192 lines
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192 lines
13 KiB
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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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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>Sorting (Guile Reference Manual)</title>
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<meta name="description" content="Sorting (Guile Reference Manual)">
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<meta name="keywords" content="Sorting (Guile Reference Manual)">
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<link href="index.html#SEC_Contents" rel="contents" title="Table of Contents">
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<link href="Utility-Functions.html" rel="up" title="Utility Functions">
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<link href="Copying.html" rel="next" title="Copying">
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</head>
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<body lang="en">
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<div class="subsection-level-extent" id="Sorting">
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<div class="nav-panel">
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<p>
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Next: <a href="Copying.html" accesskey="n" rel="next">Copying Deep Structures</a>, Previous: <a href="Object-Properties.html" accesskey="p" rel="prev">Object Properties</a>, Up: <a href="Utility-Functions.html" accesskey="u" rel="up">General Utility Functions</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="Sorting-1"><span>6.9.3 Sorting<a class="copiable-link" href="#Sorting-1"> ¶</a></span></h4>
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<a class="index-entry-id" id="index-sorting"></a>
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<a class="index-entry-id" id="index-sorting-lists"></a>
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<a class="index-entry-id" id="index-sorting-vectors"></a>
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<p>Sorting is very important in computer programs. Therefore, Guile comes
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with several sorting procedures built-in. As always, procedures with
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names ending in <code class="code">!</code> are side-effecting, that means that they may
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modify their parameters in order to produce their results.
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</p>
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<p>The first group of procedures can be used to merge two lists (which must
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be already sorted on their own) and produce sorted lists containing
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all elements of the input lists.
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</p>
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<dl class="first-deffn">
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<dt class="deffn" id="index-merge"><span class="category-def">Scheme Procedure: </span><span><strong class="def-name">merge</strong> <var class="def-var-arguments">alist blist less</var><a class="copiable-link" href="#index-merge"> ¶</a></span></dt>
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<dt class="deffnx def-cmd-deffn" id="index-scm_005fmerge"><span class="category-def">C Function: </span><span><strong class="def-name">scm_merge</strong> <var class="def-var-arguments">(alist, blist, less)</var><a class="copiable-link" href="#index-scm_005fmerge"> ¶</a></span></dt>
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<dd><p>Merge two already sorted lists into one.
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Given two lists <var class="var">alist</var> and <var class="var">blist</var>, such that
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<code class="code">(sorted? alist less?)</code> and <code class="code">(sorted? blist less?)</code>,
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return a new list in which the elements of <var class="var">alist</var> and
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<var class="var">blist</var> have been stably interleaved so that
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<code class="code">(sorted? (merge alist blist less?) less?)</code>.
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Note: this does _not_ accept vectors.
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</p></dd></dl>
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<dl class="first-deffn">
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<dt class="deffn" id="index-merge_0021"><span class="category-def">Scheme Procedure: </span><span><strong class="def-name">merge!</strong> <var class="def-var-arguments">alist blist less</var><a class="copiable-link" href="#index-merge_0021"> ¶</a></span></dt>
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<dt class="deffnx def-cmd-deffn" id="index-scm_005fmerge_005fx"><span class="category-def">C Function: </span><span><strong class="def-name">scm_merge_x</strong> <var class="def-var-arguments">(alist, blist, less)</var><a class="copiable-link" href="#index-scm_005fmerge_005fx"> ¶</a></span></dt>
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<dd><p>Takes two lists <var class="var">alist</var> and <var class="var">blist</var> such that
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<code class="code">(sorted? alist less?)</code> and <code class="code">(sorted? blist less?)</code> and
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returns a new list in which the elements of <var class="var">alist</var> and
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<var class="var">blist</var> have been stably interleaved so that
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<code class="code">(sorted? (merge alist blist less?) less?)</code>.
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This is the destructive variant of <code class="code">merge</code>
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Note: this does _not_ accept vectors.
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</p></dd></dl>
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<p>The following procedures can operate on sequences which are either
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vectors or list. According to the given arguments, they return sorted
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vectors or lists, respectively. The first of the following procedures
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determines whether a sequence is already sorted, the other sort a given
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sequence. The variants with names starting with <code class="code">stable-</code> are
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special in that they maintain a special property of the input sequences:
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If two or more elements are the same according to the comparison
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predicate, they are left in the same order as they appeared in the
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input.
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</p>
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<dl class="first-deffn">
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<dt class="deffn" id="index-sorted_003f"><span class="category-def">Scheme Procedure: </span><span><strong class="def-name">sorted?</strong> <var class="def-var-arguments">items less</var><a class="copiable-link" href="#index-sorted_003f"> ¶</a></span></dt>
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<dt class="deffnx def-cmd-deffn" id="index-scm_005fsorted_005fp"><span class="category-def">C Function: </span><span><strong class="def-name">scm_sorted_p</strong> <var class="def-var-arguments">(items, less)</var><a class="copiable-link" href="#index-scm_005fsorted_005fp"> ¶</a></span></dt>
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<dd><p>Return <code class="code">#t</code> if <var class="var">items</var> is a list or vector such that,
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for each element <var class="var">x</var> and the next element <var class="var">y</var> of
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<var class="var">items</var>, <code class="code">(<var class="var">less</var> <var class="var">y</var> <var class="var">x</var>)</code> returns
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<code class="code">#f</code>. Otherwise return <code class="code">#f</code>.
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</p></dd></dl>
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<dl class="first-deffn">
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<dt class="deffn" id="index-sort"><span class="category-def">Scheme Procedure: </span><span><strong class="def-name">sort</strong> <var class="def-var-arguments">items less</var><a class="copiable-link" href="#index-sort"> ¶</a></span></dt>
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<dt class="deffnx def-cmd-deffn" id="index-scm_005fsort"><span class="category-def">C Function: </span><span><strong class="def-name">scm_sort</strong> <var class="def-var-arguments">(items, less)</var><a class="copiable-link" href="#index-scm_005fsort"> ¶</a></span></dt>
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<dd><p>Sort the sequence <var class="var">items</var>, which may be a list or a
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vector. <var class="var">less</var> is used for comparing the sequence
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elements. This is not a stable sort.
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</p></dd></dl>
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<dl class="first-deffn">
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<dt class="deffn" id="index-sort_0021"><span class="category-def">Scheme Procedure: </span><span><strong class="def-name">sort!</strong> <var class="def-var-arguments">items less</var><a class="copiable-link" href="#index-sort_0021"> ¶</a></span></dt>
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<dt class="deffnx def-cmd-deffn" id="index-scm_005fsort_005fx"><span class="category-def">C Function: </span><span><strong class="def-name">scm_sort_x</strong> <var class="def-var-arguments">(items, less)</var><a class="copiable-link" href="#index-scm_005fsort_005fx"> ¶</a></span></dt>
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<dd><p>Sort the sequence <var class="var">items</var>, which may be a list or a
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vector. <var class="var">less</var> is used for comparing the sequence
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elements. The sorting is destructive, that means that the
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input sequence is modified to produce the sorted result.
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This is not a stable sort.
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</p></dd></dl>
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<dl class="first-deffn">
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<dt class="deffn" id="index-stable_002dsort"><span class="category-def">Scheme Procedure: </span><span><strong class="def-name">stable-sort</strong> <var class="def-var-arguments">items less</var><a class="copiable-link" href="#index-stable_002dsort"> ¶</a></span></dt>
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<dt class="deffnx def-cmd-deffn" id="index-scm_005fstable_005fsort"><span class="category-def">C Function: </span><span><strong class="def-name">scm_stable_sort</strong> <var class="def-var-arguments">(items, less)</var><a class="copiable-link" href="#index-scm_005fstable_005fsort"> ¶</a></span></dt>
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<dd><p>Sort the sequence <var class="var">items</var>, which may be a list or a
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vector. <var class="var">less</var> is used for comparing the sequence elements.
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This is a stable sort.
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</p></dd></dl>
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<dl class="first-deffn">
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<dt class="deffn" id="index-stable_002dsort_0021"><span class="category-def">Scheme Procedure: </span><span><strong class="def-name">stable-sort!</strong> <var class="def-var-arguments">items less</var><a class="copiable-link" href="#index-stable_002dsort_0021"> ¶</a></span></dt>
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<dt class="deffnx def-cmd-deffn" id="index-scm_005fstable_005fsort_005fx"><span class="category-def">C Function: </span><span><strong class="def-name">scm_stable_sort_x</strong> <var class="def-var-arguments">(items, less)</var><a class="copiable-link" href="#index-scm_005fstable_005fsort_005fx"> ¶</a></span></dt>
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<dd><p>Sort the sequence <var class="var">items</var>, which may be a list or a
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vector. <var class="var">less</var> is used for comparing the sequence elements.
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The sorting is destructive, that means that the input sequence
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is modified to produce the sorted result.
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This is a stable sort.
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</p></dd></dl>
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<p>The procedures in the last group only accept lists or vectors as input,
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as their names indicate.
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</p>
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<dl class="first-deffn">
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<dt class="deffn" id="index-sort_002dlist"><span class="category-def">Scheme Procedure: </span><span><strong class="def-name">sort-list</strong> <var class="def-var-arguments">items less</var><a class="copiable-link" href="#index-sort_002dlist"> ¶</a></span></dt>
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<dt class="deffnx def-cmd-deffn" id="index-scm_005fsort_005flist"><span class="category-def">C Function: </span><span><strong class="def-name">scm_sort_list</strong> <var class="def-var-arguments">(items, less)</var><a class="copiable-link" href="#index-scm_005fsort_005flist"> ¶</a></span></dt>
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<dd><p>Sort the list <var class="var">items</var>, using <var class="var">less</var> for comparing the
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list elements. This is a stable sort.
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</p></dd></dl>
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<dl class="first-deffn">
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<dt class="deffn" id="index-sort_002dlist_0021"><span class="category-def">Scheme Procedure: </span><span><strong class="def-name">sort-list!</strong> <var class="def-var-arguments">items less</var><a class="copiable-link" href="#index-sort_002dlist_0021"> ¶</a></span></dt>
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<dt class="deffnx def-cmd-deffn" id="index-scm_005fsort_005flist_005fx"><span class="category-def">C Function: </span><span><strong class="def-name">scm_sort_list_x</strong> <var class="def-var-arguments">(items, less)</var><a class="copiable-link" href="#index-scm_005fsort_005flist_005fx"> ¶</a></span></dt>
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<dd><p>Sort the list <var class="var">items</var>, using <var class="var">less</var> for comparing the
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list elements. The sorting is destructive, that means that the
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input list is modified to produce the sorted result.
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This is a stable sort.
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</p></dd></dl>
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<dl class="first-deffn">
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<dt class="deffn" id="index-restricted_002dvector_002dsort_0021"><span class="category-def">Scheme Procedure: </span><span><strong class="def-name">restricted-vector-sort!</strong> <var class="def-var-arguments">vec less startpos endpos</var><a class="copiable-link" href="#index-restricted_002dvector_002dsort_0021"> ¶</a></span></dt>
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<dt class="deffnx def-cmd-deffn" id="index-scm_005frestricted_005fvector_005fsort_005fx"><span class="category-def">C Function: </span><span><strong class="def-name">scm_restricted_vector_sort_x</strong> <var class="def-var-arguments">(vec, less, startpos, endpos)</var><a class="copiable-link" href="#index-scm_005frestricted_005fvector_005fsort_005fx"> ¶</a></span></dt>
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<dd><p>Sort the vector <var class="var">vec</var>, using <var class="var">less</var> for comparing
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the vector elements. <var class="var">startpos</var> (inclusively) and
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<var class="var">endpos</var> (exclusively) delimit
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the range of the vector which gets sorted. The return value
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is not specified.
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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="Copying.html">Copying Deep Structures</a>, Previous: <a href="Object-Properties.html">Object Properties</a>, Up: <a href="Utility-Functions.html">General Utility Functions</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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