141 lines
8.8 KiB
HTML
141 lines
8.8 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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<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 Length Append etc (Guile Reference Manual)</title>
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<meta name="description" content="SRFI-1 Length Append etc (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="SRFI_002d1.html" rel="up" title="SRFI-1">
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<link href="SRFI_002d1-Fold-and-Map.html" rel="next" title="SRFI-1 Fold and Map">
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<link href="SRFI_002d1-Selectors.html" rel="prev" title="SRFI-1 Selectors">
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<style type="text/css">
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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-Length-Append-etc">
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<div class="nav-panel">
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<p>
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Next: <a href="SRFI_002d1-Fold-and-Map.html" accesskey="n" rel="next">Fold, Unfold & Map</a>, Previous: <a href="SRFI_002d1-Selectors.html" accesskey="p" rel="prev">Selectors</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="Length_002c-Append_002c-Concatenate_002c-etc_002e"><span>7.5.3.4 Length, Append, Concatenate, etc.<a class="copiable-link" href="#Length_002c-Append_002c-Concatenate_002c-etc_002e"> ¶</a></span></h4>
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<dl class="first-deffn">
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<dt class="deffn" id="index-length_002b"><span class="category-def">Scheme Procedure: </span><span><strong class="def-name">length+</strong> <var class="def-var-arguments">lst</var><a class="copiable-link" href="#index-length_002b"> ¶</a></span></dt>
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<dd><p>Return the length of the argument list <var class="var">lst</var>. When <var class="var">lst</var> is a
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circular list, <code class="code">#f</code> is returned.
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</p></dd></dl>
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<dl class="first-deffn">
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<dt class="deffn" id="index-concatenate"><span class="category-def">Scheme Procedure: </span><span><strong class="def-name">concatenate</strong> <var class="def-var-arguments">list-of-lists</var><a class="copiable-link" href="#index-concatenate"> ¶</a></span></dt>
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<dt class="deffnx def-cmd-deffn" id="index-concatenate_0021"><span class="category-def">Scheme Procedure: </span><span><strong class="def-name">concatenate!</strong> <var class="def-var-arguments">list-of-lists</var><a class="copiable-link" href="#index-concatenate_0021"> ¶</a></span></dt>
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<dd><p>Construct a list by appending all lists in <var class="var">list-of-lists</var>.
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</p>
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<p><code class="code">concatenate!</code> may modify the structure of the given lists in
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order to produce the result.
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</p>
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<p><code class="code">concatenate</code> is the same as <code class="code">(apply append
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<var class="var">list-of-lists</var>)</code>. It exists because some Scheme implementations
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have a limit on the number of arguments a function takes, which the
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<code class="code">apply</code> might exceed. In Guile there is no such limit.
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</p></dd></dl>
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<dl class="first-deffn">
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<dt class="deffn" id="index-append_002dreverse"><span class="category-def">Scheme Procedure: </span><span><strong class="def-name">append-reverse</strong> <var class="def-var-arguments">rev-head tail</var><a class="copiable-link" href="#index-append_002dreverse"> ¶</a></span></dt>
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<dt class="deffnx def-cmd-deffn" id="index-append_002dreverse_0021"><span class="category-def">Scheme Procedure: </span><span><strong class="def-name">append-reverse!</strong> <var class="def-var-arguments">rev-head tail</var><a class="copiable-link" href="#index-append_002dreverse_0021"> ¶</a></span></dt>
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<dd><p>Reverse <var class="var">rev-head</var>, append <var class="var">tail</var> to it, and return the
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result. This is equivalent to <code class="code">(append (reverse <var class="var">rev-head</var>)
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<var class="var">tail</var>)</code>, but its implementation is more efficient.
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</p>
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<div class="example">
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<pre class="example-preformatted">(append-reverse '(1 2 3) '(4 5 6)) ⇒ (3 2 1 4 5 6)
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</pre></div>
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<p><code class="code">append-reverse!</code> may modify <var class="var">rev-head</var> in order to produce
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the result.
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</p></dd></dl>
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<dl class="first-deffn">
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<dt class="deffn" id="index-zip"><span class="category-def">Scheme Procedure: </span><span><strong class="def-name">zip</strong> <var class="def-var-arguments">lst1 lst2 …</var><a class="copiable-link" href="#index-zip"> ¶</a></span></dt>
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<dd><p>Return a list as long as the shortest of the argument lists, where
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each element is a list. The first list contains the first elements of
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the argument lists, the second list contains the second elements, and
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so on.
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</p></dd></dl>
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<dl class="first-deffn">
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<dt class="deffn" id="index-unzip1"><span class="category-def">Scheme Procedure: </span><span><strong class="def-name">unzip1</strong> <var class="def-var-arguments">lst</var><a class="copiable-link" href="#index-unzip1"> ¶</a></span></dt>
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<dt class="deffnx def-cmd-deffn" id="index-unzip2"><span class="category-def">Scheme Procedure: </span><span><strong class="def-name">unzip2</strong> <var class="def-var-arguments">lst</var><a class="copiable-link" href="#index-unzip2"> ¶</a></span></dt>
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<dt class="deffnx def-cmd-deffn" id="index-unzip3"><span class="category-def">Scheme Procedure: </span><span><strong class="def-name">unzip3</strong> <var class="def-var-arguments">lst</var><a class="copiable-link" href="#index-unzip3"> ¶</a></span></dt>
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<dt class="deffnx def-cmd-deffn" id="index-unzip4"><span class="category-def">Scheme Procedure: </span><span><strong class="def-name">unzip4</strong> <var class="def-var-arguments">lst</var><a class="copiable-link" href="#index-unzip4"> ¶</a></span></dt>
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<dt class="deffnx def-cmd-deffn" id="index-unzip5"><span class="category-def">Scheme Procedure: </span><span><strong class="def-name">unzip5</strong> <var class="def-var-arguments">lst</var><a class="copiable-link" href="#index-unzip5"> ¶</a></span></dt>
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<dd><p><code class="code">unzip1</code> takes a list of lists, and returns a list containing the
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first elements of each list, <code class="code">unzip2</code> returns two lists, the
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first containing the first elements of each lists and the second
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containing the second elements of each lists, and so on.
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</p></dd></dl>
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<dl class="first-deffn">
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<dt class="deffn" id="index-count"><span class="category-def">Scheme Procedure: </span><span><strong class="def-name">count</strong> <var class="def-var-arguments">pred lst1 lst2 …</var><a class="copiable-link" href="#index-count"> ¶</a></span></dt>
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<dd><p>Return a count of the number of times <var class="var">pred</var> returns true when
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called on elements from the given lists.
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</p>
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<p><var class="var">pred</var> is called with <var class="var">N</var> parameters <code class="code">(<var class="var">pred</var>
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<var class="var">elem1</var> … <var class="var">elemN</var> )</code>, each element being from the
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corresponding list. The first call is with the first element of each
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list, the second with the second element from each, and so on.
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</p>
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<p>Counting stops when the end of the shortest list is reached. At least
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one list must be non-circular.
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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-Fold-and-Map.html">Fold, Unfold & Map</a>, Previous: <a href="SRFI_002d1-Selectors.html">Selectors</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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