95 lines
4.8 KiB
HTML
95 lines
4.8 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>List Mapping (Guile Reference Manual)</title>
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<meta name="description" content="List Mapping (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="Lists.html" rel="up" title="Lists">
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<link href="List-Searching.html" rel="prev" title="List Searching">
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</head>
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<body lang="en">
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<div class="subsubsection-level-extent" id="List-Mapping">
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<div class="nav-panel">
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<p>
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Previous: <a href="List-Searching.html" accesskey="p" rel="prev">List Searching</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-Mapping-1"><span>6.6.9.8 List Mapping<a class="copiable-link" href="#List-Mapping-1"> ¶</a></span></h4>
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<p>List processing is very convenient in Scheme because the process of
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iterating over the elements of a list can be highly abstracted. The
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procedures in this section are the most basic iterating procedures for
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lists. They take a procedure and one or more lists as arguments, and
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apply the procedure to each element of the list. They differ in their
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return value.
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</p>
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<a class="index-entry-id" id="index-map-2"></a>
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<dl class="first-deffn">
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<dt class="deffn" id="index-map"><span class="category-def">Scheme Procedure: </span><span><strong class="def-name">map</strong> <var class="def-var-arguments">proc arg1 arg2 …</var><a class="copiable-link" href="#index-map"> ¶</a></span></dt>
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<dt class="deffnx def-cmd-deffn" id="index-map_002din_002dorder"><span class="category-def">Scheme Procedure: </span><span><strong class="def-name">map-in-order</strong> <var class="def-var-arguments">proc arg1 arg2 …</var><a class="copiable-link" href="#index-map_002din_002dorder"> ¶</a></span></dt>
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<dt class="deffnx def-cmd-deffn" id="index-scm_005fmap"><span class="category-def">C Function: </span><span><strong class="def-name">scm_map</strong> <var class="def-var-arguments">(proc, arg1, args)</var><a class="copiable-link" href="#index-scm_005fmap"> ¶</a></span></dt>
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<dd><p>Apply <var class="var">proc</var> to each element of the list <var class="var">arg1</var> (if only two
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arguments are given), or to the corresponding elements of the argument
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lists (if more than two arguments are given). The result(s) of the
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procedure applications are saved and returned in a list. For
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<code class="code">map</code>, the order of procedure applications is not specified,
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<code class="code">map-in-order</code> applies the procedure from left to right to the list
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elements.
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</p></dd></dl>
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<a class="index-entry-id" id="index-for_002deach-3"></a>
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<dl class="first-deffn">
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<dt class="deffn" id="index-for_002deach"><span class="category-def">Scheme Procedure: </span><span><strong class="def-name">for-each</strong> <var class="def-var-arguments">proc arg1 arg2 …</var><a class="copiable-link" href="#index-for_002deach"> ¶</a></span></dt>
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<dd><p>Like <code class="code">map</code>, but the procedure is always applied from left to right,
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and the result(s) of the procedure applications are thrown away. The
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return value is not specified.
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</p></dd></dl>
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<p>See also SRFI-1 which extends these functions to take lists of unequal
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lengths (<a class="ref" href="SRFI_002d1-Fold-and-Map.html">Fold, Unfold & Map</a>).
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</p>
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</div>
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</body>
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</html>
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