Decidable.For
module D : Preface_specs.DECIDABLE
val decidable_1 : unit -> ('a -> Preface_core.Void.t, 'a D.t -> 'a D.t) Law.t
val decidable_2 : unit -> ('a -> Preface_core.Void.t, 'a D.t -> 'a D.t) Law.t