# Module Extended_list

    module Extended_list: sig .. end

Extensions to `Core.Core_list`.

    val of_option : 'a option -> 'a list

`of_option o` returns a list that is empty if `o` is None, otherwise it is a singleton list. Useful to get filter_map-like behavior in the context of something like a concat_map.

    val set_inter : 'a list -> 'a list -> 'a list

`set_inter l1 l2` returns a list without duplicates of all elements of l1 that are in l2

    val set_diff : 'a list -> 'a list -> 'a list

`set_diff l1 l2` returns a list of all elements of l1 that are not in l2

    val classify : ?equal:('b -> 'b -> bool) -> f:('a -> 'b) -> 'a list -> ('b * 'a list) list

`classify l ~equal ~f` elements `x` and `y` of list `l` are assigned to the same class iff `equal (f x) (f y)` returns true. The default for `equal` is ( = )

    val enumerate_from : int -> 'a list -> ('a * int) list

`enumerate_from n xs` returns a list of pairs constructed by pairing an incrementing counter, starting at `n`, with the elements of `xs`. e.g. enumerate_from 1 `a,b,c` = `a,1; b,2; c,3`

    val fold_left_term : 'a list ->
           f:('b -> 'a -> [ `Continue of 'b | `Final of 'b ]) -> init:'b -> 'b

fold_left_term is like fold_left, except that you can halt early. The function to be folded should return a bool along with the new accumulator. True indicates that it should continue, false means it should halt

    val map_accum : 'a list -> f:('b -> 'a -> 'b * 'c) -> init:'b -> 'b * 'c list

A combination of `map` and `fold`. Applies a function to each element of the input list, building up an accumulator, returning both the final state of the accumulator and a new list.

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

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

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

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

    val lcs : 'a list -> 'a list -> 'a list

Find the longest common subsequence between two list.
Numbers the elements in a list by occurence:

`[a;b;c;a;d] -> [(a,0);(b,0);(c,0);(a,1);(d,0)]`

    val number : 'a list -> ('a * int) list

    val multimerge : 'a list list -> 'a list

Merges several list trying to keep the order in which the elements appear. The elements of the individual are not deduped.

multimerge `[[a;b;d;a] [b;c;d]] -> [a;b;c;d;a]`

    val multimerge_unique : 'a list list -> 'a list

    val square : ?null:'v -> ('k * 'v) list list -> 'k list * 'v list list

Takes a list of ``key*`value lists` and returns a header * table_body body that is obtained by splitting the lists and re-ordering the terms (so that they all have the same header).

If `null_value` is not specified and the rows have different keys the function will raise an exception. `square ~null [[(1,a_1);(2,b_1);(4,c_1)]; [(3,a_2)]; [(0,a_3);(1,b_3);(2,c_3);(3,d_3);(4,e_3)]] = ([0 ;1 ;2 ;3 ;4], [[null;a_1 ;b_1 ;null;c_1 ] [null;null;null;a_2 ;null] [a_3 ;b_3 ;c_3 ;d_3 ;e_3 ]])`

    val square_unique : ?null:'v -> ('k * 'v) list list -> 'k list * 'v list list

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

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