Module Async_kernel.Ivar

A write-once cell that can be empty or full (i.e. hold a single value).

One can read an ivar to obtain a deferred that becomes determined when the ivar is filled. An ivar is similar to an 'a option ref, except it is an error to fill an already full ivar.

type 'a t = 'a Async_kernel__.Types.Ivar.t
include sig ... end
val sexp_of_t : ('a ‑> Sexplib.Sexp.t) ‑> 'a t ‑> Sexplib.Sexp.t
val bin_read_t : 'a Bin_prot.Read.reader ‑> 'a t Bin_prot.Read.reader
val __bin_read_t__ : 'a Bin_prot.Read.reader ‑> (int ‑> 'a t) Bin_prot.Read.reader
val bin_size_t : 'a Bin_prot.Size.sizer ‑> 'a t Bin_prot.Size.sizer
val bin_write_t : 'a Bin_prot.Write.writer ‑> 'a t Bin_prot.Write.writer
val bin_shape_t : Bin_prot.Shape.t ‑> Bin_prot.Shape.t
type 'a ivar = 'a t
include Core_kernel.Invariant.S1 with type a t := a t
type 'a t
val equal : 'a t ‑> 'a t ‑> bool

equal t t' is physical equality of t and t'.

val create : unit ‑> 'a t

create () returns an empty ivar, create_full, a full one.

val create_full : 'a ‑> 'a t
val fill : 'a t ‑> 'a ‑> unit

fill t v fills t with value v if t was empty. If t was full, fill raises an exception.

It is guaranteed that immediately after calling fill t, is_some (Deferred.peek (read t)).

val fill_if_empty : 'a t ‑> 'a ‑> unit

fill_if_empty t v fills t with v if t is currently empty. If t is full, then fill_if_empty does nothing.

val is_empty : 'a t ‑> bool

is_empty t returns true if t is empty

val is_full : 'a t ‑> bool

is_full t returns true if t is full

val read : 'a t ‑> 'a Async_kernel__.Deferred0.t

read t returns a deferred that becomes enabled with value v after the ivar is filled with v.

val peek : 'a t ‑> 'a option

peek t returns Some v iff t is full with value v.

val value_exn : 'a t ‑> 'a

value_exn t returns v if t is full with value v, and raises otherwise.

val has_handlers : _ t ‑> bool

has_handlers t returns true if t has handlers waiting on read t.