Module String.Utf8

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.

map f (of_list [a1; ...; an]) applies f to a1, a2, ..., an, in order, and builds a result equivalent to of_list [f a1; ...; f an].

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

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_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).

partition_map t ~f partitions t according to f.

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

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

fold t ~init ~f returns f (... f (f (f init e1) e2) e3 ...) en, where e1..en are the elements of 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.

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.

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.

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.

This function only needs implementation if t exposed to be a polymorphic variant. Despite what the type reads, this does *not* produce a function after reading; instead it takes the constructor tag (int) before reading and reads the rest of the variant t afterwards.

ascending is identical to compare. descending x y = ascending y x. These are intended to be mnemonic when used like List.sort ~compare:ascending and List.sort ~cmp:descending, since they cause the list to be sorted in ascending or descending order, respectively.

between t ~low ~high means low <= t <= high

clamp_exn t ~min ~max returns t', the closest value to t such that between t' ~low:min ~high:max is true.

Raises if not (min <= max).