102 lines
4.5 KiB
HTML
102 lines
4.5 KiB
HTML
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<!DOCTYPE html>
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<html>
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<!-- Created by GNU Texinfo 7.1, https://www.gnu.org/software/texinfo/ -->
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<head>
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<meta http-equiv="Content-Type" content="text/html; charset=utf-8">
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<!-- This manual documents Guile version 3.0.10.
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Copyright (C) 1996-1997, 2000-2005, 2009-2023 Free Software Foundation,
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Inc.
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Copyright (C) 2021 Maxime Devos
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Copyright (C) 2024 Tomas Volf
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Permission is granted to copy, distribute and/or modify this document
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under the terms of the GNU Free Documentation License, Version 1.3 or
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any later version published by the Free Software Foundation; with no
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Invariant Sections, no Front-Cover Texts, and no Back-Cover Texts. A
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copy of the license is included in the section entitled "GNU Free
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Documentation License." -->
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<title>Association Lists (Guile Reference Manual)</title>
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<meta name="description" content="Association Lists (Guile Reference Manual)">
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<meta name="keywords" content="Association Lists (Guile Reference Manual)">
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<meta name="resource-type" content="document">
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<meta name="distribution" content="global">
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<meta name="Generator" content=".texi2any-real">
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<meta name="viewport" content="width=device-width,initial-scale=1">
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<link href="index.html" rel="start" title="Top">
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<link href="Concept-Index.html" rel="index" title="Concept Index">
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<link href="index.html#SEC_Contents" rel="contents" title="Table of Contents">
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<link href="Data-Types.html" rel="up" title="Data Types">
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<link href="VHashes.html" rel="next" title="VHashes">
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<link href="Dictionary-Types.html" rel="prev" title="Dictionary Types">
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<style type="text/css">
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<!--
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a.copiable-link {visibility: hidden; text-decoration: none; line-height: 0em}
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div.example {margin-left: 3.2em}
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span:hover a.copiable-link {visibility: visible}
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-->
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</style>
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<link rel="stylesheet" type="text/css" href="https://www.gnu.org/software/gnulib/manual.css">
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</head>
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<body lang="en">
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<div class="subsection-level-extent" id="Association-Lists">
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<div class="nav-panel">
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<p>
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Next: <a href="VHashes.html" accesskey="n" rel="next">VList-Based Hash Lists or “VHashes”</a>, Previous: <a href="Dictionary-Types.html" accesskey="p" rel="prev">Dictionary Types</a>, Up: <a href="Data-Types.html" accesskey="u" rel="up">Data Types</a> [<a href="index.html#SEC_Contents" title="Table of contents" rel="contents">Contents</a>][<a href="Concept-Index.html" title="Index" rel="index">Index</a>]</p>
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</div>
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<hr>
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<h4 class="subsection" id="Association-Lists-1"><span>6.6.20 Association Lists<a class="copiable-link" href="#Association-Lists-1"> ¶</a></span></h4>
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<a class="index-entry-id" id="index-Association-Lists"></a>
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<a class="index-entry-id" id="index-Alist"></a>
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<a class="index-entry-id" id="index-association-List"></a>
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<a class="index-entry-id" id="index-alist"></a>
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<a class="index-entry-id" id="index-database"></a>
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<p>An association list is a conventional data structure that is often used
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to implement simple key-value databases. It consists of a list of
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entries in which each entry is a pair. The <em class="dfn">key</em> of each entry is
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the <code class="code">car</code> of the pair and the <em class="dfn">value</em> of each entry is the
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<code class="code">cdr</code>.
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</p>
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<div class="example">
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<pre class="example-preformatted">ASSOCIATION LIST ::= '( (KEY1 . VALUE1)
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(KEY2 . VALUE2)
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(KEY3 . VALUE3)
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...
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)
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</pre></div>
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<p>Association lists are also known, for short, as <em class="dfn">alists</em>.
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</p>
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<p>The structure of an association list is just one example of the infinite
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number of possible structures that can be built using pairs and lists.
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As such, the keys and values in an association list can be manipulated
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using the general list structure procedures <code class="code">cons</code>, <code class="code">car</code>,
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<code class="code">cdr</code>, <code class="code">set-car!</code>, <code class="code">set-cdr!</code> and so on. However,
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because association lists are so useful, Guile also provides specific
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procedures for manipulating them.
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</p>
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<ul class="mini-toc">
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<li><a href="Alist-Key-Equality.html" accesskey="1">Alist Key Equality</a></li>
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<li><a href="Adding-or-Setting-Alist-Entries.html" accesskey="2">Adding or Setting Alist Entries</a></li>
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<li><a href="Retrieving-Alist-Entries.html" accesskey="3">Retrieving Alist Entries</a></li>
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<li><a href="Removing-Alist-Entries.html" accesskey="4">Removing Alist Entries</a></li>
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<li><a href="Sloppy-Alist-Functions.html" accesskey="5">Sloppy Alist Functions</a></li>
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<li><a href="Alist-Example.html" accesskey="6">Alist Example</a></li>
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</ul>
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</div>
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</body>
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</html>
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