let Integer/negative = ./negative.dhall

let Integer/abs = ./abs.dhall

let fold
    : Integer →
      ∀(integer : Type) →
      ∀(succ : integer → integer) →
      ∀(negate : integer → integer) →
      ∀(zero : integer) →
        integer
    = λ(e : Integer) →
      λ(integer : Type) →
      λ(succ : integer → integer) →
      λ(negate : integer → integer) →
      λ(zero : integer) →
        let folded = Natural/fold (Integer/abs e) integer succ zero

        in  if Integer/negative e then negate folded else folded

in  fold