renamed kill_all to kill, in conformance with atp_kill command;
simplified/unified treatment of preferences;
check_thread_manager: CRITICAL due to global ref;
goal addressing via Thm.cprem_of;
reduced NJ basis library stuff to bare minimum;
structure Nat =
struct
datatype nat = Suc of nat | Zero_nat;
end; (*struct Nat*)
structure Codegen =
struct
type 'a null = {null : 'a};
fun null (A_:'a null) = #null A_;
fun head A_ (x :: xs) = x
| head A_ [] = null A_;
val null_option : 'a option = NONE;
fun null_optiona () = {null = null_option} : ('a option) null;
val dummy : Nat.nat option =
head (null_optiona ()) [SOME (Nat.Suc Nat.Zero_nat), NONE];
end; (*struct Codegen*)