Module Core_kernel__.Bus

module Callback_arity : sig ... end

Callback_arity states the type of callbacks stored in a bus. Using Callback_arity is an implementation technique that allows callbacks to be defined as ordinary n-ary curried functions (e.g., a1 -> a2 -> a3 -> r), instead of forcing n-ary-variadic callbacks to use tuples (e.g., a1 * a2 * a3 -> r). This also avoids extra allocation.

type ('callback, 'phantom) t
val sexp_of_t : ('callback -> Ppx_sexp_conv_lib.Sexp.t) -> ('phantom -> Ppx_sexp_conv_lib.Sexp.t) -> ('callback'phantom) t -> Ppx_sexp_conv_lib.Sexp.t
type ('callback, 'phantom) bus = ('callback'phantom) t
module Read_write : sig ... end
module Read_only : sig ... end
module On_subscription_after_first_write : sig ... end
val read_only : ('callback_) t -> 'callback Read_only.t
val create : ?⁠name:Core_kernel.Info.t -> Core_kernel.Source_code_position.t -> 'callback Callback_arity.t -> on_subscription_after_first_write:On_subscription_after_first_write.t -> on_callback_raise:(Core_kernel.Error.t -> Core_kernel__.Import.unit) -> 'callback Read_write.t

In create [%here] ArityN ~on_subscription_after_first_write ~on_callback_raise, [%here] is stored in the resulting bus, and contained in %sexp_of: t, which can help with debugging.

If on_subscription_after_first_write is Raise, then subscribe_exn will raise if it is called after write has been called the first time. If on_subscription_after_first_write is Allow_and_send_last_value, then the bus will remember the last value written and will send it to new subscribers.

If a callback raises, on_callback_raise is called with an error containing the exception.

If on_callback_raise raises, then the exception is raised to write and the bus is closed.

val callback_arity : ('callback_) t -> 'callback Callback_arity.t
val num_subscribers : (__) t ->
val is_closed : (__) t -> Core_kernel__.Import.bool
val close : 'callback Read_write.t -> Core_kernel__.Import.unit

close disallows future writes -- once close t is called, all further calls to write t will raise. close is idempotent. If close is called from within a callback, the current message will still be sent to all subscribed callbacks that have not yet seen it before the close takes effect.

val write : ('a -> Core_kernel__.Import.unit) Read_write.t -> 'a -> Core_kernel__.Import.unit
val write2 : ('a -> 'b -> Core_kernel__.Import.unit) Read_write.t -> 'a -> 'b -> Core_kernel__.Import.unit
val write3 : ('a -> 'b -> 'c -> Core_kernel__.Import.unit) Read_write.t -> 'a -> 'b -> 'c -> Core_kernel__.Import.unit
val write4 : ('a -> 'b -> 'c -> 'd -> Core_kernel__.Import.unit) Read_write.t -> 'a -> 'b -> 'c -> 'd -> Core_kernel__.Import.unit
module Subscriber : sig ... end
val subscribe_exn : ?⁠extract_exn:Core_kernel__.Import.bool -> ?⁠on_callback_raise:(Core_kernel.Error.t -> Core_kernel__.Import.unit) -> ?⁠on_close:(Core_kernel__.Import.unit -> Core_kernel__.Import.unit) -> ('callback[> ]) t -> Core_kernel.Source_code_position.t -> f:'callback -> 'callback Subscriber.t

subscribe_exn t [%here] ~f adds the callback f to the set of t's subscribers, and returns a Subscriber.t that can later be used to unsubscribe. [%here] is stored in the Subscriber.t, and contained in %sexp_of: Subscriber.t, which can help with debugging. If subscribe_exn t is called by a callback in t, i.e., during write t, the subscription takes effect for the next write, but does not affect the current write. subscribe_exn takes amortized constant time.

If on_callback_raise is supplied, then it will be called by write whenever f raises; only if that subsequently raises will t's on_callback_raise be called. If on_callback_raise is not supplied, then t's on_callback_raise will be called whenever f raises.

If on_callback_raise is supplied and extract_exn is set to true, then the error passed to the on_callback_raise method will contain only the exception raised by f without any additional information about the bus subscription or backtrace.

on_close is called if you are still subscribed when Bus.close is called.

val iter_exn : ('callback[> ]) t -> Core_kernel.Source_code_position.t -> f:'callback -> Core_kernel__.Import.unit

iter_exn t [%here] ~f is ignore (subscribe_exn t [%here] ~callback:f). This captures the common usage in which one never wants to unsubscribe from a bus.

module Fold_arity : sig ... end
val fold_exn : ('callback[> ]) t -> Core_kernel.Source_code_position.t -> ('callback'f's) Fold_arity.t -> init:'s -> f:'f -> Core_kernel__.Import.unit

fold_exn t [%here] arity ~init ~f folds over the bus events, threading a state value to every call. It is otherwise similar to iter_exn.

val unsubscribe : ('callback[> ]) t -> 'callback Subscriber.t -> Core_kernel__.Import.unit

unsubscribe t subscriber removes the callback corresponding to subscriber from t. unsubscribe never raises and is idempotent. As with subscribe_exn, unsubscribe t during write t takes effect after the current write finishes. Also like subscribe_exn, unsubscribe takes amortized constant time.