links 0.9.2 · OCaml Package

include module type of List

type 'a t = 'a list =

| []
| :: of 'a * 'a list

An alias for the type of lists.

val length : 'a list -> int

Return the length (number of elements) of the given list.

val compare_lengths : 'a list -> 'b list -> int

Compare the lengths of two lists. compare_lengths l1 l2 is equivalent to compare (length l1) (length l2), except that the computation stops after itering on the shortest list.

since 4.05.0

val compare_length_with : 'a list -> int -> int

Compare the length of a list to an integer. compare_length_with l n is equivalent to compare (length l) n, except that the computation stops after at most n iterations on the list.

since 4.05.0

val cons : 'a -> 'a list -> 'a list

cons x xs is x :: xs

since 4.03.0

val hd : 'a list -> 'a

Return the first element of the given list.

raises Failure
if the list is empty.

val tl : 'a list -> 'a list

Return the given list without its first element.

raises Failure
if the list is empty.

val nth : 'a list -> int -> 'a

Return the n-th element of the given list. The first element (head of the list) is at position 0.

raises Failure
if the list is too short.

raises Invalid_argument
if n is negative.

val nth_opt : 'a list -> int -> 'a option

Return the n-th element of the given list. The first element (head of the list) is at position 0. Return None if the list is too short.

raises Invalid_argument
if n is negative.

since 4.05

val rev : 'a list -> 'a list

List reversal.

val init : int -> (int -> 'a) -> 'a list

List.init len f is [f 0; f 1; ...; f (len-1)], evaluated left to right.

raises Invalid_argument
if len < 0.

since 4.06.0

val append : 'a list -> 'a list -> 'a list

Concatenate two lists. Same as the infix operator @. Not tail-recursive (length of the first argument).

val rev_append : 'a list -> 'a list -> 'a list

List.rev_append l1 l2 reverses l1 and concatenates it to l2. This is equivalent to List.rev l1 @ l2, but rev_append is tail-recursive and more efficient.

val concat : 'a list list -> 'a list

Concatenate a list of lists. The elements of the argument are all concatenated together (in the same order) to give the result. Not tail-recursive (length of the argument + length of the longest sub-list).

val flatten : 'a list list -> 'a list

An alias for concat.

Iterators

val iteri : (int -> 'a -> unit) -> 'a list -> unit

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

since 4.00.0

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

List.rev_map f l gives the same result as List.rev (List.map f l), but is tail-recursive and more efficient.

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

List.concat_map f l gives the same result as List.concat (List.map f l). Tail-recursive.

since 4.10.0

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

fold_left_map is a combination of fold_left and map that threads an accumulator through calls to f

since 4.11.0

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

List.fold_left f a [b1; ...; bn] is f (... (f (f a b1) b2) ...) bn.

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

List.fold_right f [a1; ...; an] b is f a1 (f a2 (... (f an b) ...)). Not tail-recursive.

Iterators on two lists

val iter2 : ('a -> 'b -> unit) -> 'a list -> 'b list -> unit

List.iter2 f [a1; ...; an] [b1; ...; bn] calls in turn f a1 b1; ...; f an bn.

raises Invalid_argument
if the two lists are determined to have different lengths.

val map2 : ('a -> 'b -> 'c) -> 'a list -> 'b list -> 'c list

List.map2 f [a1; ...; an] [b1; ...; bn] is [f a1 b1; ...; f an bn].

raises Invalid_argument
if the two lists are determined to have different lengths. Not tail-recursive.

val rev_map2 : ('a -> 'b -> 'c) -> 'a list -> 'b list -> 'c list

List.rev_map2 f l1 l2 gives the same result as List.rev (List.map2 f l1 l2), but is tail-recursive and more efficient.

val fold_left2 : ('a -> 'b -> 'c -> 'a) -> 'a -> 'b list -> 'c list -> 'a

List.fold_left2 f a [b1; ...; bn] [c1; ...; cn] is f (... (f (f a b1 c1) b2 c2) ...) bn cn.

raises Invalid_argument
if the two lists are determined to have different lengths.

val fold_right2 : ('a -> 'b -> 'c -> 'c) -> 'a list -> 'b list -> 'c -> 'c

List.fold_right2 f [a1; ...; an] [b1; ...; bn] c is f a1 b1 (f a2 b2 (... (f an bn c) ...)).

raises Invalid_argument
if the two lists are determined to have different lengths. Not tail-recursive.

List scanning

val exists : ('a -> bool) -> 'a list -> bool

exists p [a1; ...; an] checks if at least one element of the list satisfies the predicate p. That is, it returns (p a1) || (p a2) || ... || (p an) for a non-empty list and false if the list is empty.

val for_all2 : ('a -> 'b -> bool) -> 'a list -> 'b list -> bool

Same as List.for_all, but for a two-argument predicate.

raises Invalid_argument
if the two lists are determined to have different lengths.

val exists2 : ('a -> 'b -> bool) -> 'a list -> 'b list -> bool

Same as List.exists, but for a two-argument predicate.

raises Invalid_argument
if the two lists are determined to have different lengths.

val memq : 'a -> 'a list -> bool

Same as List.mem, but uses physical equality instead of structural equality to compare list elements.

List searching

val find_opt : ('a -> bool) -> 'a list -> 'a option

find_opt p l returns the first element of the list l that satisfies the predicate p, or None if there is no value that satisfies p in the list l.

since 4.05

val find_map : ('a -> 'b option) -> 'a list -> 'b option

find_map f l applies f to the elements of l in order, and returns the first result of the form Some v, or None if none exist.

since 4.10.0

val filter : ('a -> bool) -> 'a list -> 'a list

filter p l returns all the elements of the list l that satisfy the predicate p. The order of the elements in the input list is preserved.

val find_all : ('a -> bool) -> 'a list -> 'a list

find_all is another name for List.filter.

val filteri : (int -> 'a -> bool) -> 'a list -> 'a list

Same as List.filter, but the predicate is applied to the index of the element as first argument (counting from 0), and the element itself as second argument.

since 4.11.0

val partition : ('a -> bool) -> 'a list -> 'a list * 'a list

partition p l returns a pair of lists (l1, l2), where l1 is the list of all the elements of l that satisfy the predicate p, and l2 is the list of all the elements of l that do not satisfy p. The order of the elements in the input list is preserved.

Association lists

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

assoc a l returns the value associated with key a in the list of pairs l. That is, assoc a [ ...; (a,b); ...] = b if (a,b) is the leftmost binding of a in list l.

raises Not_found
if there is no value associated with a in the list l.

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

assoc_opt a l returns the value associated with key a in the list of pairs l. That is, assoc_opt a [ ...; (a,b); ...] = b if (a,b) is the leftmost binding of a in list l. Returns None if there is no value associated with a in the list l.

since 4.05

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

Same as List.assoc, but uses physical equality instead of structural equality to compare keys.

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

Same as List.assoc_opt, but uses physical equality instead of structural equality to compare keys.

since 4.05

val mem_assoc : 'a -> ('a * 'b) list -> bool

Same as List.assoc, but simply return true if a binding exists, and false if no bindings exist for the given key.

val mem_assq : 'a -> ('a * 'b) list -> bool

Same as List.mem_assoc, but uses physical equality instead of structural equality to compare keys.

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

remove_assoc a l returns the list of pairs l without the first pair with key a, if any. Not tail-recursive.

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

Same as List.remove_assoc, but uses physical equality instead of structural equality to compare keys. Not tail-recursive.

Lists of pairs

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

Transform a list of pairs into a pair of lists: split [(a1,b1); ...; (an,bn)] is ([a1; ...; an], [b1; ...; bn]). Not tail-recursive.

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

Transform a pair of lists into a list of pairs: combine [a1; ...; an] [b1; ...; bn] is [(a1,b1); ...; (an,bn)].

raises Invalid_argument
if the two lists have different lengths. Not tail-recursive.

Sorting

val sort : ('a -> 'a -> int) -> 'a list -> 'a list

Sort a list in increasing order according to a comparison function. The comparison function must return 0 if its arguments compare as equal, a positive integer if the first is greater, and a negative integer if the first is smaller (see Array.sort for a complete specification). For example, Stdlib.compare is a suitable comparison function. The resulting list is sorted in increasing order. List.sort is guaranteed to run in constant heap space (in addition to the size of the result list) and logarithmic stack space.

The current implementation uses Merge Sort. It runs in constant heap space and logarithmic stack space.

val stable_sort : ('a -> 'a -> int) -> 'a list -> 'a list

Same as List.sort, but the sorting algorithm is guaranteed to be stable (i.e. elements that compare equal are kept in their original order) .

The current implementation uses Merge Sort. It runs in constant heap space and logarithmic stack space.

val fast_sort : ('a -> 'a -> int) -> 'a list -> 'a list

Same as List.sort or List.stable_sort, whichever is faster on typical input.

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

Same as List.sort, but also remove duplicates.

since 4.02.0

val merge : ('a -> 'a -> int) -> 'a list -> 'a list -> 'a list

Merge two lists: Assuming that l1 and l2 are sorted according to the comparison function cmp, merge cmp l1 l2 will return a sorted list containing all the elements of l1 and l2. If several elements compare equal, the elements of l1 will be before the elements of l2. Not tail-recursive (sum of the lengths of the arguments).

Iterators

val of_seq : 'a Seq.t -> 'a list

Create a list from the iterator

since 4.07

module Seq : sig ... end

This is the lazy evaluated sequence module for OCaml 4.06 compatability. The signatures and comments are based on the standard OCaml library.

val mem : 'a list -> 'a -> equal:('a -> 'a -> bool) -> bool

val findi : 'a list -> f:('a -> bool) -> (int * 'a) option

val find : 'a list -> f:('a -> bool) -> 'a option

val find_exn : 'a list -> f:('a -> bool) -> 'a

val for_all2_exn : 'a list -> 'b list -> f:('a -> 'b -> bool) -> bool

val for_all : 'a list -> f:('a -> bool) -> bool

val for_all_or_error : 
  'a list ->
  f:('a -> bool) ->
  error:('a -> 'b) ->
  (unit, 'b) result

val iter : 'a list -> f:('a -> unit) -> unit

val mapi : 'a list -> f:(int -> 'a -> 'b) -> 'b list

val map : 'a list -> f:('a -> 'b) -> 'b list

val map_if : 'a list -> b:('a -> bool) -> f:('a -> 'a) -> 'a list

val map_result : 'a list -> f:('a -> ('b, 'c) result) -> ('b list, 'c) result

val filter_opt : 'a option list -> 'a list

val filter_map : 'a list -> f:('a -> 'b option) -> 'b list

val unzip3 : ('a * 'b * 'c) list -> 'a list * 'b list * 'c list

val take : 'a list -> n:int -> 'a list

Take up to the first n elements of a list.

val drop : 'a list -> n:int -> 'a list

Remove the first n elements of a list.

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

Like zip, but in the case of length mismatch it zips as many elements as possible and then ends.

val to_seq : 'a list -> 'a Seq.t

Turn a list into a lazily evaluated sequence. This is for ocaml 4.06 compatibility.

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

Create a tuple using the elements of two lists. Requires lists to be of equal length or fail.

val groupBy : 
  (module Links_lens__.Lens_map_intf.S with type key = 'gr) ->
  f:('el -> 'gr) ->
  'el list ->
  ('gr * 'el list) list

Take a list of elements and group them by the value generated by `f`.

package links

Iterators

Iterators on two lists

List scanning

List searching

Association lists

Lists of pairs

Sorting

Iterators