 +780,8 @@ begin
             ALayout,
             ADescriptor,
             AUpvalues,
-            AHasNestedLambdas
+            AHasNestedLambdas,
+            AIsPure
         );
 end;
 
@@ -1247,7 +1257,8 @@ constructor TLambdaExpressionNode.Create(
     const ALayout: IScopeLayout;
     const ADescriptor: IScopeDescriptor;
     const AUpvalues: TArray<TResolvedAddress>;
-    const AHasNestedLambdas: Boolean
+    const AHasNestedLambdas: Boolean;
+    const AIsPure: Boolean // (* ADDED *)
 );
 begin
     inherited Create(AStaticType);
@@ -1257,6 +1268,7 @@ begin
     FDescriptor := ADescriptor;
     FUpvalues := AUpvalues;
     FHasNestedLambdas := AHasNestedLambdas;
+    FIsPure := AIsPure;
 
     // Consistency Check
     if Assigned(FDescriptor) and (FDescriptor.Layout <> FLayout) then
@@ -1308,6 +1320,11 @@ begin
     Result := FHasNestedLambdas;
 end;
 
+function TLambdaExpressionNode.GetIsPure: Boolean; // (* ADDED *)
+begin
+    Result := FIsPure;
+end;
+
 function TLambdaExpressionNode.GetKind: TAstNodeKind;
 begin
     Result := akLambdaExpression;
@@ -1444,7 +1461,8 @@ constructor TFunctionCallNode.Create(
     const AArguments: TArray<IAstNode>;
     const AStaticType: IStaticType;
     const AIsTailCall: Boolean;
-    const AStaticTarget: TDataValue.TFunc
+    const AStaticTarget: TDataValue.TFunc;
+    const AIsTargetPure: Boolean // (* ADDED *)
 );
 begin
     inherited Create(AStaticType);
@@ -1452,6 +1470,7 @@ begin
     FArguments := AArguments;
     FIsTailCall := AIsTailCall;
     FStaticTarget := AStaticTarget;
+    FIsTargetPure := AIsTargetPure;
 end;
 
 function TFunctionCallNode.Accept(const Visitor: IAstVisitor): TDataValue;
@@ -1489,6 +1508,11 @@ begin
     Result := FStaticTarget;
 end;
 
+function TFunctionCallNode.GetIsTargetPure: Boolean; // (* ADDED *)
+begin
+    Result := FIsTargetPure;
+end;
+
 { TMacroExpansionNode }
 
 constructor TMacroExpansionNode.Create(const ACallNode: IFunctionCallNode; const AExpandedBody: IAstNode);