Module Core_kernel.Set_once

A 'a Set_once.t is like an 'a option ref that can only be set once. A Set_once.t starts out as None, the first set transitions it to Some, and subsequent sets fail.

type 'a t

include sig ... end

val sexp_of_t : ('a ‑> Sexplib.Sexp.t) ‑> 'a t ‑> Sexplib.Sexp.t

Passes when unset.

include Core_kernel__.Import.Invariant.S1 with type a t := a t

type 'a t

val invariant : 'a Base__.Invariant_intf.inv ‑> 'a t Base__.Invariant_intf.inv

val create : Core_kernel__.Import.unit ‑> _ t

val set : 'a t ‑> Source_code_position.t ‑> 'a ‑> Core_kernel__.Import.unit Or_error.t

val set_exn : 'a t ‑> Source_code_position.t ‑> 'a ‑> Core_kernel__.Import.unit

val get : 'a t ‑> 'a Core_kernel__.Import.option

val get_exn : 'a t ‑> Source_code_position.t ‑> 'a

val is_none : _ t ‑> Core_kernel__.Import.bool

val is_some : _ t ‑> Core_kernel__.Import.bool

val iter : 'a t ‑> f:('a ‑> Core_kernel__.Import.unit) ‑> Core_kernel__.Import.unit

module Optional_syntax : Optional_syntax.S1 with type a t := a t with type a value := a Core_kernel__.Import.identity

module Unstable : sig ... end

module Stable : sig ... end