loop.fs

  let events = ResizeArray()
  let rec stateMachine (smodel: StateModel) (rmodel: RenderModel option) lastDelta: Async<unit> = async {
   let! delta = awaitAnimationFrame()
   let diff = delta - lastDelta
   let newState =
      (smodel, events)
      ||> Seq.fold (fun smodel ev ->
        match ev with
        | DonePreparing -> Run
        | _ -> ev
      )

   events.Clear()
   let newRender = render newState rmodel events.Add app scale renderer diff
   return! stateMachine newState (Some newRender) delta
  }
  let state = Init
  stateMachine state None