package incremental

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type 'a t
val sexp_of_t : ('a -> Ppx_sexp_conv_lib.Sexp.t) -> 'a t -> Ppx_sexp_conv_lib.Sexp.t
val create : ?use_current_scope:bool -> 'a -> 'a t

By default, a variable is created in, on the theory that its value depends on external stimuli (via Var.set), not on the current scope. However, in some situations it is useful to supply ~use_current_scope:true to create a variable that is invalidated when the current scope is invalidated, e.g. if one wants to use on_update (watch var) ~f:(function Invalidated -> ... | ...) to remove the external stimulus that was setting var.

It is allowed to do let t = create a during stabilization; for that stabilization, watch t will have value a.

val set : 'a t -> 'a -> unit

set t a sets the value of t to a. Outside of stabilization, subsequent calls to Var.value t will see a, but the set will not have any effect on incrementals until the next stabilization, at which point watch t will take on whatever value t was at the start of stabilization, causing incremental recomputation as usual.

During a stabilization, calling set will behave as if set was called after stabilization finished: the new value will not be seen (by value v or watch v) until after the stabilization finishes.

val watch : 'a t -> 'a incremental

watch t returns an incremental that tracks the value of t. For a given t, all calls to watch t return the same incremental.

val value : 'a t -> 'a

value t returns the value most recently set for t outside of stabilization.

val latest_value : 'a t -> 'a

latest_value t returns the value most recently set for t. It can differ from value t only during stabilization.


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