Definition reptype_gen {cs: compspecs} : type -> (sigT (fun x => x)) :=
type_func (fun _ => (sigT (fun x => x)))
(fun t =>
if (type_is_by_value t)
then existT (fun x => x) val Vundef
else existT (fun x => x) unit tt)
(fun t n a TV => existT (fun x => x) (list (projT1 TV)) (list_repeat (Z.to_nat n) (projT2 TV)))
(fun id a TVs => existT (fun x => x) (compact_prod_sigT_type (decay TVs)) (compact_prod_sigT_value (decay TVs)))
(fun id a TVs => existT (fun x => x) (compact_sum_sigT_type (decay TVs)) (compact_sum_sigT_value (decay TVs))).
Definition reptype {cs: compspecs} t: Type := match reptype_gen t with existT t _ => t end.
Definition default_val {cs: compspecs} t: reptype t :=
match reptype_gen t as tv
return match tv with existT t _ => t end
with existT t v => v end.
Instance Inhabitant_reptype {cs: compspecs} (t: type) : Inhabitant (reptype t) := default_val t.
Section CENV.
Context {cs: compspecs}.

Lemma reptype_gen_eq: forall t,
reptype_gen t =
match t with
| Tarray t0 n _ => existT (fun x => x) (list (projT1 (reptype_gen t0))) (list_repeat (Z.to_nat n) (projT2 (reptype_gen t0)))
| Tstruct id _ => existT (fun x => x)
(compact_prod_sigT_type (map reptype_gen (map (fun it => field_type (fst it) (co_members (get_co id))) (co_members (get_co id)))))
(compact_prod_sigT_value (map reptype_gen (map (fun it => field_type (fst it) (co_members (get_co id))) (co_members (get_co id)))))
| Tunion id _ => existT (fun x => x)
(compact_sum_sigT_type (map reptype_gen (map (fun it => field_type (fst it) (co_members (get_co id))) (co_members (get_co id)))))
(compact_sum_sigT_value (map reptype_gen (map (fun it => field_type (fst it) (co_members (get_co id))) (co_members (get_co id)))))
| _ => if (type_is_by_value t)
then existT (fun x => x) val Vundef
else existT (fun x => x) unit tt
end.