Module `Stdlib.List`

Extensions to the List module

type 'a t = 'a list

val is_empty : 'a list -> bool

is_empty l is true if and only if l has no elements. It is equivalent to compare_length_with l 0 = 0.

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

The lexicographic order supported by the provided order. There is no constraint on the relative lengths of the lists.

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

Returns true if and only if the given lists have the same length and content with respect to the given equality function.

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

If all elements of the given list are Some _ then Some xs is returned with the xs being the contents of those Somes, with order preserved. Otherwise return None.

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

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

map_option f l is some_if_all_elements_are_some (map f l), but with short circuiting.

val map2_option : ('a -> 'b -> 'c option) -> 'a t -> 'b t -> 'c t option

val map2_prefix : ('a -> 'b -> 'c) -> 'a t -> 'b t -> 'c t * 'b t

let r1, r2 = map2_prefix f l1 l2 If l1 is of length n and l2 = h2 @ t2 with h2 of length n, r1 is List.map2 f l1 h1 and r2 is t2.

val map3 : ('a -> 'b -> 'c -> 'd) -> 'a list -> 'b list -> 'c list -> 'd list

val concat_map2 : ('a -> 'b -> 'c list) -> 'a list -> 'b list -> 'c list

concat_map2 f l1 l2 gives the same result as concat (map2 f l1 l2). Tail-recursive.

val iteri2 : (int -> 'a -> 'b -> unit) -> 'a list -> 'b list -> unit

Same as List.iter2, but the function is applied to the index of the element as first argument (counting from 0)

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

split_at n l returns the pair before, after where before is the n first elements of l and after the remaining ones. If l has less than n elements, raises Invalid_argument.

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

map_sharing f l is map f l. If for all elements of the list f e == e then map_sharing f l == l

val fold_lefti : (int -> 'a -> 'b -> 'a) -> 'a -> 'b list -> 'a

fold_lefti f init l is like fold_left but also takes as parameter the zero-based index of the element

val fold_left_map2 : 
  ('acc -> 'a -> 'b -> 'acc * 'r) ->
  'acc ->
  'a list ->
  'b list ->
  'acc * 'r list

fold_left_map2 is a combination of fold_left2 and map2 that threads an accumulator through calls to f.

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

chunks_of n t returns a list of nonempty lists whose concatenation is equal to the original list. Every list has n elements, except for possibly the last list, which may have fewer. chunks_of raises if n <= 0.

val is_prefix : equal:('a -> 'a -> bool) -> 'a list -> of_:'a list -> bool

Returns true if and only if the given list, with respect to the given equality function on list members, is a prefix of the list of_.

type 'a longest_common_prefix_result = private {

longest_common_prefix : 'a list;
first_without_longest_common_prefix : 'a list;
second_without_longest_common_prefix : 'a list;

}

val find_and_chop_longest_common_prefix : 
  equal:('a -> 'a -> bool) ->
  first:'a list ->
  second:'a list ->
  'a longest_common_prefix_result

Returns the longest list that, with respect to the provided equality function, is a prefix of both of the given lists. The input lists, each with such longest common prefix removed, are also returned.

val iter_until_error : 
  f:('a -> (unit, 'b) Result.t) ->
  'a list ->
  (unit, 'b) Result.t

iter_until_error f l applies f to each element of l, in order, short-circuiting in the case f returns Error on any element.

val merge_iter : 
  cmp:('a -> 'b -> int) ->
  left_only:('a -> unit) ->
  right_only:('b -> unit) ->
  both:('a -> 'b -> unit) ->
  'a t ->
  'b t ->
  unit

Iterates over two sorted lists, calling left_only on those elements that appear only in the left list, right_only on those elements that appear only in the right list, and both on those elements that appear in both.

val merge_fold : 
  cmp:('a -> 'b -> int) ->
  left_only:('acc -> 'a -> 'acc) ->
  right_only:('acc -> 'b -> 'acc) ->
  both:('acc -> 'a -> 'b -> 'acc) ->
  init:'acc ->
  'a t ->
  'b t ->
  'acc

Folds over two sorted lists, calling left_only on those elements that appear only in the left list, right_only on those elements that appear only in the right list, and both on those elements that appear in both.

Module Stdlib.List

Extensions to the List module

Module `Stdlib.List`