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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>6.1 Module Basics</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="tocviewselflink" 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="tocviewlink" data-pltdoc="x">Creating Languages</a></td></tr><tr><td align="right">18 </td><td><a href="concurrency.html" class="tocviewlink"
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suppose the file <span class="stt">"cake.rkt"</span> contains the following module:</p><blockquote class="SCodeFlow"><blockquote class="Rfilebox"><p class="Rfiletitle"><span class="Rfilename"><span class="stt">"cake.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">print-cake</span><span class="RktPn">)</span></td></tr><tr><td><span class="hspace"> </span></td></tr><tr><td><span class="RktCmt">;</span><span class="RktCmt"> </span><span class="RktCmt">draws a cake with </span><span class="RktSym">n</span><span class="RktCmt"> candles</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">print-cake</span><span class="hspace"> </span><span class="RktSym">n</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="RktVal">"</span><span class="hspace"> </span><span class="RktVal">~a</span><span class="hspace"> </span><span class="RktVal">"</span><span class="hspace"> </span><span class="RktSym">n</span><span class="hspace"> </span><span class="RktVal">#\.</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="RktVal">" .-~a-. "</span><span class="hspace"> </span><span class="RktSym">n</span><span class="hspace"> </span><span class="RktVal">#\|</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="RktVal">" | ~a | "</span><span class="hspace"> </span><span class="RktSym">n</span><span class="hspace"> </span><span class="RktVal">#\space</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="RktVal">"---~a---"</span><span class="hspace"> </span><span class="RktSym">n</span><span class="hspace"> </span><span class="RktVal">#\-</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">fmt</span><span cla
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<span class="RktSym">print-cake</span> function, since the <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> line in
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<span class="stt">"cake.rkt"</span> explicitly exports the definition
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<span class="RktSym">print-cake</span>. The <span class="RktSym">show</span> function is private to
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<span class="stt">"cake.rkt"</span> (i.e., it cannot be used from other modules),
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since <span class="RktSym">show</span> is not exported.</p><p>The following <span class="stt">"random-cake.rkt"</span> module imports
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<span class="stt">"cake.rkt"</span>:</p><blockquote class="SCodeFlow"><blockquote class="Rfilebox"><p class="Rfiletitle"><span class="Rfilename"><span class="stt">"random-cake.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._require%2529%2529&version=8.6" class="RktStxLink Sq" data-pltdoc="x">require</a></span><span class="hspace"> </span><span class="RktVal">"cake.rkt"</span><span class="RktPn">)</span></td></tr><tr><td><span class="hspace"> </span></td></tr><tr><td><span class="RktPn">(</span><span class="RktSym">print-cake</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=generic-numbers.html%23%2528def._%2528%2528lib._racket%252Fprivate%252Fbase..rkt%2529._random%2529%2529&version=8.6" class="RktValLink Sq" data-pltdoc="x">random</a></span><span class="hspace"> </span><span class="RktVal">30</span><span class="RktPn">)</span><span class="RktPn">)</span></td></tr></table></blockquote></blockquote></blockquote><p>The relative reference <span class="RktVal">"cake.rkt"</span> in the import
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<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="stt"> </span><span class="RktVal">"cake.rkt"</span><span class="RktPn">)</span> works if the <span class="stt">"cake.rkt"</span> and
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<span class="stt">"random-cake.rkt"</span> modules are in the same
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directory. Unix-style relative paths are used for relative module
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references on all platforms, much like relative URLs in HTML pages.</p><h5 x-source-module="(lib "scribblings/guide/guide.scrbl")" x-source-pkg="racket-doc" x-part-tag=""module-org"">6.1.1<tt> </tt><a name="(part._module-org)"></a>Organizing Modules</h5><p>The <span class="stt">"cake.rkt"</span> and <span class="stt">"random-cake.rkt"</span> example
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demonstrates the most common way to organize a program into modules:
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put all module files in a single directory (perhaps with
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subdirectories), and then have the modules reference each other
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through relative paths. A directory of modules can act as a
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project, since it can be moved around on the filesystem or copied to
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other machines, and relative paths preserve the connections among
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modules.</p><p>As another example, if you are building a candy-sorting program, you
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might have a main <span class="stt">"sort.rkt"</span> module that uses other modules
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to access a candy database and a control sorting machine. If the
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candy-database module itself is organized into sub-modules that handle
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barcode and manufacturer information, then the database module could
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be <span class="stt">"db/lookup.rkt"</span> that uses helper modules
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<span class="stt">"db/barcodes.rkt"</span> and <span class="stt">"db/makers.rkt"</span>. Similarly,
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the sorting-machine driver <span class="stt">"machine/control.rkt"</span> might use
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helper modules <span class="stt">"machine/sensors.rkt"</span> and
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<span class="stt">"machine/actuators.rkt"</span>.</p><blockquote class="SCentered"><p><img style="vertical-align: -16.830078125px; margin: -3px -3px -3px -3px;" src="pict.png" alt="image" width="462.33203125" height="322.0"/></p></blockquote><p>The <span class="stt">"sort.rkt"</span> module uses the relative paths
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<span class="stt">"db/lookup.rkt"</span> and <span class="stt">"machine/control.rkt"</span> to import
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from the database and machine-control libraries:</p><blockquote class="SCodeFlow"><blockquote class="Rfilebox"><p class="Rfiletitle"><span class="Rfilename"><span class="stt">"sort.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=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">"db/lookup.rkt"</span><span class="hspace"> </span><span class="RktVal">"machine/control.rkt"</span><span class="RktPn">)</span></td></tr><tr><td><span class="RktSym">....</span></td></tr></table></blockquote></blockquote></blockquote><p>The <span class="stt">"db/lookup.rkt"</span> module similarly uses paths relative to
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its own source to access the <span class="stt">"db/barcodes.rkt"</span> and
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<span class="stt">"db/makers.rkt"</span> modules:</p><blockquote class="SCodeFlow"><blockquote class="Rfilebox"><p class="Rfiletitle"><span class="Rfilename"><span class="stt">"db/lookup.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=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">"barcode.rkt"</span><span class="hspace"> </span><span class="RktVal">"makers.rkt"</span><span class="RktPn">)</span></td></tr><tr><td><span class="RktSym">....</span></td></tr></table></blockquote></blockquote></blockquote><p>Ditto for <span class="stt">"machine/control.rkt"</span>:</p><blockquote class="SCodeFlow"><blockquote class="Rfilebox"><p class="Rfiletitle"><span class="Rfilename"><span class="stt">"machine/control.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=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">"sensors.rkt"</span><span class="hspace"> </span><span class="RktVal">"actuators.rkt"</span><span class="RktPn">)</span></td></tr><tr><td><span class="RktSym">....</span></td></tr></table></blockquote></blockquote></blockquote><p>Racket tools all work automatically with relative paths. For example,</p><p><span class="hspace"> </span><span class="stt">racket sort.rkt</span></p><p>on the command line runs the <span class="stt">"sort.rkt"</span> program and
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automatically loads and compiles required modules. With a large enough
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program, compilation from source can take too long, so use</p><p><span class="hspace"> </span><span class="stt">raco make sort.rkt</span></p><blockquote class="refpara"><blockquote class="refcolumn"><blockquote class="refcontent"><p>See <a href="https://download.racket-lang.org/releases/8.6/doc/local-redirect/index.html?doc=raco&rel=make.html&version=8.6" class="Sq" data-pltdoc="x"><span class="stt">raco make</span>: Compiling Source to Bytecode</a> for more information on <span class="stt">raco make</span>.</p></blockquote></blockquote></blockquote><p>to compile <span class="stt">"sort.rkt"</span> and all its dependencies to bytecode
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files. Running <span class="stt">racket sort.rkt</span> will automatically use bytecode
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files when they are present.</p><h5 x-source-module="(lib "scribblings/guide/guide.scrbl")" x-source-pkg="racket-doc" x-part-tag=""Library_Collections"">6.1.2<tt> </tt><a name="(part._.Library_.Collections)"></a>Library Collections</h5><p>A <a name="(tech._collection)"></a><span style="font-style: italic">collection</span> is a hierarchical grouping of installed library modules. A
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module in a <a href="module-basics.html#%28tech._collection%29" class="techoutside" data-pltdoc="x"><span class="techinside">collection</span></a> is referenced through an unquoted,
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suffixless path. For example, the following module refers to the
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<span class="stt">"date.rkt"</span> library that is part of the <span class="stt">"racket"</span>
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<a href="module-basics.html#%28tech._collection%29" class="techoutside" data-pltdoc="x"><span class="techinside">collection</span></a>:</p><blockquote class="SCodeFlow"><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._require%2529%2529&version=8.6" class="RktStxLink Sq" data-pltdoc="x">require</a></span><span class="hspace"> </span><span class="RktSym">racket/date</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=Writing.html%23%2528def._%2528%2528quote._%7E23%7E25kernel%2529._printf%2529%2529&version=8.6" class="RktValLink Sq" data-pltdoc="x">printf</a></span><span class="hspace"> </span><span class="RktVal">"Today is ~s\n"</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=time.html%23%2528def._%2528%2528lib._racket%252Fdate..rkt%2529._date-%7E3estring%2529%2529&version=8.6" class="RktValLink Sq" data-pltdoc="x">date->string</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=time.html%23%2528def._%2528%2528quote._%7E23%7E25kernel%2529._seconds-%7E3edate%2529%2529&version=8.6" class="RktValLink Sq" data-pltdoc="x">seconds->date</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=time.html%23%2528def._%2528%2528quote._%7E23%7E25kernel%2529._current-seconds%2529%2529&version=8.6" class="RktValLink Sq" data-pltdoc="x">current-seconds</a></span><span class="RktPn">)</span><span class="RktPn">)</span><span class="RktPn">)</span><span class="RktPn">)</span></td></tr></table></blockquote><p>When you search the online Racket documentation, the search results
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indicate the module that provides each binding. Alternatively, if you
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reach a binding’s documentation by clicking on hyperlinks, you can
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hover over the binding name to find out which modules provide
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|
|
it.</p><p>A module reference like <a href="https://download.racket-lang.org/releases/8.6/doc/local-redirect/index.html?doc=reference&rel=time.html%23%2528mod-path._racket%252Fdate%2529&version=8.6" class="RktModLink Sq" data-pltdoc="x"><span class="RktSym">racket/date</span></a> looks like an
|
||
|
|
identifier, but it is not treated in the same way as <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._printf%2529%2529&version=8.6" class="RktValLink Sq" data-pltdoc="x">printf</a></span>
|
||
|
|
or <span class="RktSym"><a href="https://download.racket-lang.org/releases/8.6/doc/local-redirect/index.html?doc=reference&rel=time.html%23%2528def._%2528%2528lib._racket%252Fdate..rkt%2529._date-%7E3estring%2529%2529&version=8.6" class="RktValLink Sq" data-pltdoc="x">date->string</a></span>. Instead, when <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> sees a module
|
||
|
|
reference that is unquoted, it converts the reference to a
|
||
|
|
collection-based module path:</p><ul><li><p>First, if the unquoted path contains no <span class="RktInBG"><span class="hspace"></span><span class="RktIn">/</span><span class="hspace"></span></span>, then
|
||
|
|
<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> automatically adds a <span class="stt">"/main"</span> to the
|
||
|
|
reference. For example, <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="stt"> </span><a href="https://download.racket-lang.org/releases/8.6/doc/local-redirect/index.html?doc=slideshow&rel=index.html&version=8.6" class="RktModLink Sq" data-pltdoc="x"><span class="RktSym">slideshow</span></a><span class="RktPn">)</span> is equivalent to <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="stt"> </span><span class="RktSym">slideshow/main</span><span class="RktPn">)</span>.</p></li><li><p>Second, <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> implicitly adds a <span class="stt">".rkt"</span>
|
||
|
|
suffix to the path.</p></li><li><p>Finally, <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> resolves the path by searching among
|
||
|
|
installed <a href="module-basics.html#%28tech._collection%29" class="techoutside" data-pltdoc="x"><span class="techinside">collections</span></a>, instead of treating the path as relative to
|
||
|
|
the enclosing module’s path.</p></li></ul><p>To a first approximation, a <a href="module-basics.html#%28tech._collection%29" class="techoutside" data-pltdoc="x"><span class="techinside">collection</span></a> is implemented as a
|
||
|
|
filesystem directory. For example, the <span class="stt">"racket"</span> collection is
|
||
|
|
mostly located in a <span class="stt">"racket"</span> directory within the Racket
|
||
|
|
installation’s <span class="stt">"collects"</span> directory, as reported by</p><blockquote class="SCodeFlow"><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._require%2529%2529&version=8.6" class="RktStxLink Sq" data-pltdoc="x">require</a></span><span class="hspace"> </span><span class="RktSym">setup/dirs</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=Manipulating_Paths.html%23%2528def._%2528%2528quote._%7E23%7E25kernel%2529._build-path%2529%2529&version=8.6" class="RktValLink Sq" data-pltdoc="x">build-path</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=raco&rel=dirs.html%23%2528def._%2528%2528lib._setup%252Fdirs..rkt%2529._find-collects-dir%2529%2529&version=8.6" class="RktValLink Sq" data-pltdoc="x">find-collects-dir</a></span><span class="RktPn">)</span><span class="hspace"> </span><span class="RktCmt">;</span><span class="RktCmt"> </span><span class="RktCmt">main collection directory</span></td></tr><tr><td><span class="hspace"> </span><span class="RktVal">"racket"</span><span class="RktPn">)</span></td></tr></table></blockquote><p>The Racket installation’s <span class="stt">"collects"</span> directory, however, is
|
||
|
|
only one place that <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> looks for collection directories.
|
||
|
|
Other places include the user-specific directory reported by
|
||
|
|
<span class="RktPn">(</span><span class="RktSym"><a href="https://download.racket-lang.org/releases/8.6/doc/local-redirect/index.html?doc=raco&rel=dirs.html%23%2528def._%2528%2528lib._setup%252Fdirs..rkt%2529._find-user-collects-dir%2529%2529&version=8.6" class="RktValLink Sq" data-pltdoc="x">find-user-collects-dir</a></span><span class="RktPn">)</span> and directories configured through
|
||
|
|
the <span class="stt">PLTCOLLECTS</span> search path. Finally, and most typically,
|
||
|
|
collections are found through installed <a href="module-basics.html#%28tech._package%29" class="techoutside" data-pltdoc="x"><span class="techinside">packages</span></a>.</p><h5 x-source-module="(lib "scribblings/guide/guide.scrbl")" x-source-pkg="racket-doc" x-part-tag=""packages-and-collections"">6.1.3<tt> </tt><a name="(part._packages-and-collections)"></a>Packages and Collections</h5><p><div class="SIntrapara">A <a name="(tech._package)"></a><span style="font-style: italic">package</span> is a set of libraries that are installed through
|
||
|
|
the Racket package manager (or included as pre-installed in a Racket
|
||
|
|
distribution). For example, the <a href="https://download.racket-lang.org/releases/8.6/doc/local-redirect/index.html?doc=gui&rel=index.html&version=8.6" class="RktModLink Sq" data-pltdoc="x"><span class="RktSym">racket/gui</span></a> library is
|
||
|
|
provided by the <span class="stt">"gui"</span> package, while
|
||
|
|
<a href="https://download.racket-lang.org/releases/8.6/doc/local-redirect/index.html?doc=parser-tools&rel=Lexers.html&version=8.6" class="RktModLink Sq" data-pltdoc="x"><span class="RktSym">parser-tools/lex</span></a> is provided by the
|
||
|
|
<span class="stt">"parser-tools"</span> library.</div><div class="SIntrapara"><blockquote class="refpara"><blockquote class="refcolumn"><blockquote class="refcontent"><p>More precisely,
|
||
|
|
<a href="https://download.racket-lang.org/releases/8.6/doc/local-redirect/index.html?doc=gui&rel=index.html&version=8.6" class="RktModLink Sq" data-pltdoc="x"><span class="RktSym">racket/gui</span></a> is provided by <span class="stt">"gui-lib"</span>,
|
||
|
|
<a href="https://download.racket-lang.org/releases/8.6/doc/local-redirect/index.html?doc=parser-tools&rel=Lexers.html&version=8.6" class="RktModLink Sq" data-pltdoc="x"><span class="RktSym">parser-tools/lex</span></a> is provided by
|
||
|
|
<span class="stt">"parser-tools-lib"</span>, and the <span class="stt">"gui"</span> and
|
||
|
|
<span class="stt">"parser-tools"</span> packages extend <span class="stt">"gui-lib"</span> and
|
||
|
|
<span class="stt">"parser-tools-lib"</span> with documentation.</p></blockquote></blockquote></blockquote></div></p><p>Racket programs do not refer to <a href="module-basics.html#%28tech._package%29" class="techoutside" data-pltdoc="x"><span class="techinside">packages</span></a> directly. Instead,
|
||
|
|
programs refer to libraries via <a href="module-basics.html#%28tech._collection%29" class="techoutside" data-pltdoc="x"><span class="techinside">collections</span></a>, and adding or
|
||
|
|
removing a <a href="module-basics.html#%28tech._package%29" class="techoutside" data-pltdoc="x"><span class="techinside">package</span></a> changes the set of collection-based
|
||
|
|
libraries that are available. A single package can supply
|
||
|
|
libraries in multiple collections, and two different packages can
|
||
|
|
supply libraries in the same collection (but not the same libraries,
|
||
|
|
and the package manager ensures that installed packages do not
|
||
|
|
conflict at that level).</p><p>For more information about packages, see <a href="https://download.racket-lang.org/releases/8.6/doc/local-redirect/index.html?doc=pkg&rel=index.html&version=8.6" class="Sq" data-pltdoc="x">Package Management in Racket</a>.</p><h5 x-source-module="(lib "scribblings/guide/guide.scrbl")" x-source-pkg="racket-doc" x-part-tag=""link-collection"">6.1.4<tt> </tt><a name="(part._link-collection)"></a>Adding Collections</h5><p>Looking back at the candy-sorting example of <a href="module-basics.html#%28part._module-org%29" data-pltdoc="x">Organizing Modules</a>,
|
||
|
|
suppose that modules in <span class="stt">"db/"</span> and <span class="stt">"machine/"</span> need a
|
||
|
|
common set of helper functions. Helper functions could be put in a
|
||
|
|
<span class="stt">"utils/"</span> directory, and modules in <span class="stt">"db/"</span> or
|
||
|
|
<span class="stt">"machine/"</span> could access utility modules with relative paths
|
||
|
|
that start <span class="stt">"../utils/"</span>. As long as a set of modules work
|
||
|
|
together in a single project, it’s best to stick with relative paths.
|
||
|
|
A programmer can follow relative-path references without knowing about
|
||
|
|
your Racket configuration.</p><p>Some libraries are meant to be used across multiple projects, so that
|
||
|
|
keeping the library source in a directory with its uses does not make
|
||
|
|
sense. In that case, the best option is add a new
|
||
|
|
<a href="module-basics.html#%28tech._collection%29" class="techoutside" data-pltdoc="x"><span class="techinside">collection</span></a>. After the library is in a collection, it can be
|
||
|
|
referenced with an unquoted path, just like libraries that are
|
||
|
|
included with the Racket distribution.</p><p>You could add a new collection by placing files in the Racket
|
||
|
|
installation or one of the directories reported by
|
||
|
|
<span class="RktPn">(</span><span class="RktSym"><a href="https://download.racket-lang.org/releases/8.6/doc/local-redirect/index.html?doc=raco&rel=dirs.html%23%2528def._%2528%2528lib._setup%252Fdirs..rkt%2529._get-collects-search-dirs%2529%2529&version=8.6" class="RktValLink Sq" data-pltdoc="x">get-collects-search-dirs</a></span><span class="RktPn">)</span>. Alternatively, you could add to
|
||
|
|
the list of searched directories by setting the <span class="stt">PLTCOLLECTS</span>
|
||
|
|
environment variable.<span class="refelem"><span class="refcolumn"><span class="refcontent">If you set <span class="stt">PLTCOLLECTS</span>,
|
||
|
|
include an empty path in by starting the value with a colon (Unix and
|
||
|
|
Mac OS) or semicolon (Windows) so that the original search paths are
|
||
|
|
preserved.</span></span></span> The best option, however, is to add a <a href="module-basics.html#%28tech._package%29" class="techoutside" data-pltdoc="x"><span class="techinside">package</span></a>.</p><p>Creating a package <span class="emph">does not</span> mean that you have to register with
|
||
|
|
a package server or perform a bundling step that copies your source
|
||
|
|
code into an archive format. Creating a package can simply mean using
|
||
|
|
the package manager to make your libraries locally accessible as a
|
||
|
|
collection from their current source locations.</p><p>For example, suppose you have a directory <span class="stt">"/usr/molly/bakery"</span>
|
||
|
|
that contains the <span class="stt">"cake.rkt"</span> module (from the
|
||
|
|
<a href="module-basics.html" data-pltdoc="x">beginning</a> of this section) and other
|
||
|
|
related modules. To make the modules available as a <span class="stt">"bakery"</span>
|
||
|
|
collection, either</p><ul><li><p>Use the <span class="stt">raco pkg</span> command-line tool:</p><p><span class="hspace"> </span><span class="stt">raco pkg install --link /usr/molly/bakery</span></p><p>where the <span class="nobreak"><span class="stt">--link</span></span> flag is not actually needed when the
|
||
|
|
provided path includes a directory separator.</p></li><li><p>Use DrRacket’s <span class="ssansserif">Package Manager</span> item from the
|
||
|
|
<span class="ssansserif">File</span> menu. In the <span class="ssansserif">Do What I Mean</span> panel,
|
||
|
|
click <span class="ssansserif">Browse...</span>, choose the
|
||
|
|
<span class="stt">"/usr/molly/bakery"</span> directory, and click
|
||
|
|
<span class="ssansserif">Install</span>.</p></li></ul><p>Afterward, <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="stt"> </span><span class="RktSym">bakery/cake</span><span class="RktPn">)</span> from any module will import
|
||
|
|
the <span class="RktSym">print-cake</span> function from
|
||
|
|
<span class="stt">"/usr/molly/bakery/cake.rkt"</span>.</p><p>By default, the name of the directory that you install is used both as
|
||
|
|
the <a href="module-basics.html#%28tech._package%29" class="techoutside" data-pltdoc="x"><span class="techinside">package</span></a> name and as the <a href="module-basics.html#%28tech._collection%29" class="techoutside" data-pltdoc="x"><span class="techinside">collection</span></a> that is provided
|
||
|
|
by the package. Also, the package manager normally defaults to
|
||
|
|
installation only for the current user, as opposed to all users of a
|
||
|
|
Racket installation. See <a href="https://download.racket-lang.org/releases/8.6/doc/local-redirect/index.html?doc=pkg&rel=index.html&version=8.6" class="Sq" data-pltdoc="x">Package Management in Racket</a> for more information.</p><p>If you intend to distribute your libraries to others, choose
|
||
|
|
collection and package names carefully. The collection namespace is
|
||
|
|
hierarchical, but top-level collection names are global, and the
|
||
|
|
package namespace is flat. Consider putting one-off libraries under
|
||
|
|
some top-level name like <span class="stt">"molly"</span> that identifies the
|
||
|
|
producer. Use a collection name like <span class="stt">"bakery"</span> when producing
|
||
|
|
the definitive collection of baked-goods libraries.</p><p>After your libraries are put in a <a href="module-basics.html#%28tech._collection%29" class="techoutside" data-pltdoc="x"><span class="techinside">collection</span></a> you can still
|
||
|
|
use <span class="stt">raco make</span> to compile the library sources, but it’s better
|
||
|
|
and more convenient to use <span class="stt">raco setup</span>. The <span class="stt">raco setup</span>
|
||
|
|
command takes a collection name (as opposed to a file name) and
|
||
|
|
compiles all libraries within the collection. In addition, <span class="stt">raco setup</span> can
|
||
|
|
build documentation for the collection and add it to the documentation
|
||
|
|
index, as specified by a <span class="stt">"info.rkt"</span> module in the collection.
|
||
|
|
See <a href="https://download.racket-lang.org/releases/8.6/doc/local-redirect/index.html?doc=raco&rel=setup.html&version=8.6" class="Sq" data-pltdoc="x"><span class="stt">raco setup</span>: Installation Management</a> for
|
||
|
|
more information on <span class="stt">raco setup</span>.</p><h5 x-source-module="(lib "scribblings/guide/guide.scrbl")" x-source-pkg="racket-doc" x-part-tag=""intracollection"">6.1.5<tt> </tt><a name="(part._intracollection)"></a>Module References Within a Collection</h5><p>When a module within a collection references another module within the
|
||
|
|
same collection, either a relative path or a collection path could
|
||
|
|
work. For example, a <span class="stt">"sort.rkt"</span> module that references
|
||
|
|
<span class="stt">"db/lookup.rkt"</span> and <span class="stt">"machine/control.rkt"</span> modules within
|
||
|
|
the same collection could be written with relative paths as in
|
||
|
|
<a href="module-basics.html#%28part._module-org%29" data-pltdoc="x">Organizing Modules</a>:</p><blockquote class="SCodeFlow"><blockquote class="Rfilebox"><p class="Rfiletitle"><span class="Rfilename"><span class="stt">"sort.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=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">"db/lookup.rkt"</span><span class="hspace"> </span><span class="RktVal">"machine/control.rkt"</span><span class="RktPn">)</span></td></tr><tr><td><span class="RktSym">....</span></td></tr></table></blockquote></blockquote></blockquote><p>Alternatively, if the collection is named <span class="stt">"candy"</span>, then
|
||
|
|
<span class="stt">"sort.rkt"</span> could use collection paths to import the two
|
||
|
|
modules:</p><blockquote class="SCodeFlow"><blockquote class="Rfilebox"><p class="Rfiletitle"><span class="Rfilename"><span class="stt">"sort.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=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">candy/db/lookup</span><span class="hspace"> </span><span class="RktSym">candy/machine/control</span><span class="RktPn">)</span></td></tr><tr><td><span class="RktSym">....</span></td></tr></table></blockquote></blockquote></blockquote><p>For most purposes, these choices will work the same, but there are
|
||
|
|
exceptions. When writing documentation with <a href="https://download.racket-lang.org/releases/8.6/doc/local-redirect/index.html?doc=scribble&rel=index.html&version=8.6" class="Sq" data-pltdoc="x">Scribble</a>, you must use
|
||
|
|
a collection path with <span class="RktSym"><a href="https://download.racket-lang.org/releases/8.6/doc/local-redirect/index.html?doc=scribble&rel=doc-modules.html%23%2528form._%2528%2528lib._scribble%252Fmanual..rkt%2529._defmodule%2529%2529&version=8.6" class="RktStxLink Sq" data-pltdoc="x">defmodule</a></span> and similar forms; that’s
|
||
|
|
partly because documentation is meant to be read by client
|
||
|
|
programmers, and so the collection-based name should appear.
|
||
|
|
Meanwhile, for <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>, using relative paths for references
|
||
|
|
within a collection tends to be the most flexible approach, but with
|
||
|
|
caveats.</p><p>Relative-path references work much like relative URL references: the
|
||
|
|
reference is expanded based on the way the enclosing module is
|
||
|
|
accessed. If the enclosing module is accessed through a filesystem
|
||
|
|
path, then a relative path in <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> is combined with that
|
||
|
|
filesystem path to form a new filesystem path. If the enclosing module
|
||
|
|
is accessed through a collection path, then a relative path in
|
||
|
|
<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> is combined with that collection path to form a new
|
||
|
|
collection path. A collection path is, in turn, converted to a
|
||
|
|
filesystem path, and so the difference between starting with a
|
||
|
|
filesystem or collection path does not usually matter. Unfortunately,
|
||
|
|
inherent complexities of path resolution can create differences in
|
||
|
|
some situations:</p><ul><li><p>Through soft links, multiple mount points, or case-insensitive
|
||
|
|
filesystems (on an operating system that does not implicitly
|
||
|
|
case-normalize paths), there may be multiple filesystem paths
|
||
|
|
that refer to the same module file.</p><p>For example, when the current directory is the <span class="stt">"candy"</span>
|
||
|
|
collection’s directory, the current-directory path that
|
||
|
|
<span class="stt">racket</span> receives on startup may cause <span class="stt">racket
|
||
|
|
sort.rkt</span> to use a different filesystem path than <span class="stt">racket
|
||
|
|
-l candy/sort</span> finds through the library-collection search
|
||
|
|
path. In that case, if <span class="stt">"sort.rkt"</span> leads to some
|
||
|
|
modules through both relative-path references and
|
||
|
|
collection-based references, it’s possible that those resolve
|
||
|
|
to difference instances of the same source module, creating
|
||
|
|
confusion through multiple instantiations.</p></li><li><p>When <a href="https://download.racket-lang.org/releases/8.6/doc/local-redirect/index.html?doc=raco&rel=exe.html&version=8.6" class="Sq" data-pltdoc="x"><span class="stt">raco exec</span></a> plus
|
||
|
|
<a href="https://download.racket-lang.org/releases/8.6/doc/local-redirect/index.html?doc=raco&rel=exe-dist.html&version=8.6" class="Sq" data-pltdoc="x"><span class="stt">raco distribute</span></a> are
|
||
|
|
used to create an executable to run on a different machine, the
|
||
|
|
paths of the current machine are likely unrelated to paths on
|
||
|
|
the target machine. The <span class="stt">raco exe</span> tool treats modules
|
||
|
|
that are referenced via filesystem paths differently than
|
||
|
|
modules reference via collection paths, because only the latter
|
||
|
|
make sense to access through reflective operations at run
|
||
|
|
time.</p><p>For example, if <span class="stt">raco exe sort.rkt</span> creates an executable
|
||
|
|
that uses <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="stt"> </span><span class="RktVal">'</span><span class="RktVal">candy/db/lookup</span><span class="stt"> </span><span class="RktVal">#f</span><span class="RktPn">)</span> at run
|
||
|
|
time, then that <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> will fail in the case
|
||
|
|
that <span class="stt">"db/lookup.rkt"</span> is resolved relative to the
|
||
|
|
filesystem path <span class="RktVal">"sort.rkt"</span> at executable-creation time.</p></li></ul><p>Using only collection-based paths (including using shell commands like
|
||
|
|
<span class="stt">racket -l candy/sort</span> and not like <span class="stt">racket sort.rkt</span>) can
|
||
|
|
avoid all problems, but then you must only develop modules within an
|
||
|
|
installed collection, which is often inconvenient. Using relative-path
|
||
|
|
references consistently tends to be the most convenient while still
|
||
|
|
working in most circumstances.</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="modules.html" title="backward to "6 Modules"" data-pltdoc="x">← prev</a> <a href="modules.html" title="up to "6 Modules"" data-pltdoc="x">up</a> <a href="Module_Syntax.html" title="forward to "6.2 Module Syntax"" data-pltdoc="x">next →</a></span> </div></div></div><div id="contextindicator"> </div></body></html>
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