Module Incremental_kernel.Incremental.Make.Observer.Update

on_update_exn t ~f calls f after the current stabilization and after each subsequent stabilization in which t changes, until disallow_future_use t is called. f will be called at most once per stabilization. Here is a state diagram for the allowable sequences of Update.t's that can be supplied to a particular f:

           /-----------------------------------------------------\
           |                 /                                   |
           |                 |                                   v
          Start ------> Initialized ------> Changed ------> Invalidated
                                              ^  |
                                              \--/

on_update_exn raises if disallow_future_use t was previously called.

type 'a t =
| Initialized of 'a
| Changed of 'a * 'a

(** Changed (old_value, new_value) *)

| Invalidated
include sig ... end
val compare : ('a ‑> 'a ‑> int) ‑> 'a t ‑> 'a t ‑> int
val sexp_of_t : ('a ‑> Base.Sexp.t) ‑> 'a t ‑> Base.Sexp.t