Technically, it can act on integers: Prelude> let zero s z = z Prelude> :t zero zero :: t -> t1 -> t1 Prelude> t and t1 can be integers. Real

Technically, it can act on integers: Prelude> let zero s z = z Prelude> :t zero zero :: t -> t1 -> t1 Prelude> t and t1 can be integers. Really the point of my comment is that the article could be written much better (assuming I'm the intended demographic).