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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>17.3.6 Module-Handling Configuration</title><link rel="stylesheet" type="text/css" href="../scribble.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 Guide</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="intro.html" class="tocviewlink" data-pltdoc="x">Welcome to Racket</a></td></tr><tr><td align="right">2 </td><td><a href="to-scheme.html" class="tocviewlink" data-pltdoc="x">Racket Essentials</a></td></tr><tr><td align="right">3 </td><td><a href="datatypes.html" class="tocviewlink" data-pltdoc="x">Built-<wbr></wbr>In Datatypes</a></td></tr><tr><td align="right">4 </td><td><a href="scheme-forms.html" class="tocviewlink" data-pltdoc="x">Expressions and Definitions</a></td></tr><tr><td align="right">5 </td><td><a href="define-struct.html" class="tocviewlink" data-pltdoc="x">Programmer-<wbr></wbr>Defined Datatypes</a></td></tr><tr><td align="right">6 </td><td><a href="modules.html" class="tocviewlink" data-pltdoc="x">Modules</a></td></tr><tr><td align="right">7 </td><td><a href="contracts.html" class="tocviewlink" data-pltdoc="x">Contracts</a></td></tr><tr><td align="right">8 </td><td><a href="i_o.html" class="tocviewlink" data-pltdoc="x">Input and Output</a></td></tr><tr><td align="right">9 </td><td><a href="regexp.html" class="tocviewlink" data-pltdoc="x">Regular Expressions</a></td></tr><tr><td align="right">10 </td><td><a href="control.html" class="tocviewlink" data-pltdoc="x">Exceptions and Control</a></td></tr><tr><td align="right">11 </td><td><a href="for.html" class="tocviewlink" data-pltdoc="x">Iterations and Comprehensions</a></td></tr><tr><td align="right">12 </td><td><a href="match.html" class="tocviewlink" data-pltdoc="x">Pattern Matching</a></td></tr><tr><td align="right">13 </td><td><a href="classes.html" class="tocviewlink" data-pltdoc="x">Classes and Objects</a></td></tr><tr><td align="right">14 </td><td><a href="units.html" class="tocviewlink" data-pltdoc="x">Units</a></td></tr><tr><td align="right">15 </td><td><a href="reflection.html" class="tocviewlink" data-pltdoc="x">Reflection and Dynamic Evaluation</a></td></tr><tr><td align="right">16 </td><td><a href="macros.html" class="tocviewlink" data-pltdoc="x">Macros</a></td></tr><tr><td align="right">17 </td><td><a href="languages.html" class="tocviewselflink" data-pltdoc="x">Creating Languages</a></td></tr><tr><td align="right">18 </td><td><a href="concurrency.html" class="tocviewlink" data-pltdoc="x">Concurrency and Synchronization</a></td></tr><tr><td align="right">19 </td><td><a href="performance.html" class="tocviewlink" data-pltdoc="x">Performance</a></td></tr><tr><td align="right">20 </td><td><a href="parallelism.html" class="tocviewlink" data-pltdoc="x">Parallelism</a></td></tr><tr><td align="right">21 </td><td><a href="running.html" class="tocviewlink" data-pltdoc="x">Running and Creating Executables</a></td></tr><tr><td align="right">22 </td><td><a href="More_Libraries.html" class="tocviewlink" data-pltdoc="x">More Libraries</a></td></tr><tr><td align="right">23 </td><td><a href="dialects.html" class="tocviewlink" data-pltdoc="x">Dialects of Racket and Scheme</a></td></tr><tr><td align="right">24 </td><td><a href="other-editors.html" class="tocviewlink" data-pltdoc="x">Command-<wbr></wbr>Line Tools and Your Editor of Choice</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>17 </td><td><a href="languages.html" class="tocviewlink" data-pltdoc="x">Creating Languages</a></td></tr></table><div class="tocviewsublist" style="display: none;" id="tocview_1"><table cellspacing="0" cellpadding="0"><tr><td align="right">17.1 </td><td><a href="module-languages.html" class="tocviewlink" data-pltdoc="x">Module Languages</a></td></tr><tr><td align="right">17.2 </td><td><a href="hash-reader.html" class="tocviewlink" data-pltdoc="x">Reader Extensions</a></td></tr><tr><td align="right">17.3 </td><td><a href="hash-languages.html" class="tocviewselflink" data-pltdoc="x">Defining new <span class="RktModLink"><span class="RktMod">#lang</span></span> Languages</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_2");">▼</a></td><td>17.3 </td><td><a href="hash-languages.html" class="tocviewlink" data-pltdoc="x">Defining new <span class="RktModLink"><span class="RktMod">#lang</span></span> Languages</a></td></tr></table><div class="tocviewsublistbottom" style="display: block;" id="tocview_2"><table cellspacing="0" cellpadding="0"><tr><td align="right">17.3.1 </td><td><a href="hash-lang_syntax.html" class="tocviewlink" data-pltdoc="x">Designating a <span class="RktModLink"><span class="RktMod">#lang</span></span> Language</a></td></tr><tr><td align="right">17.3.2 </td><td><a href="hash-lang_reader.html" class="tocviewlink" data-pltdoc="x">Using <span class="RktModLink"><span class="RktMod">#lang</span></span><span class="stt"> </span><span class="RktModLink"><span class="RktSym">reader</span></span></a></td></tr><tr><td align="right">17.3.3 </td><td><a href="syntax_module-reader.html" class="tocviewlink" data-pltdoc="x">Using <span class="RktModLink"><span class="RktMod">#lang</span></span><span class="stt"> </span><span class="RktModLink"><span class="RktSym">s-<wbr></wbr>exp</span></span><span class="stt"> </span><span class="RktModLink"><span class="RktSym">syntax/<span class="mywbr"> </span>module-<wbr></wbr>reader</span></span></a></td></tr><tr><td align="right">17.3.4 </td><td><a href="language-collection.html" class="tocviewlink" data-pltdoc="x">Installing a Language</a></td></tr><tr><td align="right">17.3.5 </td><td><a href="language-get-info.html" class="tocviewlink" data-pltdoc="x">Source-<wbr></wbr>Handling Configuration</a></td></tr><tr><td align="right">17.3.6 </td><td><a href="module-runtime-config.html" class="tocviewselflink" data-pltdoc="x">Module-<wbr></wbr>Handling Configuration</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="language-get-info.html" title="backward to "17.3.5 Source-Handling Configuration"" data-pltdoc="x">← prev</a> <a href="hash-languages.html" title="up to "17.3 Defining new #lang Languages"" data-pltdoc="x">up</a> <a href="concurrency.html" title="forward to "18 Concurrency and Synchronization"" data-pltdoc="x">next →</a></span> </div><h5 x-source-module="(lib "scribblings/guide/guide.scrbl")" x-source-pkg="racket-doc" x-part-tag=""module-runtime-config"">17.3.6<tt> </tt><a name="(part._module-runtime-config)"></a>Module-Handling Configuration</h5><p>Suppose that the file <span class="stt">"death-list-5.rkt"</span> contains</p><blockquote class="SCodeFlow"><blockquote class="Rfilebox"><p class="Rfiletitle"><span class="Rfilename"><span class="stt">"death-list-5.rkt"</span></span></p><blockquote class="Rfilecontent"><table cellspacing="0" cellpadding="0" class="RktBlk"><tr><td><a href="Module_Syntax.html#%28part._hash-lang%29" class="RktModLink" data-pltdoc="x"><span class="RktMod">#lang</span></a><span class="hspace"> </span><a href="https://download.racket-lang.org/releases/8.6/doc/local-redirect/index.html?doc=reference&rel=index.html&version=8.6" class="RktModLink Sq" data-pltdoc="x"><span class="RktSym">racket</span></a></td></tr><tr><td><span class="RktPn">(</span><span class="RktSym"><a href="https://download.racket-lang.org/releases/8.6/doc/local-redirect/index.html?doc=reference&rel=pairs.html%23%2528def._%2528%2528quote._%7E23%7E25kernel%2529._list%2529%2529&version=8.6" class="RktValLink Sq" data-pltdoc="x">list</a></span><span class="hspace"> </span><span class="RktVal">"O-Ren Ishii"</span></td></tr><tr><td><span class="hspace"> </span><span class="RktVal">"Vernita Green"</span></td></tr><tr><td><span class="hspace"> </span><span class="RktVal">"Budd"</span></td></tr><tr><td><span class="hspace"> </span><span class="RktVal">"Elle Driver"</span></td></tr><tr><td><span class="hspace"> </span><span class="RktVal">"Bill"</span><span class="RktPn">)</span></td></tr></table></blockquote></blockquote></blockquote><p>If you <span class="RktSym"><a href="https://download.racket-lang.org/releases/8.6/doc/local-redirect/index.html?doc=reference&rel=require.html%23%2528form._%2528%2528lib._racket%252Fprivate%252Fbase..rkt%2529._require%2529%2529&version=8.6" class="RktStxLink Sq" data-pltdoc="x">require</a></span> <span class="stt">"death-list-5.rkt"</span> directly, then it
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prints the list in the usual Racket result format:</p><blockquote class="SCodeFlow"><table cellspacing="0" cellpadding="0" class="RktBlk"><tr><td><span class="stt">> </span><span class="RktPn">(</span><span class="RktSym"><a href="https://download.racket-lang.org/releases/8.6/doc/local-redirect/index.html?doc=reference&rel=require.html%23%2528form._%2528%2528lib._racket%252Fprivate%252Fbase..rkt%2529._require%2529%2529&version=8.6" class="RktStxLink Sq" data-pltdoc="x">require</a></span><span class="hspace"> </span><span class="RktVal">"death-list-5.rkt"</span><span class="RktPn">)</span></td></tr><tr><td><p><span class="RktOut">'("O-Ren Ishii" "Vernita Green" "Budd" "Elle Driver" "Bill")</span></p></td></tr></table></blockquote><p>However, if <span class="stt">"death-list-5.rkt"</span> is required by a
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<span class="stt">"kiddo.rkt"</span> that is implemented with <a href="https://download.racket-lang.org/releases/8.6/doc/local-redirect/index.html?doc=scheme&rel=scheme.html&version=8.6" class="RktModLink Sq" data-pltdoc="x"><span class="RktSym">scheme</span></a>
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instead of <a href="https://download.racket-lang.org/releases/8.6/doc/local-redirect/index.html?doc=reference&rel=index.html&version=8.6" class="RktModLink Sq" data-pltdoc="x"><span class="RktSym">racket</span></a>:</p><blockquote class="SCodeFlow"><blockquote class="Rfilebox"><p class="Rfiletitle"><span class="Rfilename"><span class="stt">"kiddo.rkt"</span></span></p><blockquote class="Rfilecontent"><table cellspacing="0" cellpadding="0" class="RktBlk"><tr><td><a href="Module_Syntax.html#%28part._hash-lang%29" class="RktModLink" data-pltdoc="x"><span class="RktMod">#lang</span></a><span class="hspace"> </span><a href="https://download.racket-lang.org/releases/8.6/doc/local-redirect/index.html?doc=scheme&rel=scheme.html&version=8.6" class="RktModLink Sq" data-pltdoc="x"><span class="RktSym">scheme</span></a></td></tr><tr><td><span class="RktPn">(</span><span class="RktSym"><a href="https://download.racket-lang.org/releases/8.6/doc/local-redirect/index.html?doc=reference&rel=require.html%23%2528form._%2528%2528lib._racket%252Fprivate%252Fbase..rkt%2529._require%2529%2529&version=8.6" class="RktStxLink Sq" data-pltdoc="x">require</a></span><span class="hspace"> </span><span class="RktVal">"death-list-5.rkt"</span><span class="RktPn">)</span></td></tr></table></blockquote></blockquote></blockquote><p>then, if you run <span class="stt">"kiddo.rkt"</span> file in DrRacket or if you run it
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directly with <span class="stt">racket</span>, <span class="stt">"kiddo.rkt"</span> causes
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<span class="stt">"death-list-5.rkt"</span> to print its list in traditional Scheme
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format, without the leading quote:</p><blockquote class="SCodeFlow"><p><span class="RktOut">("O-Ren Ishii" "Vernita Green" "Budd" "Elle Driver" "Bill")</span></p></blockquote><p>The <span class="stt">"kiddo.rkt"</span> example illustrates how the format for
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printing a result value can depend on the main module of a program
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instead of the language that is used to implement it.</p><p>More broadly, certain features of a language are only invoked when
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a module written in that language is run directly with <span class="stt">racket</span>
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(as opposed to being imported into another module). One example is
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result-printing style (as shown above). Another example is REPL
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behavior. These features are part of what’s called the
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<a name="(tech._run._time._configuration)"></a><span style="font-style: italic">run-time configuration</span> of a language.</p><p>Unlike the syntax-coloring property of a language (as described in
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<a href="language-get-info.html" data-pltdoc="x">Source-Handling Configuration</a>), the run-time configuration is a
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property of a <span class="emph">module</span> per se as opposed to a property of
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the <span class="emph">source text</span> representing the module.
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For that reason, the run-time configuration for a
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module needs to be available even if the module is compiled
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to bytecode form and the source is unavailable. Therefore,
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run-time configuration cannot be handled by the
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<span class="RktSym">get-info</span> function we’re exporting from the language’s
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parser module.</p><p>Instead, it will be handled by a new
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<span class="RktSym">configure-runtime</span> submodule that we’ll add inside
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the parsed <span class="RktSym"><a href="https://download.racket-lang.org/releases/8.6/doc/local-redirect/index.html?doc=reference&rel=module.html%23%2528form._%2528%2528quote._%7E23%7E25kernel%2529._module%2529%2529&version=8.6" class="RktStxLink Sq" data-pltdoc="x">module</a></span> form. When a module is run directly
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with <span class="stt">racket</span>, <span class="stt">racket</span> looks for a
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<span class="RktSym">configure-runtime</span> submodule. If it exists, <span class="stt">racket</span>
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runs it. But if the module is imported into another module,
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the <span class="RktVal">'</span><span class="RktVal">configure-runtime</span> submodule is ignored. (And if the
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<span class="RktSym">configure-runtime</span> submodule doesn’t exist, <span class="stt">racket</span>
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just evaluates the module as usual.) That means that the
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<span class="RktSym">configure-runtime</span> submodule can be used for any special
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setup tasks that need to happen when the module is run directly.</p><p>Going back to the <span class="RktSym">literal</span> language (see
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<a href="language-get-info.html" data-pltdoc="x">Source-Handling Configuration</a>), we can adjust the language so that
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directly running a <span class="RktSym">literal</span> module causes it to print out its
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string, while using a <span class="RktSym">literal</span> module in a larger program
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simply provides <span class="RktSym">data</span> without printing. To make this
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work, we will need an extra module. (For clarity here, we will implement
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this module as a separate file. But it could equally well be
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a submodule of an existing file.)</p><blockquote class="SCodeFlow"><table cellspacing="0" cellpadding="0" class="RktBlk"><tr><td><span class="RktSym">....</span><span class="hspace"> </span>(the main installation or the user’s space)</td></tr><tr><td><span class="stt">|-</span><span class="hspace"> </span><span class="stt">"literal"</span></td></tr><tr><td><span class="hspace"> </span><span class="stt">|-</span><span class="hspace"> </span><span class="stt">"main.rkt"</span><span class="hspace"> </span>(with reader submodule)</td></tr><tr><td><span class="hspace"> </span><span class="stt">|-</span><span class="hspace"> </span><span class="stt">"show.rkt"</span><span class="hspace"> </span>(new)</td></tr></table></blockquote><ul><li><p>The <span class="stt">"literal/show.rkt"</span> module will provide a
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<span class="RktSym">show</span> function to be applied to the string
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content of a <span class="RktSym">literal</span> module, and also provide a
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<span class="RktSym">show-enabled</span> parameter that controls whether
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<span class="RktSym">show</span> actually prints the result.</p></li><li><p>The new <span class="RktSym">configure-runtime</span> submodule in
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<span class="stt">"literal/main.rkt"</span> will set the
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<span class="RktSym">show-enabled</span> parameter to <span class="RktVal">#t</span>. The
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net effect is that <span class="RktSym">show</span> will print the strings
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that it’s given, but only when a module using the <span class="RktSym">literal</span>
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language is run directly (because only then will the
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<span class="RktSym">configure-runtime</span> submodule be invoked).</p></li></ul><p>These changes are implemented in the following revised
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<span class="stt">"literal/main.rkt"</span>:</p><blockquote class="SCodeFlow"><blockquote class="Rfilebox"><p class="Rfiletitle"><span class="Rfilename"><span class="stt">"literal/main.rkt"</span></span></p><blockquote class="Rfilecontent"><table cellspacing="0" cellpadding="0" class="RktBlk"><tr><td><a href="Module_Syntax.html#%28part._hash-lang%29" class="RktModLink" data-pltdoc="x"><span class="RktMod">#lang</span></a><span class="hspace"> </span><a href="https://download.racket-lang.org/releases/8.6/doc/local-redirect/index.html?doc=reference&rel=index.html&version=8.6" class="RktModLink Sq" data-pltdoc="x"><span class="RktSym">racket</span></a></td></tr><tr><td><span class="hspace"> </span></td></tr><tr><td><span class="RktPn">(</span><span class="RktSym"><a href="https://download.racket-lang.org/releases/8.6/doc/local-redirect/index.html?doc=reference&rel=module.html%23%2528form._%2528%2528quote._%7E23%7E25kernel%2529._module%2529%2529&version=8.6" class="RktStxLink Sq" data-pltdoc="x">module</a></span><span class="hspace"> </span><span class="RktSym">reader</span><span class="hspace"> </span><span class="RktSym">racket</span></td></tr><tr><td><span class="hspace"> </span><span class="RktPn">(</span><span class="RktSym"><a href="https://download.racket-lang.org/releases/8.6/doc/local-redirect/index.html?doc=reference&rel=require.html%23%2528form._%2528%2528lib._racket%252Fprivate%252Fbase..rkt%2529._require%2529%2529&version=8.6" class="RktStxLink Sq" data-pltdoc="x">require</a></span><span class="hspace"> </span><span class="RktSym">syntax/strip-context</span><span class="RktPn">)</span></td></tr><tr><td><span class="hspace"> </span></td></tr><tr><td><span class="hspace"> </span><span class="RktPn">(</span><span class="RktSym"><a href="https://download.racket-lang.org/releases/8.6/doc/local-redirect/index.html?doc=reference&rel=require.html%23%2528form._%2528%2528lib._racket%252Fprivate%252Fbase..rkt%2529._provide%2529%2529&version=8.6" class="RktStxLink Sq" data-pltdoc="x">provide</a></span><span class="hspace"> </span><span class="RktPn">(</span><span class="RktSym"><a href="https://download.racket-lang.org/releases/8.6/doc/local-redirect/index.html?doc=reference&rel=require.html%23%2528form._%2528%2528lib._racket%252Fprivate%252Fbase..rkt%2529._rename-out%2529%2529&version=8.6" class="RktStxLink Sq" data-pltdoc="x">rename-out</a></span><span class="hspace"> </span><span class="RktPn">[</span><span class="RktSym">literal-read</span><span class="hspace"> </span><span class="RktSym"><a href="https://download.racket-lang.org/releases/8.6/doc/local-redirect/index.html?doc=reference&rel=Reading.html%23%2528def._%2528%2528quote._%7E23%7E25kernel%2529._read%2529%2529&version=8.6" class="RktValLink Sq" data-pltdoc="x">read</a></span><span class="RktPn">]</span></td></tr><tr><td><span class="hspace"> </span><span class="RktPn">[</span><span class="RktSym">literal-read-syntax</span><span class="hspace"> </span><span class="RktSym"><a href="https://download.racket-lang.org/releases/8.6/doc/local-redirect/index.html?doc=reference&rel=Reading.html%23%2528def._%2528%2528quote._%7E23%7E25kernel%2529._read-syntax%2529%2529&version=8.6" class="RktValLink Sq" data-pltdoc="x">read-syntax</a></span><span class="RktPn">]</span><span class="RktPn">)</span></td></tr><tr><td><span class="hspace"> </span><span class="RktSym">get-info</span><span class="RktPn">)</span></td></tr><tr><td><span class="hspace"> </span></td></tr><tr><td><span class="hspace"> </span><span class="RktPn">(</span><span class="RktSym"><a href="https://download.racket-lang.org/releases/8.6/doc/local-redirect/index.html?doc=reference&rel=define.html%23%2528form._%2528%2528lib._racket%252Fprivate%252Fbase..rkt%2529._define%2529%2529&version=8.6" class="RktStxLink Sq" data-pltdoc="x">define</a></span><span class="hspace"> </span><span class="RktPn">(</span><span class="RktSym">literal-read</span><span class="hspace"> </span><span class="RktSym">in</span><span class="RktPn">)</span></td></tr><tr><td><span class="hspace"> </span><span class="RktPn">(</span><span class="RktSym"><a href="https://download.racket-lang.org/releases/8.6/doc/local-redirect/index.html?doc=reference&rel=stxops.html%23%2528def._%2528%2528quote._%7E23%7E25kernel%2529._syntax-%7E3edatum%2529%2529&version=8.6" class="RktValLink Sq" data-pltdoc="x">syntax->datum</a></span></td></tr><tr><td><span class="hspace"> </span><span class="RktPn">(</span><span class="RktSym">literal-read-syntax</span><span class="hspace"> </span><span class="RktVal">#f</span><span class="hspace"> </span><span class="RktSym">in</span><span class="RktPn">)</span><span class="RktPn">)</span><span class="RktPn">)</span></td></tr><tr><td><span class="hspace"> </span></td></tr><tr><td><span class="hspace"> </span><span class="RktPn">(</span><span class="RktSym"><a href="https://download.racket-lang.org/releases/8.6/doc/local-redirect/index.html?doc=reference&rel=define.html%23%2528form._%2528%2528lib._racket%252Fprivate%252Fbase..rkt%2529._define%2529%2529&version=8.6" class="RktStxLink Sq" data-pltdoc="x">define</a></span><span class="hspace"> </span><span class="RktPn">(</span><span class="RktSym">literal-read-syntax</span><span class="hspace"> </span><span class="RktSym">src</span><span class="hspace"> </span><span class="RktSym">in</span><span class="RktPn">)</span></td></tr><tr><td><span class="hspace"> </span><span class="RktPn">(</span><span class="RktSym"><a href="https://download.racket-lang.org/releases/8.6/doc/local-redirect/index.html?doc=reference&rel=stx-patterns.html%23%2528form._%2528%2528lib._racket%252Fprivate%252Fstxcase-scheme..rkt%2529._with-syntax%2529%2529&version=8.6" class="RktStxLink Sq" data-pltdoc="x">with-syntax</a></span><span class="hspace"> </span><span class="RktPn">(</span><span class="RktPn">[</span><span class="RktSym">str</span><span class="hspace"> </span><span class="RktPn">(</span><span class="RktSym">port->string</span><span class="hspace"> </span><span class="RktSym">in</span><span class="RktPn">)</span><span class="RktPn">]</span><span class="RktPn">)</span></td></tr><tr><td><span class="hspace"> </span><span class="RktPn">(</span><span class="RktSym"><a href="https://download.racket-lang.org/releases/8.6/doc/local-redirect/index.html?doc=syntax&rel=syntax-helpers.html%23%2528def._%2528%2528lib._syntax%252Fstrip-context..rkt%2529._strip-context%2529%2529&version=8.6" class="RktValLink Sq" data-pltdoc="x">strip-context</a></span></td></tr><tr><td><span class="hspace"> </span><span class="RktRdr">#'</span><span class="RktPn">(</span><span class="RktSym"><a href="https://download.racket-lang.org/releases/8.6/doc/local-redirect/index.html?doc=reference&rel=module.html%23%2528form._%2528%2528quote._%7E23%7E25kernel%2529._module%2529%2529&version=8.6" class="RktStxLink Sq" data-pltdoc="x">module</a></span><span class="hspace"> </span><span class="RktSym">anything</span><span class="hspace"> </span><span class="RktSym">racket</span></td></tr><tr><td><span class="hspace"> </span><span class="RktPn">(</span><span class="RktSym"><a href="https://download.racket-lang.org/releases/8.6/doc/local-redirect/index.html?doc=reference&rel=module.html%23%2528form._%2528%2528quote._%7E23%7E25kernel%2529._module%2529%2529&version=8.6" class="RktStxLink Sq" data-pltdoc="x">module</a></span><span class="hspace"> </span><span class="RktSym">configure-runtime</span><span class="hspace"> </span><span class="RktSym">racket</span></td></tr><tr><td><span class="hspace"> </span><span class="RktPn">(</span><span class="RktSym"><a href="https://download.racket-lang.org/releases/8.6/doc/local-redirect/index.html?doc=reference&rel=require.html%23%2528form._%2528%2528lib._racket%252Fprivate%252Fbase..rkt%2529._require%2529%2529&version=8.6" class="RktStxLink Sq" data-pltdoc="x">require</a></span><span class="hspace"> </span><span class="RktSym">literal/show</span><span class="RktPn">)</span></td></tr><tr><td><span class="hspace"> </span><span class="RktPn">(</span><span class="RktSym">show-enabled</span><span class="hspace"> </span><span class="RktVal">#t</span><span class="RktPn">)</span><span class="RktPn">)</span></td></tr><tr><td><span class="hspace"> </span><span class="RktPn">(</span><span class="RktSym"><a href="https://download.racket-lang.org/releases/8.6/doc/local-redirect/index.html?doc=reference&rel=require.html%23%2528form._%2528%2528lib._racket%252Fprivate%252Fbase..rkt%2529._require%2529%2529&version=8.6" class="RktStxLink Sq" data-pltdoc="x">require</a></span><span class="hspace"> </span><span class="RktSym">literal/show</span><span class="RktPn">)</span></td></tr><tr><td><span class="hspace"> </span><span class="RktPn">(</span><span class="RktSym"><a href="https://download.racket-lang.org/releases/8.6/doc/local-redirect/index.html?doc=reference&rel=require.html%23%2528form._%2528%2528lib._racket%252Fprivate%252Fbase..rkt%2529._provide%2529%2529&version=8.6" class="RktStxLink Sq" data-pltdoc="x">provide</a></span><span class="hspace"> </span><span class="RktSym">data</span><span class="RktPn">)</span></td></tr><tr><td><span class="hspace"> </span><span class="RktPn">(</span><span class="RktSym"><a href="https://download.racket-lang.org/releases/8.6/doc/local-redirect/index.html?doc=reference&rel=define.html%23%2528form._%2528%2528lib._racket%252Fprivate%252Fbase..rkt%2529._define%2529%2529&version=8.6" class="RktStxLink Sq" data-pltdoc="x">define</a></span><span class="hspace"> </span><span class="RktSym">data</span><span class="hspace"> </span><span class="RktVal">'</span><span class="RktVal">str</span><span class="RktPn">)</span></td></tr><tr><td><span class="hspace"> </span><span class="RktPn">(</span><span class="RktSym">show</span><span class="hspace"> </span><span class="RktSym">data</span><span class="RktPn">)</span><span class="RktPn">)</span><span class="RktPn">)</span><span class="RktPn">)</span><span class="RktPn">)</span></td></tr><tr><td><span class="hspace"> </span></td></tr><tr><td><span class="hspace"> </span><span class="RktPn">(</span><span class="RktSym"><a href="https://download.racket-lang.org/releases/8.6/doc/local-redirect/index.html?doc=reference&rel=define.html%23%2528form._%2528%2528lib._racket%252Fprivate%252Fbase..rkt%2529._define%2529%2529&version=8.6" class="RktStxLink Sq" data-pltdoc="x">define</a></span><span class="hspace"> </span><span class="RktPn">(</span><span class="RktSym">get-info</span><span class="hspace"> </span><span class="RktSym">in</span><span class="hspace"> </span><span class="RktSym">mod</span><span class="hspace"> </span><span class="RktSym">line</span><span class="hspace"> </span><span class="RktSym">col</span><span class="hspace"> </span><span class="RktSym">pos</span><span class="RktPn">)</span></td></tr><tr><td><span class="hspace"> </span><span class="RktPn">(</span><span class="RktSym"><a href="https://download.racket-lang.org/releases/8.6/doc/local-redirect/index.html?doc=reference&rel=lambda.html%23%2528form._%2528%2528lib._racket%252Fprivate%252Fbase..rkt%2529._lambda%2529%2529&version=8.6" class="RktStxLink Sq" data-pltdoc="x">lambda</a></span><span class="hspace"> </span><span class="RktPn">(</span><span class="RktSym">key</span><span class="hspace"> </span><span class="RktSym">default</span><span class="RktPn">)</span></td></tr><tr><td><span class="hspace"> </span><span class="RktPn">(</span><span class="RktSym"><a href="https://download.racket-lang.org/releases/8.6/doc/local-redirect/index.html?doc=reference&rel=case.html%23%2528form._%2528%2528lib._racket%252Fprivate%252Fmore-scheme..rkt%2529._case%2529%2529&version=8.6" class="RktStxLink Sq" data-pltdoc="x">case</a></span><span class="hspace"> </span><span class="RktSym">key</span></td></tr><tr><td><span class="hspace"> </span><span class="RktPn">[</span><span class="RktPn">(</span><span class="RktSym">color-lexer</span><span class="RktPn">)</span></td></tr><tr><td><span class="hspace"> </span><span class="RktPn">(</span><span class="RktSym"><a href="https://download.racket-lang.org/releases/8.6/doc/local-redirect/index.html?doc=reference&rel=Module_Names_and_Loading.html%23%2528def._%2528%2528quote._%7E23%7E25kernel%2529._dynamic-require%2529%2529&version=8.6" class="RktValLink Sq" data-pltdoc="x">dynamic-require</a></span><span class="hspace"> </span><span class="RktVal">'</span><span class="RktVal">syntax-color/default-lexer</span></td></tr><tr><td><span class="hspace"> </span><span class="RktVal">'</span><span class="RktVal">default-lexer</span><span class="RktPn">)</span><span class="RktPn">]</span></td></tr><tr><td><span class="hspace"> </span><span class="RktPn">[</span><span class="RktSym"><a href="https://download.racket-lang.org/releases/8.6/doc/local-redirect/index.html?doc=reference&rel=if.html%23%2528form._%2528%2528lib._racket%252Fprivate%252Fletstx-scheme..rkt%2529._else%2529%2529&version=8.6" class="RktStxLink Sq" data-pltdoc="x">else</a></span><span class="hspace"> </span><span class="RktSym">default</span><span class="RktPn">]</span><span class="RktPn">)</span><span class="RktPn">)</span><span class="RktPn">)</span><span class="RktPn">)</span></td></tr></table></blockquote></blockquote></blockquote><p>Then the <span class="stt">"literal/show.rkt"</span> module must provide
|
|
the <span class="RktSym">show-enabled</span> parameter and <span class="RktSym">show</span>
|
|
function:</p><blockquote class="SCodeFlow"><blockquote class="Rfilebox"><p class="Rfiletitle"><span class="Rfilename"><span class="stt">"literal/show.rkt"</span></span></p><blockquote class="Rfilecontent"><table cellspacing="0" cellpadding="0" class="RktBlk"><tr><td><a href="Module_Syntax.html#%28part._hash-lang%29" class="RktModLink" data-pltdoc="x"><span class="RktMod">#lang</span></a><span class="hspace"> </span><a href="https://download.racket-lang.org/releases/8.6/doc/local-redirect/index.html?doc=reference&rel=index.html&version=8.6" class="RktModLink Sq" data-pltdoc="x"><span class="RktSym">racket</span></a></td></tr><tr><td><span class="hspace"> </span></td></tr><tr><td><span class="RktPn">(</span><span class="RktSym"><a href="https://download.racket-lang.org/releases/8.6/doc/local-redirect/index.html?doc=reference&rel=require.html%23%2528form._%2528%2528lib._racket%252Fprivate%252Fbase..rkt%2529._provide%2529%2529&version=8.6" class="RktStxLink Sq" data-pltdoc="x">provide</a></span><span class="hspace"> </span><span class="RktSym">show</span><span class="hspace"> </span><span class="RktSym">show-enabled</span><span class="RktPn">)</span></td></tr><tr><td><span class="hspace"> </span></td></tr><tr><td><span class="RktPn">(</span><span class="RktSym"><a href="https://download.racket-lang.org/releases/8.6/doc/local-redirect/index.html?doc=reference&rel=define.html%23%2528form._%2528%2528lib._racket%252Fprivate%252Fbase..rkt%2529._define%2529%2529&version=8.6" class="RktStxLink Sq" data-pltdoc="x">define</a></span><span class="hspace"> </span><span class="RktSym">show-enabled</span><span class="hspace"> </span><span class="RktPn">(</span><span class="RktSym"><a href="https://download.racket-lang.org/releases/8.6/doc/local-redirect/index.html?doc=reference&rel=parameters.html%23%2528def._%2528%2528quote._%7E23%7E25kernel%2529._make-parameter%2529%2529&version=8.6" class="RktValLink Sq" data-pltdoc="x">make-parameter</a></span><span class="hspace"> </span><span class="RktVal">#f</span><span class="RktPn">)</span><span class="RktPn">)</span></td></tr><tr><td><span class="hspace"> </span></td></tr><tr><td><span class="RktPn">(</span><span class="RktSym"><a href="https://download.racket-lang.org/releases/8.6/doc/local-redirect/index.html?doc=reference&rel=define.html%23%2528form._%2528%2528lib._racket%252Fprivate%252Fbase..rkt%2529._define%2529%2529&version=8.6" class="RktStxLink Sq" data-pltdoc="x">define</a></span><span class="hspace"> </span><span class="RktPn">(</span><span class="RktSym">show</span><span class="hspace"> </span><span class="RktSym">v</span><span class="RktPn">)</span></td></tr><tr><td><span class="hspace"> </span><span class="RktPn">(</span><span class="RktSym"><a href="https://download.racket-lang.org/releases/8.6/doc/local-redirect/index.html?doc=reference&rel=when_unless.html%23%2528form._%2528%2528lib._racket%252Fprivate%252Fletstx-scheme..rkt%2529._when%2529%2529&version=8.6" class="RktStxLink Sq" data-pltdoc="x">when</a></span><span class="hspace"> </span><span class="RktPn">(</span><span class="RktSym">show-enabled</span><span class="RktPn">)</span></td></tr><tr><td><span class="hspace"> </span><span class="RktPn">(</span><span class="RktSym"><a href="https://download.racket-lang.org/releases/8.6/doc/local-redirect/index.html?doc=reference&rel=Writing.html%23%2528def._%2528%2528quote._%7E23%7E25kernel%2529._display%2529%2529&version=8.6" class="RktValLink Sq" data-pltdoc="x">display</a></span><span class="hspace"> </span><span class="RktSym">v</span><span class="RktPn">)</span><span class="RktPn">)</span><span class="RktPn">)</span></td></tr></table></blockquote></blockquote></blockquote><p>With all of the pieces for <span class="RktSym">literal</span> in place, try running the
|
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following variant of <span class="stt">"tuvalu.rkt"</span> directly and through a
|
|
<span class="RktSym"><a href="https://download.racket-lang.org/releases/8.6/doc/local-redirect/index.html?doc=reference&rel=require.html%23%2528form._%2528%2528lib._racket%252Fprivate%252Fbase..rkt%2529._require%2529%2529&version=8.6" class="RktStxLink Sq" data-pltdoc="x">require</a></span> from another module:</p><blockquote class="SCodeFlow"><blockquote class="Rfilebox"><p class="Rfiletitle"><span class="Rfilename"><span class="stt">"tuvalu.rkt"</span></span></p><blockquote class="Rfilecontent"><table cellspacing="0" cellpadding="0" class="RktBlk"><tr><td><a href="Module_Syntax.html#%28part._hash-lang%29" class="RktModLink" data-pltdoc="x"><span class="RktMod">#lang</span></a><span class="hspace"> </span><span class="RktSym">literal</span></td></tr><tr><td><span class="RktSym">Technology!</span></td></tr><tr><td><span class="RktSym">System!</span></td></tr><tr><td><span class="RktSym">Perfect!</span></td></tr></table></blockquote></blockquote></blockquote><p>When run directly, we’ll see the result printed like so, because
|
|
our <span class="RktSym">configure-runtime</span> submodule will have set the
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<span class="RktSym">show-enabled</span> parameter to <span class="RktVal">#t</span>:</p><blockquote class="SCodeFlow"><p><span class="RktOut">Technology!
|
|
<br/>System!
|
|
<br/>Perfect!</span></p></blockquote><p>But when imported into another module, printing will be suppressed,
|
|
because the <span class="RktSym">configure-runtime</span> submodule will not be invoked,
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and therefore the <span class="RktSym">show-enabled</span> parameter will remain
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at its default value of <span class="RktVal">#f</span>.</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="language-get-info.html" title="backward to "17.3.5 Source-Handling Configuration"" data-pltdoc="x">← prev</a> <a href="hash-languages.html" title="up to "17.3 Defining new #lang Languages"" data-pltdoc="x">up</a> <a href="concurrency.html" title="forward to "18 Concurrency and Synchronization"" data-pltdoc="x">next →</a></span> </div></div></div><div id="contextindicator"> </div></body></html> |