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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_MutableStack.html"><link rel="next" href="Belt_Range.html">
<title> Belt_Option </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_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_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_internalMutableAVLMap.html">Belt_internalMutableAVLMap</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="Js.html">Js</a></li>
<li><a href="Js_array.html">Js_array</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>
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<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_typed_array.html">Js_typed_array</a></li>
<li><a href="Js_types.html">Js_types</a></li>
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<li><a href="Node.html">Node</a></li>
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<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>
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</div>
<h1>Module <a href="type_Belt_Option.html">Belt_Option</a></h1>
<pre><span class="keyword">module</span> Belt_Option: <code class="code">sig</code> <a href="Belt_Option.html">..</a> <code class="code">end</code></pre><div class="info module top">
<div class="not-examples">
<a href="Belt.Option.html"><code class="code">Belt.Option</code></a>
<p>
Utilities for option data type<br>
</div>
</div>
<hr width="100%">
<pre><span id="VALgetExn"><span class="keyword">val</span> getExn</span> : <code class="type">'a option -> 'a</code></pre><div class="info ">
<div class="not-examples">
<code class="code">getExn optionalValue</code>
Returns <code class="code">value</code> if <code class="code">optionalValue</code> is <code class="code">Some value</code>, otherwise raises <code class="code">getExn</code><br>
</div>
<div class="examples">
<pre class="example"> <pre class="codepre"><code class="code"> getExn (Some 3) = 3;;
getExn None (* Raises getExn error *)
</code></pre> </pre>
</div>
</div>
<pre><span id="VALmapWithDefaultU"><span class="keyword">val</span> mapWithDefaultU</span> : <code class="type">'a option -> 'b -> ('a -> 'b [@bs]) -> 'b</code></pre><div class="info ">
<div class="not-examples">
Uncurried version of <code class="code">mapWithDefault</code><br>
</div>
</div>
<pre><span id="VALmapWithDefault"><span class="keyword">val</span> mapWithDefault</span> : <code class="type">'a option -> 'b -> ('a -> 'b) -> 'b</code></pre><div class="info ">
<div class="not-examples">
<code class="code">mapWithDefault optionValue default f</code>
<p>
If <code class="code">optionValue</code> is <code class="code">Some value</code>, returns <code class="code">f value</code>; otherwise returns <code class="code">default</code><br>
</div>
<div class="examples">
<pre class="example"> <pre class="codepre"><code class="code"> mapWithDefault (Some 3) 0 (fun x -> x + 5) = 8;;
mapWithDefault None 0 (fun x -> x + 5) = 0;;
</code></pre> </pre>
</div>
</div>
<pre><span id="VALmapU"><span class="keyword">val</span> mapU</span> : <code class="type">'a option -> ('a -> 'b [@bs]) -> 'b option</code></pre><div class="info ">
<div class="not-examples">
Uncurried version of <code class="code">map</code><br>
</div>
</div>
<pre><span id="VALmap"><span class="keyword">val</span> map</span> : <code class="type">'a option -> ('a -> 'b) -> 'b option</code></pre><div class="info ">
<div class="not-examples">
<code class="code">map optionValue f</code>
<p>
If <code class="code">optionValue</code> is <code class="code">Some value</code>, returns <code class="code">Some (f value)</code>; otherwise returns <code class="code">None</code><br>
</div>
<div class="examples">
<pre class="example"> <pre class="codepre"><code class="code"> map (Some 3) (fun x -> x * x) = (Some 9);;
map None (fun x -> x * x) = None;;
</code></pre> </pre>
</div>
</div>
<pre><span id="VALflatMapU"><span class="keyword">val</span> flatMapU</span> : <code class="type">'a option -> ('a -> 'b option [@bs]) -> 'b option</code></pre><div class="info ">
<div class="not-examples">
Uncurried version of <code class="code">flatMap</code><br>
</div>
</div>
<pre><span id="VALflatMap"><span class="keyword">val</span> flatMap</span> : <code class="type">'a option -> ('a -> 'b option) -> 'b option</code></pre><div class="info ">
<div class="not-examples">
<code class="code">flatMap optionValue f</code>
<p>
If <code class="code">optionValue</code> is <code class="code">Some value</code>, returns <code class="code">f value</code>; otherwise returns <code class="code">None</code>
The function <code class="code">f</code> must have a return type of <code class="code">'a option</code><br>
</div>
<div class="examples">
<pre class="example"> <pre class="codepre"><code class="code"> let f (x : float) =
if x >= 0.0 then
Some (sqrt x)
else
None;;
flatMap (Some 4.0) f = Some 2.0;;
flatMap (Some (-4.0)) f = None;;
flatMap None f = None;;
</code></pre> </pre>
</div>
</div>
<pre><span id="VALgetWithDefault"><span class="keyword">val</span> getWithDefault</span> : <code class="type">'a option -> 'a -> 'a</code></pre><div class="info ">
<div class="not-examples">
<code class="code">getWithDefault optionalValue default</code>
<p>
If <code class="code">optionalValue</code> is <code class="code">Some value</code>, returns <code class="code">value</code>, otherwise <code class="code">default</code><br>
</div>
<div class="examples">
<pre class="example"> <pre class="codepre"><code class="code"> getWithDefault (Some 1812) 1066 = 1812;;
getWithDefault None 1066 = 1066;;
</code></pre> </pre>
</div>
</div>
<pre><span id="VALisSome"><span class="keyword">val</span> isSome</span> : <code class="type">'a option -> bool</code></pre><div class="info ">
<div class="not-examples">
Returns <code class="code">true</code> if the argument is <code class="code">Some value</code>, <code class="code">false</code> otherwise<br>
</div>
</div>
<pre><span id="VALisNone"><span class="keyword">val</span> isNone</span> : <code class="type">'a option -> bool</code></pre><div class="info ">
<div class="not-examples">
Returns <code class="code">true</code> if the argument is <code class="code">None</code>, <code class="code">false</code> otherwise<br>
</div>
</div>
<pre><span id="VALeqU"><span class="keyword">val</span> eqU</span> : <code class="type">'a option -> 'b option -> ('a -> 'b -> bool [@bs]) -> bool</code></pre><div class="info ">
<div class="not-examples">
Uncurried version of <code class="code">eq</code><br>
</div>
</div>
<pre><span id="VALeq"><span class="keyword">val</span> eq</span> : <code class="type">'a option -> 'b option -> ('a -> 'b -> bool) -> bool</code></pre><div class="info ">
<div class="not-examples">
<code class="code">eq optValue1 optvalue2 predicate</code>
<p>
Evaluates two optional values for equality with respect to a predicate function.
<p>
If both <code class="code">optValue1</code> and <code class="code">optValue2</code> are <code class="code">None</code>, returns <code class="code">true</code>.
<p>
If one of the arguments is <code class="code">Some value</code> and the other is <code class="code">None</code>, returns <code class="code">false</code>
<p>
If arguments are <code class="code">Some value1</code> and <code class="code">Some value2</code>, returns the result of <code class="code">predicate value1 value2</code>;
the <code class="code">predicate</code> function must return a <code class="code">bool</code><br>
</div>
<div class="examples">
<pre class="example"> <pre class="codepre"><code class="code"> let clockEqual = (fun a b -> a mod 12 = b mod 12);;
eq (Some 3) (Some 15) clockEqual = true;;
eq (Some 3) None clockEqual = false;;
eq None (Some 3) clockEqual = false;;
eq None None clockEqual = true;;
</code></pre> </pre>
</div>
</div>
<pre><span id="VALcmpU"><span class="keyword">val</span> cmpU</span> : <code class="type">'a option -> 'b option -> ('a -> 'b -> int [@bs]) -> int</code></pre><div class="info ">
<div class="not-examples">
Uncurried version of <code class="code">cmp</code><br>
</div>
</div>
<pre><span id="VALcmp"><span class="keyword">val</span> cmp</span> : <code class="type">'a option -> 'b option -> ('a -> 'b -> int) -> int</code></pre><div class="info ">
<div class="not-examples">
<code class="code">cmp optValue1 optvalue2 comparisonFcn</code>
<p>
Compares two optional values with respect to a comparison function
<p>
If both <code class="code">optValue1</code> and <code class="code">optValue2</code> are <code class="code">None</code>, returns 0.
<p>
If the first argument is <code class="code">Some value1</code> and the second is <code class="code">None</code>, returns 1 (something is greater than nothing)
<p>
If the first argument is <code class="code">None</code> and the second is <code class="code">Some value2</code>, returns -1 (nothing is less than something)
<p>
If the arguments are <code class="code">Some value1</code> and <code class="code">Some value2</code>, returns the result of <code class="code">comparisonFcn value1 value2</code>; <code class="code">comparisonFcn</code> takes two arguments and returns -1 if the first argument is less than the second, 0 if the arguments are equal, and 1 if the first argument is greater than the second.<br>
</div>
<div class="examples">
<pre class="example"> <pre class="codepre"><code class="code"> let clockCompare = fun a b -> compare (a mod 12) (b mod 12);;
cmp (Some 3) (Some 15) clockCompare = 0;;
cmp (Some 3) (Some 14) clockCompare = 1;;
cmp (Some 2) (Some 15) clockCompare = -1;;
cmp None (Some 15) clockCompare = -1;;
cmp (Some 14) None clockCompare = 1;;
cmp None None clockCompare = 0;;
</code></pre> </pre>
</div>
</div>
</body></html>