mirror of
https://github.com/wren-lang/wren.git
synced 2026-01-12 14:48:40 +01:00
227 lines
13 KiB
HTML
227 lines
13 KiB
HTML
<!DOCTYPE html>
|
|
<html>
|
|
<head>
|
|
<meta http-equiv="Content-type" content="text/html;charset=UTF-8" />
|
|
<title>Values – Wren</title>
|
|
<link rel="stylesheet" type="text/css" href="style.css" />
|
|
<link href='//fonts.googleapis.com/css?family=Source+Sans+Pro:400,700,400italic,700italic|Source+Code+Pro:400|Lato:400|Sanchez:400italic,400' rel='stylesheet' type='text/css'>
|
|
<!-- Tell mobile browsers we're optimized for them and they don't need to crop
|
|
the viewport. -->
|
|
<meta name="viewport" content="width=device-width, initial-scale=1, maximum-scale=1"/>
|
|
</head>
|
|
<body id="top">
|
|
<header>
|
|
<div class="page">
|
|
<div class="main-column">
|
|
<h1><a href="./">wren</a></h1>
|
|
<h2>a classy little scripting language</h2>
|
|
</div>
|
|
</div>
|
|
</header>
|
|
<div class="page">
|
|
<nav class="big">
|
|
<ul>
|
|
<li><a href="getting-started.html">Getting Started</a></li>
|
|
<li><a href="contributing.html">Contributing</a></li>
|
|
</ul>
|
|
<section>
|
|
<h2>language guide</h2>
|
|
<ul>
|
|
<li><a href="syntax.html">Syntax</a></li>
|
|
<li><a href="values.html">Values</a></li>
|
|
<li><a href="lists.html">Lists</a></li>
|
|
<li><a href="maps.html">Maps</a></li>
|
|
<li><a href="method-calls.html">Method Calls</a></li>
|
|
<li><a href="control-flow.html">Control Flow</a></li>
|
|
<li><a href="variables.html">Variables</a></li>
|
|
<li><a href="functions.html">Functions</a></li>
|
|
<li><a href="classes.html">Classes</a></li>
|
|
<li><a href="concurrency.html">Concurrency</a></li>
|
|
<li><a href="error-handling.html">Error Handling</a></li>
|
|
<li><a href="modularity.html">Modularity</a></li>
|
|
</ul>
|
|
</section>
|
|
<section>
|
|
<h2>reference</h2>
|
|
<ul>
|
|
<li><a href="modules">Modules</a></li>
|
|
<li><a href="embedding">Embedding</a></li>
|
|
<li><a href="performance.html">Performance</a></li>
|
|
<li><a href="qa.html">Q & A</a></li>
|
|
</ul>
|
|
</section>
|
|
</nav>
|
|
<nav class="small">
|
|
<table>
|
|
<tr>
|
|
<td><a href="getting-started.html">Getting Started</a></td>
|
|
<td><a href="contributing.html">Contributing</a></td>
|
|
</tr>
|
|
<tr>
|
|
<td colspan="2"><h2>language guide</h2></td>
|
|
<td><h2>reference</h2></td>
|
|
</tr>
|
|
<tr>
|
|
<td>
|
|
<ul>
|
|
<li><a href="syntax.html">Syntax</a></li>
|
|
<li><a href="values.html">Values</a></li>
|
|
<li><a href="lists.html">Lists</a></li>
|
|
<li><a href="maps.html">Maps</a></li>
|
|
<li><a href="method-calls.html">Method Calls</a></li>
|
|
<li><a href="control-flow.html">Control Flow</a></li>
|
|
</ul>
|
|
</td>
|
|
<td>
|
|
<ul>
|
|
<li><a href="variables.html">Variables</a></li>
|
|
<li><a href="functions.html">Functions</a></li>
|
|
<li><a href="classes.html">Classes</a></li>
|
|
<li><a href="concurrency.html">Concurrency</a></li>
|
|
<li><a href="error-handling.html">Error Handling</a></li>
|
|
<li><a href="modularity.html">Modularity</a></li>
|
|
</ul>
|
|
</td>
|
|
<td>
|
|
<ul>
|
|
<li><a href="modules">Modules</a></li>
|
|
<li><a href="embedding">Embedding</a></li>
|
|
<li><a href="performance.html">Performance</a></li>
|
|
<li><a href="qa.html">Q & A</a></li>
|
|
</ul>
|
|
</td>
|
|
</tr>
|
|
</table>
|
|
</nav>
|
|
<main>
|
|
<h1>Values</h1>
|
|
<p>Values are the built-in atomic object types that all other objects are composed
|
|
of. They can be created through <em>literals</em>, expressions that evaluate to a
|
|
value. All values are <em>immutable</em>—once created, they do not change. The
|
|
number <code>3</code> is always the number <code>3</code>. The string <code>"frozen"</code> can never have its
|
|
character array modified in place. </p>
|
|
<h2>Booleans <a href="#booleans" name="booleans" class="header-anchor">#</a></h2>
|
|
<p>A boolean value represents truth or falsehood. There are two boolean literals,
|
|
<code>true</code> and <code>false</code>. Their class is <a href="modules/core/bool.html">Bool</a>. </p>
|
|
<h2>Numbers <a href="#numbers" name="numbers" class="header-anchor">#</a></h2>
|
|
<p>Like other scripting languages, Wren has a single numeric type:
|
|
double-precision floating point. Number literals look like you expect coming
|
|
from other languages: </p>
|
|
<div class="codehilite"><pre><span class="mi">0</span>
|
|
<span class="mi">1234</span>
|
|
<span class="o">-</span><span class="mi">5678</span>
|
|
<span class="mf">3.14159</span>
|
|
<span class="mf">1.0</span>
|
|
<span class="o">-</span><span class="mf">12.34</span>
|
|
</pre></div>
|
|
|
|
|
|
<p>Numbers are instances of the <a href="modules/core/num.html">Num</a> class. </p>
|
|
<h2>Strings <a href="#strings" name="strings" class="header-anchor">#</a></h2>
|
|
<p>A string is an array of bytes. Typically, they store characters encoded in
|
|
UTF-8, but you can put any byte values in there, even zero or invalid UTF-8
|
|
sequences. (You might have some trouble <em>printing</em> the latter to your terminal,
|
|
though.) </p>
|
|
<p>String literals are surrounded in double quotes: </p>
|
|
<div class="codehilite"><pre><span class="s">"hi there"</span>
|
|
</pre></div>
|
|
|
|
|
|
<p>A handful of escape characters are supported: </p>
|
|
<div class="codehilite"><pre><span class="s">"</span><span class="se">\0</span><span class="s">"</span> <span class="c1">// The NUL byte: 0.</span>
|
|
<span class="s">"</span><span class="se">\"</span><span class="s">"</span> <span class="c1">// A double quote character.</span>
|
|
<span class="s">"</span><span class="se">\\</span><span class="s">"</span> <span class="c1">// A backslash.</span>
|
|
<span class="s">"</span><span class="se">\%</span><span class="s">"</span> <span class="c1">// A percent sign.</span>
|
|
<span class="s">"</span><span class="se">\a</span><span class="s">"</span> <span class="c1">// Alarm beep. (Who uses this?)</span>
|
|
<span class="s">"</span><span class="se">\b</span><span class="s">"</span> <span class="c1">// Backspace.</span>
|
|
<span class="s">"</span><span class="se">\f</span><span class="s">"</span> <span class="c1">// Formfeed.</span>
|
|
<span class="s">"</span><span class="se">\n</span><span class="s">"</span> <span class="c1">// Newline.</span>
|
|
<span class="s">"</span><span class="se">\r</span><span class="s">"</span> <span class="c1">// Carriage return.</span>
|
|
<span class="s">"</span><span class="se">\t</span><span class="s">"</span> <span class="c1">// Tab.</span>
|
|
<span class="s">"</span><span class="se">\v</span><span class="s">"</span> <span class="c1">// Vertical tab.</span>
|
|
</pre></div>
|
|
|
|
|
|
<p>A <code>\u</code> followed by four hex digits can be used to specify a Unicode code point: </p>
|
|
<div class="codehilite"><pre><span class="vg">System</span><span class="o">.</span><span class="n">print</span><span class="p">(</span><span class="s">"</span><span class="se">\u0041\u0b83\u00DE</span><span class="s">"</span><span class="p">)</span> <span class="output">AஃÞ</span>
|
|
</pre></div>
|
|
|
|
|
|
<p>A capital <code>\U</code> followed by <em>eight</em> hex digits allows Unicode code points outside
|
|
of the basic multilingual plane, like all-important emoji: </p>
|
|
<div class="codehilite"><pre><span class="vg">System</span><span class="o">.</span><span class="n">print</span><span class="p">(</span><span class="s">"</span><span class="se">\U0001F64A\U0001F680</span><span class="s">"</span><span class="p">)</span> <span class="output">🙊🚀</span>
|
|
</pre></div>
|
|
|
|
|
|
<p>A <code>\x</code> followed by two hex digits specifies a single unencoded byte: </p>
|
|
<div class="codehilite"><pre><span class="vg">System</span><span class="o">.</span><span class="n">print</span><span class="p">(</span><span class="s">"</span><span class="se">\x48\x69\x2e</span><span class="s">"</span><span class="p">)</span> <span class="output">Hi.</span>
|
|
</pre></div>
|
|
|
|
|
|
<p>Strings are instances of class <a href="modules/core/string.html">String</a>. </p>
|
|
<h3>Interpolation <a href="#interpolation" name="interpolation" class="header-anchor">#</a></h3>
|
|
<p>String literals also allow <em>interpolation</em>. If you have a percent sign (<code>%</code>)
|
|
followed by a parenthesized expression, the expression is evaluated. The
|
|
resulting object’s <code>toString</code> method is called and the result is inserted in the
|
|
string: </p>
|
|
<div class="codehilite"><pre><span class="vg">System</span><span class="o">.</span><span class="n">print</span><span class="p">(</span><span class="s">"Math </span><span class="si">%(</span><span class="mi">3</span> <span class="o">+</span> <span class="mi">4</span> <span class="o">*</span> <span class="mi">5</span><span class="si">)</span><span class="s"> is fun!"</span><span class="p">)</span> <span class="output">Math 23 is fun!</span>
|
|
</pre></div>
|
|
|
|
|
|
<p>Arbitrarily complex expressions are allowed inside the parentheses: </p>
|
|
<div class="codehilite"><pre><span class="vg">System</span><span class="o">.</span><span class="n">print</span><span class="p">(</span><span class="s">"wow </span><span class="si">%(</span><span class="p">(</span><span class="mi">1</span><span class="o">..</span><span class="mi">3</span><span class="p">)</span><span class="o">.</span><span class="n">map</span> <span class="p">{</span><span class="o">|</span><span class="err">n</span><span class="o">|</span> <span class="err">n</span> <span class="o">*</span> <span class="err">n</span><span class="p">}</span><span class="o">.</span><span class="n">join</span><span class="p">()</span><span class="si">)</span><span class="s">"</span><span class="p">)</span> <span class="output">wow 149</span>
|
|
</pre></div>
|
|
|
|
|
|
<p>An interpolated expression can even contain a string literal which in turn has
|
|
its own nested interpolations, but doing that gets unreadable pretty quickly. </p>
|
|
<h2>Ranges <a href="#ranges" name="ranges" class="header-anchor">#</a></h2>
|
|
<p>A range is a little object that represents a consecutive range of numbers. They
|
|
don’t have their own dedicated literal syntax. Instead, the number class
|
|
implements the <code>..</code> and <code>...</code> <a href="method-calls.html#operators">operators</a> to create them: </p>
|
|
<div class="codehilite"><pre><span class="mi">3</span><span class="o">..</span><span class="mi">8</span>
|
|
</pre></div>
|
|
|
|
|
|
<p>This creates a range from three to eight, including eight itself. If you want a
|
|
half-inclusive range, use <code>...</code>: </p>
|
|
<div class="codehilite"><pre><span class="mi">4</span><span class="o">...</span><span class="mi">6</span>
|
|
</pre></div>
|
|
|
|
|
|
<p>This creates a range from four to six <em>not</em> including six itself. Ranges are
|
|
commonly used for <a href="control-flow.html#for-statements">iterating</a> over a
|
|
sequences of numbers, but are useful in other places too. You can pass them to
|
|
a <a href="lists.html">list</a>‘s subscript operator to return a subset of the list, for
|
|
example: </p>
|
|
<div class="codehilite"><pre><span class="k">var</span> <span class="n">list</span> <span class="o">=</span> <span class="p">[</span><span class="s">"a"</span><span class="p">,</span> <span class="s">"b"</span><span class="p">,</span> <span class="s">"c"</span><span class="p">,</span> <span class="s">"d"</span><span class="p">,</span> <span class="s">"e"</span><span class="p">]</span>
|
|
<span class="k">var</span> <span class="n">slice</span> <span class="o">=</span> <span class="n">list</span><span class="p">[</span><span class="mi">1</span><span class="o">..</span><span class="mi">3</span><span class="p">]</span>
|
|
<span class="vg">System</span><span class="o">.</span><span class="n">print</span><span class="p">(</span><span class="n">slice</span><span class="p">)</span> <span class="output">[b, c, d]</span>
|
|
</pre></div>
|
|
|
|
|
|
<p>Their class is <a href="modules/core/range.html">Range</a>. </p>
|
|
<h2>Null <a href="#null" name="null" class="header-anchor">#</a></h2>
|
|
<p>Wren has a special value <code>null</code>, which is the only instance of the class
|
|
<a href="modules/core/null.html">Null</a>. (Note the difference in case.) It functions a bit like <code>void</code> in some
|
|
languages: it indicates the absence of a value. If you call a method that
|
|
doesn’t return anything and get its returned value, you get <code>null</code> back. </p>
|
|
<p><a class="right" href="lists.html">Lists →</a>
|
|
<a href="syntax.html">← Syntax</a> </p>
|
|
</main>
|
|
</div>
|
|
<footer>
|
|
<div class="page">
|
|
<div class="main-column">
|
|
<p>Wren lives
|
|
<a href="https://github.com/munificent/wren">on GitHub</a>
|
|
— Made with ❤ by
|
|
<a href="http://journal.stuffwithstuff.com/">Bob Nystrom</a> and
|
|
<a href="https://github.com/munificent/wren/blob/master/AUTHORS">friends</a>.
|
|
</p>
|
|
<div class="main-column">
|
|
</div>
|
|
</footer>
|
|
</body>
|
|
</html>
|