algebraFinite : (c : Cont) -> IsFinite c => (0 a : Type) -> Num a => Algebra (Ext c) aAny finite container (i.e. whose each set of positions is finite) can be
given an algebra instance simply by summing up all the concrete values
take : (s : Fin (S n)) -> Vect' n a -> Vect' (finToNat s) a(++) : Vect' n a -> Vect' m a -> Vect' (n + m) a