> foo : A -> A > since we know absolutely NOTHING about A, all we can really do is give it back to you, so foo turns out to be identity, or id. > another migh

> foo : A -> A > since we know absolutely NOTHING about A, all we can really do is give it back to you, so foo turns out to be identity, or id. > another might be bar: [A] -> Nat we still don't know anything about A, but we know a little about lists, so a good suggestion might be length. Certainly a good suggestion, but, unlike `foo`, not the only one—e.g., `bar xs = length xs + 1` or `bar xs = 2*(length xs)` also work.