Module Bonsai_extra_mirror

module Bonsai := Bonsai.Cont
module Effect := Bonsai.Effect
val mirror : ?sexp_of_model:('m -> Core.Sexp.t) -> equal:('m -> 'm -> bool) -> store_set:('m -> unit Effect.t) Bonsai.t -> store_value:'m Bonsai.t -> interactive_set:('m -> unit Effect.t) Bonsai.t -> interactive_value:'m Bonsai.t -> Bonsai.graph @ local -> unit

mirror is used to reflect state back and forth between locations. Frequently this will be used to back up a components model in a more persistent form of storage, such as the URL, or local-storage.

The gist of this combinator is that if you have two states that you'd like to be synchronized, you can feed the "current value" and "set value" functions for both states into mirror and they'll automatically be kept up to date. Either of these can be backed by any kind of structure, but there are some important differences in their symmetry.

When the component is first loaded, store has priority, so if the values are different, store wins, and interactive has its value "set". From that point on, if either incoming value changes, the opposite setter is called. In the case that both store and interactive change at the same time, the tie is broken in favor of interactive, and store_set is called.

val mirror' : ?sexp_of_model:('m -> Core.Sexp.t) -> equal:('m -> 'm -> bool) -> store_set:('m -> unit Effect.t) Bonsai.t -> store_value:'m option Bonsai.t -> interactive_set:('m -> unit Effect.t) Bonsai.t -> interactive_value:'m option Bonsai.t -> Bonsai.graph @ local -> unit

mirror' is like mirror, but the incoming values have the type 'a option Bonsai.t instead of just 'a Bonsai.t. When a value is changed and its new value is None, we don't propagate it to the other setter.