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

  let clamp = ./clamp.dhall nix

  let negate = ./negate.dhall nix

  let abs
      : Double → Double
      = λ(n : Double) → if isZero (clamp n) then clamp (negate n) else clamp n

  in  abs