Travesty_base_exts.Option
Option extensions.
This module contains various extensions for Base
's Option
module, including adding monadic traversal.
Options are traversable.
include Travesty.Traversable_types.S1 with type 'a t := 'a t
module On
(M : Base.Applicative.S) :
Travesty.Traversable_types.S1_on_applicative
with type 'a t := 'a t
and module M := M
On
implements applicative folding and mapping operators for a given applicative M
, including arity-1 specific operators.
module On_monad
(M : Base.Monad.S) :
Travesty.Traversable_types.S1_on_monad
with type 'a t := 'a t
and module M := M
On_monad
implements applicative folding and mapping operators for a given monad M
, including arity-1 specific operators.
module With_errors :
Travesty.Traversable_types.S1_on_monad
with type 'a t := 'a t
and module M := Base.Or_error
With_errors
is shorthand for On_monad (Or_error)
.
include Travesty.Traversable_types.Generic
with type ('a, 'phantom) t := 'a t
and type 'a elt := 'a
and module On := On
and module On_monad := On_monad
and module With_errors := With_errors
include Travesty.Generic_types.Generic
with type ('a, 'phantom) t := 'a t
with type 'a elt := 'a
We can do generic container operations.
include Base.Container.Generic
with type ('a, 'phantom) t := 'a t
and type 'a elt := 'a
We can do non-applicative mapping operations.
include Travesty.Mappable_types.Generic
with type ('a, 'phantom) t := 'a t
and type 'a elt := 'a
Generic
refers to the container type as 'a t
, and the element type as 'a elt
; substitute t
/elt
(arity-0) or 'a t
/'a
(arity-1) accordingly below.
include Travesty.Generic_types.Generic
with type ('a, 'phantom) t := 'a t
with type 'a elt := 'a
fold_map c ~f ~init
folds f
over every t
in c
, threading through an accumulator with initial value init
.
include Travesty.Mappable_types.S1_container with type 'a t := 'a t
include Travesty.Mappable_types.S1 with type 'a t := 'a t
include Travesty.Mappable_types.Generic
with type ('a, 'phantom) t := 'a t
and type 'a elt := 'a
Generic
refers to the container type as 'a t
, and the element type as 'a elt
; substitute t
/elt
(arity-0) or 'a t
/'a
(arity-1) accordingly below.
include Travesty.Generic_types.Generic
with type ('a, 'phantom) t := 'a t
with type 'a elt := 'a
include Base.Container.S1 with type 'a t := 'a t
val mem : 'a t -> 'a -> equal:('a -> 'a -> bool) -> bool
val length : 'a t -> int
val is_empty : 'a t -> bool
val iter : 'a t -> f:('a -> unit) -> unit
val fold : 'a t -> init:'acc -> f:('acc -> 'a -> 'acc) -> 'acc
val fold_result :
'a t ->
init:'acc ->
f:('acc -> 'a -> ('acc, 'e) Base__.Result.t) ->
('acc, 'e) Base__.Result.t
val fold_until :
'a t ->
init:'acc ->
f:('acc -> 'a -> ('acc, 'final) Base__Container_intf.Continue_or_stop.t) ->
finish:('acc -> 'final) ->
'final
val exists : 'a t -> f:('a -> bool) -> bool
val for_all : 'a t -> f:('a -> bool) -> bool
val count : 'a t -> f:('a -> bool) -> int
val sum :
(module Base__Container_intf.Summable with type t = 'sum) ->
'a t ->
f:('a -> 'sum) ->
'sum
val find : 'a t -> f:('a -> bool) -> 'a option
val find_map : 'a t -> f:('a -> 'b option) -> 'b option
val to_list : 'a t -> 'a list
val to_array : 'a t -> 'a array
val min_elt : 'a t -> compare:('a -> 'a -> int) -> 'a option
val max_elt : 'a t -> compare:('a -> 'a -> int) -> 'a option
include Travesty.Mappable_types.Extensions1 with type 'a t := 'a t
Extensions1
includes the container extensions from Container_exts
, as they work with any arity-1 container.
include Travesty.Container_exts_types.S1 with type 'a t := 'a t
include Travesty.Container_exts_types.Generic
with type ('a, 'phantom) t := 'a t
and type 'a elt := 'a
Generic
refers to the container type as 'a t
, and the element type as 'a elt
; substitute t
/elt
(arity-0) or 'a t
/'a
(arity-1) accordingly below.
include Travesty.Generic_types.Generic
with type ('a, 'phantom) t := 'a t
with type 'a elt := 'a
The following functions help in checking whether a container has a particular, commonly-required number of elements (zero or one, one, two, and so on).
val at_most_one : 'a t -> 'a Base.option Base.Or_error.t
at_most_one xs
returns Ok None
if xs
is empty; Ok Some(x)
if it contains only x
; and an error otherwise.
Examples (using an extended version of List):
(* ok None *)
List.at_most_one []
(* ok (Some 1) *)
List.at_most_one [1]
(* error -- too many *)
List.at_most_one [1; 2]
val one : 'a t -> 'a Base.Or_error.t
one xs
returns Ok x
if xs
contains only x
, and an error otherwise.
Examples (using an extended version of List):
(* error -- not enough *)
List.one []
(* ok 1 *)
List.one [1]
(* error -- too many *)
List.one [1; 2]
val two : 'a t -> ('a * 'a) Base.Or_error.t
two xs
returns Ok (x, y)
if xs
is a list containing only x
and y
in that order, and an error otherwise.
Examples (using an extended version of List):
(* error -- not enough *)
List.two []
(* error -- not enough *)
List.two [1]
(* ok (1, 2) *)
List.two [1; 2]
(* error -- too many *)
List.two [1; 2; 3]
val max_measure :
measure:('a -> Base.int) ->
?default:Base.int ->
'a t ->
Base.int
max_measure ~measure ~default xs
measures each item in xs
according to measure
, and returns the highest measure reported. If xs
is empty, return default
if given, and 0
otherwise.
Predicate extensions are available on all arity-1 containers, provided that we fix the element type parameter to 'a -> bool
.
include Travesty.Container_exts_types.Generic_predicate
with type ('a, 'phantom) t := ('a -> Base.bool) t
and type 'a item := 'a
val any : 'a -> predicates:('a -> Base.bool) t -> Base.bool
any x ~predicates
tests x
against predicates
until one returns true
, in which case it returns true
; or all return false
, in which case it returns false
.
val all : 'a -> predicates:('a -> Base.bool) t -> Base.bool
any x ~predicates
tests x
against predicates
until one returns false
, in which case it returns false
; or all return true
, in which case it returns true
.
val none : 'a -> predicates:('a -> Base.bool) t -> Base.bool
none x ~predicates
is the same as any x
with all predicates in predicates
negated. It tests x
against predicates
until one returns true
, in which case it returns false
; or all return false
, in which case it returns true
.
right_pad ~padding xs
pads every list in xs with padding
, ensuring all lists have equal length.
Example:
right_pad ~padding:6
[ [0; 8; 0; 0] (* [ [ 0; 8; 0; 0; 6 ] *)
; [9; 9; 9] (* ; [ 9; 9; 9; 6; 6 ] *)
; [8; 8; 1; 9; 9] (* ; [ 8; 8; 1; 9; 9 ] *)
; [9; 1; 1; 9] (* ; [ 9; 1; 1; 9; 6 ] *)
; [7; 2; 5] (* ; [ 7; 2; 5; 6; 6 ] *)
; [3] (* ; [ 3; 6; 6; 6; 6 ] *) ]
(* ] *)
Options are also filter-mappable; filter-mapping effectively behaves as monadic bind.
include Travesty.Filter_mappable_types.S1 with type 'a t := 'a t
include Travesty.Filter_mappable_types.Generic
with type ('a, 'phantom) t := 'a t
and type 'a elt := 'a
Generic
strictly extends Generic_basic
.
include Travesty.Filter_mappable_types.Generic_basic
with type ('a, 'phantom) t := 'a t
with type 'a elt := 'a
Generic_basic
refers to the container type as 'a t
, and the element type as 'a elt
; substitute t
/elt
(arity-0) or 'a t
/'a
(arity-1) accordingly below.
include Travesty.Generic_types.Generic
with type ('a, 'phantom) t := 'a t
with type 'a elt := 'a
filter c ~f
checks f
over every t
in c
, discarding any items for which f
returns false
.
exclude c ~f
checks f
over every t
in c
, discarding any items for which f
returns true
.
We can also derive Mappable
interfaces from filter-mappable ones, but leave that to a separate functor.
Finally, options are a monad, and take the various monad extensions.
include Travesty.Monad_exts_types.S with type 'a t := 'a t
S
subsumes S_let
.
then_m x y
sequentially composes the actions x
and y
as with >>=
, but, rather than using the returned value of x
, it instead just returns y
.
compose_m f g
is the Kleisli composition of f
and g
.
map_when_m ?otherwise condition ~f a
is f a
when condition
is true, and otherwise a
(by default, return
) otherwise.
when_m ?otherwise condition ~f
is f ()
when condition
is true, and otherwise ()
(by default, return
) otherwise.
map_unless_m ?otherwise condition ~f a
is f a
when condition
is false, and otherwise a
(by default, return
) otherwise.
unless_m ?otherwise condition ~f
is f ()
when condition
is false, and otherwise ()
(by default, return
) otherwise.
tee_m val ~f
executes f val
for its monadic action, then returns val
.
Example (using an extended Or_error):
let fail_if_negative x =
On_error.when_m (Int.is_negative x) ~f:(fun () ->
Or_error.error_string "value is negative!" )
in
Or_error.(42 |> tee_m ~f:fail_if_negative >>| fun x -> x * x)
(* Ok (1764) *)
val tee : 'a -> f:('a -> unit) -> 'a t
tee val ~f
behaves as tee_m
, but takes a non-monadic f
.
Example (using an extended Or_error):
let print_if_negative x =
if Int.negative x then Stdio.print_string "value is negative!"
in
Or_error.(
try_get_value () >>= tee ~f:print_if_negative >>= try_use_value () )
value_f opt ~default_f
behaves like value opt ~default:(default_f ())
, but only evaluates the thunk default_f
if value
is None.
value_f opt ~default_l
behaves like value opt ~default:(Lazy.force default_l)
, but only forces default_l
if value
is None.