Module Array
structure Array = struct ... end 
Array operations.
val length : 'a array -> int
Return the length (number of elements) of the given array.
val get : 'a array -> int -> 'a
Array.get a n returns the element number n of array a.
   The first element has number 0.
   The last element has number Array.length a - 1.
   Raise Invalid_argument "Array.get"  if n is outside the range
   0 to (Array.length a - 1).
   You can also write a.(n) instead of Array.get a n.
val set : 'a array -> int -> 'a -> unit
Array.set a n x modifies array a in place, replacing
   element number n with x.
   Raise Invalid_argument "Array.set" if n is outside the range
   0 to Array.length a - 1.
   You can also write a.(n) <- x instead of Array.set a n x.
val make (create): int -> 'a -> 'a array
Array.make n x returns a fresh array of length n,
   initialized with x.
   All the elements of this new array are initially
   physically equal to x (in the sense of the == predicate).
   Consequently, if x is mutable, it is shared among all elements
   of the array, and modifying x through one of the array entries
   will modify all other entries at the same time.
   Raise Invalid_argument if n < 0 or n > Sys.max_array_length.
   If the value of x is a floating-point number, then the maximum
   size is only Sys.max_array_length / 2.
val init : int -> (int -> 'a) -> 'a array
Array.init n f returns a fresh array of length n,
   with element number i initialized to the result of f i.
   In other terms, Array.init n f tabulates the results of f
   applied to the integers 0 to n-1.
val make_matrix (create_matrix) : int -> int -> 'a -> 'a array array
Array.make_matrix dimx dimy e returns a two-dimensional array
   (an array of arrays) with first dimension dimx and
   second dimension dimy. All the elements of this new matrix
   are initially physically equal to e.
   The element (x,y) of a matrix m is accessed
   with the notation m.(x).(y).
   Raise Invalid_argument if dimx or dimy is less than 1 or
   greater than Sys.max_array_length.
   If the value of e is a floating-point number, then the maximum
   size is only Sys.max_array_length / 2.
val append : 'a array -> 'a array -> 'a array
Array.append v1 v2 returns a fresh array containing the
   concatenation of the arrays v1 and v2.
val concat : 'a array list -> 'a array
Same as Array.append, but concatenates a list of arrays.
val sub : 'a array -> int -> int -> 'a array
Array.sub a start len returns a fresh array of length len,
   containing the elements number start to start + len - 1
   of array a.
   Raise Invalid_argument "Array.sub" if start and len do not
   designate a valid subarray of a; that is, if
   start < 0, or len < 0, or start + len > Array.length a.
val copy : 'a array -> 'a array
Array.copy a returns a copy of a, that is, a fresh array
   containing the same elements as a.
val fill : 'a array -> int -> int -> 'a -> unit
Array.fill a ofs len x modifies the array a in place,
   storing x in elements number ofs to ofs + len - 1.
   Raise Invalid_argument "Array.fill" if ofs and len do not
   designate a valid subarray of a.
val blit : 'a array -> int -> 'a array -> int -> int -> unit
Array.blit v1 o1 v2 o2 len copies len elements
   from array v1, starting at element number o1, to array v2,
   starting at element number o2. It works correctly even if
   v1 and v2 are the same array, and the source and
   destination chunks overlap.
   Raise Invalid_argument "Array.blit" if o1 and len do not
   designate a valid subarray of v1, or if o2 and len do not
   designate a valid subarray of v2.
val to_list : 'a array -> 'a list
Array.to_list a returns the list of all the elements of a.
val of_list : 'a list -> 'a array
Array.of_list l returns a fresh array containing the elements
   of l.
val iter : ('a -> unit) -> 'a array -> unit
Array.iter f a applies function f in turn to all
   the elements of a.  It is equivalent to
   f a.(0); f a.(1); ...; f a.(Array.length a - 1); ().
val map : ('a -> 'b) -> 'a array -> 'b array
Array.map f a applies function f to all the elements of a,
   and builds an array with the results returned by f:
   [| f a.(0); f a.(1); ...; f a.(Array.length a - 1) |].
val iteri : (int -> 'a -> unit) -> 'a array -> unit
Same as 
Array.iter, but the
   function is applied to the index of the element as first argument,
   and the element itself as second argument.
val mapi : (int -> 'a -> 'b) -> 'a array -> 'b array
Same as 
Array.map, but the
   function is applied to the index of the element as first argument,
   and the element itself as second argument.
val fold_left : ('a -> 'b -> 'a) -> 'a -> 'b array -> 'a
Array.fold_left f x a computes
   f (... (f (f x a.(0)) a.(1)) ...) a.(n-1),
   where n is the length of the array a.
val fold_right : ('a -> 'b -> 'b) -> 'a array -> 'b -> 'b
Array.fold_right f a x computes
   f a.(0) (f a.(1) ( ... (f a.(n-1) x) ...)),
   where n is the length of the array a.
val sort : ('a -> 'a -> int) -> 'a array -> unit
Sort an array in increasing order according to a comparison
   function.  The comparison function must return 0 if its arguments
   compare as equal, a positive integer if the first is greater,
   and a negative integer if the first is smaller.  For example,
   the 
Pervasives.compare function is a suitable comparison function.
   After calling 
Array.sort, the array is sorted in place in
   increasing order.
   
Array.sort is guaranteed to run in constant heap space
   and logarithmic stack space.
   The current implementation uses Heap Sort.  It runs in constant
   stack space.
val stable_sort : ('a -> 'a -> int) -> 'a array -> unit
Same as 
Array.sort, but the sorting algorithm is stable and
   not guaranteed to use a fixed amount of heap memory.
   The current implementation is Merge Sort. It uses 
n/2
   words of heap space, where 
n is the length of the array.
   It is faster than the current implementation of 
Array.sort.