package spin
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doc/spin.std/Spin_std/Result/index.html
Module Spin_std.Result
include module type of struct include Base.Result end
'ok
is the return type, and 'err
is often an error message string.
type nat = Zero | Succ of nat
let pred = function
| Succ n -> Ok n
| Zero -> Error "Zero does not have a predecessor"
The return type of pred
could be nat option
, but (nat, string) Result.t
gives more control over the error message.
include Sexplib0.Sexpable.S2 with type ('ok, 'err) t := ('ok, 'err) t
val t_of_sexp :
(Sexplib0__.Sexp.t -> 'a) ->
(Sexplib0__.Sexp.t -> 'b) ->
Sexplib0__.Sexp.t ->
('a, 'b) t
val sexp_of_t :
('a -> Sexplib0__.Sexp.t) ->
('b -> Sexplib0__.Sexp.t) ->
('a, 'b) t ->
Sexplib0__.Sexp.t
val t_sexp_grammar :
'ok Sexplib0.Sexp_grammar.t ->
'err Sexplib0.Sexp_grammar.t ->
('ok, 'err) t Sexplib0.Sexp_grammar.t
val hash_fold_t :
(Base.Hash.state -> 'a -> Base.Hash.state) ->
(Base.Hash.state -> 'b -> Base.Hash.state) ->
Base.Hash.state ->
('a, 'b) t ->
Base.Hash.state
include Base.Monad.S2 with type ('a, 'err) t := ('a, 'err) t
module Monad_infix = Base.Result.Monad_infix
val return : 'a -> ('a, _) t
module Error = Base.Result.Error
val invariant : ('a -> unit) -> ('b -> unit) -> ('a, 'b) t -> unit
val fail : 'err -> (_, 'err) t
e.g., failf "Couldn't find bloogle %s" (Bloogle.to_string b)
.
val is_ok : (_, _) t -> bool
val is_error : (_, _) t -> bool
val ok : ('ok, _) t -> 'ok option
val ok_exn : ('ok, exn) t -> 'ok
val ok_or_failwith : ('ok, string) t -> 'ok
val error : (_, 'err) t -> 'err option
val of_option : 'ok option -> error:'err -> ('ok, 'err) t
val iter : ('ok, _) t -> f:('ok -> unit) -> unit
val iter_error : (_, 'err) t -> f:('err -> unit) -> unit
val combine :
('ok1, 'err) t ->
('ok2, 'err) t ->
ok:('ok1 -> 'ok2 -> 'ok3) ->
err:('err -> 'err -> 'err) ->
('ok3, 'err) t
Returns Ok
if both are Ok
and Error
otherwise.
combine_errors ts
returns Ok
if every element in ts
is Ok
, else it returns Error
with all the errors in ts
.
This is similar to all
from Monad.S2
, with the difference that all
only returns the first error.
combine_errors_unit
returns Ok
if every element in ts
is Ok ()
, else it returns Error
with all the errors in ts
, like combine_errors
.
val to_either : ('ok, 'err) t -> ('ok, 'err) Base__.Either0.t
to_either
is useful with List.partition_map
. For example:
let ints, exns =
List.partition_map ["1"; "two"; "three"; "4"] ~f:(fun string ->
Result.to_either (Result.try_with (fun () -> Int.of_string string)))
val of_either : ('ok, 'err) Base__.Either0.t -> ('ok, 'err) t
val ok_fst : ('ok, 'err) t -> ('ok, 'err) Base__.Either0.t
val ok_if_true : bool -> error:'err -> (unit, 'err) t
ok_if_true
returns Ok ()
if bool
is true, and Error error
if it is false.
val try_with : (unit -> 'a) -> ('a, exn) t
module Export = Base.Result.Export
module Let_syntax : sig ... end