134 lines
7.5 KiB
HTML
134 lines
7.5 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>SRFI-1 Association Lists (Guile Reference Manual)</title>
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<meta name="description" content="SRFI-1 Association Lists (Guile Reference Manual)">
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<meta name="keywords" content="SRFI-1 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="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="SRFI_002d1.html" rel="up" title="SRFI-1">
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<link href="SRFI_002d1-Set-Operations.html" rel="next" title="SRFI-1 Set Operations">
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<link href="SRFI_002d1-Deleting.html" rel="prev" title="SRFI-1 Deleting">
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<style type="text/css">
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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="subsubsection-level-extent" id="SRFI_002d1-Association-Lists">
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<div class="nav-panel">
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<p>
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Next: <a href="SRFI_002d1-Set-Operations.html" accesskey="n" rel="next">Set Operations on Lists</a>, Previous: <a href="SRFI_002d1-Deleting.html" accesskey="p" rel="prev">Deleting</a>, Up: <a href="SRFI_002d1.html" accesskey="u" rel="up">SRFI-1 - List library</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="Association-Lists-2"><span>7.5.3.9 Association Lists<a class="copiable-link" href="#Association-Lists-2"> ¶</a></span></h4>
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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-1"></a>
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<p>Association lists are described in detail in section <a class="ref" href="Association-Lists.html">Association Lists</a>. The present section only documents the additional procedures
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for dealing with association lists defined by SRFI-1.
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</p>
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<dl class="first-deffn">
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<dt class="deffn" id="index-assoc-1"><span class="category-def">Scheme Procedure: </span><span><strong class="def-name">assoc</strong> <var class="def-var-arguments">key alist [=]</var><a class="copiable-link" href="#index-assoc-1"> ¶</a></span></dt>
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<dd><p>Return the pair from <var class="var">alist</var> which matches <var class="var">key</var>. This
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extends the core <code class="code">assoc</code> (see <a class="pxref" href="Retrieving-Alist-Entries.html">Retrieving Alist Entries</a>) by
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taking an optional <var class="var">=</var> comparison procedure.
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</p>
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<p>The default comparison is <code class="code">equal?</code>. If an <var class="var">=</var> parameter is
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given it’s called <code class="code">(<var class="var">=</var> <var class="var">key</var> <var class="var">alistcar</var>)</code>, i.e. the
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given target <var class="var">key</var> is the first argument, and a <code class="code">car</code> from
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<var class="var">alist</var> is second.
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</p>
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<p>For example a case-insensitive string lookup,
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</p>
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<div class="example">
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<pre class="example-preformatted">(assoc "yy" '(("XX" . 1) ("YY" . 2)) string-ci=?)
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⇒ ("YY" . 2)
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</pre></div>
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</dd></dl>
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<dl class="first-deffn">
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<dt class="deffn" id="index-alist_002dcons"><span class="category-def">Scheme Procedure: </span><span><strong class="def-name">alist-cons</strong> <var class="def-var-arguments">key datum alist</var><a class="copiable-link" href="#index-alist_002dcons"> ¶</a></span></dt>
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<dd><p>Cons a new association <var class="var">key</var> and <var class="var">datum</var> onto <var class="var">alist</var> and
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return the result. This is equivalent to
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</p>
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<div class="example lisp">
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<pre class="lisp-preformatted">(cons (cons <var class="var">key</var> <var class="var">datum</var>) <var class="var">alist</var>)
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</pre></div>
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<p><code class="code">acons</code> (see <a class="pxref" href="Adding-or-Setting-Alist-Entries.html">Adding or Setting Alist Entries</a>) in the Guile
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core does the same thing.
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</p></dd></dl>
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<dl class="first-deffn">
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<dt class="deffn" id="index-alist_002dcopy"><span class="category-def">Scheme Procedure: </span><span><strong class="def-name">alist-copy</strong> <var class="def-var-arguments">alist</var><a class="copiable-link" href="#index-alist_002dcopy"> ¶</a></span></dt>
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<dd><p>Return a newly allocated copy of <var class="var">alist</var>, that means that the
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spine of the list as well as the pairs are copied.
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</p></dd></dl>
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<dl class="first-deffn">
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<dt class="deffn" id="index-alist_002ddelete"><span class="category-def">Scheme Procedure: </span><span><strong class="def-name">alist-delete</strong> <var class="def-var-arguments">key alist [=]</var><a class="copiable-link" href="#index-alist_002ddelete"> ¶</a></span></dt>
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<dt class="deffnx def-cmd-deffn" id="index-alist_002ddelete_0021"><span class="category-def">Scheme Procedure: </span><span><strong class="def-name">alist-delete!</strong> <var class="def-var-arguments">key alist [=]</var><a class="copiable-link" href="#index-alist_002ddelete_0021"> ¶</a></span></dt>
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<dd><p>Return a list containing the elements of <var class="var">alist</var> but with those
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elements whose keys are equal to <var class="var">key</var> deleted. The returned
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elements will be in the same order as they were in <var class="var">alist</var>.
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</p>
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<p>Equality is determined by the <var class="var">=</var> predicate, or <code class="code">equal?</code> if
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not given. The order in which elements are tested is unspecified, but
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each equality call is made <code class="code">(= key alistkey)</code>, i.e. the given
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<var class="var">key</var> parameter is first and the key from <var class="var">alist</var> second.
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This means for instance all associations with a key greater than 5 can
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be removed with <code class="code">(alist-delete 5 alist <)</code>.
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</p>
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<p><code class="code">alist-delete</code> does not modify <var class="var">alist</var>, but the return might
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share a common tail with <var class="var">alist</var>. <code class="code">alist-delete!</code> may modify
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the list structure of <var class="var">alist</var> to construct its return.
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</p></dd></dl>
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</div>
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<hr>
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<div class="nav-panel">
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<p>
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Next: <a href="SRFI_002d1-Set-Operations.html">Set Operations on Lists</a>, Previous: <a href="SRFI_002d1-Deleting.html">Deleting</a>, Up: <a href="SRFI_002d1.html">SRFI-1 - List library</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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</body>
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</html>
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