Traversable.ConstSourceConst constructs a S0 over container T and arbitrary element type Elt that, when traversed, makes no calls to the supplied function and returns the container unchanged.
module K = Const (String) (String)
(* This would output "foo". *)
K.map "foo" ~f:String.uppercasemodule Elt : Base.Equal.SElements must have equality. While this is an extra restriction on top of the Base equivalent, it is required by Make0, and helps us define chaining operations.
We export Elt.t as elt for compatibility with Core-style containers.
include Traversable_types.Generic
with type ('a, 'phantom) t := t
and type 'a elt := Elt.tinclude Generic_types.Generic
with type ('a, 'phantom) t := t
with type 'a elt := Elt.tmodule On
(M : Base.Applicative.S) :
Traversable_types.Generic_on_applicative
with type ('a, 'phantom) t := t
and type 'a elt := Elt.t
and module M := MOn implements traversal operators for a given applicative M.
module On_monad
(M : Base.Monad.S) :
Traversable_types.Generic_on_monad
with type ('a, 'phantom) t := t
and type 'a elt := Elt.t
and module M := MOn_monad implements traversal operators for a given monad M. Compared to On(Monad_exts.App(M)), this adds various derived operators available only for monads.
We can do generic container operations.
include Base.Container.Generic
with type ('a, 'phantom) t := t
and type 'a elt := Elt.tWe can do non-applicative mapping operations.
include Mappable_types.Generic
with type ('a, 'phantom) t := t
and type 'a elt := Elt.tGeneric 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 Generic_types.Generic
with type ('a, 'phantom) t := t
with type 'a elt := Elt.tfold_map c ~f ~init folds f over every t in c, threading through an accumulator with initial value init.
mapi ~f t maps f across t, passing in an increasing position counter.
module With_errors :
Traversable_types.Generic_on_monad
with type ('a, 'phantom) t := t
and type 'a elt := Elt.t
and module M := Base.Or_errorWith_errors specialises On_applicative to the error applicative.
include Mappable_types.S0_container with type t := t and type elt := Elt.tinclude Mappable_types.S0 with type t := t with type elt := Elt.tinclude Generic_types.S0 with type t := t with type elt := Elt.tinclude Mappable_types.Generic
with type ('a, 'phantom) t := t
and type 'a elt := Elt.tGeneric 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 Generic_types.Generic
with type ('a, 'phantom) t := t
with type 'a elt := Elt.tinclude Base.Container.S0 with type t := t and type elt := Elt.tChecks whether the provided element is there, using equality on elts.
iter must allow exceptions raised in f to escape, terminating the iteration cleanly. The same holds for all functions below taking an f.
fold t ~init ~f returns f (... f (f (f init e1) e2) e3 ...) en, where e1..en are the elements of t.
val fold_result :
t ->
init:'acc ->
f:('acc -> Elt.t -> ('acc, 'e) Base.Result.t) ->
('acc, 'e) Base.Result.tfold_result t ~init ~f is a short-circuiting version of fold that runs in the Result monad. If f returns an Error _, that value is returned without any additional invocations of f.
val fold_until :
t ->
init:'acc ->
f:('acc -> Elt.t -> ('acc, 'final) Base.Container.Continue_or_stop.t) ->
finish:('acc -> 'final) ->
'finalfold_until t ~init ~f ~finish is a short-circuiting version of fold. If f returns Stop _ the computation ceases and results in that value. If f returns Continue _, the fold will proceed. If f never returns Stop _, the final result is computed by finish.
Example:
type maybe_negative =
| Found_negative of int
| All_nonnegative of { sum : int }
(** [first_neg_or_sum list] returns the first negative number in [list], if any,
otherwise returns the sum of the list. *)
let first_neg_or_sum =
List.fold_until ~init:0
~f:(fun sum x ->
if x < 0
then Stop (Found_negative x)
else Continue (sum + x))
~finish:(fun sum -> All_nonnegative { sum })
;;
let x = first_neg_or_sum [1; 2; 3; 4; 5]
val x : maybe_negative = All_nonnegative {sum = 15}
let y = first_neg_or_sum [1; 2; -3; 4; 5]
val y : maybe_negative = Found_negative -3Returns true if and only if there exists an element for which the provided function evaluates to true. This is a short-circuiting operation.
Returns true if and only if the provided function evaluates to true for all elements. This is a short-circuiting operation.
Returns the number of elements for which the provided function evaluates to true.
val sum :
(module Base.Container.Summable with type t = 'sum) ->
t ->
f:(Elt.t -> 'sum) ->
'sumReturns the sum of f i for all i in the container.
Returns as an option the first element for which f evaluates to true.
Returns the first evaluation of f that returns Some, and returns None if there is no such element.
Returns a min (resp. max) element from the collection using the provided compare function. In case of a tie, the first element encountered while traversing the collection is returned. The implementation uses fold so it has the same complexity as fold. Returns None iff the collection is empty.