Module Lazy_deferred

module Lazy_deferred: sig .. end

A Lazy_deferred.t is a delayed computation that can produce a deferred. Nothing happens with a lazy deferred unless one forces it. Forcing a lazy deferred starts the computation, which will eventually cause the deferred to become determined. As usual with laziness, multiply forcing a lazy deferred is no different than forcing it a single time.

Exceptions (both synchronous and asynchronous) raised by a delayed computation are returned by force (wait, peek, etc.), or will be raised to the monitor in effect when force_exn (wait_exn, peek_exn, etc.) was called.

type 'a t

val create : (unit -> 'a Deferred.t) -> 'a t

create f creates a new lazy deferred that will call f when it is forced.

val force : 'a t -> ('a, exn) Core.Std.Result.t Deferred.t

force t forces evaluation of t and returns a deferred that becomes determined when the deferred computation becomes determined or raises.

val force_exn : 'a t -> 'a Deferred.t

val wait : 'a t -> ('a, exn) Core.Std.Result.t Deferred.t

wait t waits for t to be forced. If no one ever calls force t, wait will wait forever.

val wait_exn : 'a t -> 'a Deferred.t

include Monad

bind t f in the lazy-deferred monad creates a computation that, when forced, will force t, apply f to the result, and then force the result of that.

val bind' : 'a t -> ('a -> 'b Deferred.t) -> 'b t

bind' differs from bind in that the supplied function produces an 'a Deferred.t rather than an 'a t.

val follow : 'a t -> ('a -> 'b Deferred.t) -> 'b t

follow t f returns a new lazy deferred almost like bind' with the notable difference that its computation will start as soon as the deferred it is following becomes determined. Since the resulting deferred depends on the 'a value computed by t forcing the resulting of follow will force the compuation of t.

Read-only operations.

val peek : 'a t -> ('a, exn) Core.Std.Result.t option

peek t = Deferred.peek (wait t)

val peek_exn : 'a t -> 'a option

val is_determined : 'a t -> bool

val is_forced : 'a t -> bool