Module Bare.Option

type 'a t = 'a option =
  1. | None
  2. | Some of 'a
val none : 'a option
val none_e : ('a option, 'trace) Stdlib.result
val none_s : 'a option Lwt.t
val none_es : ('a option, 'trace) Stdlib.result Lwt.t
val some : 'a -> 'a option
val some_unit : unit option
val some_unit_e : (unit option, 'error) Stdlib.result
val some_unit_s : unit option Lwt.t
val some_unit_es : (unit option, 'error) Stdlib.result Lwt.t
val some_nil : 'a list option
val some_nil_e : ('a list option, 'error) Stdlib.result
val some_nil_s : 'a list option Lwt.t
val some_nil_es : ('a list option, 'error) Stdlib.result Lwt.t
val some_true : bool option
val some_true_e : (bool option, 'error) Stdlib.result
val some_true_s : bool option Lwt.t
val some_true_es : (bool option, 'error) Stdlib.result Lwt.t
val some_false : bool option
val some_false_e : (bool option, 'error) Stdlib.result
val some_false_s : bool option Lwt.t
val some_false_es : (bool option, 'error) Stdlib.result Lwt.t
val some_e : 'a -> ('a option, 'trace) Stdlib.result
val some_s : 'a -> 'a option Lwt.t
val some_es : 'a -> ('a option, 'trace) Stdlib.result Lwt.t
val value : 'a option -> default:'a -> 'a
val value_e : 'a option -> error:'trace -> ('a, 'trace) Stdlib.result
val value_f : 'a option -> default:(unit -> 'a) -> 'a
val value_fe : 'a option -> error:(unit -> 'trace) -> ('a, 'trace) Stdlib.result
val bind : 'a option -> ('a -> 'b option) -> 'b option
val join : 'a option option -> 'a option
val either : 'a option -> 'a option -> 'a option

either picks the first Some _ value of its arguments if any. More formally, either (Some x) _ is Some x, either None (Some y) is Some y, and either None None is None.

val either_f : 'a option -> (unit -> 'a option) -> 'a option
val merge : ('a -> 'a -> 'a) -> 'a option -> 'a option -> 'a option
val merge_e : ('a -> 'a -> ('a, 'e) Stdlib.result) -> 'a option -> 'a option -> ('a option, 'e) Stdlib.result
val merge_s : ('a -> 'a -> 'a Lwt.t) -> 'a option -> 'a option -> 'a option Lwt.t
val merge_es : ('a -> 'a -> ('a, 'e) Stdlib.result Lwt.t) -> 'a option -> 'a option -> ('a option, 'e) Stdlib.result Lwt.t
val map : ('a -> 'b) -> 'a option -> 'b option
val map_s : ('a -> 'b Lwt.t) -> 'a option -> 'b option Lwt.t
val map_e : ('a -> ('b, 'trace) Stdlib.result) -> 'a option -> ('b option, 'trace) Stdlib.result
val map_es : ('a -> ('b, 'trace) Stdlib.result Lwt.t) -> 'a option -> ('b option, 'trace) Stdlib.result Lwt.t
val fold : none:'a -> some:('b -> 'a) -> 'b option -> 'a
val fold_s : none:'a -> some:('b -> 'a Lwt.t) -> 'b option -> 'a Lwt.t
val fold_f : none:(unit -> 'a) -> some:('b -> 'a) -> 'b option -> 'a
val filter : ('a -> bool) -> 'a option -> 'a option

filter p o is Some x iff o is Some x and p o is true.

In other words, filter is like List.filter if option is the type of lists of either zero or one elements. In fact, the following equality holds for all p and for all o: Option.filter p o = List.hd (List.filter p (Option.to_list o))

The other filter variants below are also equivalent to their List counterpart and a similar equality holds.

val filter_map : ('a -> 'b option) -> 'a option -> 'b option

filter_map is the Option counterpart to List's filter_map. Incidentally, filter_map f o is also bind o f.

val filter_s : ('a -> bool Lwt.t) -> 'a option -> 'a option Lwt.t

filter_s is filter where the predicate returns a promise.

val filter_map_s : ('a -> 'b option Lwt.t) -> 'a option -> 'b option Lwt.t

filter_map_s is filter_map where the function returns a promise.

val filter_e : ('a -> (bool, 'e) Stdlib.result) -> 'a option -> ('a option, 'e) Stdlib.result

filter_e is filter where the predicate returns a result.

val filter_map_e : ('a -> ('b option, 'e) Stdlib.result) -> 'a option -> ('b option, 'e) Stdlib.result

filter_map_e is filter_map where the function returns a result.

val filter_es : ('a -> (bool, 'e) Stdlib.result Lwt.t) -> 'a option -> ('a option, 'e) Stdlib.result Lwt.t

filter_es is filter where the predicate returns a promise of a result.

val filter_map_es : ('a -> ('b option, 'e) Stdlib.result Lwt.t) -> 'a option -> ('b option, 'e) Stdlib.result Lwt.t

filter_map_es is filter_map where the function returns a promise of a result.

val filter_ok : ('a, 'e) Stdlib.result option -> 'a option

filter_ok o is Some x iff o is Some (Ok x).

val filter_error : ('a, 'e) Stdlib.result option -> 'e option

filter_error o is Some x iff o is Some (Error x).

val filter_left : ('a, 'b) Stdlib.Either.t option -> 'a option

filter_left o is Some x iff o is Some (Either.Left x).

val filter_right : ('a, 'b) Stdlib.Either.t option -> 'b option

filter_right o is Some x iff o is Some (Either.Right x).

val iter : ('a -> unit) -> 'a option -> unit
val iter_s : ('a -> unit Lwt.t) -> 'a option -> unit Lwt.t
val iter_e : ('a -> (unit, 'trace) Stdlib.result) -> 'a option -> (unit, 'trace) Stdlib.result
val iter_es : ('a -> (unit, 'trace) Stdlib.result Lwt.t) -> 'a option -> (unit, 'trace) Stdlib.result Lwt.t
val is_none : 'a option -> bool
val is_some : 'a option -> bool
val equal : ('a -> 'a -> bool) -> 'a option -> 'a option -> bool
val compare : ('a -> 'a -> int) -> 'a option -> 'a option -> int
val to_result : none:'trace -> 'a option -> ('a, 'trace) Stdlib.result
val of_result : ('a, 'e) Stdlib.result -> 'a option
val to_list : 'a option -> 'a list
val to_seq : 'a option -> 'a Stdlib.Seq.t
val catch : ?catch_only:(exn -> bool) -> (unit -> 'a) -> 'a option

catch f is Some (f ()) if f does not raise an exception, it is None otherwise.

You should only use catch when you truly do not care about what exception may be raised during the evaluation of f (). If you need to inspect the raised exception, or if you need to pass it along, consider Result.catch instead.

If catch_only is set, then only exceptions e such that catch_only e is true are caught.

Whether catch_only is set or not, this function never catches non-deterministic runtime exceptions of OCaml such as Stack_overflow and Out_of_memory.

val catch_o : ?catch_only:(exn -> bool) -> (unit -> 'a option) -> 'a option

catch_o f is equivalent to join @@ catch f. In other words, it is f () if f doesn't raise any exception, and it is None otherwise.

catch_only has the same behaviour and limitations as with catch.

val catch_s : ?catch_only:(exn -> bool) -> (unit -> 'a Lwt.t) -> 'a option Lwt.t

catch_s f is a promise that resolves to Some x if and when f () resolves to x. Alternatively, it resolves to None if and when f () is rejected.

You should only use catch_s when you truly do not care about what exception may be raised during the evaluation of f (). If you need to inspect the raised exception, or if you need to pass it along, consider Result.catch_s instead.

If catch_only is set, then only exceptions e such that catch_only e is true are caught.

Whether catch_only is set or not, this function never catches non-deterministic runtime exceptions of OCaml such as Stack_overflow and Out_of_memory.

val catch_os : ?catch_only:(exn -> bool) -> (unit -> 'a option Lwt.t) -> 'a option Lwt.t

catch_os f is like catch_s f where f returns a promise that resolves to an option. catch_os f resolves to None if f () resolves to None or is rejected. It resolves to Some _ if f () does.

catch_only has the same behaviour and limitations as with catch.