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<html><head><meta http-equiv="content-type" content="text/html; charset=utf-8"/><title>6.6&nbsp;Assignment and Redefinition</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,&quot;tocview_0&quot;);">&#9658;</a></td><td></td><td><a href="index.html" class="tocviewlink" data-pltdoc="x"><span style="font-weight: bold">The Racket Guide</span></a></td></tr></table></div><div class="tocviewsublisttop" style="display: none;" id="tocview_0"><table cellspacing="0" cellpadding="0"><tr><td align="right">1&nbsp;</td><td><a href="intro.html" class="tocviewlink" data-pltdoc="x">Welcome to Racket</a></td></tr><tr><td align="right">2&nbsp;</td><td><a href="to-scheme.html" class="tocviewlink" data-pltdoc="x">Racket Essentials</a></td></tr><tr><td align="right">3&nbsp;</td><td><a href="datatypes.html" class="tocviewlink" data-pltdoc="x">Built-<wbr></wbr>In Datatypes</a></td></tr><tr><td align="right">4&nbsp;</td><td><a href="scheme-forms.html" class="tocviewlink" data-pltdoc="x">Expressions and Definitions</a></td></tr><tr><td align="right">5&nbsp;</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&nbsp;</td><td><a href="modules.html" class="tocviewselflink" data-pltdoc="x">Modules</a></td></tr><tr><td align="right">7&nbsp;</td><td><a href="contracts.html" class="tocviewlink" data-pltdoc="x">Contracts</a></td></tr><tr><td align="right">8&nbsp;</td><td><a href="i_o.html" class="tocviewlink" data-pltdoc="x">Input and Output</a></td></tr><tr><td align="right">9&nbsp;</td><td><a href="regexp.html" class="tocviewlink" data-pltdoc="x">Regular Expressions</a></td></tr><tr><td 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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,&quot;tocview_1&quot;);">&#9660;</a></td><td>6&nbsp;</td><td><a href="modules.html" class="tocviewlink" data-pltdoc="x">Modules</a></td></tr></table><div class="tocviewsublistbottom" style="display: block;" id="tocview_1"><table cellspacing="0" cellpadding="0"><tr><td align="right">6.1&nbsp;</td><td><a href="module-basics.html" class="tocviewlink" data-pltdoc="x">Module Basics</a></td></tr><tr><td align="right">6.2&nbsp;</td><td><a href="Module_Syntax.html" class="tocviewlink" data-pltdoc="x">Module Syntax</a></td></tr><tr><td align="right">6.3&nbsp;</td><td><a href="module-paths.html" class="tocviewlink" data-pltdoc="x">Module Paths</a></td></tr><tr><td align="right">6.4&nbsp;</td><td><a href="module-require.html" class="tocviewlink" data-pltdoc="x">Imports:<span class="mywbr"> &nbsp;</span> <span class="RktSym"><span class="RktStxLink">require</span></span></a></td></tr><tr><td align="right">6.5&nbsp;</td><td><a href="module-provide.html" class="tocviewlink" data-pltdoc="x">Exports:<span class="mywbr"> &nbsp;</span> <span class="RktSym"><span class="RktStxLink">provide</span></span></a></td></tr><tr><td align="right">6.6&nbsp;</td><td><a href="" class="tocviewselflink" data-pltdoc="x">Assignment and Redefinition</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" style="color: #888;" type="text" value="...search manuals..." title="Enter a search string to search the manuals" onkeypress="return DoSearchKey(event, this, &quot;6.1&quot;, &quot;../&quot;);" onfocus="this.style.color=&quot;black&quot;; this.style.textAlign=&quot;left&quot;; if (this.value == &quot;...search manuals...&quot;) this.value=&quot;&quot;;" onblur="if (this.value.match(/^ *$/)) { this.style.color=&quot;#888&quot;; this.style.textAlign=&quot;center&quot;; this.value=&quot;...search manuals...&quot;; }"/></form>&nbsp;&nbsp;<a href="../index.html" title="up to the documentation top" data-pltdoc="x" onclick="return GotoPLTRoot(&quot;6.1&quot;);">top</a></span><span class="navright">&nbsp;&nbsp;<a href="module-provide.html" title="backward to &quot;6.5 Exports: provide&quot;" data-pltdoc="x">&larr; prev</a>&nbsp;&nbsp;<a href="modules.html" title="up to &quot;6 Modules&quot;" data-pltdoc="x">up</a>&nbsp;&nbsp;<a href="contracts.html" title="forward to &quot;7 Contracts&quot;" data-pltdoc="x">next &rarr;</a></span>&nbsp;</div><h4 x-source-module="(lib &quot;scribblings/guide/guide.scrbl&quot;)" x-part-tag="&quot;module-set&quot;">6.6<tt>&nbsp;</tt><a name="(part._module-set)"></a>Assignment and Redefinition</h4><p>The use of <span class="RktSym"><a href="http://download.racket-lang.org/docs/6.1/html/local-redirect/index.html?doc=reference&amp;rel=set_.html%23%2528form._%2528%2528quote._%7E23%7E25kernel%2529._set%2521%2529%2529&amp;version=6.1" class="RktStxLink Sq" data-pltdoc="x">set!</a></span> on variables defined within a module is
limited to the body of the defining module. That is, a module is
allowed to change the value of its own definitions, and such changes
are visible to importing modules. However, an importing context is not
allowed to change the value of an imported binding.</p><p><table cellspacing="0" cellpadding="0" class="RktBlk"><tr><td><p>Examples:</p></td></tr><tr><td><blockquote class="SCodeFlow"><table cellspacing="0" cellpadding="0" class="RktBlk"><tr><td><table cellspacing="0" cellpadding="0" class="RktBlk"><tr><td><span class="stt">&gt; </span><span class="RktPn">(</span><span class="RktSym"><a href="http://download.racket-lang.org/docs/6.1/html/local-redirect/index.html?doc=reference&amp;rel=module.html%23%2528form._%2528%2528quote._%7E23%7E25kernel%2529._module%2529%2529&amp;version=6.1" class="RktStxLink Sq" data-pltdoc="x">module</a></span><span class="hspace">&nbsp;</span><span class="RktSym">m</span><span class="hspace">&nbsp;</span><span class="RktSym">racket</span></td></tr><tr><td><span class="hspace">&nbsp;&nbsp;</span><span class="hspace">&nbsp;&nbsp;</span><span class="RktPn">(</span><span class="RktSym"><a href="http://download.racket-lang.org/docs/6.1/html/local-redirect/index.html?doc=reference&amp;rel=require.html%23%2528form._%2528%2528lib._racket%252Fprivate%252Fbase..rkt%2529._provide%2529%2529&amp;version=6.1" class="RktStxLink Sq" data-pltdoc="x">provide</a></span><span class="hspace">&nbsp;</span><span class="RktSym">counter</span><span class="hspace">&nbsp;</span><span class="RktSym">increment!</span><span class="RktPn">)</span></td></tr><tr><td><span class="hspace">&nbsp;&nbsp;</span><span class="hspace">&nbsp;&nbsp;</span><span class="RktPn">(</span><span class="RktSym"><a href="http://download.racket-lang.org/docs/6.1/html/local-redirect/index.html?doc=reference&amp;rel=define.html%23%2528form._%2528%2528lib._racket%252Fprivate%252Fbase..rkt%2529._define%2529%2529&amp;version=6.1" class="RktStxLink Sq" data-pltdoc="x">define</a></span><span class="hspace">&nbsp;</span><span class="RktSym">counter</span><span class="hspace">&nbsp;</span><span class="RktVal">0</span><span class="RktPn">)</span></td></tr><tr><td><span class="hspace">&nbsp;&nbsp;</span><span class="hspace">&nbsp;&nbsp;</span><span class="RktPn">(</span><span class="RktSym"><a href="http://download.racket-lang.org/docs/6.1/html/local-redirect/index.html?doc=reference&amp;rel=define.html%23%2528form._%2528%2528lib._racket%252Fprivate%252Fbase..rkt%2529._define%2529%2529&amp;version=6.1" class="RktStxLink Sq" data-pltdoc="x">define</a></span><span class="hspace">&nbsp;</span><span class="RktPn">(</span><span class="RktSym">increment!</span><span class="RktPn">)</span></td></tr><tr><td><span class="hspace">&nbsp;&nbsp;</span><span class="hspace">&nbsp;&nbsp;&nbsp;&nbsp;</span><span class="RktPn">(</span><span class="RktSym"><a href="http://download.racket-lang.org/docs/6.1/html/local-redirect/index.html?doc=reference&amp;rel=set_.html%23%2528form._%2528%2528quote._%7E23%7E25kernel%2529._set%2521%2529%2529&amp;version=6.1" class="RktStxLink Sq" data-pltdoc="x">set!</a></span><span class="hspace">&nbsp;</span><span class="RktSym">counter</span><span class="hspace">&nbsp;</span><span class="RktPn">(</span><span class="RktSym"><a href="http://download.racket-lang.org/docs/6.1/html/local-redirect/index.html?doc=reference&amp;rel=generic-numbers.html%23%2528def._%2528%2528quote._%7E23%7E25kernel%2529._add1%2529%2529&amp;version=6.1" class="RktValLink Sq" data-pltdoc="x">add1</a></span><span class="hspace">&nbsp;</span><span class="RktSym">counter</span><span class="RktPn">)</span><span class="RktPn">)</span><span class="RktPn">)</span><span class="RktPn">)</span></td></tr></table></td></tr><tr><td><table cellspacing="0" cellpadding="0"><tr><td></td></tr></table></td></tr><tr><td><span class="stt">&gt; </span><span class="RktPn">(</span><span class="RktSym"><a href="http://download.racket-lang.org/docs/6.1/html/local-redirect/index.html?doc=reference&amp;rel=require.html%23%2528form._%2528%2528lib._racket%252Fprivate%252Fbase..rkt%2529._require%2529%2529&amp;version=6.1" class="RktStxLink Sq" data-pltdoc="x">require</a></span><span class="hspace">&nbsp;</span><span class="RktVal">'</span><span class="RktVal">m</span><span class="RktPn">)</span></td></tr><tr><td><table cellspacing="0" cellpadding="0"><tr><td></td></tr></table></td></tr><tr><td><span class="stt">&gt; </span><span class="RktSym">counter</span></td></tr><tr><td><p><span class="RktRes">0</span></p></td></tr><tr><td><span class="stt">&gt; </span><span class="RktPn">(</span><span class="RktSym">increment!</span><span class="RktPn">)</span></td></tr><tr><td><table cellspacing="0" cellpadding="0"><tr><td></td></tr></table></td></tr><tr><td><span class="stt">&gt; </span><span class="RktSym">counter</span></td></tr><tr><td><p><span class="RktRes">1</span></p></td></tr><tr><td><span class="stt">&gt; </span><span class="RktPn">(</span><span class="RktSym"><a href="http://download.racket-lang.org/docs/6.1/html/local-redirect/index.html?doc=reference&amp;rel=set_.html%23%2528form._%2528%2528quote._%7E23%7E25kernel%2529._set%2521%2529%2529&amp;version=6.1" class="RktStxLink Sq" data-pltdoc="x">set!</a></span><span class="hspace">&nbsp;</span><span class="RktSym">counter</span><span class="hspace">&nbsp;</span><span class="RktVal"><span class="nobreak">-1</span></span><span class="RktPn">)</span></td></tr><tr><td><p><span class="RktErr">set!: cannot mutate module-required identifier</span></p></td></tr><tr><td><p><span class="RktErr"></span><span class="hspace">&nbsp;&nbsp;</span><span class="RktErr">in: counter</span></p></td></tr></table></blockquote></td></tr></table></p><p>As the above example illustrates, a module can always grant others the
ability to change its exports by providing a mutator function, such as
<span class="RktSym">increment!</span>.</p><p>The prohibition on assignment of imported variables helps support
modular reasoning about programs. For example, in the module,</p><blockquote class="SCodeFlow"><table cellspacing="0" cellpadding="0" class="RktBlk"><tr><td><span class="RktPn">(</span><span class="RktSym"><a href="http://download.racket-lang.org/docs/6.1/html/local-redirect/index.html?doc=reference&amp;rel=module.html%23%2528form._%2528%2528quote._%7E23%7E25kernel%2529._module%2529%2529&amp;version=6.1" class="RktStxLink Sq" data-pltdoc="x">module</a></span><span class="hspace">&nbsp;</span><span class="RktSym">m</span><span class="hspace">&nbsp;</span><span class="RktSym">racket</span></td></tr><tr><td><span class="hspace">&nbsp;&nbsp;</span><span class="RktPn">(</span><span class="RktSym"><a href="http://download.racket-lang.org/docs/6.1/html/local-redirect/index.html?doc=reference&amp;rel=require.html%23%2528form._%2528%2528lib._racket%252Fprivate%252Fbase..rkt%2529._provide%2529%2529&amp;version=6.1" class="RktStxLink Sq" data-pltdoc="x">provide</a></span><span class="hspace">&nbsp;</span><span class="RktSym">rx:fish</span><span class="hspace">&nbsp;</span><span class="RktSym">fishy-string?</span><span class="RktPn">)</span></td></tr><tr><td><span class="hspace">&nbsp;&nbsp;</span><span class="RktPn">(</span><span class="RktSym"><a href="http://download.racket-lang.org/docs/6.1/html/local-redirect/index.html?doc=reference&amp;rel=define.html%23%2528form._%2528%2528lib._racket%252Fprivate%252Fbase..rkt%2529._define%2529%2529&amp;version=6.1" class="RktStxLink Sq" data-pltdoc="x">define</a></span><span class="hspace">&nbsp;</span><span class="RktSym">rx:fish</span><span class="hspace">&nbsp;</span><span class="RktVal">#rx"fish"</span><span class="RktPn">)</span></td></tr><tr><td><span class="hspace">&nbsp;&nbsp;</span><span class="RktPn">(</span><span class="RktSym"><a href="http://download.racket-lang.org/docs/6.1/html/local-redirect/index.html?doc=reference&amp;rel=define.html%23%2528form._%2528%2528lib._racket%252Fprivate%252Fbase..rkt%2529._define%2529%2529&amp;version=6.1" class="RktStxLink Sq" data-pltdoc="x">define</a></span><span class="hspace">&nbsp;</span><span class="RktPn">(</span><span class="RktSym">fishy-string?</span><span class="hspace">&nbsp;</span><span class="RktSym">s</span><span class="RktPn">)</span></td></tr><tr><td><span class="hspace">&nbsp;&nbsp;&nbsp;&nbsp;</span><span class="RktPn">(</span><span class="RktSym"><a href="http://download.racket-lang.org/docs/6.1/html/local-redirect/index.html?doc=reference&amp;rel=regexp.html%23%2528def._%2528%2528quote._%7E23%7E25kernel%2529._regexp-match%7E3f%2529%2529&amp;version=6.1" class="RktValLink Sq" data-pltdoc="x">regexp-match?</a></span><span class="hspace">&nbsp;</span><span class="RktSym">s</span><span class="hspace">&nbsp;</span><span class="RktSym">rx:fish</span><span class="RktPn">)</span><span class="RktPn">)</span><span class="RktPn">)</span></td></tr></table></blockquote><p>the function <span class="RktSym">fishy-string?</span> will always match strings that
contain &ldquo;fish&rdquo;, no matter how other modules use the <span class="RktSym">rx:fish</span>
binding.  For essentially the same reason that it helps programmers,
the prohibition on assignment to imports also allows many programs to
be executed more efficiently.</p><p>Along the same lines, when a module contains no <span class="RktSym"><a href="http://download.racket-lang.org/docs/6.1/html/local-redirect/index.html?doc=reference&amp;rel=set_.html%23%2528form._%2528%2528quote._%7E23%7E25kernel%2529._set%2521%2529%2529&amp;version=6.1" class="RktStxLink Sq" data-pltdoc="x">set!</a></span> of a
particular identifier that is defined within the module, then the
identifier is considered a <span style="font-style: italic">constant</span> that cannot be
changed&#8212;<wbr></wbr>not even by re-declaring the module.</p><p>Consequently, re-declaration of a module is not generally allowed.
For file-based modules, simply changing the file does not lead to a
re-declaration in any case, because file-based modules are loaded on
demand, and the previously loaded declarations satisfy future
requests. It is possible to use Racket&rsquo;s reflection support to
re-declare a module, however, and non-file modules can be re-declared
in the <a href="intro.html#%28tech._repl%29" class="techoutside" data-pltdoc="x"><span class="techinside">REPL</span></a>; in such cases, the re-declaration may fail if it
involves the re-definition of a previously constant binding.</p><blockquote class="SCodeFlow"><table cellspacing="0" cellpadding="0" class="RktBlk"><tr><td><table cellspacing="0" cellpadding="0" class="RktBlk"><tr><td><span class="stt">&gt; </span><span class="RktPn">(</span><span class="RktSym"><a href="http://download.racket-lang.org/docs/6.1/html/local-redirect/index.html?doc=reference&amp;rel=module.html%23%2528form._%2528%2528quote._%7E23%7E25kernel%2529._module%2529%2529&amp;version=6.1" class="RktStxLink Sq" data-pltdoc="x">module</a></span><span class="hspace">&nbsp;</span><span class="RktSym">m</span><span class="hspace">&nbsp;</span><span class="RktSym">racket</span></td></tr><tr><td><span class="hspace">&nbsp;&nbsp;</span><span class="hspace">&nbsp;&nbsp;</span><span class="RktPn">(</span><span class="RktSym"><a href="http://download.racket-lang.org/docs/6.1/html/local-redirect/index.html?doc=reference&amp;rel=define.html%23%2528form._%2528%2528lib._racket%252Fprivate%252Fbase..rkt%2529._define%2529%2529&amp;version=6.1" class="RktStxLink Sq" data-pltdoc="x">define</a></span><span class="hspace">&nbsp;</span><span class="RktSym">pie</span><span class="hspace">&nbsp;</span><span class="RktVal">3.141597</span><span class="RktPn">)</span><span class="RktPn">)</span></td></tr></table></td></tr><tr><td><table cellspacing="0" cellpadding="0"><tr><td></td></tr></table></td></tr><tr><td><span class="stt">&gt; </span><span class="RktPn">(</span><span class="RktSym"><a href="http://download.racket-lang.org/docs/6.1/html/local-redirect/index.html?doc=reference&amp;rel=require.html%23%2528form._%2528%2528lib._racket%252Fprivate%252Fbase..rkt%2529._require%2529%2529&amp;version=6.1" class="RktStxLink Sq" data-pltdoc="x">require</a></span><span class="hspace">&nbsp;</span><span class="RktVal">'</span><span class="RktVal">m</span><span class="RktPn">)</span></td></tr><tr><td><table cellspacing="0" cellpadding="0"><tr><td></td></tr></table></td></tr><tr><td><table cellspacing="0" cellpadding="0" class="RktBlk"><tr><td><span class="stt">&gt; </span><span class="RktPn">(</span><span class="RktSym"><a href="http://download.racket-lang.org/docs/6.1/html/local-redirect/index.html?doc=reference&amp;rel=module.html%23%2528form._%2528%2528quote._%7E23%7E25kernel%2529._module%2529%2529&amp;version=6.1" class="RktStxLink Sq" data-pltdoc="x">module</a></span><span class="hspace">&nbsp;</span><span class="RktSym">m</span><span class="hspace">&nbsp;</span><span class="RktSym">racket</span></td></tr><tr><td><span class="hspace">&nbsp;&nbsp;</span><span class="hspace">&nbsp;&nbsp;</span><span class="RktPn">(</span><span class="RktSym"><a href="http://download.racket-lang.org/docs/6.1/html/local-redirect/index.html?doc=reference&amp;rel=define.html%23%2528form._%2528%2528lib._racket%252Fprivate%252Fbase..rkt%2529._define%2529%2529&amp;version=6.1" class="RktStxLink Sq" data-pltdoc="x">define</a></span><span class="hspace">&nbsp;</span><span class="RktSym">pie</span><span class="hspace">&nbsp;</span><span class="RktVal">3</span><span class="RktPn">)</span><span class="RktPn">)</span></td></tr></table></td></tr><tr><td><p><span class="RktErr">define-values: assignment disallowed;</span></p></td></tr><tr><td><p><span class="RktErr"></span><span class="hspace">&nbsp;</span><span class="RktErr">cannot re-define a constant</span></p></td></tr><tr><td><p><span class="RktErr"></span><span class="hspace">&nbsp;&nbsp;</span><span class="RktErr">constant: pie</span></p></td></tr><tr><td><p><span class="RktErr"></span><span class="hspace">&nbsp;&nbsp;</span><span class="RktErr">in module: 'm</span></p></td></tr></table></blockquote><p>For exploration and debugging purposes, the Racket reflective layer
provides a <span class="RktSym"><a href="http://download.racket-lang.org/docs/6.1/html/local-redirect/index.html?doc=reference&amp;rel=eval.html%23%2528def._%2528%2528quote._%7E23%7E25kernel%2529._compile-enforce-module-constants%2529%2529&amp;version=6.1" class="RktValLink Sq" data-pltdoc="x">compile-enforce-module-constants</a></span> parameter
to disable the enforcement of constants.</p><blockquote class="SCodeFlow"><table cellspacing="0" cellpadding="0" class="RktBlk"><tr><td><span class="stt">&gt; </span><span class="RktPn">(</span><span class="RktSym"><a href="http://download.racket-lang.org/docs/6.1/html/local-redirect/index.html?doc=reference&amp;rel=eval.html%23%2528def._%2528%2528quote._%7E23%7E25kernel%2529._compile-enforce-module-constants%2529%2529&amp;version=6.1" class="RktValLink Sq" data-pltdoc="x">compile-enforce-module-constants</a></span><span class="hspace">&nbsp;</span><span class="RktVal">#f</span><span class="RktPn">)</span></td></tr><tr><td><table cellspacing="0" cellpadding="0"><tr><td></td></tr></table></td></tr><tr><td><table cellspacing="0" cellpadding="0" class="RktBlk"><tr><td><span class="stt">&gt; </span><span class="RktPn">(</span><span class="RktSym"><a href="http://download.racket-lang.org/docs/6.1/html/local-redirect/index.html?doc=reference&amp;rel=module.html%23%2528form._%2528%2528quote._%7E23%7E25kernel%2529._module%2529%2529&amp;version=6.1" class="RktStxLink Sq" data-pltdoc="x">module</a></span><span class="hspace">&nbsp;</span><span class="RktSym">m2</span><span class="hspace">&nbsp;</span><span class="RktSym">racket</span></td></tr><tr><td><span class="hspace">&nbsp;&nbsp;</span><span class="hspace">&nbsp;&nbsp;</span><span class="RktPn">(</span><span class="RktSym"><a href="http://download.racket-lang.org/docs/6.1/html/local-redirect/index.html?doc=reference&amp;rel=require.html%23%2528form._%2528%2528lib._racket%252Fprivate%252Fbase..rkt%2529._provide%2529%2529&amp;version=6.1" class="RktStxLink Sq" data-pltdoc="x">provide</a></span><span class="hspace">&nbsp;</span><span class="RktSym">pie</span><span class="RktPn">)</span></td></tr><tr><td><span class="hspace">&nbsp;&nbsp;</span><span class="hspace">&nbsp;&nbsp;</span><span class="RktPn">(</span><span class="RktSym"><a href="http://download.racket-lang.org/docs/6.1/html/local-redirect/index.html?doc=reference&amp;rel=define.html%23%2528form._%2528%2528lib._racket%252Fprivate%252Fbase..rkt%2529._define%2529%2529&amp;version=6.1" class="RktStxLink Sq" data-pltdoc="x">define</a></span><span class="hspace">&nbsp;</span><span class="RktSym">pie</span><span class="hspace">&nbsp;</span><span class="RktVal">3.141597</span><span class="RktPn">)</span><span class="RktPn">)</span></td></tr></table></td></tr><tr><td><table cellspacing="0" cellpadding="0"><tr><td></td></tr></table></td></tr><tr><td><span class="stt">&gt; </span><span class="RktPn">(</span><span class="RktSym"><a href="http://download.racket-lang.org/docs/6.1/html/local-redirect/index.html?doc=reference&amp;rel=require.html%23%2528form._%2528%2528lib._racket%252Fprivate%252Fbase..rkt%2529._require%2529%2529&amp;version=6.1" class="RktStxLink Sq" data-pltdoc="x">require</a></span><span class="hspace">&nbsp;</span><span class="RktVal">'</span><span class="RktVal">m2</span><span class="RktPn">)</span></td></tr><tr><td><table cellspacing="0" cellpadding="0"><tr><td></td></tr></table></td></tr><tr><td><table cellspacing="0" cellpadding="0" class="RktBlk"><tr><td><span class="stt">&gt; </span><span class="RktPn">(</span><span class="RktSym"><a href="http://download.racket-lang.org/docs/6.1/html/local-redirect/index.html?doc=reference&amp;rel=module.html%23%2528form._%2528%2528quote._%7E23%7E25kernel%2529._module%2529%2529&amp;version=6.1" class="RktStxLink Sq" data-pltdoc="x">module</a></span><span class="hspace">&nbsp;</span><span class="RktSym">m2</span><span class="hspace">&nbsp;</span><span class="RktSym">racket</span></td></tr><tr><td><span class="hspace">&nbsp;&nbsp;</span><span class="hspace">&nbsp;&nbsp;</span><span class="RktPn">(</span><span class="RktSym"><a href="http://download.racket-lang.org/docs/6.1/html/local-redirect/index.html?doc=reference&amp;rel=require.html%23%2528form._%2528%2528lib._racket%252Fprivate%252Fbase..rkt%2529._provide%2529%2529&amp;version=6.1" class="RktStxLink Sq" data-pltdoc="x">provide</a></span><span class="hspace">&nbsp;</span><span class="RktSym">pie</span><span class="RktPn">)</span></td></tr><tr><td><span class="hspace">&nbsp;&nbsp;</span><span class="hspace">&nbsp;&nbsp;</span><span class="RktPn">(</span><span class="RktSym"><a href="http://download.racket-lang.org/docs/6.1/html/local-redirect/index.html?doc=reference&amp;rel=define.html%23%2528form._%2528%2528lib._racket%252Fprivate%252Fbase..rkt%2529._define%2529%2529&amp;version=6.1" class="RktStxLink Sq" data-pltdoc="x">define</a></span><span class="hspace">&nbsp;</span><span class="RktSym">pie</span><span class="hspace">&nbsp;</span><span class="RktVal">3</span><span class="RktPn">)</span><span class="RktPn">)</span></td></tr></table></td></tr><tr><td><table cellspacing="0" cellpadding="0"><tr><td></td></tr></table></td></tr><tr><td><span class="stt">&gt; </span><span class="RktPn">(</span><span class="RktSym"><a href="http://download.racket-lang.org/docs/6.1/html/local-redirect/index.html?doc=reference&amp;rel=eval.html%23%2528def._%2528%2528quote._%7E23%7E25kernel%2529._compile-enforce-module-constants%2529%2529&amp;version=6.1" class="RktValLink Sq" data-pltdoc="x">compile-enforce-module-constants</a></span><span class="hspace">&nbsp;</span><span class="RktVal">#t</span><span class="RktPn">)</span></td></tr><tr><td><table cellspacing="0" cellpadding="0"><tr><td></td></tr></table></td></tr><tr><td><span class="stt">&gt; </span><span class="RktSym">pie</span></td></tr><tr><td><p><span class="RktRes">3</span></p></td></tr></table></blockquote><div class="navsetbottom"><span class="navleft"><form class="searchform"><input class="searchbox" style="color: #888;" type="text" value="...search manuals..." title="Enter a search string to search the manuals" onkeypress="return DoSearchKey(event, this, &quot;6.1&quot;, &quot;../&quot;);" onfocus="this.style.color=&quot;black&quot;; this.style.textAlign=&quot;left&quot;; if (this.value == &quot;...search manuals...&quot;) this.value=&quot;&quot;;" onblur="if (this.value.match(/^ *$/)) { this.style.color=&quot;#888&quot;; this.style.textAlign=&quot;center&quot;; this.value=&quot;...search manuals...&quot;; }"/></form>&nbsp;&nbsp;<a href="../index.html" title="up to the documentation top" data-pltdoc="x" onclick="return GotoPLTRoot(&quot;6.1&quot;);">top</a></span><span class="navright">&nbsp;&nbsp;<a href="module-provide.html" title="backward to &quot;6.5 Exports: provide&quot;" data-pltdoc="x">&larr; prev</a>&nbsp;&nbsp;<a href="modules.html" title="up to &quot;6 Modules&quot;" data-pltdoc="x">up</a>&nbsp;&nbsp;<a href="contracts.html" title="forward to &quot;7 Contracts&quot;" data-pltdoc="x">next &rarr;</a></span>&nbsp;</div></div></div><div id="contextindicator">&nbsp;</div></body></html>