Source file predicate.ml

type 'a t = 'a -> bool

module Contravariant = Preface_make.Contravariant.Via_contramap (struct
  type nonrec 'a t = 'a t

  let contramap f g = Preface_core.Fun.(g % f)
end)

module Divisible =
  Preface_make.Divisible.Over_contravariant
    (Contravariant)
    (struct
      type nonrec 'a t = 'a t

      let divide f pa pb x =
        let (a, b) = f x in
        pa a && pb b
      ;;

      let conquer _ = true
    end)

let negate p x = not (p x)

let tautology _ = true

let contradiction _ = false

let and_ l r x = l x && r x

let or_ l r x = l x || r x

module Infix = struct
  let ( && ) = and_

  let ( || ) = or_

  let ( ! ) = negate
end

include Infix