93 lines
4.8 KiB
HTML
93 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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<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>rnrs control (Guile Reference Manual)</title>
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<meta name="description" content="rnrs control (Guile Reference Manual)">
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<meta name="keywords" content="rnrs control (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="Generator" content=".texi2any-real">
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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="R6RS-Standard-Libraries.html" rel="up" title="R6RS Standard Libraries">
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<link href="R6RS-Records.html" rel="next" title="R6RS Records">
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<link href="rnrs-sorting.html" rel="prev" title="rnrs sorting">
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<style type="text/css">
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a.copiable-link {visibility: hidden; text-decoration: none; line-height: 0em}
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span:hover a.copiable-link {visibility: visible}
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strong.def-name {font-family: monospace; font-weight: bold; font-size: larger}
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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="rnrs-control">
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<div class="nav-panel">
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<p>
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Next: <a href="R6RS-Records.html" accesskey="n" rel="next">R6RS Records</a>, Previous: <a href="rnrs-sorting.html" accesskey="p" rel="prev">rnrs sorting</a>, Up: <a href="R6RS-Standard-Libraries.html" accesskey="u" rel="up">R6RS Standard Libraries</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="rnrs-control-1"><span>7.6.2.7 rnrs control<a class="copiable-link" href="#rnrs-control-1"> ¶</a></span></h4>
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<p>The <code class="code">(rnrs control (6))</code> library provides syntactic forms useful
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for constructing conditional expressions and controlling the flow of
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execution.
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</p>
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<dl class="first-deffn">
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<dt class="deffn" id="index-when-2"><span class="category-def">Scheme Syntax: </span><span><strong class="def-name">when</strong> <var class="def-var-arguments">test expression1 expression2 ...</var><a class="copiable-link" href="#index-when-2"> ¶</a></span></dt>
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<dt class="deffnx def-cmd-deffn" id="index-unless-2"><span class="category-def">Scheme Syntax: </span><span><strong class="def-name">unless</strong> <var class="def-var-arguments">test expression1 expression2 ...</var><a class="copiable-link" href="#index-unless-2"> ¶</a></span></dt>
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<dd><p>The <code class="code">when</code> form is evaluated by evaluating the specified <var class="var">test</var>
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expression; if the result is a true value, the <var class="var">expression</var>s that
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follow it are evaluated in order, and the value of the final
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<var class="var">expression</var> becomes the value of the entire <code class="code">when</code> expression.
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</p>
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<p>The <code class="code">unless</code> form behaves similarly, with the exception that the
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specified <var class="var">expression</var>s are only evaluated if the value of
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<var class="var">test</var> is false.
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</p></dd></dl>
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<dl class="first-deffn">
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<dt class="deffn" id="index-do-1"><span class="category-def">Scheme Syntax: </span><span><strong class="def-name">do</strong> <var class="def-var-arguments">((variable init step) ...) (test expression ...) command ...</var><a class="copiable-link" href="#index-do-1"> ¶</a></span></dt>
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<dd><p>This form is identical to the one provided by Guile’s core library.
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See <a class="xref" href="while-do.html">Iteration mechanisms</a>, for documentation.
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</p></dd></dl>
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<dl class="first-deffn">
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<dt class="deffn" id="index-case_002dlambda-1"><span class="category-def">Scheme Syntax: </span><span><strong class="def-name">case-lambda</strong> <var class="def-var-arguments">clause ...</var><a class="copiable-link" href="#index-case_002dlambda-1"> ¶</a></span></dt>
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<dd><p>This form is identical to the one provided by Guile’s core library.
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See <a class="xref" href="Case_002dlambda.html">Case-lambda</a>, for documentation.
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</p></dd></dl>
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</div>
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</body>
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</html>
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