```idris
data Vect : Nat -> Type -> Type where
     Nil : Vect Z a
     (::) : a -> Vect k a -> Vect (S k) a
```

<!-- idris
%name Vect xs, ys, zs
-->

```idris
dupAll : Vect n a -> Vect n (a, a)
dupAll xs = zipHere xs xs
  where
    zipHere : forall n . Vect n a -> Vect n b -> Vect n (a, b)
```


<!-- idris

data Foobar = MkFoo

-->


```idris
showFooBar : Foobar -> String
showFooBar MkFoo = "MkFoo"
```