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<img alt="Erlang logo" src="../erlang-logo.png"><br><small><a href="users_guide.html">User's Guide</a><br><a href="../pdf/otp-system-documentation-5.9.3.1.pdf">PDF</a><br><a href="../index.html">Top</a></small><p><strong>Erlang Reference Manual</strong><br><strong>User's Guide</strong><br><small>Version 5.9.3.1</small></p>
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<div id="content">
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<h1>1 Introduction</h1>
<h3><a name="id73748">1.1
Purpose</a></h3>
<p>This reference manual describes the Erlang programming
language. The focus is on the language itself, not
the implementation. The language constructs are described in
text and with examples rather than formally specified, with
the intention to make the manual more readable.
The manual is not intended as a tutorial.</p>
<p>Information about this implementation of Erlang can be found, for
example, in <strong>System Principles</strong> (starting and stopping,
boot scripts, code loading, error logging, creating target
systems), <strong>Efficiency Guide</strong> (memory consumption, system
limits) and <strong>ERTS User's Guide</strong> (crash dumps, drivers).</p>
<h3><a name="id66106">1.2
Prerequisites</a></h3>
<p>It is assumed that the reader has done some programming and
is familiar with concepts such as data types and programming
language syntax.</p>
<h3><a name="id67296">1.3
Document Conventions</a></h3>
<p>In the document, the following terminology is used:</p>
<ul>
<li>A <strong>sequence</strong> is one or more items. For example, a
clause body consists of a sequence of expressions. This
means that there must be at least one expression.</li>
<li>A <strong>list</strong> is any number of items. For example,
an argument list can consist of zero, one or more arguments.</li>
</ul>
<p>If a feature has been added recently, in Erlang 5.0/OTP R7 or
later, this is mentioned in the text.</p>
<h3><a name="id68121">1.4
Complete List of BIFs</a></h3>
<p>For a complete list of BIFs, their arguments and return values,
refer to <span class="code">erlang(3)</span>.</p>
<h3><a name="id60679">1.5
Reserved Words</a></h3>
<p>The following are reserved words in Erlang:</p>
<p>after and andalso band begin bnot bor bsl bsr bxor case catch
cond div end fun if let not of or orelse query receive rem try
when xor</p>
<h3><a name="id61758">1.6
Character Set</a></h3>
<p>In Erlang 4.8/OTP R5A the syntax of Erlang tokens was extended to
allow the use of the full ISO-8859-1 (Latin-1) character set. This
is noticeable in the following ways:</p>
<ul>
<li>
<p>All the Latin-1 printable characters can be used and are
shown without the escape backslash convention.</p>
</li>
<li>
<p>Atoms and variables can use all Latin-1 letters.</p>
</li>
</ul>
<table border="1" cellpadding="2" cellspacing="0">
<tr>
<td align="left" valign="middle"><strong>Octal</strong></td>
<td align="left" valign="middle"><strong>Decimal</strong></td>
<td align="left" valign="middle"> </td>
<td align="left" valign="middle"><strong>Class</strong></td>
</tr>
<tr>
<td align="left" valign="middle">200 - 237</td>
<td align="left" valign="middle">128 - 159</td>
<td align="left" valign="middle"> </td>
<td align="left" valign="middle">Control characters</td>
</tr>
<tr>
<td align="left" valign="middle">240 - 277</td>
<td align="left" valign="middle">160 - 191</td>
<td align="left" valign="middle">- ¿</td>
<td align="left" valign="middle">Punctuation characters</td>
</tr>
<tr>
<td align="left" valign="middle">300 - 326</td>
<td align="left" valign="middle">192 - 214</td>
<td align="left" valign="middle">À - Ö</td>
<td align="left" valign="middle">Uppercase letters</td>
</tr>
<tr>
<td align="left" valign="middle">327</td>
<td align="left" valign="middle">215</td>
<td align="left" valign="middle">×</td>
<td align="left" valign="middle">Punctuation character</td>
</tr>
<tr>
<td align="left" valign="middle">330 - 336</td>
<td align="left" valign="middle">216 - 222</td>
<td align="left" valign="middle">Ø - Þ</td>
<td align="left" valign="middle">Uppercase letters</td>
</tr>
<tr>
<td align="left" valign="middle">337 - 366</td>
<td align="left" valign="middle">223 - 246</td>
<td align="left" valign="middle">ß - ö</td>
<td align="left" valign="middle">Lowercase letters</td>
</tr>
<tr>
<td align="left" valign="middle">367</td>
<td align="left" valign="middle">247</td>
<td align="left" valign="middle">÷</td>
<td align="left" valign="middle">Punctuation character</td>
</tr>
<tr>
<td align="left" valign="middle">370 - 377</td>
<td align="left" valign="middle">248 - 255</td>
<td align="left" valign="middle">ø - ÿ</td>
<td align="left" valign="middle">Lowercase letters</td>
</tr>
</table>
<em>Table
1.1:
Character Classes.</em>
</div>
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