104 lines
5 KiB
HTML
104 lines
5 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>Record Overview (Guile Reference Manual)</title>
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<meta name="description" content="Record Overview (Guile Reference Manual)">
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<meta name="keywords" content="Record Overview (Guile Reference Manual)">
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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="Data-Types.html" rel="up" title="Data Types">
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<link href="SRFI_002d9-Records.html" rel="next" title="SRFI-9 Records">
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<link href="VLists.html" rel="prev" title="VLists">
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<style type="text/css">
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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="subsection-level-extent" id="Record-Overview">
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<div class="nav-panel">
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<p>
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Next: <a href="SRFI_002d9-Records.html" accesskey="n" rel="next">SRFI-9 Records</a>, Previous: <a href="VLists.html" accesskey="p" rel="prev">VLists</a>, Up: <a href="Data-Types.html" accesskey="u" rel="up">Data Types</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="subsection" id="Record-Overview-1"><span>6.6.15 Record Overview<a class="copiable-link" href="#Record-Overview-1"> ¶</a></span></h4>
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<a class="index-entry-id" id="index-record"></a>
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<a class="index-entry-id" id="index-structure"></a>
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<p><em class="dfn">Records</em>, also called <em class="dfn">structures</em>, are Scheme’s primary
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mechanism to define new disjoint types. A <em class="dfn">record type</em> defines a
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list of <em class="dfn">fields</em> that instances of the type consist of. This is like
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C’s <code class="code">struct</code>.
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</p>
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<p>Historically, Guile has offered several different ways to define record
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types and to create records, offering different features, and making
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different trade-offs. Over the years, each “standard” has also come
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with its own new record interface, leading to a maze of record APIs.
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</p>
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<p>At the highest level is SRFI-9, a high-level record interface
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implemented by most Scheme implementations (see <a class="pxref" href="SRFI_002d9-Records.html">SRFI-9 Records</a>). It
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defines a simple and efficient syntactic abstraction of record types and
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their associated type predicate, fields, and field accessors. SRFI-9 is
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suitable for most uses, and this is the recommended way to create record
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types in Guile. Similar high-level record APIs include SRFI-35
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(see <a class="pxref" href="SRFI_002d35.html">SRFI-35 - Conditions</a>) and R6RS records (see <a class="pxref" href="rnrs-records-syntactic.html">rnrs records syntactic</a>).
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</p>
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<p>Then comes Guile’s historical “records” API (see <a class="pxref" href="Records.html">Records</a>). Record
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types defined this way are first-class objects. Introspection
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facilities are available, allowing users to query the list of fields or
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the value of a specific field at run-time, without prior knowledge of
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the type.
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</p>
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<p>Finally, the common denominator of these interfaces is Guile’s
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<em class="dfn">structure</em> API (see <a class="pxref" href="Structures.html">Structures</a>). Guile’s structures are the
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low-level building block for all other record APIs. Application writers
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will normally not need to use it.
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</p>
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<p>Records created with these APIs may all be pattern-matched using Guile’s
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standard pattern matcher (see <a class="pxref" href="Pattern-Matching.html">Pattern Matching</a>).
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</p>
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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_002d9-Records.html">SRFI-9 Records</a>, Previous: <a href="VLists.html">VLists</a>, Up: <a href="Data-Types.html">Data Types</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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