anchor.diff:              )
           )
   
  +
   type Cont<'s, 'a> = { run : State<'s, Res<'s, 'a>> }
   
   and Res<'s, 'a> =
  
positive.code:         let d = delay r
          r := f(r)
          d
  
  type Future<'a> =
      | Later of (('a -> unit) -> IDisposable)
  
negative.code:                 | Not cancel -> Cont.repeatUntil cancel body
  
          member x.Delay(f : unit -> Cont<'s, 'a>) =
              f()
  //            { run =
  //                state {
  //                    return! f().run
  //                }
  //            }
  
  
          member x.Combine(l : Cont<'s, unit>, r : Cont<'s, 'a>) =
  