166 lines
13 KiB
HTML
166 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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<title>List Modification (Guile Reference Manual)</title>
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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="Lists.html" rel="up" title="Lists">
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<body lang="en">
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<div class="subsubsection-level-extent" id="List-Modification">
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<div class="nav-panel">
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<p>
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Next: <a href="List-Searching.html" accesskey="n" rel="next">List Searching</a>, Previous: <a href="Append_002fReverse.html" accesskey="p" rel="prev">Append and Reverse</a>, Up: <a href="Lists.html" accesskey="u" rel="up">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="List-Modification-1"><span>6.6.9.6 List Modification<a class="copiable-link" href="#List-Modification-1"> ¶</a></span></h4>
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<p>The following procedures modify an existing list, either by changing
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elements of the list, or by changing the list structure itself.
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</p>
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<dl class="first-deffn">
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<dt class="deffn" id="index-list_002dset_0021"><span class="category-def">Scheme Procedure: </span><span><strong class="def-name">list-set!</strong> <var class="def-var-arguments">list k val</var><a class="copiable-link" href="#index-list_002dset_0021"> ¶</a></span></dt>
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<dt class="deffnx def-cmd-deffn" id="index-scm_005flist_005fset_005fx"><span class="category-def">C Function: </span><span><strong class="def-name">scm_list_set_x</strong> <var class="def-var-arguments">(list, k, val)</var><a class="copiable-link" href="#index-scm_005flist_005fset_005fx"> ¶</a></span></dt>
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<dd><p>Set the <var class="var">k</var>th element of <var class="var">list</var> to <var class="var">val</var>.
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</p></dd></dl>
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<dl class="first-deffn">
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<dt class="deffn" id="index-list_002dcdr_002dset_0021"><span class="category-def">Scheme Procedure: </span><span><strong class="def-name">list-cdr-set!</strong> <var class="def-var-arguments">list k val</var><a class="copiable-link" href="#index-list_002dcdr_002dset_0021"> ¶</a></span></dt>
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<dt class="deffnx def-cmd-deffn" id="index-scm_005flist_005fcdr_005fset_005fx"><span class="category-def">C Function: </span><span><strong class="def-name">scm_list_cdr_set_x</strong> <var class="def-var-arguments">(list, k, val)</var><a class="copiable-link" href="#index-scm_005flist_005fcdr_005fset_005fx"> ¶</a></span></dt>
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<dd><p>Set the <var class="var">k</var>th cdr of <var class="var">list</var> to <var class="var">val</var>.
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</p></dd></dl>
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<dl class="first-deffn">
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<dt class="deffn" id="index-delq"><span class="category-def">Scheme Procedure: </span><span><strong class="def-name">delq</strong> <var class="def-var-arguments">item lst</var><a class="copiable-link" href="#index-delq"> ¶</a></span></dt>
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<dt class="deffnx def-cmd-deffn" id="index-scm_005fdelq"><span class="category-def">C Function: </span><span><strong class="def-name">scm_delq</strong> <var class="def-var-arguments">(item, lst)</var><a class="copiable-link" href="#index-scm_005fdelq"> ¶</a></span></dt>
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<dd><p>Return a newly-created copy of <var class="var">lst</var> with elements
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<code class="code">eq?</code> to <var class="var">item</var> removed. This procedure mirrors
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<code class="code">memq</code>: <code class="code">delq</code> compares elements of <var class="var">lst</var> against
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<var class="var">item</var> with <code class="code">eq?</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-delv"><span class="category-def">Scheme Procedure: </span><span><strong class="def-name">delv</strong> <var class="def-var-arguments">item lst</var><a class="copiable-link" href="#index-delv"> ¶</a></span></dt>
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<dt class="deffnx def-cmd-deffn" id="index-scm_005fdelv"><span class="category-def">C Function: </span><span><strong class="def-name">scm_delv</strong> <var class="def-var-arguments">(item, lst)</var><a class="copiable-link" href="#index-scm_005fdelv"> ¶</a></span></dt>
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<dd><p>Return a newly-created copy of <var class="var">lst</var> with elements
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<code class="code">eqv?</code> to <var class="var">item</var> removed. This procedure mirrors
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<code class="code">memv</code>: <code class="code">delv</code> compares elements of <var class="var">lst</var> against
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<var class="var">item</var> with <code class="code">eqv?</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-delete"><span class="category-def">Scheme Procedure: </span><span><strong class="def-name">delete</strong> <var class="def-var-arguments">item lst</var><a class="copiable-link" href="#index-delete"> ¶</a></span></dt>
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<dt class="deffnx def-cmd-deffn" id="index-scm_005fdelete"><span class="category-def">C Function: </span><span><strong class="def-name">scm_delete</strong> <var class="def-var-arguments">(item, lst)</var><a class="copiable-link" href="#index-scm_005fdelete"> ¶</a></span></dt>
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<dd><p>Return a newly-created copy of <var class="var">lst</var> with elements
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<code class="code">equal?</code> to <var class="var">item</var> removed. This procedure mirrors
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<code class="code">member</code>: <code class="code">delete</code> compares elements of <var class="var">lst</var>
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against <var class="var">item</var> with <code class="code">equal?</code>.
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</p>
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<p>See also SRFI-1 which has an extended <code class="code">delete</code> (<a class="ref" href="SRFI_002d1-Deleting.html">Deleting</a>), and also an <code class="code">lset-difference</code> which can delete
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multiple <var class="var">item</var>s in one call (<a class="ref" href="SRFI_002d1-Set-Operations.html">Set Operations on Lists</a>).
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</p></dd></dl>
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<dl class="first-deffn">
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<dt class="deffn" id="index-delq_0021"><span class="category-def">Scheme Procedure: </span><span><strong class="def-name">delq!</strong> <var class="def-var-arguments">item lst</var><a class="copiable-link" href="#index-delq_0021"> ¶</a></span></dt>
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<dt class="deffnx def-cmd-deffn" id="index-delv_0021"><span class="category-def">Scheme Procedure: </span><span><strong class="def-name">delv!</strong> <var class="def-var-arguments">item lst</var><a class="copiable-link" href="#index-delv_0021"> ¶</a></span></dt>
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<dt class="deffnx def-cmd-deffn" id="index-delete_0021"><span class="category-def">Scheme Procedure: </span><span><strong class="def-name">delete!</strong> <var class="def-var-arguments">item lst</var><a class="copiable-link" href="#index-delete_0021"> ¶</a></span></dt>
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<dt class="deffnx def-cmd-deffn" id="index-scm_005fdelq_005fx"><span class="category-def">C Function: </span><span><strong class="def-name">scm_delq_x</strong> <var class="def-var-arguments">(item, lst)</var><a class="copiable-link" href="#index-scm_005fdelq_005fx"> ¶</a></span></dt>
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<dt class="deffnx def-cmd-deffn" id="index-scm_005fdelv_005fx"><span class="category-def">C Function: </span><span><strong class="def-name">scm_delv_x</strong> <var class="def-var-arguments">(item, lst)</var><a class="copiable-link" href="#index-scm_005fdelv_005fx"> ¶</a></span></dt>
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<dt class="deffnx def-cmd-deffn" id="index-scm_005fdelete_005fx"><span class="category-def">C Function: </span><span><strong class="def-name">scm_delete_x</strong> <var class="def-var-arguments">(item, lst)</var><a class="copiable-link" href="#index-scm_005fdelete_005fx"> ¶</a></span></dt>
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<dd><p>These procedures are destructive versions of <code class="code">delq</code>, <code class="code">delv</code>
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and <code class="code">delete</code>: they modify the pointers in the existing <var class="var">lst</var>
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rather than creating a new list. Caveat evaluator: Like other
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destructive list functions, these functions cannot modify the binding of
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<var class="var">lst</var>, and so cannot be used to delete the first element of
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<var class="var">lst</var> destructively.
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</p></dd></dl>
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<dl class="first-deffn">
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<dt class="deffn" id="index-delq1_0021"><span class="category-def">Scheme Procedure: </span><span><strong class="def-name">delq1!</strong> <var class="def-var-arguments">item lst</var><a class="copiable-link" href="#index-delq1_0021"> ¶</a></span></dt>
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<dt class="deffnx def-cmd-deffn" id="index-scm_005fdelq1_005fx"><span class="category-def">C Function: </span><span><strong class="def-name">scm_delq1_x</strong> <var class="def-var-arguments">(item, lst)</var><a class="copiable-link" href="#index-scm_005fdelq1_005fx"> ¶</a></span></dt>
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<dd><p>Like <code class="code">delq!</code>, but only deletes the first occurrence of
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<var class="var">item</var> from <var class="var">lst</var>. Tests for equality using
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<code class="code">eq?</code>. See also <code class="code">delv1!</code> and <code class="code">delete1!</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-delv1_0021"><span class="category-def">Scheme Procedure: </span><span><strong class="def-name">delv1!</strong> <var class="def-var-arguments">item lst</var><a class="copiable-link" href="#index-delv1_0021"> ¶</a></span></dt>
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<dt class="deffnx def-cmd-deffn" id="index-scm_005fdelv1_005fx"><span class="category-def">C Function: </span><span><strong class="def-name">scm_delv1_x</strong> <var class="def-var-arguments">(item, lst)</var><a class="copiable-link" href="#index-scm_005fdelv1_005fx"> ¶</a></span></dt>
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<dd><p>Like <code class="code">delv!</code>, but only deletes the first occurrence of
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<var class="var">item</var> from <var class="var">lst</var>. Tests for equality using
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<code class="code">eqv?</code>. See also <code class="code">delq1!</code> and <code class="code">delete1!</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-delete1_0021"><span class="category-def">Scheme Procedure: </span><span><strong class="def-name">delete1!</strong> <var class="def-var-arguments">item lst</var><a class="copiable-link" href="#index-delete1_0021"> ¶</a></span></dt>
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<dt class="deffnx def-cmd-deffn" id="index-scm_005fdelete1_005fx"><span class="category-def">C Function: </span><span><strong class="def-name">scm_delete1_x</strong> <var class="def-var-arguments">(item, lst)</var><a class="copiable-link" href="#index-scm_005fdelete1_005fx"> ¶</a></span></dt>
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<dd><p>Like <code class="code">delete!</code>, but only deletes the first occurrence of
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<var class="var">item</var> from <var class="var">lst</var>. Tests for equality using
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<code class="code">equal?</code>. See also <code class="code">delq1!</code> and <code class="code">delv1!</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-filter"><span class="category-def">Scheme Procedure: </span><span><strong class="def-name">filter</strong> <var class="def-var-arguments">pred lst</var><a class="copiable-link" href="#index-filter"> ¶</a></span></dt>
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<dt class="deffnx def-cmd-deffn" id="index-filter_0021"><span class="category-def">Scheme Procedure: </span><span><strong class="def-name">filter!</strong> <var class="def-var-arguments">pred lst</var><a class="copiable-link" href="#index-filter_0021"> ¶</a></span></dt>
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<dd><p>Return a list containing all elements from <var class="var">lst</var> which satisfy the
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predicate <var class="var">pred</var>. The elements in the result list have the same
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order as in <var class="var">lst</var>. The order in which <var class="var">pred</var> is applied to
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the list elements is not specified.
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</p>
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<p><code class="code">filter</code> does not change <var class="var">lst</var>, but the result may share a
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tail with it. <code class="code">filter!</code> may modify <var class="var">lst</var> to construct its
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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="List-Searching.html">List Searching</a>, Previous: <a href="Append_002fReverse.html">Append and Reverse</a>, Up: <a href="Lists.html">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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