package combinat

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Compute the unique permutations of an array. See (Knuth 2b, pg. 1).

Checks whether the provided element is there, using equality on elts.

val length : Base.int Base.array -> int
val is_empty : Base.int Base.array -> bool

iter must allow exceptions raised in f to escape, terminating the iteration cleanly. The same holds for all functions below taking an f.

val fold : Base.int Base.array -> init:'acc -> f: ('acc -> (Base.int, Bigarray.int_elt, Bigarray.c_layout) Bigarray.Array1.t -> 'acc) -> 'acc

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 : Base.int Base.array -> init:'acc -> f: ('acc -> (Base.int, Bigarray.int_elt, Bigarray.c_layout) Bigarray.Array1.t -> ('acc, 'e) Base.Result.t) -> ('acc, 'e) Base.Result.t

fold_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 : Base.int Base.array -> init:'acc -> f: ('acc -> (Base.int, Bigarray.int_elt, Bigarray.c_layout) Bigarray.Array1.t -> ('acc, 'final) Base.Container.Continue_or_stop.t) -> finish:('acc -> 'final) -> 'final

fold_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 -3

Returns 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) -> Base.int Base.array -> f:((Base.int, Bigarray.int_elt, Bigarray.c_layout) Bigarray.Array1.t -> 'sum) -> 'sum

Returns the sum of f i for all i in the container.

Returns as an option the first element for which f evaluates to true.

val find_map : Base.int Base.array -> f: ((Base.int, Bigarray.int_elt, Bigarray.c_layout) Bigarray.Array1.t -> 'a option) -> 'a option

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.

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