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<p><strong>symbol</strong> <span><i>System Class</i></span></p>
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<p><strong>Class Precedence List:</strong></p>
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<p><span><b>symbol</b></span>, <span><b>t</b></span></p>
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<p><strong>Description:</strong></p>
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<p><span><i>Symbols</i></span> are used for their <span><i>object</i></span> identity to name various entities in Common Lisp, including (but not limited to) linguistic entities such as <span><i>variables</i></span> and <span><i>functions</i></span>.</p>
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<p><span><i>Symbols</i></span> can be collected together into <span><i>packages</i></span>. A <span><i>symbol</i></span> is said to be <span><i>interned</i></span> in a <span><i>package</i></span> if it is <span><i>accessible</i></span> in that <span><i>package</i></span>; the same <span><i>symbol</i></span> can be <span><i>interned</i></span> in more than one <span><i>package</i></span>. If a <span><i>symbol</i></span> is not <span><i>interned</i></span> in any <span><i>package</i></span>, it is called <span><i>uninterned</i></span>.</p>
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<p>An <em>interned symbol</em> is uniquely identifiable by its <span><i>name</i></span> from any <span><i>package</i></span> in which it is <span><i>accessible</i></span>.</p>
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<p><span><i>Symbols</i></span> have the following attributes. For historical reasons, these are sometimes referred to as <span><i>cells</i></span>, although the actual internal representation of <span><i>symbols</i></span> and their attributes is <span><i>implementation-dependent</i></span>.</p>
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<p><strong>Name</strong></p>
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<p>The <span><i>name</i></span> of a <span><i>symbol</i></span> is a <span><i>string</i></span> used to identify the <span><i>symbol</i></span>. Every <span><i>symbol</i></span> has a <span><i>name</i></span>, and the consequences are undefined if that <span><i>name</i></span> is altered. The <span><i>name</i></span> is used as part of the external, printed representation of the <span><i>symbol</i></span>; see Section 2.1 (Character Syntax). The <span><i>function</i></span> <span><b>symbol-name</b></span> returns the <span><i>name</i></span> of a given <span><i>symbol</i></span>. A <span><i>symbol</i></span> may have any <span><i>character</i></span> in its <span><i>name</i></span>.</p>
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<p><strong>Package</strong></p>
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<p>The <span><i>object</i></span> in this <span><i>cell</i></span> is called the <span><i>home package</i></span> of the <span><i>symbol</i></span>. If the <span><i>home package</i></span> is <span><b>nil</b></span>, the <span><i>symbol</i></span> is sometimes said to have no <span><i>home package</i></span>.</p>
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<p>When a <span><i>symbol</i></span> is first created, it has no <span><i>home package</i></span>. When it is first <span><i>interned</i></span>, the <span><i>package</i></span> in which it is initially <span><i>interned</i></span> becomes its <span><i>home package</i></span>. The <span><i>home package</i></span> of a <span><i>symbol</i></span> can be <em>accessed</em> by using the <span><i>function</i></span> <span><b>symbol-package</b></span>.</p>
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<p>If a <span><i>symbol</i></span> is <span><i>uninterned</i></span> from the <span><i>package</i></span> which is its <span><i>home package</i></span>, its <span><i>home package</i></span> is set to <span><b>nil</b></span>. Depending on whether there is another <span><i>package</i></span> in which the <span><i>symbol</i></span> is <span><i>interned</i></span>, the symbol might or might not really be an <em>uninterned symbol</em>. A <span><i>symbol</i></span> with no <span><i>home package</i></span> is therefore called <span><i>apparently uninterned</i></span>.</p>
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<p>The consequences are undefined if an attempt is made to alter the <span><i>home package</i></span> of a <span><i>symbol</i></span> external in the COMMON-LISP <span><i>package</i></span> or the KEYWORD <span><i>package</i></span>.</p>
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<p><strong>Property list</strong></p>
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<p>The <span><i>property list</i></span> of a <span><i>symbol</i></span> provides a mechanism for associating named attributes</p>
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<p>with that <span><i>symbol</i></span>. The operations for adding and removing entries are <span><i>destructive</i></span> to the <span><i>property list</i></span>. Common Lisp provides <span><i>operators</i></span> both for direct manipulation of <em>property list objects</em> (<em>e.g.</em>, see <span><b>getf</b></span>, <span><b>remf</b></span>, and <span><b>symbol-plist</b></span>) and for implicit manipulation of a <span><i>symbol</i></span>’s <span><i>property list</i></span> by reference to the <span><i>symbol</i></span> (<em>e.g.</em>, see <span><b>get</b></span> and <span><b>remprop</b></span>). The <span><i>property list</i></span> associated with a <em>fresh symbol</em> is initially <span><i>null</i></span>.</p>
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<p><strong>Value</strong></p>
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<p>If a symbol has a value attribute, it is said to be <span><i>bound</i></span>, and that fact can be detected by the <span><i>function</i></span> <span><b>boundp</b></span>. The <span><i>object</i></span> contained in the <span><i>value cell</i></span> of a <em>bound symbol</em> is the <span><i>value</i></span> of the <span><i>global variable</i></span> named by that <span><i>symbol</i></span>, and can be <em>accessed</em> by the <span><i>function</i></span> <span><b>symbol-value</b></span>. A <span><i>symbol</i></span> can be made to be <span><i>unbound</i></span> by the <span><i>function</i></span> <span><b>makunbound</b></span>.</p>
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<p>The consequences are undefined if an attempt is made to change the <span><i>value</i></span> of a <span><i>symbol</i></span> that names a <span><i>constant variable</i></span>, or to make such a <span><i>symbol</i></span> be <span><i>unbound</i></span>.</p>
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<p><strong>Function</strong></p>
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<p>If a symbol has a function attribute, it is said to be <span><i>fbound</i></span>, and that fact can be detected by the <span><i>function</i></span> <span><b>fboundp</b></span>. If the <span><i>symbol</i></span> is the <span><i>name</i></span> of a <span><i>function</i></span> in the <span><i>global environment</i></span>, the <span><i>function cell</i></span> contains the <span><i>function</i></span>, and can be <em>accessed</em> by the <span><i>function</i></span> <span><b>symbol-function</b></span>. If the <span><i>symbol</i></span> is the <span><i>name</i></span> of either a <span><i>macro</i></span> in the <span><i>global environment</i></span> (see <span><b>macro-function</b></span>) or a <span><i>special operator</i></span> (see <span><b>special-operator-p</b></span>), the <span><i>symbol</i></span> is <span><i>fbound</i></span>, and can be <em>accessed</em> by the <span><i>function</i></span> <span><b>symbol-function</b></span>, but the <span><i>object</i></span> which the <span><i>function cell</i></span> contains is of <em>implementation-dependent type</em> and purpose. A <span><i>symbol</i></span> can be made to be <span><i>funbound</i></span> by the <span><i>function</i></span> <span><b>fmakunbound</b></span>.</p>
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<p>The consequences are undefined if an attempt is made to change the <span><i>functional value</i></span> of a <span><i>symbol</i></span> that names a <span><i>special form</i></span>.</p>
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<p>Operations on a <span><i>symbol</i></span>’s <span><i>value cell</i></span> and <span><i>function cell</i></span> are sometimes described in terms of their effect on the <span><i>symbol</i></span> itself, but the user should keep in mind that there is an intimate relationship between the contents of those <span><i>cells</i></span> and the <span><i>global variable</i></span> or global <span><i>function</i></span> definition, respectively.</p>
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<p><span><i>Symbols</i></span> are used as identifiers for <span><i>lexical variables</i></span> and lexical <span><i>function</i></span> definitions, but in that role, only their <span><i>object</i></span> identity is significant. Common Lisp provides no operation on a <span><i>symbol</i></span> that can have any effect on a <span><i>lexical variable</i></span> or on a lexical <span><i>function</i></span> definition.</p>
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<p><strong>See Also:</strong></p>
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<p>Section 2.3.4 (Symbols as Tokens), Section 2.3.1.1 (Potential Numbers as Tokens), Section 22.1.3.3 (Printing Symbols)</p>
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<h2 class="anchor anchorWithStickyNavbar_LWe7" id="expanded-reference-symbol">Expanded Reference: symbol<a href="symbol_system-class.html#expanded-reference-symbol" class="hash-link" aria-label="Direct link to Expanded Reference: symbol" title="Direct link to Expanded Reference: symbol"></a></h2>
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<div class="theme-admonition theme-admonition-tip admonition_xJq3 alert alert--success"><div class="admonitionHeading_Gvgb"><span class="admonitionIcon_Rf37"><svg viewBox="0 0 12 16"><path fill-rule="evenodd" d="M6.5 0C3.48 0 1 2.19 1 5c0 .92.55 2.25 1 3 1.34 2.25 1.78 2.78 2 4v1h5v-1c.22-1.22.66-1.75 2-4 .45-.75 1-2.08 1-3 0-2.81-2.48-5-5.5-5zm3.64 7.48c-.25.44-.47.8-.67 1.11-.86 1.41-1.25 2.06-1.45 3.23-.02.05-.02.11-.02.17H5c0-.06 0-.13-.02-.17-.2-1.17-.59-1.83-1.45-3.23-.2-.31-.42-.67-.67-1.11C2.44 6.78 2 5.65 2 5c0-2.2 2.02-4 4.5-4 1.22 0 2.36.42 3.22 1.19C10.55 2.94 11 3.94 11 5c0 .66-.44 1.78-.86 2.48zM4 14h5c-.23 1.14-1.3 2-2.5 2s-2.27-.86-2.5-2z"></path></svg></span>tip</div><div class="admonitionContent_BuS1"><p>TODO: Please contribute to this page by adding explanations and examples</p></div></div>
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<div class="language-lisp codeBlockContainer_Ckt0 theme-code-block" style="--prism-color:#393A34;--prism-background-color:#f6f8fa"><div class="codeBlockContent_biex"><pre tabindex="0" class="prism-code language-lisp codeBlock_bY9V thin-scrollbar" style="color:#393A34;background-color:#f6f8fa"><code class="codeBlockLines_e6Vv"><span class="token-line" style="color:#393A34"><span class="token punctuation" style="color:#393A34">(</span><span class="token car">symbol</span><span class="token plain"> </span><span class="token punctuation" style="color:#393A34">)</span><br></span></code></pre><div class="buttonGroup__atx"><button type="button" aria-label="Copy code to clipboard" title="Copy" class="clean-btn"><span class="copyButtonIcons_eSgA" aria-hidden="true"><svg viewBox="0 0 24 24" class="copyButtonIcon_y97N"><path fill="currentColor" d="M19,21H8V7H19M19,5H8A2,2 0 0,0 6,7V21A2,2 0 0,0 8,23H19A2,2 0 0,0 21,21V7A2,2 0 0,0 19,5M16,1H4A2,2 0 0,0 2,3V17H4V3H16V1Z"></path></svg><svg viewBox="0 0 24 24" class="copyButtonSuccessIcon_LjdS"><path fill="currentColor" d="M21,7L9,19L3.5,13.5L4.91,12.09L9,16.17L19.59,5.59L21,7Z"></path></svg></span></button></div></div></div></div><footer class="theme-doc-footer docusaurus-mt-lg"><div class="theme-doc-footer-edit-meta-row row"><div class="col"><a href="https://github.com/lisp-docs/cl-language-reference/tree/main/docs/chap-10/ba-c-dictionary/symbol_system-class.md" target="_blank" rel="noopener noreferrer" class="theme-edit-this-page"><svg fill="currentColor" height="20" width="20" viewBox="0 0 40 40" class="iconEdit_Z9Sw" aria-hidden="true"><g><path d="m34.5 11.7l-3 3.1-6.3-6.3 3.1-3q0.5-0.5 1.2-0.5t1.1 0.5l3.9 3.9q0.5 0.4 0.5 1.1t-0.5 1.2z m-29.5 17.1l18.4-18.5 6.3 6.3-18.4 18.4h-6.3v-6.2z"></path></g></svg>Edit this page</a></div><div class="col lastUpdated_vwxv"><span class="theme-last-updated">Last updated<!-- --> by <b>daninus14</b></span></div></div></footer></article><nav class="pagination-nav docusaurus-mt-lg" aria-label="Docs pages"><a class="pagination-nav__link pagination-nav__link--prev" href="symbol-value_accessor.html"><div class="pagination-nav__sublabel">Previous</div><div class="pagination-nav__label">symbol-value</div></a><a class="pagination-nav__link pagination-nav__link--next" href="symbolp_function.html"><div class="pagination-nav__sublabel">Next</div><div class="pagination-nav__label">symbolp</div></a></nav></div></div><div class="col col--3"><div class="tableOfContents_bqdL thin-scrollbar theme-doc-toc-desktop"><ul class="table-of-contents table-of-contents__left-border"><li><a href="symbol_system-class.html#expanded-reference-symbol" class="table-of-contents__link toc-highlight">Expanded Reference: symbol</a></li></ul></div></div></div></div></main></div></div></div><footer class="footer footer--dark"><div class="container container-fluid"><div class="row footer__links"><div class="col footer__col"><div class="footer__title">Docs</div><ul class="footer__items clean-list"><li class="footer__item"><a href="../../../docs/tutorial.html" target="_blank" rel="noopener noreferrer" class="footer__link-item">Common Lisp Tutorial</a></li><li class="footer__item"><a href="../../index.html" target="_blank" rel="noopener noreferrer" class="footer__link-item">Common Lisp Technical Reference</a></li><li class="footer__item"><a href="../../../docs/help.html" target="_blank" rel="noopener noreferrer" class="footer__link-item">Help</a></li></ul></div><div class="col footer__col"><div class="footer__title">Community</div><ul class="footer__items clean-list"><li class="footer__item"><a href="https://stackoverflow.com/questions/tagged/common-lisp" target="_blank" rel="noopener noreferrer" class="footer__link-item">Stack Overflow<svg width="13.5" height="13.5" aria-hidden="true" viewBox="0 0 24 24" class="iconExternalLink_nPIU"><path fill="currentColor" d="M21 13v10h-21v-19h12v2h-10v15h17v-8h2zm3-12h-10.988l4.035 4-6.977 7.07 2.828 2.828 6.977-7.07 4.125 4.172v-11z"></path></svg></a></li><li class="footer__item"><a href="https://discord.gg/hhk46CE" target="_blank" rel="noopener nor
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