λ(nix : ../NixPrelude.dhall) →
  let Number = ./Type.dhall

  let nonPositive = ./nonPositive.dhall nix

  let nonNegative = ./nonNegative.dhall nix

  let isZero
      : Number → Bool
      = λ(v : Number) → nonPositive v && nonNegative v

  in  isZero