fact: Definition append : forall {A : Type} {n1 n2 : nat} (v1 : t A n1) (v2 : t A n2), t A (n1 + n2) := fun A n1 n2 v1 v2 => (fix F n (v : t A n) {struct v} : t A (n + n2) := match v with | nil => v2 | @cons _ n a v => cons a (F n v) end) n1 v1.
imports: Coq(ssreflect) HoTT(HoTT) HoTT_additions Hierarchy Param_nat