(* This assumes that T has both finType and subCountType structures. *)
Notation "[ 'subFinType' 'of' T ]" := (@pack_subFinType _ _ T _ _ _ id _ _ id)
(at level 0, format "[ 'subFinType'  'of'  T ]") : form_scope.
Section FinTypeForSub.
Variables (T : finType) (P : pred T) (sT : subCountType P).
Definition sub_enum : seq sT := pmap insub (enumF T).

(* Specifications: *)
Lemma mem_sub_enum u : u \in sub_enum.
Definition SubFinMixin := UniqFinMixin sub_enum_uniq mem_sub_enum.