Module `Stdlib.Result`

Results

type ('a, 'e) t = ('a, 'e) Stdlib.result = | Ok of 'a | Error of 'e: The type for result values. Either a value Ok v or an error Error e.

val ok : 'a -> ('a, 'e) Stdlib.result: ok v is Ok v.

val error : 'e -> ('a, 'e) Stdlib.result: error e is Error e.

val value : ('a, 'e) Stdlib.result -> default:'a -> 'a: value r ~default is v if r is Ok v and default otherwise.

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

get_ok r is v if r is Ok v and

raises Invalid_argument: otherwise.

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

get_error r is e if r is Error e and

raises Invalid_argument: otherwise.

val bind : ('a, 'e) Stdlib.result -> ('a -> ('b, 'e) Stdlib.result) -> ('b, 'e) Stdlib.result: bind r f is f v if r is Ok v and r if r is Error _.

val join : (('a, 'e) Stdlib.result, 'e) Stdlib.result -> ('a, 'e) Stdlib.result: join rr is r if rr is Ok r and rr if rr is Error _.

val map : ('a -> 'b) -> ('a, 'e) Stdlib.result -> ('b, 'e) Stdlib.result: map f r is Ok (f v) if r is Ok v and r if r is Error _.

val map_error : ('e -> 'f) -> ('a, 'e) Stdlib.result -> ('a, 'f) Stdlib.result: map_error f r is Error (f e) if r is Error e and r if r is Ok _.

val fold : ok:('a -> 'c) -> error:('e -> 'c) -> ('a, 'e) Stdlib.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) Stdlib.result -> unit: iter f r is f v if r is Ok v and () otherwise.

val iter_error : ('e -> unit) -> ('a, 'e) Stdlib.result -> unit: iter_error f r is f e if r is Error e and () otherwise.

Predicates and comparisons

val is_ok : ('a, 'e) Stdlib.result -> bool: is_ok r is true iff r is Ok _.

val is_error : ('a, 'e) Stdlib.result -> bool: is_error r is true iff r is Error _.

val equal : ok:('a -> 'a -> bool) -> error:('e -> 'e -> bool) -> ('a, 'e) Stdlib.result -> ('a, 'e) Stdlib.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) Stdlib.result -> ('a, 'e) Stdlib.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) Stdlib.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) Stdlib.result -> 'a list: to_list r is [v] if r is Ok v and [] otherwise.

val to_seq : ('a, 'e) Stdlib.result -> 'a Stdlib.Seq.t: to_seq r is r as a sequence. Ok v is the singleton sequence containing v and Error _ is the empty sequence.