/usr/lib/swi-prolog/doc/Manual/help.html

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<h2 id="sec:help"><a id="sec:2.6"><span class="sec-nr">2.6</span> <span class="sec-title">Online 
Help</span></a></h2>

<a id="sec:help"></a>

<p>SWI-Prolog provides an online help system that covers this manual. If 
the XPCE graphics system is available, online help opens a graphical 
window. Otherwise the documentation is shown in the Prolog console. The 
help system is controlled by the predicates below. Note that this help 
system only covers the core SWI-Prolog manual. The website<sup class="fn">9<span class="fn-text"><a class="url" href="http://www.swi-prolog.org">http://www.swi-prolog.org</a></span></sup> 
provides an integrated manual that covers the core system as well as all 
standard extension packages. It is possible to install the SWI-Prolog 
website locally by cloning the website repository
<a class="url" href="git://www.swi-prolog.org/home/pl/git/plweb.git">git://www.swi-prolog.org/home/pl/git/plweb.git</a> 
and following the instructions in the <code>README</code> file.

<dl class="latex">
<dt class="pubdef"><a id="help/0"><strong>help</strong></a></dt>
<dd class="defbody">
Equivalent to <code>help(<a id="idx:help1:32"></a><a class="pred" href="help.html#help/1">help/1</a>)</code>.</dd>
<dt class="pubdef"><a id="help/1"><strong>help</strong>(<var>+What</var>)</a></dt>
<dd class="defbody">
Show specified part of the manual. <var>What</var> is one of:
<table class="latex frame-void center">
<tr><td>&lt;<var>Name</var>&gt;/&lt;<var>Arity</var>&gt; </td><td>Give 
help on specified predicate </td></tr>
<tr><td>&lt;<var>Name</var>&gt; </td><td>Give help on named predicate 
with any arity or C interface function with that name </td></tr>
<tr><td>&lt;<var>Section</var>&gt; </td><td>Display specified section. 
Section numbers are dash-separated numbers: <code>2-3</code> refers to 
section 2.3 of the manual. Section numbers are obtained using <a id="idx:apropos1:33"></a><a class="pred" href="help.html#apropos/1">apropos/1</a>.</td></tr>
</table>

<p>Examples:
<table class="latex frame-void center">
<tr><td><code>?- help(assert).</code> </td><td>Give help on predicate 
assert </td></tr>
<tr><td><code>?- help(3-4).</code> </td><td>Display section 3.4 of the 
manual </td></tr>
<tr><td><code>?- help('PL_retry').</code></td><td>Give help on interface 
function <a class="func" href="foreigninclude.html#PL_retry()">PL_retry()</a> </td></tr>
</table>

<p>See also <a id="idx:apropos1:34"></a><a class="pred" href="help.html#apropos/1">apropos/1</a> 
and the SWI-Prolog home page at
<a class="url" href="http://www.swi-prolog.org">http://www.swi-prolog.org</a>, 
which provides a FAQ, an HTML version of the manual for online browsing, 
and HTML and PDF versions for downloading.</dd>
<dt class="pubdef"><a id="apropos/1"><strong>apropos</strong>(<var>+Pattern</var>)</a></dt>
<dd class="defbody">
Display all predicates, functions and sections that have <em>Pattern</em> 
in their name or summary description. Lowercase letters in
<var>Pattern</var> also match a corresponding uppercase letter. Example:
<table class="latex frame-void center">
<tr><td><code>?- apropos(file).</code> </td><td>Display predicates, 
functions and sections that have `file' (or `File', etc.) in their 
summary description. </td></tr>
</table>
</dd>
<dt class="pubdef"><a id="explain/1"><strong>explain</strong>(<var>+ToExplain</var>)</a></dt>
<dd class="defbody">
Give an explanation on the given `object'. The argument may be any 
Prolog data object. If the argument is an atom, a term of the form
<var>Name/Arity</var> or a term of the form <em>Module:Name/Arity</em>,
<a id="idx:explain1:35"></a><a class="pred" href="help.html#explain/1">explain/1</a> 
describes the predicate as well as possible references to it. See also <a id="idx:gxref0:36"></a><a class="pred" href="xref.html#gxref/0">gxref/0</a>.</dd>
<dt class="pubdef"><a id="explain/2"><strong>explain</strong>(<var>+ToExplain, 
-Explanation</var>)</a></dt>
<dd class="defbody">
Unify <var>Explanation</var> with an explanation for <var>ToExplain</var>. 
Backtracking yields further explanations.
</dd>
</dl>

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swi-prolog-nox 6.6.4-2ubuntu1 / usr / lib / swi-prolog / doc / Manual / help.html
