extended simple types with polymorphism -- the implementation still needs some work though
(* Classical Higher-order Logic -- batteries included *)
use_thys ["Library", "List_Cset", "List_Prefix", "List_lexord", "Sublist_Order",
"Product_Lattice",
"Code_Char_chr", "Code_Char_ord", "Code_Integer", "Efficient_Nat", "Executable_Set"(*, "Code_Prolog"*)];