octez-libs 20.1 (latest) · OCaml Package

type ('a, 'e) t = ('a, 'e) result =

| Ok of 'a
| Error of 'e

val ok : 'a -> ('a, 'e) result

val ok_s : 'a -> ('a, 'e) result Lwt.t

val error : 'e -> ('a, 'e) result

val error_s : 'e -> ('a, 'e) result Lwt.t

val value : ('a, 'e) result -> default:'a -> 'a

val value_f : ('a, 'e) result -> default:(unit -> 'a) -> 'a

val bind : ('a, 'e) result -> ('a -> ('b, 'e) result) -> ('b, 'e) result

val bind_error : ('a, 'e) result -> ('e -> ('a, 'f) result) -> ('a, 'f) result

val map : ('a -> 'b) -> ('a, 'e) result -> ('b, 'e) result

val map_error : ('e -> 'f) -> ('a, 'e) result -> ('a, 'f) result

val bind_s : 
  ('a, 'e) result ->
  ('a -> ('b, 'e) result Lwt.t) ->
  ('b, 'e) result Lwt.t

val bind_error_s : 
  ('a, 'e) result ->
  ('e -> ('a, 'f) result Lwt.t) ->
  ('a, 'f) result Lwt.t

val join : (('a, 'e) result, 'e) result -> ('a, 'e) result

val map_e : ('a -> ('b, 'e) result) -> ('a, 'e) result -> ('b, 'e) result

val map_s : ('a -> 'b Lwt.t) -> ('a, 'e) result -> ('b, 'e) result Lwt.t

val map_es : 
  ('a -> ('b, 'e) result Lwt.t) ->
  ('a, 'e) result ->
  ('b, 'e) result Lwt.t

val map_error_e : ('e -> ('a, 'f) result) -> ('a, 'e) result -> ('a, 'f) result

val map_error_s : ('e -> 'f Lwt.t) -> ('a, 'e) result -> ('a, 'f) result Lwt.t

val map_error_es : 
  ('e -> ('a, 'f) result Lwt.t) ->
  ('a, 'e) result ->
  ('a, 'f) result Lwt.t

val fold : ok:('a -> 'c) -> error:('e -> 'c) -> ('a, 'e) result -> 'c

val iter : ('a -> unit) -> ('a, 'e) result -> unit

val iter_s : ('a -> unit Lwt.t) -> ('a, 'e) result -> unit Lwt.t

val iter_error : ('e -> unit) -> ('a, 'e) result -> unit

val iter_error_s : ('e -> unit Lwt.t) -> ('a, 'e) result -> unit Lwt.t

val is_ok : ('a, 'e) result -> bool

val is_error : ('a, 'e) result -> bool

val equal : 
  ok:('a -> 'a -> bool) ->
  error:('e -> 'e -> bool) ->
  ('a, 'e) result ->
  ('a, 'e) result ->
  bool

val compare : 
  ok:('a -> 'a -> int) ->
  error:('e -> 'e -> int) ->
  ('a, 'e) result ->
  ('a, 'e) result ->
  int

val to_option : ('a, 'e) result -> 'a option

val of_option : error:'e -> 'a option -> ('a, 'e) result

val to_list : ('a, 'e) result -> 'a list

val to_seq : ('a, 'e) result -> 'a Seq.t

val catch : ?catch_only:(exn -> bool) -> (unit -> 'a) -> ('a, exn) result

catch f is try Ok (f ()) with e -> Error e: it is Ok x if f () evaluates to x, and it is Error e if f () raises e.

See WithExceptions.S.Result.to_exn for a converse function.

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_f : 
  ?catch_only:(exn -> bool) ->
  (unit -> 'a) ->
  (exn -> 'e) ->
  ('a, 'e) result

catch_f f handler is equivalent to map_error (catch f) handler. In other words, it catches exceptions in f () and either returns the value in an Ok or passes the exception to handler for the Error.

No attempt is made to catch the exceptions raised by handler.

catch_only has the same use as with catch. The same restriction on catching non-deterministic runtime exceptions applies.

val catch_ef : 
  ?catch_only:(exn -> bool) ->
  (unit -> ('a, 'error) result) ->
  (exn -> 'error) ->
  ('a, 'error) result

catch_ef f handler is equivalent to join @@ map_error (catch f) handler. In other words, it catches exceptions in f () and either returns the value as is or passes the exception to handler for the Error. The handler must return an error of the same type as that carried by f ().

No attempt is made to catch the exceptions raised by handler.

catch_only has the same use as with catch. The same restriction on catching non-deterministic runtime exceptions applies.

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

catch_s is catch but for Lwt promises. Specifically, catch_s f returns a promise that resolves to Ok x if and when f () resolves to x, or to Error exc if and when f () is rejected with exc.

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.

We do not provide catch_s_f because (a) the suffix becomes confusing, (b) it's not used, (c) it is not obvious whether we want the handler to be within Lwt (gives more flexibility) or not (gives more guarantee about the timeliness of learning about rejections). We will revisit this if a needs for it arises.

package octez-libs