111 lines
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111 lines
5 KiB
HTML
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Copyright (C) 1996-1997, 2000-2005, 2009-2023 Free Software Foundation,
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Copyright (C) 2021 Maxime Devos
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Copyright (C) 2024 Tomas Volf
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<title>Macros (Guile Reference Manual)</title>
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<div class="section-level-extent" id="Macros">
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<p>
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Next: <a href="Utility-Functions.html" accesskey="n" rel="next">General Utility Functions</a>, Previous: <a href="Procedures.html" accesskey="p" rel="prev">Procedures</a>, Up: <a href="API-Reference.html" accesskey="u" rel="up">API Reference</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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<h3 class="section" id="Macros-1"><span>6.8 Macros<a class="copiable-link" href="#Macros-1"> ¶</a></span></h3>
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<p>At its best, programming in Lisp is an iterative process of building up a
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language appropriate to the problem at hand, and then solving the problem in
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that language. Defining new procedures is part of that, but Lisp also allows
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the user to extend its syntax, with its famous <em class="dfn">macros</em>.
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</p>
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<a class="index-entry-id" id="index-macros"></a>
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<a class="index-entry-id" id="index-transformation"></a>
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<p>Macros are syntactic extensions which cause the expression that they appear in
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to be transformed in some way <em class="emph">before</em> being evaluated. In expressions that
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are intended for macro transformation, the identifier that names the relevant
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macro must appear as the first element, like this:
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</p>
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<div class="example lisp">
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<pre class="lisp-preformatted">(<var class="var">macro-name</var> <var class="var">macro-args</var> ...)
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</pre></div>
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<a class="index-entry-id" id="index-macro-expansion"></a>
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<a class="index-entry-id" id="index-domain_002dspecific-language"></a>
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<a class="index-entry-id" id="index-embedded-domain_002dspecific-language"></a>
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<a class="index-entry-id" id="index-DSL"></a>
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<a class="index-entry-id" id="index-EDSL"></a>
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<p>Macro expansion is a separate phase of evaluation, run before code is
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interpreted or compiled. A macro is a program that runs on programs, translating
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an embedded language into core Scheme<a class="footnote" id="DOCF13" href="#FOOT13"><sup>13</sup></a>.
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</p>
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<ul class="mini-toc">
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<li><a href="Defining-Macros.html" accesskey="1">Defining Macros</a></li>
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<li><a href="Syntax-Rules.html" accesskey="2">Syntax-rules Macros</a></li>
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<li><a href="Syntax-Case.html" accesskey="3">Support for the <code class="code">syntax-case</code> System</a></li>
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<li><a href="Syntax-Transformer-Helpers.html" accesskey="4">Syntax Transformer Helpers</a></li>
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<li><a href="Defmacros.html" accesskey="5">Lisp-style Macro Definitions</a></li>
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<li><a href="Identifier-Macros.html" accesskey="6">Identifier Macros</a></li>
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<li><a href="Syntax-Parameters.html" accesskey="7">Syntax Parameters</a></li>
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<li><a href="Eval-When.html" accesskey="8">Eval-when</a></li>
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<li><a href="Macro-Expansion.html" accesskey="9">Macro Expansion</a></li>
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<li><a href="Hygiene-and-the-Top_002dLevel.html">Hygiene and the Top-Level</a></li>
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<li><a href="Internal-Macros.html">Internal Macros</a></li>
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</ul>
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</div>
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<div class="footnotes-segment">
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<hr>
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<h4 class="footnotes-heading">Footnotes</h4>
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<h5 class="footnote-body-heading"><a id="FOOT13" href="#DOCF13">(13)</a></h5>
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<p>These days such embedded
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languages are often referred to as <em class="dfn">embedded domain-specific
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languages</em>, or EDSLs.</p>
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