1      let DifferenceList = ./Type
 2  
 3  in    { fold =
 4              λ(a : Type)
 5            → λ(ts : DifferenceList a)
 6            → λ(b : Type)
 7            → λ(f : a → b → b)
 8            → λ(z : b)
 9            → (./../List/foldable).fold a (./toList a ts) b f z
10        }
11      : ./../Foldable/Type DifferenceList