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<!doctype html>
<html>
<head>
<link rel="stylesheet" href="../api_static/tomorrow-night.css">
<link rel="stylesheet" href="../api_static/style.css" type="text/css">
<script src="../api_static//highlight.pack.js"></script>
<script src="../api_static//script.js"></script>
<script>hljs.initHighlightingOnLoad();</script>
<meta charset="utf8">
<link rel="previous" href="Belt.Id.html"><link rel="next" href="Belt.SortArray.html">
<title> Belt.Array </title></head>
<body>
<nav class="module-index"><ul><li><a href="Belt.html">Belt</a></li>
<li><a href="Belt_Array.html">Belt_Array</a></li>
<li><a href="Belt_Debug.html">Belt_Debug</a></li>
<li><a href="Belt_Float.html">Belt_Float</a></li>
<li><a href="Belt_HashMap.html">Belt_HashMap</a></li>
<li><a href="Belt_HashMapInt.html">Belt_HashMapInt</a></li>
<li><a href="Belt_HashMapString.html">Belt_HashMapString</a></li>
<li><a href="Belt_HashSet.html">Belt_HashSet</a></li>
<li><a href="Belt_HashSetInt.html">Belt_HashSetInt</a></li>
<li><a href="Belt_HashSetString.html">Belt_HashSetString</a></li>
<li><a href="Belt_Id.html">Belt_Id</a></li>
<li><a href="Belt_Int.html">Belt_Int</a></li>
<li><a href="Belt_List.html">Belt_List</a></li>
<li><a href="Belt_Map.html">Belt_Map</a></li>
<li><a href="Belt_MapDict.html">Belt_MapDict</a></li>
<li><a href="Belt_MapInt.html">Belt_MapInt</a></li>
<li><a href="Belt_MapString.html">Belt_MapString</a></li>
<li><a href="Belt_MutableMap.html">Belt_MutableMap</a></li>
<li><a href="Belt_MutableMapInt.html">Belt_MutableMapInt</a></li>
<li><a href="Belt_MutableMapString.html">Belt_MutableMapString</a></li>
<li><a href="Belt_MutableQueue.html">Belt_MutableQueue</a></li>
<li><a href="Belt_MutableSet.html">Belt_MutableSet</a></li>
<li><a href="Belt_MutableSetInt.html">Belt_MutableSetInt</a></li>
<li><a href="Belt_MutableSetString.html">Belt_MutableSetString</a></li>
<li><a href="Belt_MutableStack.html">Belt_MutableStack</a></li>
<li><a href="Belt_Option.html">Belt_Option</a></li>
<li><a href="Belt_Range.html">Belt_Range</a></li>
<li><a href="Belt_Result.html">Belt_Result</a></li>
<li><a href="Belt_Set.html">Belt_Set</a></li>
<li><a href="Belt_SetDict.html">Belt_SetDict</a></li>
<li><a href="Belt_SetInt.html">Belt_SetInt</a></li>
<li><a href="Belt_SetString.html">Belt_SetString</a></li>
<li><a href="Belt_SortArray.html">Belt_SortArray</a></li>
<li><a href="Belt_SortArrayInt.html">Belt_SortArrayInt</a></li>
<li><a href="Belt_SortArrayString.html">Belt_SortArrayString</a></li>
<li><a href="Belt_internalAVLset.html">Belt_internalAVLset</a></li>
<li><a href="Belt_internalAVLtree.html">Belt_internalAVLtree</a></li>
<li><a href="Belt_internalBuckets.html">Belt_internalBuckets</a></li>
<li><a href="Belt_internalBucketsType.html">Belt_internalBucketsType</a></li>
<li><a href="Belt_internalMapInt.html">Belt_internalMapInt</a></li>
<li><a href="Belt_internalMapString.html">Belt_internalMapString</a></li>
<li><a href="Belt_internalSetBuckets.html">Belt_internalSetBuckets</a></li>
<li><a href="Belt_internalSetInt.html">Belt_internalSetInt</a></li>
<li><a href="Belt_internalSetString.html">Belt_internalSetString</a></li>
<li><a href="Dom.html">Dom</a></li>
<li><a href="Dom_storage.html">Dom_storage</a></li>
<li><a href="Dom_storage2.html">Dom_storage2</a></li>
<li><a href="Js.html">Js</a></li>
<li><a href="Js_array.html">Js_array</a></li>
<li><a href="Js_array2.html">Js_array2</a></li>
<li><a href="Js_cast.html">Js_cast</a></li>
<li><a href="Js_console.html">Js_console</a></li>
<li><a href="Js_date.html">Js_date</a></li>
<li><a href="Js_dict.html">Js_dict</a></li>
<li><a href="Js_exn.html">Js_exn</a></li>
<li><a href="Js_float.html">Js_float</a></li>
<li><a href="Js_global.html">Js_global</a></li>
<li><a href="Js_int.html">Js_int</a></li>
<li><a href="Js_json.html">Js_json</a></li>
<li><a href="Js_list.html">Js_list</a></li>
<li><a href="Js_mapperRt.html">Js_mapperRt</a></li>
<li><a href="Js_math.html">Js_math</a></li>
<li><a href="Js_null.html">Js_null</a></li>
<li><a href="Js_null_undefined.html">Js_null_undefined</a></li>
<li><a href="Js_obj.html">Js_obj</a></li>
<li><a href="Js_option.html">Js_option</a></li>
<li><a href="Js_promise.html">Js_promise</a></li>
<li><a href="Js_re.html">Js_re</a></li>
<li><a href="Js_result.html">Js_result</a></li>
<li><a href="Js_string.html">Js_string</a></li>
<li><a href="Js_string2.html">Js_string2</a></li>
<li><a href="Js_typed_array.html">Js_typed_array</a></li>
<li><a href="Js_typed_array2.html">Js_typed_array2</a></li>
<li><a href="Js_types.html">Js_types</a></li>
<li><a href="Js_undefined.html">Js_undefined</a></li>
<li><a href="Js_vector.html">Js_vector</a></li>
<li><a href="Node.html">Node</a></li>
<li><a href="Node_buffer.html">Node_buffer</a></li>
<li><a href="Node_child_process.html">Node_child_process</a></li>
<li><a href="Node_fs.html">Node_fs</a></li>
<li><a href="Node_module.html">Node_module</a></li>
<li><a href="Node_path.html">Node_path</a></li>
<li><a href="Node_process.html">Node_process</a></li></ul></nav>
<div class="navbar"><a class="pre" href="Belt.Id.html" title="Belt.Id">Previous</a>
<a class="up" href="Belt.html" title="Belt">Up</a>
<a class="post" href="Belt.SortArray.html" title="Belt.SortArray">Next</a>
</div>
<h1>Module <a href="type_Belt.Array.html">Belt.Array</a></h1>
<pre><span id="MODULEArray"><span class="keyword">module</span> Array</span>: <code class="type"><a href="Belt_Array.html">Belt_Array</a></code></pre><div class="info module top">
<div class="not-examples">
<a href="Belt.Array.html"><code class="code">Belt.Array</code></a>
<b>mutable array</b>: Utilities functions<br>
</div>
</div>
<hr width="100%">
<pre><span id="VALlength"><span class="keyword">val</span> length</span> : <code class="type">'a array -> int</code></pre><div class="info ">
<div class="not-examples">
<code class="code">length xs</code> return the size of the array<br>
</div>
</div>
<pre><span id="VALsize"><span class="keyword">val</span> size</span> : <code class="type">'a array -> int</code></pre><div class="info ">
<div class="not-examples">
<b>See</b> <a href="Belt_Array.html#VALlength"><code class="code">Belt_Array.length</code></a><br>
</div>
</div>
<pre><span id="VALget"><span class="keyword">val</span> get</span> : <code class="type">'a array -> int -> 'a option</code></pre><div class="info ">
<div class="not-examples">
<code class="code">get arr i</code>
If <code class="code">i <= 0 <= length arr</code>;returns <code class="code">Some value</code> where <code class="code">value</code> is the item at index <code class="code">i</code>
If <code class="code">i</code> is out of range;returns <code class="code">None</code><br>
</div>
<div class="examples">
<pre class="example"> <pre class="codepre"><code class="code"> 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;;
</code></pre> </pre>
</div>
</div>
<pre><span id="VALgetExn"><span class="keyword">val</span> getExn</span> : <code class="type">'a array -> int -> 'a</code></pre><div class="info ">
<div class="not-examples">
<code class="code">getExn arr i</code>
<b>raise</b> an exception if <code class="code">i</code> is out of range;otherwise return the value at index <code class="code">i</code> in <code class="code">arr</code><br>
</div>
</div>
<pre><span id="VALgetUnsafe"><span class="keyword">val</span> getUnsafe</span> : <code class="type">'a array -> int -> 'a</code></pre><div class="info ">
<div class="not-examples">
<code class="code">getUnsafe arr i</code>
<b>Unsafe</b>
no bounds checking;this would cause type error
if <code class="code">i</code> does not stay within range<br>
</div>
</div>
<pre><span id="VALgetUndefined"><span class="keyword">val</span> getUndefined</span> : <code class="type">'a array -> int -> 'a <a href="Js.html#TYPEundefined">Js.undefined</a></code></pre><div class="info ">
<div class="not-examples">
<code class="code">getUndefined arr i</code>
It does the samething in the runtime as <a href="Belt_Array.html#VALgetUnsafe"><code class="code">Belt_Array.getUnsafe</code></a>;
it is <i>type safe</i> since the return type still track whether it is
in range or not<br>
</div>
</div>
<pre><span id="VALset"><span class="keyword">val</span> set</span> : <code class="type">'a array -> int -> 'a -> bool</code></pre><div class="info ">
<div class="not-examples">
<code class="code">set arr n x</code> modifies <code class="code">arr</code> in place;
it replaces the nth element of <code class="code">arr</code> with <code class="code">x</code><br>
<div class="tag"> <li><b>Returns</b> false means not updated due to out of range</li>
</div>
</div>
</div>
<pre><span id="VALsetExn"><span class="keyword">val</span> setExn</span> : <code class="type">'a array -> int -> 'a -> unit</code></pre><div class="info ">
<div class="not-examples">
<code class="code">setExn arr i x</code>
<b>raise</b> an exception if <code class="code">i</code> is out of range<br>
</div>
</div>
<pre><span id="VALsetUnsafe"><span class="keyword">val</span> setUnsafe</span> : <code class="type">'a array -> int -> 'a -> unit</code></pre>
<pre><span id="VALshuffleInPlace"><span class="keyword">val</span> shuffleInPlace</span> : <code class="type">'a array -> unit</code></pre><div class="info ">
<div class="not-examples">
<code class="code">shuffleInPlace arr</code> randomly re-orders the items in <code class="code">arr</code><br>
</div>
</div>
<pre><span id="VALshuffle"><span class="keyword">val</span> shuffle</span> : <code class="type">'a array -> 'a array</code></pre><div class="info ">
<div class="not-examples">
<code class="code">shuffle xs</code><br>
<div class="tag"> <li><b>Returns</b> a fresh array with items in original array randomly shuffled</li>
</div>
</div>
</div>
<pre><span id="VALreverseInPlace"><span class="keyword">val</span> reverseInPlace</span> : <code class="type">'a array -> unit</code></pre><div class="info ">
<div class="not-examples">
<code class="code">reverseInPlace arr</code> reverses items in <code class="code">arr</code> in place<br>
</div>
<div class="examples">
<pre class="example"> <pre class="codepre"><code class="code"> let arr = [|10;11;12;13;14|];;
let () = reverseInPlace arr;;
arr = [|14;13;12;11;10|];;
</code></pre> </pre>
</div>
</div>
<pre><span id="VALreverse"><span class="keyword">val</span> reverse</span> : <code class="type">'a array -> 'a array</code></pre><div class="info ">
<div class="not-examples">
<code class="code">reverse arr</code><br>
<div class="tag"> <li><b>Returns</b> a fresh array with items in <code class="code">arr</code> in reverse order</li>
</div>
</div>
<div class="examples">
<pre class="example"> <pre class="codepre"><code class="code"> reverse [|10;11;12;13;14|] = [|14;13;12;11;10|];;
</code></pre> </pre>
</div>
</div>
<pre><span id="VALmakeUninitialized"><span class="keyword">val</span> makeUninitialized</span> : <code class="type">int -> 'a <a href="Js.html#TYPEundefined">Js.undefined</a> array</code></pre><div class="info ">
<div class="not-examples">
<code class="code">makeUninitialized n</code> creates an array of length <code class="code">n</code> filled with the undefined value.
You must specify the type of data that will eventually fill the array.<br>
</div>
<div class="examples">
<pre class="example"> <pre class="codepre"><code class="code"> let arr: string Js.undefined array = makeUninitialized 5;;
getExn arr 0 = Js.undefined;;
</code></pre> </pre>
</div>
</div>
<pre><span id="VALmakeUninitializedUnsafe"><span class="keyword">val</span> makeUninitializedUnsafe</span> : <code class="type">int -> 'a array</code></pre><div class="info ">
<div class="not-examples">
<code class="code">makeUninitializedUnsafe n</code>
<b>Unsafe</b><br>
</div>
<div class="examples">
<pre class="example"> <pre class="codepre"><code class="code"> let arr = Belt.Array.makeUninitializedUnsafe 5;;
let () = Js.log(Belt.Array.getExn arr 0);; (* undefined *)
Belt.Array.setExn arr 0 "example";;
let () = Js.log(Belt.Array.getExn arr 0 = "example");;
</code></pre> </pre>
</div>
</div>
<pre><span id="VALmake"><span class="keyword">val</span> make</span> : <code class="type">int -> 'a -> 'a array</code></pre><div class="info ">
<div class="not-examples">
<code class="code">make n e</code>
return an array of size <code class="code">n</code> filled with value <code class="code">e</code><br>
<div class="tag"> <li><b>Returns</b> an empty array when <code class="code">n</code> is negative.</li>
</div>
</div>
</div>
<pre><span id="VALrange"><span class="keyword">val</span> range</span> : <code class="type">int -> int -> int array</code></pre><div class="info ">
<div class="not-examples">
<code class="code">range start finish</code> create an inclusive array<br>
</div>
<div class="examples">
<pre class="example"> <pre class="codepre"><code class="code"> range 0 3 = [|0;1;2;3|];;
range 3 0 = [||] ;;
range 3 3 = [|3|];;
</code></pre> </pre>
</div>
</div>
<pre><span id="VALrangeBy"><span class="keyword">val</span> rangeBy</span> : <code class="type">int -> int -> step:int -> int array</code></pre><div class="info ">
<div class="not-examples">
<code class="code">rangeBy start finish ~step</code><br>
<div class="tag"> <li><b>Returns</b> empty array when step is 0 or negative
it also return empty array when <code class="code">start > finish</code></li>
</div>
</div>
<div class="examples">
<pre class="example"> <pre class="codepre"><code class="code"> 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|] ;;
</code></pre> </pre>
</div>
</div>
<pre><span id="VALmakeByU"><span class="keyword">val</span> makeByU</span> : <code class="type">int -> (int -> 'a [@bs]) -> 'a array</code></pre>
<pre><span id="VALmakeBy"><span class="keyword">val</span> makeBy</span> : <code class="type">int -> (int -> 'a) -> 'a array</code></pre><div class="info ">
<div class="not-examples">
<code class="code">makeBy n f</code>
return an empty array when <code class="code">n</code> is negative
return an array of size <code class="code">n</code> populated by <code class="code">f i</code> start from <code class="code">0</code> to <code class="code">n - 1</code><br>
</div>
<div class="examples">
<pre class="example"> <pre class="codepre"><code class="code"> makeBy 5 (fun i -> i) = [|0;1;2;3;4|];;
makeBy 5 (fun i -> i * i) = [|0;1;4;9;16|]
</code></pre> </pre>
</div>
</div>
<pre><span id="VALmakeByAndShuffleU"><span class="keyword">val</span> makeByAndShuffleU</span> : <code class="type">int -> (int -> 'a [@bs]) -> 'a array</code></pre>
<pre><span id="VALmakeByAndShuffle"><span class="keyword">val</span> makeByAndShuffle</span> : <code class="type">int -> (int -> 'a) -> 'a array</code></pre><div class="info ">
<div class="not-examples">
<code class="code">makeByAndShuffle n f</code>
Equivalent to <code class="code">shuffle (makeBy n f)</code><br>
</div>
</div>
<pre><span id="VALzip"><span class="keyword">val</span> zip</span> : <code class="type">'a array -> 'b array -> ('a * 'b) array</code></pre><div class="info ">
<div class="not-examples">
<code class="code">zip a b</code>
Create an array of pairs from corresponding elements of <code class="code">a</code> and <code class="code">b</code>.
Stop with the shorter array<br>
</div>
<div class="examples">
<pre class="example"> <pre class="codepre"><code class="code"> zip [|1;2|] [|3;4;5|] = [|(1, 3);(2, 4)|]
</code></pre> </pre>
</div>
</div>
<pre><span id="VALzipByU"><span class="keyword">val</span> zipByU</span> : <code class="type">'a array -> 'b array -> ('a -> 'b -> 'c [@bs]) -> 'c array</code></pre>
<pre><span id="VALzipBy"><span class="keyword">val</span> zipBy</span> : <code class="type">'a array -> 'b array -> ('a -> 'b -> 'c) -> 'c array</code></pre><div class="info ">
<div class="not-examples">
<code class="code">zipBy xs ys f</code>
Create an array by applying <code class="code">f</code> to corresponding elements of <code class="code">xs</code> and <code class="code">ys</code>
Stops with shorter array
Equivalent to <code class="code">map (zip xs ys) (fun (a,b) -> f a b) </code><br>
</div>
<div class="examples">
<pre class="example"> <pre class="codepre"><code class="code"> zipBy [|1;2;3|] [|4;5|] (fun a b -> 2 * a + b) = [|6;9|];;
</code></pre> </pre>
</div>
</div>
<pre><span id="VALunzip"><span class="keyword">val</span> unzip</span> : <code class="type">('a * 'b) array -> 'a array * 'b array</code></pre><div class="info ">
<div class="not-examples">
<code class="code">unzip a</code> 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.<br>
</div>
<div class="examples">
<pre class="example"> <pre class="codepre"><code class="code"> 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|]);;
</code></pre> </pre>
</div>
</div>
<pre><span id="VALconcat"><span class="keyword">val</span> concat</span> : <code class="type">'a array -> 'a array -> 'a array</code></pre><div class="info ">
<div class="not-examples">
<code class="code">concat xs ys</code><br>
<div class="tag"> <li><b>Returns</b> a fresh array containing the
concatenation of the arrays <code class="code">v1</code> and <code class="code">v2</code>;so even if <code class="code">v1</code> or <code class="code">v2</code>
is empty;it can not be shared</li>
</div>
</div>
<div class="examples">
<pre class="example"> <pre class="codepre"><code class="code"> concat [|1;2;3|] [|4;5|] = [|1;2;3;4;5|];;
concat [| |] [|"a";"b";"c"|] = [|"a";"b";"c"|];;
</code></pre> </pre>
</div>
</div>
<pre><span id="VALconcatMany"><span class="keyword">val</span> concatMany</span> : <code class="type">'a array array -> 'a array</code></pre><div class="info ">
<div class="not-examples">
<code class="code">concatMany xss</code><br>
<div class="tag"> <li><b>Returns</b> a fresh array as the concatenation of <code class="code">xss</code> (an array of arrays)</li>
</div>
</div>
<div class="examples">
<pre class="example"> <pre class="codepre"><code class="code"> concatMany [| [|1;2;3|]; [|4;5;6|]; [|7;8|] |] = [|1;2;3;4;5;6;7;8|];;
</code></pre> </pre>
</div>
</div>
<pre><span id="VALslice"><span class="keyword">val</span> slice</span> : <code class="type">'a array -> offset:int -> len:int -> 'a array</code></pre><div class="info ">
<div class="not-examples">
<code class="code">slice xs offset len</code> creates a new array with the <code class="code">len</code> elements of <code class="code">xs</code> starting at <code class="code">offset</code> for
<code class="code">offset</code> can be negative;and is evaluated as <code class="code">length xs - offset</code>
<code class="code">slice xs -1 1</code> means get the last element as a singleton array
<code class="code">slice xs (-len) len</code> will return a copy of the array
if the array does not have enough data;<code class="code">slice</code> extracts through
the end of sequence.
if <code class="code">len</code> is negative;returns the empty array.<br>
</div>
<div class="examples">
<pre class="example"> <pre class="codepre"><code class="code"> 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|];;
</code></pre> </pre>
</div>
</div>
<pre><span id="VALsliceToEnd"><span class="keyword">val</span> sliceToEnd</span> : <code class="type">'a array -> int -> 'a array</code></pre><div class="info ">
<div class="not-examples">
<code class="code">sliceToEnd xs offset</code> creates a new array with the elements of <code class="code">xs</code> starting at <code class="code">offset</code>
<code class="code">offset</code> can be negative;and is evaluated as <code class="code">length xs - offset</code>
<code class="code">sliceToEnd xs -1</code> means get the last element as a singleton array
<code class="code">sliceToEnd xs 0</code> will return a copy of the array<br>
</div>
<div class="examples">
<pre class="example"> <pre class="codepre"><code class="code"> 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|];;
</code></pre> </pre>
</div>
</div>
<pre><span id="VALcopy"><span class="keyword">val</span> copy</span> : <code class="type">'a array -> 'a array</code></pre><div class="info ">
<div class="not-examples">
<code class="code">copy a</code><br>
<div class="tag"> <li><b>Returns</b> a copy of <code class="code">a</code>;that is;a fresh array
containing the same elements as <code class="code">a</code>.</li>
</div>
</div>
</div>
<pre><span id="VALfill"><span class="keyword">val</span> fill</span> : <code class="type">'a array -> offset:int -> len:int -> 'a -> unit</code></pre><div class="info ">
<div class="not-examples">
<code class="code">fill arr ~offset ~len x</code>
Modifies <code class="code">arr</code> in place,
storing <code class="code">x</code> in elements number <code class="code">offset</code> to <code class="code">offset + len - 1</code>.
<code class="code">offset</code> can be negative;and is evaluated as <code class="code">length arr - offset</code>
<code class="code">fill arr ~offset:(-1) ~len:1</code> means fill the last element,
if the array does not have enough data;<code class="code">fill</code> will ignore it<br>
</div>
<div class="examples">
<pre class="example"> <pre class="codepre"><code class="code"> 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|];;
</code></pre> </pre>
</div>
</div>
<pre><span id="VALblit"><span class="keyword">val</span> blit</span> : <code class="type">src:'a array -><br> srcOffset:int -> dst:'a array -> dstOffset:int -> len:int -> unit</code></pre><div class="info ">
<div class="not-examples">
<code class="code">blit ~src:v1 ~srcOffset:o1 ~dst:v2 ~dstOffset:o2 ~len</code>
copies <code class="code">len</code> elements
from array <code class="code">v1</code>;starting at element number <code class="code">o1</code>;to array <code class="code">v2</code>,
starting at element number <code class="code">o2</code>.
It works correctly even if
<code class="code">v1</code> and <code class="code">v2</code> are the same array;and the source and
destination chunks overlap.
<code class="code">offset</code> can be negative;<code class="code">-1</code> means <code class="code">len - 1</code>;if <code class="code">len + offset</code> is still
negative;it will be set as 0
For each of the examples;presume that <code class="code">v1 = [|10;11;12;13;14;15;16;17|]</code> and
<code class="code">v2 = [|20;21;22;23;24;25;26;27|]</code>. The result shown is the content of the destination array.<br>
</div>
<div class="examples">
<pre class="example"> <pre class="codepre"><code class="code"> 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|]
</code></pre> </pre>
</div>
</div>
<pre><span id="VALblitUnsafe"><span class="keyword">val</span> blitUnsafe</span> : <code class="type">src:'a array -><br> srcOffset:int -> dst:'a array -> dstOffset:int -> len:int -> unit</code></pre><div class="info ">
<div class="not-examples">
<b>Unsafe</b> blit without bounds checking<br>
</div>
</div>
<pre><span id="VALforEachU"><span class="keyword">val</span> forEachU</span> : <code class="type">'a array -> ('a -> unit [@bs]) -> unit</code></pre>
<pre><span id="VALforEach"><span class="keyword">val</span> forEach</span> : <code class="type">'a array -> ('a -> unit) -> unit</code></pre><div class="info ">
<div class="not-examples">
<code class="code">forEach xs f</code>
Call <code class="code">f</code> on each element of <code class="code">xs</code> from the beginning to end. <code class="code">f</code> returns <code class="code">unit</code>;so no
new array is created. Use <code class="code">forEach</code> when you are primarily concerned with repetitively
creating side effects.<br>
</div>
<div class="examples">
<pre class="example"> <pre class="codepre"><code class="code"> 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;;
</code></pre> </pre>
</div>
</div>
<pre><span id="VALmapU"><span class="keyword">val</span> mapU</span> : <code class="type">'a array -> ('a -> 'b [@bs]) -> 'b array</code></pre>
<pre><span id="VALmap"><span class="keyword">val</span> map</span> : <code class="type">'a array -> ('a -> 'b) -> 'b array</code></pre><div class="info ">
<div class="not-examples">
<code class="code">map xs f </code><br>
<div class="tag"> <li><b>Returns</b> a new array by calling <code class="code">f</code> for each element of <code class="code">xs</code> from
the beginning to end</li>
</div>
</div>
<div class="examples">
<pre class="example"> <pre class="codepre"><code class="code"> map [|1;2|] (fun x-> x + 1) = [|3;4|]
</code></pre> </pre>
</div>
</div>
<pre><span id="VALgetByU"><span class="keyword">val</span> getByU</span> : <code class="type">'a array -> ('a -> bool [@bs]) -> 'a option</code></pre>
<pre><span id="VALgetBy"><span class="keyword">val</span> getBy</span> : <code class="type">'a array -> ('a -> bool) -> 'a option</code></pre><div class="info ">
<div class="not-examples">
<code class="code">getBy xs p</code> returns <code class="code">Some value</code> for the first value in <code class="code">xs</code> that satisifies the predicate function <code class="code">p</code>; returns <code class="code">None</code> if no element satisifies the function.<br>
</div>
<div class="examples">
<pre class="example"> <pre class="codepre"><code class="code"> getBy [|1;4;3;2|] (fun x -> x mod 2 = 0) = Some 4
getBy [|15;13;11|] (fun x -> x mod 2 = 0) = None
</code></pre> </pre>
</div>
</div>
<pre><span id="VALgetIndexByU"><span class="keyword">val</span> getIndexByU</span> : <code class="type">'a array -> ('a -> bool [@bs]) -> int option</code></pre>
<pre><span id="VALgetIndexBy"><span class="keyword">val</span> getIndexBy</span> : <code class="type">'a array -> ('a -> bool) -> int option</code></pre><div class="info ">
<div class="not-examples">
<code class="code">getIndexBy xs p</code> returns <code class="code">Some index</code> for the first value in <code class="code">xs</code> that satisifies the predicate function <code class="code">p</code>; returns <code class="code">None</code> if no element satisifies the function.<br>
</div>
<div class="examples">
<pre class="example"> <pre class="codepre"><code class="code"> getIndexBy [|1;4;3;2|] (fun x -> x mod 2 = 0) = Some 1
getIndexBy [|15;13;11|] (fun x -> x mod 2 = 0) = None
</code></pre> </pre>
</div>
</div>
<pre><span id="VALkeepU"><span class="keyword">val</span> keepU</span> : <code class="type">'a array -> ('a -> bool [@bs]) -> 'a array</code></pre>
<pre><span id="VALkeep"><span class="keyword">val</span> keep</span> : <code class="type">'a array -> ('a -> bool) -> 'a array</code></pre><div class="info ">
<div class="not-examples">
<code class="code">keep xs p </code><br>
<div class="tag"> <li><b>Returns</b> a new array that keep all elements satisfy <code class="code">p</code></li>
</div>
</div>
<div class="examples">
<pre class="example"> <pre class="codepre"><code class="code"> keep [|1;2;3|] (fun x -> x mod 2 = 0) = [|2|]
</code></pre> </pre>
</div>
</div>
<pre><span id="VALkeepWithIndexU"><span class="keyword">val</span> keepWithIndexU</span> : <code class="type">'a array -> ('a -> int -> bool [@bs]) -> 'a array</code></pre>
<pre><span id="VALkeepWithIndex"><span class="keyword">val</span> keepWithIndex</span> : <code class="type">'a array -> ('a -> int -> bool) -> 'a array</code></pre><div class="info ">
<div class="not-examples">
<code class="code">keepWithIndex xs p </code><br>
<div class="tag"> <li><b>Returns</b> a new array that keep all elements satisfy <code class="code">p</code></li>
</div>
</div>
<div class="examples">
<pre class="example"> <pre class="codepre"><code class="code"> keepWithIndex [|1;2;3|] (fun _x i -> i = 1) = [|2|]
</code></pre> </pre>
</div>
</div>
<pre><span id="VALkeepMapU"><span class="keyword">val</span> keepMapU</span> : <code class="type">'a array -> ('a -> 'b option [@bs]) -> 'b array</code></pre>
<pre><span id="VALkeepMap"><span class="keyword">val</span> keepMap</span> : <code class="type">'a array -> ('a -> 'b option) -> 'b array</code></pre><div class="info ">
<div class="not-examples">
<code class="code">keepMap xs p</code><br>
<div class="tag"> <li><b>Returns</b> a new array that keep all elements that return a non-None applied <code class="code">p</code></li>
</div>
</div>
<div class="examples">
<pre class="example"> <pre class="codepre"><code class="code"> keepMap [|1;2;3|] (fun x -> if x mod 2 then Some x else None)
= [| 2 |]
</code></pre> </pre>
</div>
</div>
<pre><span id="VALforEachWithIndexU"><span class="keyword">val</span> forEachWithIndexU</span> : <code class="type">'a array -> (int -> 'a -> unit [@bs]) -> unit</code></pre>
<pre><span id="VALforEachWithIndex"><span class="keyword">val</span> forEachWithIndex</span> : <code class="type">'a array -> (int -> 'a -> unit) -> unit</code></pre><div class="info ">
<div class="not-examples">
<code class="code">forEachWithIndex xs f</code>
The same as <a href="Belt_Array.html#VALforEach"><code class="code">Belt_Array.forEach</code></a>;except that <code class="code">f</code> is supplied two arguments:
the index starting from 0 and the element from <code class="code">xs</code><br>
</div>
<div class="examples">
<pre class="example"> <pre class="codepre"><code class="code"> forEach [|"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 cc
*)
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;;
</code></pre> </pre>
</div>
</div>
<pre><span id="VALmapWithIndexU"><span class="keyword">val</span> mapWithIndexU</span> : <code class="type">'a array -> (int -> 'a -> 'b [@bs]) -> 'b array</code></pre>
<pre><span id="VALmapWithIndex"><span class="keyword">val</span> mapWithIndex</span> : <code class="type">'a array -> (int -> 'a -> 'b) -> 'b array</code></pre><div class="info ">
<div class="not-examples">
<code class="code">mapWithIndex xs f </code>
<code class="code">mapWithIndex xs f</code> applies <code class="code">f</code> to each element of <code class="code">xs</code>. Function <code class="code">f</code> takes two arguments:
the index starting from 0 and the element from <code class="code">xs</code>.<br>
</div>
<div class="examples">
<pre class="example"> <pre class="codepre"><code class="code"> mapWithIndex [|1;2;3|] (fun i x -> i + x) =
[|0 + 1; 1 + 2; 2 + 3|]
</code></pre> </pre>
</div>
</div>
<pre><span id="VALpartitionU"><span class="keyword">val</span> partitionU</span> : <code class="type">'a array -> ('a -> bool [@bs]) -> 'a array * 'a array</code></pre>
<pre><span id="VALpartition"><span class="keyword">val</span> partition</span> : <code class="type">'a array -> ('a -> bool) -> 'a array * 'a array</code></pre><div class="info ">
<div class="not-examples">
<code class="code">partition f a</code> split array into tuple of two arrays based on predicate f; first of tuple where predicate cause true, second where predicate cause false<br>
</div>
<div class="examples">
<pre class="example"> <pre class="codepre"><code class="code"> 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|]);;
</code></pre> </pre>
</div>
</div>
<pre><span id="VALreduceU"><span class="keyword">val</span> reduceU</span> : <code class="type">'b array -> 'a -> ('a -> 'b -> 'a [@bs]) -> 'a</code></pre>
<pre><span id="VALreduce"><span class="keyword">val</span> reduce</span> : <code class="type">'b array -> 'a -> ('a -> 'b -> 'a) -> 'a</code></pre><div class="info ">
<div class="not-examples">
<code class="code">reduce xs init f</code>
Applies <code class="code">f</code> to each element of <code class="code">xs</code> from beginning to end. Function <code class="code">f</code> has two parameters: the item
from the list and an “accumulator”;which starts with a value of <code class="code">init</code>. <code class="code">reduce</code>
returns the final value of the accumulator.<br>
</div>
<div class="examples">
<pre class="example"> <pre class="codepre"><code class="code"> reduce [|2;3;4|] 1 (+) = 10;;
reduce [|"a";"b";"c";"d"|] "" (^) = "abcd";;
</code></pre> </pre>
</div>
</div>
<pre><span id="VALreduceReverseU"><span class="keyword">val</span> reduceReverseU</span> : <code class="type">'b array -> 'a -> ('a -> 'b -> 'a [@bs]) -> 'a</code></pre>
<pre><span id="VALreduceReverse"><span class="keyword">val</span> reduceReverse</span> : <code class="type">'b array -> 'a -> ('a -> 'b -> 'a) -> 'a</code></pre><div class="info ">
<div class="not-examples">
<code class="code">reduceReverse xs init f</code>
Works like <a href="Belt_Array.html#VALreduce"><code class="code">Belt_Array.reduce</code></a>;except that function <code class="code">f</code> is applied to each item of <code class="code">xs</code> from the last
back to the first.<br>
</div>
<div class="examples">
<pre class="example"> <pre class="codepre"><code class="code"> reduceReverse [|"a";"b";"c";"d"|] "" (^) = "dcba";;
</code></pre> </pre>
</div>
</div>
<pre><span id="VALreduceReverse2U"><span class="keyword">val</span> reduceReverse2U</span> : <code class="type">'a array -> 'b array -> 'c -> ('c -> 'a -> 'b -> 'c [@bs]) -> 'c</code></pre>
<pre><span id="VALreduceReverse2"><span class="keyword">val</span> reduceReverse2</span> : <code class="type">'a array -> 'b array -> 'c -> ('c -> 'a -> 'b -> 'c) -> 'c</code></pre><div class="info ">
<div class="not-examples">
<code class="code">reduceReverse2 xs ys init f</code>
Reduces two arrays <code class="code">xs</code> and <code class="code">ys</code>;taking items starting at <code class="code">min (length xs) (length ys)</code>
down to and including zero.<br>
</div>
<div class="examples">
<pre class="example"> <pre class="codepre"><code class="code"> reduceReverse2 [|1;2;3|] [|1;2|] 0 (fun acc x y -> acc + x + y) = 6
</code></pre> </pre>
</div>
</div>
<pre><span id="VALreduceWithIndexU"><span class="keyword">val</span> reduceWithIndexU</span> : <code class="type">'a array -> 'b -> ('b -> 'a -> int -> 'b [@bs]) -> 'b</code></pre>
<pre><span id="VALreduceWithIndex"><span class="keyword">val</span> reduceWithIndex</span> : <code class="type">'a array -> 'b -> ('b -> 'a -> int -> 'b) -> 'b</code></pre><div class="info ">
<div class="not-examples">
<code class="code">reduceWithIndex xs f</code>
Applies <code class="code">f</code> to each element of <code class="code">xs</code> from beginning to end. Function <code class="code">f</code> has three parameters: the item
from the array and an “accumulator”, which starts with a value of <code class="code">init</code> and the index of each element. <code class="code">reduceWithIndex</code>
returns the final value of the accumulator.<br>
</div>
<div class="examples">
<pre class="example"> <pre class="codepre"><code class="code"> reduceWithIndex [|1;2;3;4|] 0 (fun acc x i -> acc + x + i) = 16;
</code></pre> </pre>
</div>
</div>
<pre><span id="VALsomeU"><span class="keyword">val</span> someU</span> : <code class="type">'a array -> ('a -> bool [@bs]) -> bool</code></pre>
<pre><span id="VALsome"><span class="keyword">val</span> some</span> : <code class="type">'a array -> ('a -> bool) -> bool</code></pre><div class="info ">
<div class="not-examples">
<code class="code">some xs p</code><br>
<div class="tag"> <li><b>Returns</b> true if at least one of the elements in <code class="code">xs</code> satifies <code class="code">p</code>;where <code class="code">p</code> is a <i>predicate</i>: a function taking
an element and returning a <code class="code">bool</code>.</li>
</div>
</div>
<div class="examples">
<pre class="example"> <pre class="codepre"><code class="code"> some [|2; 3; 4|] (fun x -> x mod 2 = 1) = true;;
some [|-1; -3; -5|] (fun x -> x > 0) = false;;
</code></pre> </pre>
</div>
</div>
<pre><span id="VALeveryU"><span class="keyword">val</span> everyU</span> : <code class="type">'a array -> ('a -> bool [@bs]) -> bool</code></pre>
<pre><span id="VALevery"><span class="keyword">val</span> every</span> : <code class="type">'a array -> ('a -> bool) -> bool</code></pre><div class="info ">
<div class="not-examples">
<code class="code">every xs p</code><br>
<div class="tag"> <li><b>Returns</b> true if all elements satisfy <code class="code">p</code>;where <code class="code">p</code> is a <i>predicate</i>: a function taking
an element and returning a <code class="code">bool</code>.</li>
</div>
</div>
<div class="examples">
<pre class="example"> <pre class="codepre"><code class="code"> every [|1; 3; 5|] (fun x -> x mod 2 = 1) = true;;
every [|1; -3; 5|] (fun x -> x > 0) = false;;
</code></pre> </pre>
</div>
</div>
<pre><span id="VALevery2U"><span class="keyword">val</span> every2U</span> : <code class="type">'a array -> 'b array -> ('a -> 'b -> bool [@bs]) -> bool</code></pre>
<pre><span id="VALevery2"><span class="keyword">val</span> every2</span> : <code class="type">'a array -> 'b array -> ('a -> 'b -> bool) -> bool</code></pre><div class="info ">
<div class="not-examples">
<code class="code">every2 xs ys p</code> returns true if <code class="code">p xi yi</code> is true for all pairs of elements
up to the shorter length (i.e. <code class="code">min (length xs) (length ys)</code>)<br>
</div>
<div class="examples">
<pre class="example"> <pre class="codepre"><code class="code"> 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;
</code></pre> </pre>
</div>
</div>
<pre><span id="VALsome2U"><span class="keyword">val</span> some2U</span> : <code class="type">'a array -> 'b array -> ('a -> 'b -> bool [@bs]) -> bool</code></pre>
<pre><span id="VALsome2"><span class="keyword">val</span> some2</span> : <code class="type">'a array -> 'b array -> ('a -> 'b -> bool) -> bool</code></pre><div class="info ">
<div class="not-examples">
<code class="code">some2 xs ys p</code> returns true if <code class="code">p xi yi</code> is true for any pair of elements
up to the shorter length (i.e. <code class="code">min (length xs) (length ys)</code>)<br>
</div>
<div class="examples">
<pre class="example"> <pre class="codepre"><code class="code"> 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;;
</code></pre> </pre>
</div>
</div>
<pre><span id="VALcmpU"><span class="keyword">val</span> cmpU</span> : <code class="type">'a array -> 'a array -> ('a -> 'a -> int [@bs]) -> int</code></pre>
<pre><span id="VALcmp"><span class="keyword">val</span> cmp</span> : <code class="type">'a array -> 'a array -> ('a -> 'a -> int) -> int</code></pre><div class="info ">
<div class="not-examples">
<code class="code">cmp xs ys f</code>
<ul>
<li>Compared by length if <code class="code">length xs <> length ys</code>;returning -1 if<code class="code">length xs < length ys</code> or 1 if <code class="code">length xs > length ys</code></li>
<li>Otherwise compare one by one <code class="code">f x y</code>. <code class="code">f</code> returns</li>
<li>a negative number if <code class="code">x</code> is “less than” <code class="code">y</code></li>
<li>zero if <code class="code">x</code> is “equal to” <code class="code">y</code></li>
<li>a positive number if <code class="code">x</code> is “greater than” <code class="code">y</code></li>
<li>The comparison returns the first non-zero result of <code class="code">f</code>;or zero if <code class="code">f</code> returns zero for all <code class="code">x</code> and <code class="code">y</code>.</li>
</ul>
<br>
</div>
<div class="examples">
<pre class="example"> <pre class="codepre"><code class="code"> 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;;
</code></pre> </pre>
</div>
</div>
<pre><span id="VALeqU"><span class="keyword">val</span> eqU</span> : <code class="type">'a array -> 'a array -> ('a -> 'a -> bool [@bs]) -> bool</code></pre>
<pre><span id="VALeq"><span class="keyword">val</span> eq</span> : <code class="type">'a array -> 'a array -> ('a -> 'a -> bool) -> bool</code></pre><div class="info ">
<div class="not-examples">
<code class="code">eq xs ys</code>
<ul>
<li>return false if length is not the same</li>
<li>otherwise compare items one by one using <code class="code">f xi yi</code>;and return true if all results are true;false otherwise</li>
</ul>
<br>
</div>
<div class="examples">
<pre class="example"> <pre class="codepre"><code class="code"> eq [|1; 2; 3|] [|-1; -2; -3|] (fun a b -> abs a = abs b) = true
</code></pre> </pre>
</div>
</div>
<pre><span id="VALtruncateToLengthUnsafe"><span class="keyword">val</span> truncateToLengthUnsafe</span> : <code class="type">'a array -> int -> unit</code></pre><div class="info ">
<div class="not-examples">
<b>Unsafe</b>
<code class="code">truncateToLengthUnsafe xs n</code> sets length of array <code class="code">xs</code> to <code class="code">n</code>.
If <code class="code">n</code> is greater than the length of <code class="code">xs</code>;the extra elements are set to <code class="code">Js.Null_undefined.null</code>
If <code class="code">n</code> is less than zero;raises a <code class="code">RangeError</code>.<br>
</div>
<div class="examples">
<pre class="example"> <pre class="codepre"><code class="code"> let arr = [|"ant";"bee";"cat";"dog";"elk"|];;
let () = truncateToLengthUnsafe arr 3;;
arr = [|"ant";"bee";"cat"|];;
</code></pre> </pre>
</div>
</div>
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