package combinat

  1. Overview
  2. Docs

Module Combinat.CombinationSource

Compute all of the t combinations of the numbers in 0, {i n}.

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

Sourceval length : (Base.int * Base.int) -> int
Sourceval is_empty : (Base.int * Base.int) -> bool

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

Sourceval fold : (Base.int * Base.int) -> 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.

Sourceval fold_result : (Base.int * Base.int) -> 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.

Sourceval fold_until : (Base.int * Base.int) -> 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.

Sourceval sum : (module Base.Container.Summable with type t = 'sum) -> (Base.int * Base.int) -> 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.

Sourceval find_map : (Base.int * Base.int) -> 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.