@hackage empty-monad0.1.0.0

Like arithmetics is incomplete without zero, set theory is impossible without a notion of an empty set, algorithm theory must take into account totally undefined functions -- so the domain of data types needs its absolute zero. Void type from the void package https://hackage.haskell.org/package/void provides a zero element for the kind * of unparametrized types. This package does the same for the kind *->* of types with one parameter.