101 lines
3.8 KiB
HTML
101 lines
3.8 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>Alist Example (Guile Reference Manual)</title>
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<meta name="description" content="Alist Example (Guile Reference Manual)">
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<meta name="keywords" content="Alist Example (Guile Reference Manual)">
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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="Association-Lists.html" rel="up" title="Association Lists">
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<link href="Sloppy-Alist-Functions.html" rel="prev" title="Sloppy Alist Functions">
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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="subsubsection-level-extent" id="Alist-Example">
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<div class="nav-panel">
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<p>
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Previous: <a href="Sloppy-Alist-Functions.html" accesskey="p" rel="prev">Sloppy Alist Functions</a>, Up: <a href="Association-Lists.html" accesskey="u" rel="up">Association Lists</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="subsubsection" id="Alist-Example-1"><span>6.6.20.6 Alist Example<a class="copiable-link" href="#Alist-Example-1"> ¶</a></span></h4>
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<p>Here is a longer example of how alists may be used in practice.
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</p>
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<div class="example lisp">
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<pre class="lisp-preformatted">(define capitals '(("New York" . "Albany")
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("Oregon" . "Salem")
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("Florida" . "Miami")))
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;; What's the capital of Oregon?
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(assoc "Oregon" capitals) ⇒ ("Oregon" . "Salem")
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(assoc-ref capitals "Oregon") ⇒ "Salem"
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;; We left out South Dakota.
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(set! capitals
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(assoc-set! capitals "South Dakota" "Pierre"))
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capitals
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⇒ (("South Dakota" . "Pierre")
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("New York" . "Albany")
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("Oregon" . "Salem")
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("Florida" . "Miami"))
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;; And we got Florida wrong.
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(set! capitals
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(assoc-set! capitals "Florida" "Tallahassee"))
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capitals
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⇒ (("South Dakota" . "Pierre")
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("New York" . "Albany")
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("Oregon" . "Salem")
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("Florida" . "Tallahassee"))
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;; After Oregon secedes, we can remove it.
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(set! capitals
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(assoc-remove! capitals "Oregon"))
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capitals
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⇒ (("South Dakota" . "Pierre")
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("New York" . "Albany")
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("Florida" . "Tallahassee"))
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</pre></div>
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</div>
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</body>
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</html>
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