Array (p.server-reason-react.0.5.1.doc.server-reason-react.belt.Belt.Array)

type 'a t = 'a array

val length : 'a t -> int

length xs return the size of the array

val size : 'a t -> int

See length

val get : 'a t -> int -> 'a option

get arr i

If i <= 0 <= length arr;returns Some value where value is the item at index i If i is out of range;returns None

  Belt.Array.get [| "a"; "b"; "c" |] 0 = Some "a";;
  Belt.Array.get [| "a"; "b"; "c" |] 3 = None;;
  Belt.Array.get [| "a"; "b"; "c" |] (-1) = None

val getExn : 'a t -> int -> 'a

getExn arr i

raise an exception if i is out of range;otherwise return the value at index i in arr

val getUnsafe : 'a t -> int -> 'a

getUnsafe arr i

Unsafe

no bounds checking;this would cause type error if i does not stay within range

val getUndefined : 'a t -> int -> 'a Js.undefined

getUndefined arr i

It does the same thing in the runtime as getUnsafe; it is type safe since the return type still tracks whether it is in range or not. On native this is represented using the same option-backed encoding as Js.Undefined.

val set : 'a t -> int -> 'a -> bool

set arr n x modifies arr in place; it replaces the nth element of arr with x

returns
false means not updated due to out of range

val setExn : 'a t -> int -> 'a -> unit

setExn arr i x raise an exception if i is out of range

val setUnsafe : 'a t -> int -> 'a -> unit

val shuffleInPlace : 'a t -> unit

shuffleInPlace arr randomly re-orders the items in arr

val shuffle : 'a t -> 'a t

shuffle xs

returns
a fresh array with items in original array randomly shuffled

val reverseInPlace : 'a t -> unit

reverseInPlace arr reverses items in arr in place

  let arr = [| 10; 11; 12; 13; 14 |]
  let () = reverseInPlace arr;;

  arr = [| 14; 13; 12; 11; 10 |]

val reverse : 'a t -> 'a t

reverse arr

returns
a fresh array with items in arr in reverse order

  reverse [| 10; 11; 12; 13; 14 |] = [| 14; 13; 12; 11; 10 |]

val makeUninitialized : int -> 'a Js.undefined array

makeUninitialized n creates an array of length n filled with the undefined value. You must specify the type of data that will eventually fill the array.

  let arr : string Js.undefined array = makeUninitialized 5;;

  getExn arr 0 = Js.undefined

val makeUninitializedUnsafe : int -> 'a -> 'a array

makeUninitializedUnsafe n filler

Unsafe

Native approximation of the JavaScript makeUninitializedUnsafe. Since OCaml arrays must be fully initialized, the filler value is used to allocate the array before callers overwrite the slots they need. Unread slots therefore contain filler, not JavaScript-style holes or undefined.

  let arr = Belt.Array.makeUninitializedUnsafe 5 "placeholder";;

  Belt.Array.setExn arr 0 "example";;
  Belt.Array.getExn arr 0 = "example"

val make : int -> 'a -> 'a t

make n e return an array of size n filled with value e

returns
an empty array when n is negative.

val range : int -> int -> int t

range start finish create an inclusive array

  range 0 3 = [| 0; 1; 2; 3 |];;
  range 3 0 = [||];;
  range 3 3 = [| 3 |]

val rangeBy : int -> int -> step:int -> int t

rangeBy start finish ~step

returns
empty array when step is 0 or negative it also return empty array when start > finish

  rangeBy 0 10 ~step:3 = [| 0; 3; 6; 9 |];;
  rangeBy 0 12 ~step:3 = [| 0; 3; 6; 9; 12 |];;
  rangeBy 33 0 ~step:1 = [||];;
  rangeBy 33 0 ~step:(-1) = [||];;
  rangeBy 3 12 ~step:(-1) = [||];;
  rangeBy 3 3 ~step:0 = [||];;
  rangeBy 3 3 ~step:1 = [| 3 |]

val makeByU : int -> (int -> 'a) -> 'a t

val makeBy : int -> (int -> 'a) -> 'a t

makeBy n f

return an empty array when n is negative return an array of size n populated by f i start from 0 to n - 1

  makeBy 5 (fun i -> i) = [| 0; 1; 2; 3; 4 |];;
  makeBy 5 (fun i -> i * i) = [| 0; 1; 4; 9; 16 |]

val makeByAndShuffleU : int -> (int -> 'a) -> 'a t

val makeByAndShuffle : int -> (int -> 'a) -> 'a t

makeByAndShuffle n f

Equivalent to shuffle (makeBy n f)

val zip : 'a t -> 'b array -> ('a * 'b) array

zip a b

Create an array of pairs from corresponding elements of a and b. Stop with the shorter array

  zip [| 1; 2 |] [| 3; 4; 5 |] = [| (1, 3); (2, 4) |]

val zipByU : 'a t -> 'b array -> ('a -> 'b -> 'c) -> 'c array

val zipBy : 'a t -> 'b array -> ('a -> 'b -> 'c) -> 'c array

zipBy xs ys f

Create an array by applying f to corresponding elements of xs and ys Stops with shorter array

Equivalent to map (zip xs ys) (fun (a,b) -> f a b)

  zipBy [| 1; 2; 3 |] [| 4; 5 |] (fun a b -> (2 * a) + b) = [| 6; 9 |]

val unzip : ('a * 'b) array -> 'a t * 'b array

unzip a takes an array of pairs and creates a pair of arrays. The first array contains all the first items of the pairs; the second array contains all the second items.

  unzip [| (1, 2); (3, 4) |] = ([| 1; 3 |], [| 2; 4 |]);;
  unzip [| (1, 2); (3, 4); (5, 6); (7, 8) |] = ([| 1; 3; 5; 7 |], [| 2; 4; 6; 8 |])

val concat : 'a t -> 'a t -> 'a t

concat xs ys

returns
a fresh array containing the concatenation of the arrays v1 and v2;so even if v1 or v2 is empty;it can not be shared

  concat [| 1; 2; 3 |] [| 4; 5 |] = [| 1; 2; 3; 4; 5 |];;
  concat [||] [| "a"; "b"; "c" |] = [| "a"; "b"; "c" |]

val concatMany : 'a t t -> 'a t

concatMany xss

returns
a fresh array as the concatenation of xss (an array of arrays)

  concatMany [| [| 1; 2; 3 |]; [| 4; 5; 6 |]; [| 7; 8 |] |] = [| 1; 2; 3; 4; 5; 6; 7; 8 |]

val slice : 'a t -> offset:int -> len:int -> 'a t

slice xs offset len creates a new array with the len elements of xs starting at offset for

offset can be negative;and is evaluated as length xs - offset slice xs -1 1 means get the last element as a singleton array

slice xs (-len) len will return a copy of the array

if the array does not have enough data;slice extracts through the end of sequence.

if len is negative;returns the empty array.

  slice [| 10; 11; 12; 13; 14; 15; 16 |] ~offset:2 ~len:3 = [| 12; 13; 14 |];;
  slice [| 10; 11; 12; 13; 14; 15; 16 |] ~offset:(-4) ~len:3 = [| 13; 14; 15 |];;
  slice [| 10; 11; 12; 13; 14; 15; 16 |] ~offset:4 ~len:9 = [| 14; 15; 16 |]

val sliceToEnd : 'a t -> int -> 'a t

sliceToEnd xs offset creates a new array with the elements of xs starting at offset

offset can be negative;and is evaluated as length xs - offset sliceToEnd xs -1 means get the last element as a singleton array

sliceToEnd xs 0 will return a copy of the array

  sliceToEnd [| 10; 11; 12; 13; 14; 15; 16 |] 2 = [| 12; 13; 14; 15; 16 |];;
  sliceToEnd [| 10; 11; 12; 13; 14; 15; 16 |] (-4) = [| 13; 14; 15; 16 |]

val copy : 'a t -> 'a t

copy a

returns
a copy of a;that is;a fresh array containing the same elements as a.

val fill : 'a t -> offset:int -> len:int -> 'a -> unit

fill arr ~offset ~len x

Modifies arr in place, storing x in elements number offset to offset + len - 1.

offset can be negative;and is evaluated as length arr - offset

fill arr ~offset:(-1) ~len:1 means fill the last element, if the array does not have enough data;fill will ignore it

  let arr = makeBy 5 (fun i -> i);;

  fill arr ~offset:2 ~len:2 9;;
  arr = [| 0; 1; 9; 9; 4 |];;
  fill arr ~offset:7 ~len:2 8;;
  arr = [| 0; 1; 9; 9; 4 |]

val blit : 
  src:'a t ->
  srcOffset:int ->
  dst:'a t ->
  dstOffset:int ->
  len:int ->
  unit

blit ~src:v1 ~srcOffset:o1 ~dst:v2 ~dstOffset: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.

offset can be negative;-1 means len - 1;if len + offset is still negative;it will be set as 0

For each of the examples;presume that v1 = [|10;11;12;13;14;15;16;17|] and v2 = [|20;21;22;23;24;25;26;27|]. The result shown is the content of the destination array.

  Belt.Array.blit ~src:v1 ~srcOffset:4 ~dst:v2 ~dstOffset:2 ~len:3
  |. [| 20; 21; 14; 15; 16; 25; 26; 27 |] Belt.Array.blit ~src:v1 ~srcOffset:4 ~dst:v1 ~dstOffset:2 ~len:3
  |. [| 10; 11; 14; 15; 16; 15; 16; 17 |]

val blitUnsafe : 
  src:'a t ->
  srcOffset:int ->
  dst:'a t ->
  dstOffset:int ->
  len:int ->
  unit

Unsafe blit without bounds checking

val forEachU : 'a t -> ('a -> unit) -> unit

val forEach : 'a t -> ('a -> unit) -> unit

forEach xs f

Call f on each element of xs from the beginning to end. f returns unit;so no new array is created. Use forEach when you are primarily concerned with repetitively creating side effects.

  forEach [| "a"; "b"; "c" |] (fun x -> Js.log ("Item: " ^ x));;

  (*  prints:
    Item: a
    Item: b
    Item: c
  *)

  let total = ref 0;;

  forEach [| 1; 2; 3; 4 |] (fun x -> total := !total + x);;
  !total = 1 + 2 + 3 + 4

val mapU : 'a t -> ('a -> 'b) -> 'b array

val map : 'a t -> ('a -> 'b) -> 'b array

map xs f

returns
a new array by calling f for each element of xs from the beginning to end

  map [| 1; 2 |] (fun x -> x + 10) = [| 11; 12 |]

val flatMapU : 'a t -> ('a -> 'b t) -> 'b t

val flatMap : 'a t -> ('a -> 'b t) -> 'b t

flatMap xs f **return** a new array by calling `f` for each element of `xs` from the beginning to end, and then concatenating the results ``` flatMap |1;2| (fun x-> |x + 10;x + 20|) = |11;21;12;22| ```

val getByU : 'a t -> ('a -> bool) -> 'a option

val getBy : 'a t -> ('a -> bool) -> 'a option

getBy xs p returns Some value for the first value in xs that satisifies the predicate function p; returns None if no element satisifies the function.

  getBy [|1;4;3;2|] (fun x -> x mod 2 = 0) = Some 4
  getBy [|15;13;11|] (fun x -> x mod 2 = 0) = None

val getIndexByU : 'a t -> ('a -> bool) -> int option

val getIndexBy : 'a t -> ('a -> bool) -> int option

getIndexBy xs p returns Some index for the first value in xs that satisifies the predicate function p; returns None if no element satisifies the function.

  getIndexBy [|1;4;3;2|] (fun x -> x mod 2 = 0) = Some 1
  getIndexBy [|15;13;11|] (fun x -> x mod 2 = 0) = None

val keepU : 'a t -> ('a -> bool) -> 'a t

val keep : 'a t -> ('a -> bool) -> 'a t

keep xs p

returns
a new array that keeps all elements satisfying p

  keep [| 1; 2; 3 |] (fun x -> x mod 2 = 0) = [| 2 |]

val keepWithIndexU : 'a t -> ('a -> int -> bool) -> 'a t

val keepWithIndex : 'a t -> ('a -> int -> bool) -> 'a t

keepWithIndex xs p

returns
a new array that keeps all elements satisfying p. The predicate p takes two arguments: the element from xs and the index starting from 0.

  keepWithIndex [| 1; 2; 3 |] (fun _x i -> i = 1) = [| 2 |]

val keepMapU : 'a t -> ('a -> 'b option) -> 'b array

val keepMap : 'a t -> ('a -> 'b option) -> 'b array

keepMap xs p

returns
a new array that keeps all elements that return a non-None when applied to p

  keepMap [| 1; 2; 3 |] (fun x -> if x mod 2 = 0 then Some x else None) = [| 2 |]

val forEachWithIndexU : 'a t -> (int -> 'a -> unit) -> unit

val forEachWithIndex : 'a t -> (int -> 'a -> unit) -> unit

forEachWithIndex xs f

The same as forEach; except that f is supplied with two arguments: the index starting from 0 and the element from xs

  forEachWithIndex [| "a"; "b"; "c" |] (fun i x -> Js.log ("Item " ^ string_of_int i ^ " is " ^ x));;

  (*  prints:
    Item 0 is a
    Item 1 is b
    Item 2 is c
  *)

  let total = ref 0;;

  forEachWithIndex [| 10; 11; 12; 13 |] (fun i x -> total := !total + x + i);;
  !total = 0 + 10 + 1 + 11 + 2 + 12 + 3 + 13

val mapWithIndexU : 'a t -> (int -> 'a -> 'b) -> 'b t

val mapWithIndex : 'a t -> (int -> 'a -> 'b) -> 'b t

mapWithIndex xs f applies f to each element of xs. Function f takes two arguments: the index starting from 0 and the element from xs.

  mapWithIndex [| 1; 2; 3 |] (fun i x -> i + x) = [| 0 + 1; 1 + 2; 2 + 3 |]

val partitionU : 'a t -> ('a -> bool) -> 'a t * 'a t

val partition : 'a t -> ('a -> bool) -> 'a t * 'a t

partition f a split array into tuple of two arrays based on predicate f; first of tuple where predicate cause true, second where predicate cause false

  partition [| 1; 2; 3; 4; 5 |] (fun x -> x mod 2 = 0) = ([| 2; 4 |], [| 1; 2; 3 |]);;
  partition [| 1; 2; 3; 4; 5 |] (fun x -> x mod 2 <> 0) = ([| 1; 2; 3 |], [| 2; 4 |])

val reduceU : 'b array -> 'a -> ('a -> 'b -> 'a) -> 'a

val reduce : 'b array -> 'a -> ('a -> 'b -> 'a) -> 'a

reduce xs init f

Applies f to each element of xs from beginning to end. Function f has two parameters: the item from the list and an “accumulator”;which starts with a value of init. reduce returns the final value of the accumulator.

  reduce [| 2; 3; 4 |] 1 ( + ) = 10;;
  reduce [| "a"; "b"; "c"; "d" |] "" ( ^ ) = "abcd"

val reduceReverseU : 'b array -> 'a -> ('a -> 'b -> 'a) -> 'a

val reduceReverse : 'b array -> 'a -> ('a -> 'b -> 'a) -> 'a

reduceReverse xs init f

Works like reduce;except that function f is applied to each item of xs from the last back to the first.

  reduceReverse [| "a"; "b"; "c"; "d" |] "" ( ^ ) = "dcba"

val reduceReverse2U : 'a t -> 'b array -> 'c -> ('c -> 'a -> 'b -> 'c) -> 'c

val reduceReverse2 : 'a t -> 'b array -> 'c -> ('c -> 'a -> 'b -> 'c) -> 'c

reduceReverse2 xs ys init f Reduces two arrays xs and ys;taking items starting at min (length xs) (length ys) down to and including zero.

  reduceReverse2 [| 1; 2; 3 |] [| 1; 2 |] 0 (fun acc x y -> acc + x + y) = 6

val reduceWithIndexU : 'a t -> 'b -> ('b -> 'a -> int -> 'b) -> 'b

val reduceWithIndex : 'a t -> 'b -> ('b -> 'a -> int -> 'b) -> 'b

reduceWithIndex xs f

Applies f to each element of xs from beginning to end. Function f has three parameters: the item from the array and an “accumulator”, which starts with a value of init and the index of each element. reduceWithIndex returns the final value of the accumulator.

  reduceWithIndex [| 1; 2; 3; 4 |] 0 (fun acc x i -> acc + x + i) = 16

val joinWithU : 'a t -> string -> ('a -> string) -> string

val joinWith : 'a t -> string -> ('a -> string) -> string

joinWith xs sep toString

Concatenates all the elements of xs converted to string with toString, each separated by sep, the string given as the second argument, into a single string. If the array has only one element, then that element will be returned without using the separator. If the array is empty, the empty string will be returned.

  joinWith [| 0; 1 |] ", " string_of_int
  = "0, 1" joinWith [||] " " string_of_int
  = "" joinWith [| 1 |] " " string_of_int = "1"

val someU : 'a t -> ('a -> bool) -> bool

val some : 'a t -> ('a -> bool) -> bool

some xs p

returns
true if at least one of the elements in xs satifies p;where p is a predicate: a function taking an element and returning a bool.

  some [| 2; 3; 4 |] (fun x -> x mod 2 = 1) = true;;
  some [| -1; -3; -5 |] (fun x -> x > 0) = false

val everyU : 'a t -> ('a -> bool) -> bool

val every : 'a t -> ('a -> bool) -> bool

every xs p

returns
true if all elements satisfy p;where p is a predicate: a function taking an element and returning a bool.

  every [| 1; 3; 5 |] (fun x -> x mod 2 = 1) = true;;
  every [| 1; -3; 5 |] (fun x -> x > 0) = false

val every2U : 'a t -> 'b t -> ('a -> 'b -> bool) -> bool

val every2 : 'a t -> 'b t -> ('a -> 'b -> bool) -> bool

every2 xs ys p returns true if p xi yi is true for all pairs of elements up to the shorter length (i.e. min (length xs) (length ys))

  every2 [| 1; 2; 3 |] [| 0; 1 |] ( > ) = true;;
  every2 [||] [| 1 |] (fun x y -> x > y) = true;;
  every2 [| 2; 3 |] [| 1 |] (fun x y -> x > y) = true;;
  every2 [| 0; 1 |] [| 5; 0 |] (fun x y -> x > y) = false

val some2U : 'a t -> 'b t -> ('a -> 'b -> bool) -> bool

val some2 : 'a t -> 'b t -> ('a -> 'b -> bool) -> bool

some2 xs ys p returns true if p xi yi is true for any pair of elements up to the shorter length (i.e. min (length xs) (length ys))

  some2 [| 0; 2 |] [| 1; 0; 3 |] ( > ) = true;;
  some2 [||] [| 1 |] (fun x y -> x > y) = false;;
  some2 [| 2; 3 |] [| 1; 4 |] (fun x y -> x > y) = true

val cmpU : 'a t -> 'a t -> ('a -> 'a -> int) -> int

val cmp : 'a t -> 'a t -> ('a -> 'a -> int) -> int

cmp xs ys f

Compared by length if length xs <> length ys;returning -1 iflength xs < length ys or 1 if length xs > length ys
Otherwise compare one by one f x y. f returns
a negative number if x is “less than” y
zero if x is “equal to” y
a positive number if x is “greater than” y
The comparison returns the first non-zero result of f;or zero if f returns zero for all x and y.

  cmp [| 1; 3; 5 |] [| 1; 4; 2 |] (fun a b -> compare a b) = -1;;
  cmp [| 1; 3; 5 |] [| 1; 2; 3 |] (fun a b -> compare a b) = 1;;
  cmp [| 1; 3; 5 |] [| 1; 3; 5 |] (fun a b -> compare a b) = 0

val eqU : 'a t -> 'a t -> ('a -> 'a -> bool) -> bool

val eq : 'a t -> 'a t -> ('a -> 'a -> bool) -> bool

eq xs ys

return false if length is not the same
otherwise compare items one by one using f xi yi;and return true if all results are true;false otherwise

  eq [| 1; 2; 3 |] [| -1; -2; -3 |] (fun a b -> abs a = abs b) = true

val truncateToLengthUnsafe : 'a t -> int -> 'a t

Unsafe Native-only approximation of the JavaScript truncateToLengthUnsafe.

On native this returns a fresh truncated copy of xs. It does not mutate the input array length, and it cannot grow the array because OCaml arrays are fixed length.

Raises Invalid_argument if n is negative or larger than length xs.

  let arr = [| "ant"; "bee"; "cat"; "dog"; "elk" |]
  let truncated = truncateToLengthUnsafe arr 3;;

  truncated = [| "ant"; "bee"; "cat" |];;
  arr = [| "ant"; "bee"; "cat"; "dog"; "elk" |]

val initU : int -> (int -> 'a) -> 'a t

val init : int -> (int -> 'a) -> 'a t

val push : 'a t -> 'a -> unit

OCaml arrays are fixed length and cannot grow in place like JavaScript arrays: raises at runtime. Use a copy-based helper instead when you need to append on native.

alert not_implemented is not implemented in native under server-reason-react.belt