Module Containers.List

module List: CCList

type 'a sequence = ('a -> unit) -> unit

type 'a gen = unit -> 'a option

type 'a klist = unit -> [ `Cons of 'a * 'a klist | `Nil ]

type 'a printer = Format.formatter -> 'a -> unit

type 'a random_gen = Random.State.t -> 'a

include List

type 'a t = 'a list

val empty : 'a t

val is_empty : 'a t -> bool

is_empty l returns true iff l = []
Since 0.11

val map : ('a -> 'b) -> 'a t -> 'b t

Safe version of map

val (>|=) : 'a t -> ('a -> 'b) -> 'b t

Infix version of map with reversed arguments
Since 0.5

val cons : 'a -> 'a t -> 'a t

cons x l is x::l
Since 0.12

val append : 'a t -> 'a t -> 'a t

Safe version of append

val cons_maybe : 'a option -> 'a t -> 'a t

cons_maybe (Some x) l is x :: l cons_maybe None l is l
Since 0.13

val (@) : 'a t -> 'a t -> 'a t

val filter : ('a -> bool) -> 'a t -> 'a t

Safe version of List.filter

val fold_right : ('a -> 'b -> 'b) -> 'a t -> 'b -> 'b

Safe version of fold_right

val fold_while : ('a -> 'b -> 'a * [ `Continue | `Stop ]) -> 'a -> 'b t -> 'a

Fold until a stop condition via ('a, `Stop) is indicated by the accumulator
Since 0.8

val fold_map : ('acc -> 'a -> 'acc * 'b) -> 'acc -> 'a list -> 'acc * 'b list

fold_map f acc l is a fold_left-like function, but it also maps the list to another list.
Since 0.14

val scan_left : ('acc -> 'a -> 'acc) -> 'acc -> 'a list -> 'acc list

scan_left f acc l returns the list [acc; f acc x0; f (f acc x0) x1; …] where x0, x1, etc. are the elements of l
Since 1.2

val fold_map2 : ('acc -> 'a -> 'b -> 'acc * 'c) ->
       'acc -> 'a list -> 'b list -> 'acc * 'c list

fold_map2 is to fold_map what List.map2 is to List.map.
Since 0.16
Raises Invalid_argument if the lists do not have the same length

val fold_filter_map : ('acc -> 'a -> 'acc * 'b option) -> 'acc -> 'a list -> 'acc * 'b list

fold_filter_map f acc l is a fold_left-like function, but also generates a list of output in a way similar to CCList.filter_map
Since 0.17

val fold_flat_map : ('acc -> 'a -> 'acc * 'b list) -> 'acc -> 'a list -> 'acc * 'b list

fold_flat_map f acc l is a fold_left-like function, but it also maps the list to a list of lists that is then flatten'd..
Since 0.14

val init : int -> (int -> 'a) -> 'a t

Similar to Array.init
Since 0.6

val combine : 'a list -> 'b list -> ('a * 'b) list

Similar to List.combine but tail-recursive.
Since 1.2
Raises Invalid_argument if the lists have distinct lengths.

val combine_gen : 'a list -> 'b list -> ('a * 'b) gen

Lazy version of CCList.combine. Unlike CCList.combine, it does not fail if the lists have different lengths; instead, the output has as many pairs as the smallest input list.
Since 1.2

val split : ('a * 'b) t -> 'a t * 'b t

A tail-recursive version of List.split.

val compare : ('a -> 'a -> int) -> 'a t -> 'a t -> int

val equal : ('a -> 'a -> bool) -> 'a t -> 'a t -> bool

val flat_map : ('a -> 'b t) -> 'a t -> 'b t

Map and flatten at the same time (safe). Evaluation order is not guaranteed.

val flatten : 'a t t -> 'a t

Safe flatten

val product : ('a -> 'b -> 'c) -> 'a t -> 'b t -> 'c t

Cartesian product of the two lists, with the given combinator

val fold_product : ('c -> 'a -> 'b -> 'c) -> 'c -> 'a t -> 'b t -> 'c

Fold on the cartesian product

val cartesian_product : 'a t t -> 'a t t

For example:

     # cartesian_product [[1;2];[3];[4;5;6]] =
     [[1;3;4];[1;3;5];[1;3;6];[2;3;4];[2;3;5];[2;3;6]];;
     # cartesian_product [[1;2];[];[4;5;6]] = [];;
     # cartesian_product [[1;2];[3];[4];[5];[6]] =
     [[1;3;4;5;6];[2;3;4;5;6]];;

invariant: cartesian_product l = map_product id l.
Since 1.2

val map_product_l : ('a -> 'b list) -> 'a list -> 'b list list

map_product_l f l maps each element of l to a list of objects of type 'b using f. We obtain [l1;l2;…;ln] where length l=n and li : 'b list. Then, it returns all the ways of picking exactly one element per li.
Since 1.2

val diagonal : 'a t -> ('a * 'a) t

All pairs of distinct positions of the list. list_diagonal l will return the list of List.nth i l, List.nth j l if i < j.

val partition_map : ('a -> [< `Drop | `Left of 'b | `Right of 'c ]) ->
       'a list -> 'b list * 'c list

partition_map f l maps f on l and gather results in lists:

if f x = `Left y, adds y to the first list
if f x = `Right z, adds z to the second list
if f x = `Drop, ignores x

Since 0.11

val sublists_of_len : ?last:('a list -> 'a list option) ->
       ?offset:int -> int -> 'a list -> 'a list list

sublists_of_len n l returns sub-lists of l that have length n. By default, these sub-lists are non overlapping: sublists_of_len 2 [1;2;3;4;5;6] returns [1;2]; [3;4]; [5;6]

Examples:

sublists_of_len 2 [1;2;3;4;5;6] = [[1;2]; [3;4]; [5;6]]
sublists_of_len 2 ~offset:3 [1;2;3;4;5;6] = [1;2];[4;5]
sublists_of_len 3 ~last:CCOpt.return [1;2;3;4] = [1;2;3];[4]
sublists_of_len 2 [1;2;3;4;5] = [[1;2]; [3;4]]

Since 1.0
Raises Invalid_argument if offset <= 0 or n <= 0

last : if provided and the last group of elements g is such that length g < n, last g is called. If last g = Some g', g' is appended; otherwise g is dropped. If last = CCOpt.return, it will simply keep the last group. By default, last = fun _ -> None, i.e. the last group is dropped if shorter than n.

offset : the number of elements skipped between two consecutive sub-lists. By default it is n. If offset < n, the sub-lists will overlap; if offset > n, some elements will not appear at all.

val pure : 'a -> 'a t

val (<*>) : ('a -> 'b) t -> 'a t -> 'b t

val (<$>) : ('a -> 'b) -> 'a t -> 'b t

val return : 'a -> 'a t

val (>>=) : 'a t -> ('a -> 'b t) -> 'b t

val take : int -> 'a t -> 'a t

Take the n first elements, drop the rest

val drop : int -> 'a t -> 'a t

Drop the n first elements, keep the rest

val hd_tl : 'a t -> 'a * 'a t

hd_tl (x :: l) returns hd, l.
Since 0.16
Raises Failure if the list is empty

val take_drop : int -> 'a t -> 'a t * 'a t

take_drop n l returns l1, l2 such that l1 @ l2 = l and length l1 = min (length l) n

val take_while : ('a -> bool) -> 'a t -> 'a t

Since 0.13

val drop_while : ('a -> bool) -> 'a t -> 'a t

Since 0.13

val take_drop_while : ('a -> bool) -> 'a t -> 'a t * 'a t

take_drop_while p l = take_while p l, drop_while p l
Since 1.2

val last : int -> 'a t -> 'a t

last n l takes the last n elements of l (or less if l doesn't have that many elements

val head_opt : 'a t -> 'a option

First element.
Since 0.20

val last_opt : 'a t -> 'a option

Last element.
Since 0.20

val find_pred : ('a -> bool) -> 'a t -> 'a option

find_pred p l finds the first element of l that satisfies p, or returns None if no element satisfies p
Since 0.11

val find_pred_exn : ('a -> bool) -> 'a t -> 'a

Unsafe version of CCList.find_pred
Since 0.11
Raises Not_found if no such element is found

val find_map : ('a -> 'b option) -> 'a t -> 'b option

find_map f l traverses l, applying f to each element. If for some element x, f x = Some y, then Some y is returned. Otherwise the call returns None
Since 0.11

val find_mapi : (int -> 'a -> 'b option) -> 'a t -> 'b option

Like CCList.find_map, but also pass the index to the predicate function.
Since 0.11

val find_idx : ('a -> bool) -> 'a t -> (int * 'a) option

find_idx p x returns Some (i,x) where x is the i-th element of l, and p x holds. Otherwise returns None

val remove : ?eq:('a -> 'a -> bool) -> x:'a -> 'a t -> 'a t

remove ~x l removes every instance of x from l. Tailrec.
Since 0.11

eq : equality function

val filter_map : ('a -> 'b option) -> 'a t -> 'b t

Map and remove elements at the same time

val keep_some : 'a option t -> 'a t

filter_some l retains only elements of the form Some x. Same as filter_map CCFun.id
Since 1.3

val keep_ok : ('a, 'b) Result.result t -> 'a t

filter_some l retains only elements of the form Some x. Same as filter_map CCFun.id
Since 1.3

val all_some : 'a option t -> 'a t option

all_some l returns Some l' if all elements of l are of the form Some x, or None otherwise.
Since 1.3

val all_ok : ('a, 'err) Result.result t -> ('a t, 'err) Result.result

all_ok l returns Ok l' if all elements of l are of the form Ok x, or Error e otherwise (with the first error met).
Since 1.3

val sorted_merge : ?cmp:('a -> 'a -> int) -> 'a list -> 'a list -> 'a list

Merges elements from both sorted list

val sort_uniq : ?cmp:('a -> 'a -> int) -> 'a list -> 'a list

Sort the list and remove duplicate elements

val sorted_merge_uniq : ?cmp:('a -> 'a -> int) -> 'a list -> 'a list -> 'a list

sorted_merge_uniq l1 l2 merges the sorted lists l1 and l2 and removes duplicates
Since 0.10

val is_sorted : ?cmp:('a -> 'a -> int) -> 'a list -> bool

is_sorted l returns true iff l is sorted (according to given order)
Since 0.17

cmp : the comparison function (default Pervasives.compare)

val sorted_insert : ?cmp:('a -> 'a -> int) -> ?uniq:bool -> 'a -> 'a list -> 'a list

sorted_insert x l inserts x into l such that, if l was sorted, then sorted_insert x l is sorted too.
Since 0.17

uniq : if true and x is already in sorted position in l, then x is not duplicated. Default false (x will be inserted in any case).

val uniq_succ : ?eq:('a -> 'a -> bool) -> 'a list -> 'a list

uniq_succ l removes duplicate elements that occur one next to the other. Examples: uniq_succ [1;2;1] = [1;2;1] uniq_succ [1;1;2] = [1;2]
Since 0.10

val group_succ : ?eq:('a -> 'a -> bool) -> 'a list -> 'a list list

group_succ ~eq l groups together consecutive elements that are equal according to eq
Since 0.11

Indices

val mapi : (int -> 'a -> 'b) -> 'a t -> 'b t

val iteri : (int -> 'a -> unit) -> 'a t -> unit

val foldi : ('b -> int -> 'a -> 'b) -> 'b -> 'a t -> 'b

Fold on list, with index

val get_at_idx : int -> 'a t -> 'a option

val get_at_idx_exn : int -> 'a t -> 'a

Get the i-th element, or
Raises Not_found if the index is invalid

val set_at_idx : int -> 'a -> 'a t -> 'a t

Set i-th element (removes the old one), or does nothing if index is too high

val insert_at_idx : int -> 'a -> 'a t -> 'a t

Insert at i-th position, between the two existing elements. If the index is too high, append at the end of the list

val remove_at_idx : int -> 'a t -> 'a t

Remove element at given index. Does nothing if the index is too high.

Set Operators

Those operations maintain the invariant that the list does not contain duplicates (if it already satisfies it)

val add_nodup : ?eq:('a -> 'a -> bool) -> 'a -> 'a t -> 'a t

add_nodup x set adds x to set if it was not already present. Linear time.
Since 0.11

val remove_one : ?eq:('a -> 'a -> bool) -> 'a -> 'a t -> 'a t

remove_one x set removes one occurrence of x from set. Linear time.
Since 0.11

val mem : ?eq:('a -> 'a -> bool) -> 'a -> 'a t -> bool

Membership to the list. Linear time

val subset : ?eq:('a -> 'a -> bool) -> 'a t -> 'a t -> bool

Test for inclusion

val uniq : ?eq:('a -> 'a -> bool) -> 'a t -> 'a t

Remove duplicates w.r.t the equality predicate. Complexity is quadratic in the length of the list, but the order of elements is preserved. If you wish for a faster de-duplication but do not care about the order, use CCList.sort_uniq

val union : ?eq:('a -> 'a -> bool) -> 'a t -> 'a t -> 'a t

List union. Complexity is product of length of inputs.

val inter : ?eq:('a -> 'a -> bool) -> 'a t -> 'a t -> 'a t

List intersection. Complexity is product of length of inputs.

Other Constructors

val range_by : step:int -> int -> int -> int t

range_by ~step i j iterates on integers from i to j included, where the difference between successive elements is step. use a negative step for a decreasing list.
Since 0.18
Raises Invalid_argument if step=0

val range : int -> int -> int t

range i j iterates on integers from i to j included . It works both for decreasing and increasing ranges

val range' : int -> int -> int t

Same as CCList.range but the second bound is excluded. For instance range' 0 5 = [0;1;2;3;4]

val (--) : int -> int -> int t

Infix alias for range

val (--^) : int -> int -> int t

Infix alias for range'
Since 0.17

val replicate : int -> 'a -> 'a t

Replicate the given element n times

val repeat : int -> 'a t -> 'a t

Concatenate the list with itself n times

Association Lists

module Assoc: sig .. end

References on Lists

module Ref: sig .. end

module type MONAD = sig .. end

Monadic Operations

module Traverse (M : MONAD) : sig .. end

Conversions

val random : 'a random_gen -> 'a t random_gen

val random_non_empty : 'a random_gen -> 'a t random_gen

val random_len : int -> 'a random_gen -> 'a t random_gen

val random_choose : 'a t -> 'a random_gen

Randomly choose an element in the list.
Raises Not_found if the list is empty

val random_sequence : 'a random_gen t -> 'a t random_gen

val to_seq : 'a t -> 'a sequence

val of_seq : 'a sequence -> 'a t

val to_gen : 'a t -> 'a gen

val of_gen : 'a gen -> 'a t

val to_klist : 'a t -> 'a klist

val of_klist : 'a klist -> 'a t

Infix Operators

It is convenient to open CCList.Infix to access the infix operators without cluttering the scope too much.

module Infix: sig .. end

IO

val pp : ?start:string ->
       ?stop:string ->
       ?sep:string -> 'a printer -> 'a t printer