Module Base.IarraySource

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 the number of elements for which the provided function evaluates to true.

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

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.

Returns the sum of f i for all i in the container. The order in which the elements will be summed is unspecified.

iter_until t ~f ~finish is a short-circuiting version of iter. If f returns Stop x the computation ceases and returns x. If f always returns Continue () the final result is computed by finish.

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.

Returns the first evaluation of f that returns Some, and returns None if there is no such element.

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

E.g., append (of_list [a; b]) (of_list [c; d; e]) is of_list [a; b; c; d; e]

Concatenates a nested container. The elements of the inner containers are concatenated together in order to give the result.

filter t ~f returns all the elements of t that satisfy the predicate f.

partition_tf t ~f returns a pair t1, t2, where t1 is all elements of t that satisfy f, and t2 is all elements of t that do not satisfy f. The "tf" suffix is mnemonic to remind readers that the result is (trues, falses).

filter_map t ~f applies f to every x in t. The result contains every y for which f x returns Some y.

concat_map t ~f is equivalent to concat (map t ~f).

partition_map t ~f partitions t according to f.