Have not done much Generics stuff, but the trivial stuff.   I think this must be class of some sort, right? To get the/return T Something like :  (This could be actual helper also, maybe??)   TGenericListHelper<T> = class(TObject) public   function Diffference(const AList1, AList2: TLIst<T>): TList<T>; end;   Something like that. And then add rest.  I'll try to implement that on my own but if someone has good code/ideas for that, let me know.