functor (D : sig type left type right type diff type state end) ->
  sig
    type diff = (D.left, D.right, D.diff) Diffing_with_keys.mismatch
    type left = D.left Diffing_with_keys.with_pos
    type right = D.right Diffing_with_keys.with_pos
    type composite_change =
        (D.left, D.right, D.diff) Diffing_with_keys.change
    type patch = Diffing_with_keys.Define.composite_change list
    type change =
        (Diffing_with_keys.Define.left, Diffing_with_keys.Define.right, 
         unit, Diffing_with_keys.Define.diff)
        Diffing.change
    module type Parameters =
      sig
        val weight : Diffing_with_keys.Define.change -> int
        val test :
          D.state ->
          Diffing_with_keys.Define.left ->
          Diffing_with_keys.Define.right ->
          (unit, Diffing_with_keys.Define.diff) Stdlib.result
        val update : Diffing_with_keys.Define.change -> D.state -> D.state
        val key_left : D.left -> string
        val key_right : D.right -> string
      end
    module Simple :
      Parameters ->
        sig
          val diff :
            D.state ->
            D.left list -> D.right list -> Diffing_with_keys.Define.patch
        end
  end