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include module type of struct include Result end
include module type of struct include Result end

Results

type ('a, 'e) t = ('a, 'e) result =
  1. | Ok of 'a
  2. | Error of 'e

The type for result values. Either a value Ok v or an error Error e.

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

ok v is Ok v.

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

value r ~default is v if r is Ok v and default otherwise.

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

get_ok r is v if r is Ok v and raise otherwise.

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

get_error r is e if r is Error e and raise otherwise.

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

join rr is r if rr is Ok r and rr if rr is Error _.

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

fold ~ok ~error r is ok v if r is Ok v and error e if r is Error e.

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

iter f r is f v if r is Ok v and () otherwise.

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

iter_error f r is f e if r is Error e and () otherwise.

Predicates and comparisons

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

equal ~ok ~error r0 r1 tests equality of r0 and r1 using ok and error to respectively compare values wrapped by Ok _ and Error _.

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

compare ~ok ~error r0 r1 totally orders r0 and r1 using ok and error to respectively compare values wrapped by Ok _ and Error _. Ok _ values are smaller than Error _ values.

Converting

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

to_option r is r as an option, mapping Ok v to Some v and Error _ to None.

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

to_list r is [v] if r is Ok v and [] otherwise.

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

to_seq r is r as a sequence. Ok v is the singleton sequence containing v and Error _ is the empty sequence.

type ('a, 'b) result = ('a, 'b) Result.t =
  1. | Ok of 'a
  2. | Error of 'b
val return : 'a -> ('b, 'c) Result.result
val error : 'a -> ('b, 'c) Result.result
val bind : ('a, 'b) Result.result -> f:('c -> ('d, 'e) Result.result) -> ('d, 'e) Result.result
val map : ('a, 'b) Result.result -> f:('c -> 'd) -> ('e, 'b) Result.result
val ok_exn : ('a, 'b) Result.result -> 'c
val ok_internal : ('a, 'b) Result.result -> pp:(Format.formatter -> 'c -> unit) -> 'd
val of_option : 'a option -> error:('a option -> ('b, 'c) Result.result) -> ('b, 'c) Result.result
val try_with : (unit -> 'a) -> ('b, exn) Result.result
val map_error : f:('a -> 'b) -> ('c, 'd) result -> ('e, 'f) Result.result
val of_bool : bool -> error:'a -> (unit, 'b) Result.result
val unpack_error_exn : ('a, 'b) result -> 'c
val is_ok : ('a, 'b) result -> bool
val is_error : ('a, 'b) result -> bool
module O : sig ... end