Module Observer.Update

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

Changed (old_value, new_value)

| Invalidated
val compare : ('a -> 'a -> int) -> 'a t -> 'a t -> int
val sexp_of_t : ('a -> Ppx_sexp_conv_lib.Sexp.t) -> 'a t -> Ppx_sexp_conv_lib.Sexp.t