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<html><head><meta http-equiv="content-type" content="text/html; charset=utf-8"/><meta name="viewport" content="width=device-width, initial-scale=0.8"/><title>7.11 Single-Signature Modules</title><link rel="stylesheet" type="text/css" href="../scribble.css" title="default"/><link rel="stylesheet" type="text/css" href="extras.css" title="default"/><link rel="stylesheet" type="text/css" href="../racket.css" title="default"/><link rel="stylesheet" type="text/css" href="../manual-style.css" title="default"/><link rel="stylesheet" type="text/css" href="../manual-racket.css" title="default"/><link rel="stylesheet" type="text/css" href="../manual-racket.css" title="default"/><link rel="stylesheet" type="text/css" href="../doc-site.css" title="default"/><script type="text/javascript" src="../scribble-common.js"></script><script type="text/javascript" src="../manual-racket.js"></script><script type="text/javascript" src="../manual-racket.js"></script><script type="text/javascript" src="../doc-site.js"></script><script type="text/javascript" src="../local-redirect/local-redirect.js"></script><script type="text/javascript" src="../local-redirect/local-user-redirect.js"></script><!--[if IE 6]><style type="text/css">.SIEHidden { overflow: hidden; }</style><![endif]--></head><body id="doc-racket-lang-org"><div class="tocset"><div class="tocview"><div class="tocviewlist tocviewlisttopspace"><div class="tocviewtitle"><table cellspacing="0" cellpadding="0"><tr><td style="width: 1em;"><a href="javascript:void(0);" title="Expand/Collapse" class="tocviewtoggle" onclick="TocviewToggle(this,"tocview_0");">►</a></td><td></td><td><a href="index.html" class="tocviewlink" data-pltdoc="x">The Racket Reference</a></td></tr></table></div><div class="tocviewsublisttop" style="display: none;" id="tocview_0"><table cellspacing="0" cellpadding="0"><tr><td align="right">1 </td><td><a href="model.html" class="tocviewlink" data-pltdoc="x">Language Model</a></td></tr><tr><td align="right">2 </td><td><a href="notation.html" class="tocviewlink" data-pltdoc="x">Notation for Documentation</a></td></tr><tr><td align="right">3 </td><td><a href="syntax.html" class="tocviewlink" data-pltdoc="x">Syntactic Forms</a></td></tr><tr><td align="right">4 </td><td><a href="data.html" class="tocviewlink" data-pltdoc="x">Datatypes</a></td></tr><tr><td align="right">5 </td><td><a href="structures.html" class="tocviewlink" data-pltdoc="x">Structures</a></td></tr><tr><td align="right">6 </td><td><a href="mzlib_class.html" class="tocviewlink" data-pltdoc="x">Classes and Objects</a></td></tr><tr><td align="right">7 </td><td><a href="mzlib_unit.html" class="tocviewselflink" data-pltdoc="x">Units</a></td></tr><tr><td align="right">8 </td><td><a href="contracts.html" class="tocviewlink" data-pltdoc="x">Contracts</a></td></tr><tr><td align="right">9 </td><td><a href="match.html" class="tocviewlink" data-pltdoc="x">Pattern Matching</a></td></tr><tr><td align="right">10 </td><td><a href="control.html" class="tocviewlink" data-pltdoc="x">Control Flow</a></td></tr><tr><td align="right">11 </td><td><a href="concurrency.html" class="tocviewlink" data-pltdoc="x">Concurrency and Parallelism</a></td></tr><tr><td align="right">12 </td><td><a href="Macros.html" class="tocviewlink" data-pltdoc="x">Macros</a></td></tr><tr><td align="right">13 </td><td><a href="input-and-output.html" class="tocviewlink" data-pltdoc="x">Input and Output</a></td></tr><tr><td align="right">14 </td><td><a href="security.html" class="tocviewlink" data-pltdoc="x">Reflection and Security</a></td></tr><tr><td align="right">15 </td><td><a href="os.html" class="tocviewlink" data-pltdoc="x">Operating System</a></td></tr><tr><td align="right">16 </td><td><a href="memory.html" class="tocviewlink" data-pltdoc="x">Memory Management</a></td></tr><tr><td align="right">17 </td><td><a href="unsafe.html" class="tocviewlink" data-pltdoc="x">Unsafe Operations</a></td></tr><tr><td align="right">18 </td><td><a href="running.html" class="tocviewlink" data-pltdoc="x">Running Racket</a></td></tr><tr><td align="right"></td><td><a href="doc-bibliography.html" class="tocviewlink" data-pltdoc="x">Bibliography</a></td></tr><tr><td align="right"></td><td><a href="doc-index.html" class="tocviewlink" data-pltdoc="x">Index</a></td></tr></table></div></div><div class="tocviewlist"><table cellspacing="0" cellpadding="0"><tr><td style="width: 1em;"><a href="javascript:void(0);" title="Expand/Collapse" class="tocviewtoggle" onclick="TocviewToggle(this,"tocview_1");">▼</a></td><td>7 </td><td><a href="mzlib_unit.html" class="tocviewlink" data-pltdoc="x">Units</a></td></tr></table><div class="tocviewsublistbottom" style="display: block;" id="tocview_1"><table cellspacing="0" cellpadding="0"><tr><td align="right">7.1 </td><td><a href="creatingunits.html" class="tocviewlink" data-pltdoc="x">Creating Units</a></td></tr><tr><td align="right">7.2 </td><td><a href="invokingunits.html" class="tocviewlink" data-pltdoc="x">Invoking Units</a></td></tr><tr><td align="right">7.3 </td><td><a href="compoundunits.html" class="tocviewlink" data-pltdoc="x">Linking Units and Creating Compound Units</a></td></tr><tr><td align="right">7.4 </td><td><a href="linkinference.html" class="tocviewlink" data-pltdoc="x">Inferred Linking</a></td></tr><tr><td align="right">7.5 </td><td><a href="Generating_A_Unit_from_Context.html" class="tocviewlink" data-pltdoc="x">Generating A Unit from Context</a></td></tr><tr><td align="right">7.6 </td><td><a href="Structural_Matching.html" class="tocviewlink" data-pltdoc="x">Structural Matching</a></td></tr><tr><td align="right">7.7 </td><td><a href="define-sig-form.html" class="tocviewlink" data-pltdoc="x">Extending the Syntax of Signatures</a></td></tr><tr><td align="right">7.8 </td><td><a href="Unit_Utilities.html" class="tocviewlink" data-pltdoc="x">Unit Utilities</a></td></tr><tr><td align="right">7.9 </td><td><a href="unitcontracts.html" class="tocviewlink" data-pltdoc="x">Unit Contracts</a></td></tr><tr><td align="right">7.10 </td><td><a href="single-unit.html" class="tocviewlink" data-pltdoc="x">Single-<wbr></wbr>Unit Modules</a></td></tr><tr><td align="right">7.11 </td><td><a href="Single-Signature_Modules.html" class="tocviewselflink" data-pltdoc="x">Single-<wbr></wbr>Signature Modules</a></td></tr><tr><td align="right">7.12 </td><td><a href="Transformer_Helpers.html" class="tocviewlink" data-pltdoc="x">Transformer Helpers</a></td></tr></table></div></div></div></div><div class="maincolumn"><div class="main"><div class="navsettop"><span class="navleft"><form class="searchform"><input class="searchbox" id="searchbox" type="text" tabindex="1" placeholder="...search manuals..." title="Enter a search string to search the manuals" onkeypress="return DoSearchKey(event, this, "8.6", "../");"/></form> <a href="https://docs.racket-lang.org/index.html" title="up to the documentation top" data-pltdoc="x" onclick="return GotoPLTRoot("8.6");">top</a><span class="tocsettoggle"> <a href="javascript:void(0);" title="show/hide table of contents" onclick="TocsetToggle();">contents</a></span></span><span class="navright"> <a href="single-unit.html" title="backward to "7.10 Single-Unit Modules"" data-pltdoc="x">← prev</a> <a href="mzlib_unit.html" title="up to "7 Units"" data-pltdoc="x">up</a> <a href="Transformer_Helpers.html" title="forward to "7.12 Transformer Helpers"" data-pltdoc="x">next →</a></span> </div><h4 x-source-module="(lib "scribblings/reference/reference.scrbl")" x-source-pkg="racket-doc" x-part-tag=""Single-Signature_Modules"">7.11<tt> </tt><a name="(part._.Single-.Signature_.Modules)"></a><a name="(mod-path._racket/signature)"></a>Single-Signature Modules</h4><p><div class="SIntrapara"><table cellspacing="0" cellpadding="0" class="defmodule"><tr><td align="left"><span class="hspace"> </span><a href="https://download.racket-lang.org/releases/8.6/doc/local-redirect/index.html?doc=guide&rel=Module_Syntax.html%23%2528part._hash-lang%2529&version=8.6" class="RktModLink Sq" data-pltdoc="x"><span class="RktMod">#lang</span></a><span class="hspace"> </span><a href="Single-Signature_Modules.html" class="RktModLink" data-pltdoc="x"><span class="RktSym">racket/signature</span></a></td><td align="right"><span class="RpackageSpec"><span class="Smaller"> package:</span> <a href="https://pkgs.racket-lang.org/package/base" title="Install this package using `raco pkg install base`"><span class="stt">base</span></a></span></td></tr></table></div><div class="SIntrapara">The <a href="Single-Signature_Modules.html" class="RktModLink" data-pltdoc="x"><span class="RktSym">racket/signature</span></a>
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language treats a module body as a unit signature.</div></p><p>The body must match the following <span class="RktVar">module-body</span> grammar:</p><p><table cellspacing="0" cellpadding="0"><tr><td align="right" valign="baseline"><span class="hspace"> </span><span class="RktVar">module-body</span></td><td align="left" valign="baseline"><span class="stt"> </span></td><td align="center" valign="baseline">=</td><td align="left" valign="baseline"><span class="stt"> </span></td><td align="left" valign="baseline"><span class="RktPn">(</span><span class="RktSym"><a href="require.html#%28form._%28%28lib._racket%2Fprivate%2Fbase..rkt%29._require%29%29" class="RktStxLink" data-pltdoc="x">require</a></span><span class="hspace"> </span><span class="RktVar">require-spec</span><span class="hspace"> </span><span class="RktSym">...</span><span class="RktPn">)</span><span class="hspace"> </span><span class="RktSym">...</span><span class="hspace"> </span><span class="RktVar">sig-spec</span><span class="hspace"> </span><span class="RktSym">...</span></td></tr></table></p><p>See <a href="creatingunits.html" data-pltdoc="x">Creating Units</a> for the grammar of <span class="RktVar">sig-spec</span>.
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Unlike the body of a <a href="mzlib_unit.html" class="RktModLink" data-pltdoc="x"><span class="RktSym">racket/unit</span></a> module, a
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<span class="RktSym"><a href="require.html#%28form._%28%28lib._racket%2Fprivate%2Fbase..rkt%29._require%29%29" class="RktStxLink" data-pltdoc="x">require</a></span> in a <a href="Single-Signature_Modules.html" class="RktModLink" data-pltdoc="x"><span class="RktSym">racket/signature</span></a> module must be
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a literal use of <span class="RktSym"><a href="require.html#%28form._%28%28lib._racket%2Fprivate%2Fbase..rkt%29._require%29%29" class="RktStxLink" data-pltdoc="x">require</a></span>.</p><p>The resulting signature is exported as
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<span class="RktVar">base</span><span class="RktSym">^</span>, where <span class="RktVar">base</span> is derived from
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the enclosing module’s name (i.e., its symbolic name, or its path
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without the directory and file suffix). If the module name ends in
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<span class="RktSym">-sig</span>, then <span class="RktVar">base</span> corresponds to the module
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name before <span class="RktSym">-sig</span>. Otherwise, the module name serves as
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<span class="RktVar">base</span>.</p><p>A <span class="RktSym"><a href="define-struct.html#%28form._%28%28lib._racket%2Fprivate%2Fbase..rkt%29._struct%29%29" class="RktStxLink" data-pltdoc="x">struct</a></span> form as a <span class="RktSym">sig-spec</span> is consistent with the
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definitions introduced by <span class="RktSym"><a href="define-struct.html#%28form._%28%28lib._racket%2Fprivate%2Fbase..rkt%29._define-struct%29%29" class="RktStxLink" data-pltdoc="x">define-struct</a></span>, as opposed to
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definitions introduced <span class="RktSym"><a href="define-struct.html#%28form._%28%28lib._racket%2Fprivate%2Fbase..rkt%29._struct%29%29" class="RktStxLink" data-pltdoc="x">struct</a></span>. (That behavior was originally
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a bug, but it is preserved for compatibility.)</p><div class="navsetbottom"><span class="navleft"><form class="searchform"><input class="searchbox" id="searchbox" type="text" tabindex="1" placeholder="...search manuals..." title="Enter a search string to search the manuals" onkeypress="return DoSearchKey(event, this, "8.6", "../");"/></form> <a href="https://docs.racket-lang.org/index.html" title="up to the documentation top" data-pltdoc="x" onclick="return GotoPLTRoot("8.6");">top</a><span class="tocsettoggle"> <a href="javascript:void(0);" title="show/hide table of contents" onclick="TocsetToggle();">contents</a></span></span><span class="navright"> <a href="single-unit.html" title="backward to "7.10 Single-Unit Modules"" data-pltdoc="x">← prev</a> <a href="mzlib_unit.html" title="up to "7 Units"" data-pltdoc="x">up</a> <a href="Transformer_Helpers.html" title="forward to "7.12 Transformer Helpers"" data-pltdoc="x">next →</a></span> </div></div></div><div id="contextindicator"> </div></body></html> |