Fixpoint compact_prod (T: list Type): Type :=
  match T with
  | nil => unit
  | t :: nil => t
  | t :: T0 => (t * compact_prod T0)%type
  end.Fixpoint compact_sum (T: list Type): Type :=
  match T with
  | nil => unit
  | t :: nil => t
  | t :: T0 => (t + compact_sum T0)%type
  end.Definition compact_prod_gen {A} {F} (gen: forall a: A, F a) (l: list A): compact_prod (map F l).Definition compact_sum_gen {A} {F} (filter: A -> bool) (gen: forall a: A, F a) (l: list A): compact_sum (map F l).Definition upd_compact_prod {A} {F} (l: list A) (v: compact_prod (map F l)) (a: A) (v0: F a) (H: forall a b: A, {a = b} + {a <> b}) : compact_prod (map F l).

Lemma compact_prod_eq: forall {A} {F1: A -> Type} {F2: A -> Type} (l: list A), (forall a, In a l -> @eq Type (F1 a) (F2 a)) -> @eq Type (compact_prod (map F1 l)) (compact_prod (map F2 l)).