AST function purity analysis

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;