(* We recover the usual mathematical notation *)
Notation "'K'" := (K p).(* A vector is a list of length n *)

Fixpoint kn (n: nat): Set := 
  match n with O => unit | S n1 => (K * kn n1)%type end.(* Generate the constant k for the dimension n *)
Fixpoint genk (n: nat) (k: K) {struct n}: (kn n) :=
   match n return kn n with 0%nat => tt |  
                            (S n1) => (k, genk n1 k) end.Notation " [ k ] " := (genk _ k) (at level 10): kn_scope.(* Adding two vectors as list *)
Fixpoint add (n : nat) : kn n -> kn n -> kn n :=
  match n return (kn n -> kn n -> kn n) with
  | 0%nat => fun a b => tt
  | S n1 =>
      fun l1 l2 =>
      let (v1, l3) := l1 in
      let (v2, l4) := l2 in ((v1 + v2)%f, add n1 l3 l4)
  end.(* Multiplication by a scalar *)
Fixpoint scal (n : nat) (k: K) {struct n}: kn n -> kn n :=
  match n return (kn n -> kn n) with
  | 0%nat => fun a => tt
  | S n1 =>
      fun l1 =>
      let (v1,l2) := l1 in ((k * v1)%f , scal n1 k l2)
  end.Canonical Structure vn_eparams (n: nat) :=
  Build_eparams (kn n) K (genk n 0%f) (eq n) (add n) (scal n).Definition fn n : vparamsProp (vn_eparams n).Ltac Kfold n :=
     change (add n) with (addE (vn_eparams n));
     change (scal n) with (scalE (vn_eparams n));
     change (genk n 0%f) with (E0 (vn_eparams n)).

Lemma genk0_dec n (x: kn n) : x = 0 \/ x <> 0.