If so, you could write a SmallCheck Series instance as follows.

instance Serial (Vec Zero a) where series = cons0 nil

instance (Serial a, Serial (Vec n a)) => Serial (Vec (Succ n) a) where series = cons2 (|>)

If we have the property

prop_vector :: Vec (Succ (Succ Zero)) Bool -> Bool prop_vector (V xs) = xs == xs

we can check it, and only 2 element vectors will be tested

I have some code up now at http://hpaste.org/8420 It looks pretty much like what you've written above and is what I am doing for the moment, but for various size vectors from zero to four.

Now, it seems what you really want to do is define polymorphic properties like

prop_poly :: Vec n Bool -> Vec n Bool -> Bool

and have SmallCheck check all equal-sized vectors. If so, good question! :-)

Yep, this would be exactly what I'm after. Thanks for a better write up and background on what I'm after than I gave :) I'm thinking the property might be written as prop_poly:: size -> Vec size Bool -> Vec size Bool -> Bool, so that the size is generated randomly and the types take care of ensuring the vectors generated are of the same size. Levi