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<html><head><meta http-equiv="content-type" content="text/html; charset=utf-8"/><title>4.1 Booleans and Equality</title><link rel="stylesheet" type="text/css" href="../scribble.css" title="default"/><link rel="stylesheet" type="text/css" href="extras.css" title="default"/><link rel="stylesheet" type="text/css" href="../racket.css" title="default"/><link rel="stylesheet" type="text/css" href="../manual-style.css" title="default"/><link rel="stylesheet" type="text/css" href="../manual-racket.css" title="default"/><link rel="stylesheet" type="text/css" href="../manual-racket.css" title="default"/><link rel="stylesheet" type="text/css" href="../doc-site.css" title="default"/><script type="text/javascript" src="../scribble-common.js"></script><script type="text/javascript" src="../manual-racket.js"></script><script type="text/javascript" src="../manual-racket.js"></script><script type="text/javascript" src="../doc-site.js"></script><script type="text/javascript" src="../local-redirect/local-redirect.js"></script><script type="text/javascript" src="../local-redirect/local-user-redirect.js"></script><!--[if IE 6]><style type="text/css">.SIEHidden { overflow: hidden; }</style><![endif]--></head><body id="doc-racket-lang-org"><div class="tocset"><div class="tocview"><div class="tocviewlist tocviewlisttopspace"><div class="tocviewtitle"><table cellspacing="0" cellpadding="0"><tr><td style="width: 1em;"><a href="javascript:void(0);" title="Expand/Collapse" class="tocviewtoggle" onclick="TocviewToggle(this,"tocview_0");">►</a></td><td></td><td><a href="index.html" class="tocviewlink" data-pltdoc="x"><span style="font-weight: bold">The Racket Reference</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 </td><td><a href="model.html" class="tocviewlink" data-pltdoc="x">Language Model</a></td></tr><tr><td align="right">2 </td><td><a href="notation.html" class="tocviewlink" data-pltdoc="x">Notation for Documentation</a></td></tr><tr><td align="right">3 </td><td><a href="syntax.html" class="tocviewlink" data-pltdoc="x">Syntactic Forms</a></td></tr><tr><td align="right">4 </td><td><a href="data.html" class="tocviewselflink" data-pltdoc="x">Datatypes</a></td></tr><tr><td align="right">5 </td><td><a href="structures.html" class="tocviewlink" data-pltdoc="x">Structures</a></td></tr><tr><td align="right">6 </td><td><a href="mzlib_class.html" class="tocviewlink" data-pltdoc="x">Classes and Objects</a></td></tr><tr><td align="right">7 </td><td><a href="mzlib_unit.html" class="tocviewlink" data-pltdoc="x">Units</a></td></tr><tr><td align="right">8 </td><td><a href="contracts.html" class="tocviewlink" data-pltdoc="x">Contracts</a></td></tr><tr><td align="right">9 </td><td><a href="match.html" class="tocviewlink" data-pltdoc="x">Pattern Matching</a></td></tr><tr><td align="right">10 </td><td><a href="control.html" class="tocviewlink" data-pltdoc="x">Control Flow</a></td></tr><tr><td align="right">11 </td><td><a href="concurrency.html" class="tocviewlink" data-pltdoc="x">Concurrency and Parallelism</a></td></tr><tr><td align="right">12 </td><td><a href="Macros.html" class="tocviewlink" data-pltdoc="x">Macros</a></td></tr><tr><td align="right">13 </td><td><a href="input-and-output.html" class="tocviewlink" data-pltdoc="x">Input and Output</a></td></tr><tr><td align="right">14 </td><td><a href="security.html" class="tocviewlink" data-pltdoc="x">Reflection and Security</a></td></tr><tr><td align="right">15 </td><td><a href="os.html" class="tocviewlink" data-pltdoc="x">Operating System</a></td></tr><tr><td align="right">16 </td><td><a href="memory.html" class="tocviewlink" data-pltdoc="x">Memory Management</a></td></tr><tr><td align="right">17 </td><td><a href="unsafe.html" class="tocviewlink" data-pltdoc="x">Unsafe Operations</a></td></tr><tr><td align="right">18 </td><td><a href="running.html" class="tocviewlink" data-pltdoc="x">Running Racket</a></td></tr><tr><td align="right"></td><td><a href="doc-bibliography.html" class="tocviewlink" data-pltdoc="x">Bibliography</a></td></tr><tr><td align="right"></td><td><a href="doc-index.html" class="tocviewlink" data-pltdoc="x">Index</a></td></tr></table></div></div><div class="tocviewlist"><table cellspacing="0" cellpadding="0"><tr><td style="width: 1em;"><a href="javascript:void(0);" title="Expand/Collapse" class="tocviewtoggle" onclick="TocviewToggle(this,"tocview_1");">▼</a></td><td>4 </td><td><a href="data.html" class="tocviewlink" data-pltdoc="x">Datatypes</a></td></tr></table><div class="tocviewsublist" style="display: block;" id="tocview_1"><table cellspacing="0" cellpadding="0"><tr><td align="right">4.1 </td><td><a href="" class="tocviewselflink" data-pltdoc="x">Booleans and Equality</a></td></tr><tr><td align="right">4.2 </td><td><a href="numbers.html" class="tocviewlink" data-pltdoc="x">Numbers</a></td></tr><tr><td align="right">4.3 </td><td><a href="strings.html" class="tocviewlink" data-pltdoc="x">Strings</a></td></tr><tr><td align="right">4.4 </td><td><a href="bytestrings.html" class="tocviewlink" data-pltdoc="x">Byte Strings</a></td></tr><tr><td align="right">4.5 </td><td><a href="characters.html" class="tocviewlink" data-pltdoc="x">Characters</a></td></tr><tr><td align="right">4.6 </td><td><a href="symbols.html" class="tocviewlink" data-pltdoc="x">Symbols</a></td></tr><tr><td align="right">4.7 </td><td><a href="regexp.html" class="tocviewlink" data-pltdoc="x">Regular Expressions</a></td></tr><tr><td align="right">4.8 </td><td><a href="keywords.html" class="tocviewlink" data-pltdoc="x">Keywords</a></td></tr><tr><td align="right">4.9 </td><td><a href="pairs.html" class="tocviewlink" data-pltdoc="x">Pairs and Lists</a></td></tr><tr><td align="right">4.10 </td><td><a href="mpairs.html" class="tocviewlink" data-pltdoc="x">Mutable Pairs and Lists</a></td></tr><tr><td align="right">4.11 </td><td><a href="vectors.html" class="tocviewlink" data-pltdoc="x">Vectors</a></td></tr><tr><td align="right">4.12 </td><td><a href="boxes.html" class="tocviewlink" data-pltdoc="x">Boxes</a></td></tr><tr><td align="right">4.13 </td><td><a href="hashtables.html" class="tocviewlink" data-pltdoc="x">Hash Tables</a></td></tr><tr><td align="right">4.14 </td><td><a href="sequences_streams.html" class="tocviewlink" data-pltdoc="x">Sequences and Streams</a></td></tr><tr><td align="right">4.15 </td><td><a href="dicts.html" class="tocviewlink" data-pltdoc="x">Dictionaries</a></td></tr><tr><td align="right">4.16 </td><td><a href="sets.html" class="tocviewlink" data-pltdoc="x">Sets</a></td></tr><tr><td align="right">4.17 </td><td><a href="procedures.html" class="tocviewlink" data-pltdoc="x">Procedures</a></td></tr><tr><td align="right">4.18 </td><td><a href="void.html" class="tocviewlink" data-pltdoc="x">Void</a></td></tr><tr><td align="right">4.19 </td><td><a href="undefined.html" class="tocviewlink" data-pltdoc="x">Undefined</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>4.1 </td><td><a href="" class="tocviewselflink" data-pltdoc="x">Booleans and Equality</a></td></tr></table><div class="tocviewsublistbottom" style="display: none;" id="tocview_2"><table cellspacing="0" cellpadding="0"><tr><td align="right">4.1.1 </td><td><a href="#%28part._.Boolean_.Aliases%29" class="tocviewlink" data-pltdoc="x">Boolean Aliases</a></td></tr></table></div></div></div><div class="tocsub"><div class="tocsubtitle">On this page:</div><table class="tocsublist" cellspacing="0"><tr><td><a href="#%28def._%28%28quote._~23~25kernel%29._boolean~3f%29%29" class="tocsubnonseclink" data-pltdoc="x"><span class="RktSym"><span class="RktValLink">boolean?</span></span></a></td></tr><tr><td><a href="#%28def._%28%28quote._~23~25kernel%29._not%29%29" class="tocsubnonseclink" data-pltdoc="x"><span class="RktSym"><span class="RktValLink">not</span></span></a></td></tr><tr><td><a href="#%28def._%28%28quote._~23~25kernel%29._equal~3f%29%29" class="tocsubnonseclink" data-pltdoc="x"><span class="RktSym"><span class="RktValLink">equal?</span></span></a></td></tr><tr><td><a href="#%28def._%28%28quote._~23~25kernel%29._eqv~3f%29%29" class="tocsubnonseclink" data-pltdoc="x"><span class="RktSym"><span class="RktValLink">eqv?</span></span></a></td></tr><tr><td><a href="#%28def._%28%28quote._~23~25kernel%29._eq~3f%29%29" class="tocsubnonseclink" data-pltdoc="x"><span class="RktSym"><span class="RktValLink">eq?</span></span></a></td></tr><tr><td><a href="#%28def._%28%28quote._~23~25kernel%29._equal~3f%2Frecur%29%29" class="tocsubnonseclink" data-pltdoc="x"><span class="RktSym"><span class="RktValLink">equal?/<span class="mywbr"> </span>recur</span></span></a></td></tr><tr><td><a href="#%28def._%28%28quote._~23~25kernel%29._immutable~3f%29%29" class="tocsubnonseclink" data-pltdoc="x"><span class="RktSym"><span class="RktValLink">immutable?</span></span></a></td></tr><tr><td><a href="#%28def._%28%28lib._racket%2Fprivate%2Fbase..rkt%29._gen~3aequal%2Bhash%29%29" class="tocsubnonseclink" data-pltdoc="x"><span class="RktSym"><span class="RktValLink">gen:<span class="mywbr"> </span>equal+<span class="mywbr"> </span>hash</span></span></a></td></tr><tr><td><a href="#%28def._%28%28quote._~23~25kernel%29._prop~3aequal%2Bhash%29%29" class="tocsubnonseclink" data-pltdoc="x"><span class="RktSym"><span class="RktValLink">prop:<span class="mywbr"> </span>equal+<span class="mywbr"> </span>hash</span></span></a></td></tr><tr><td><span class="tocsublinknumber">4.1.1<tt> </tt></span><a href="#%28part._.Boolean_.Aliases%29" class="tocsubseclink" data-pltdoc="x">Boolean Aliases</a></td></tr><tr><td><a href="#%28def._%28%28lib._racket%2Fbool..rkt%29._true%29%29" class="tocsubnonseclink" data-pltdoc="x"><span class="RktSym"><span class="RktValLink">true</span></span></a></td></tr><tr><td><a href="#%28def._%28%28lib._racket%2Fbool..rkt%29._false%29%29" class="tocsubnonseclink" data-pltdoc="x"><span class="RktSym"><span class="RktValLink">false</span></span></a></td></tr><tr><td><a href="#%28def._%28%28lib._racket%2Fbool..rkt%29._symbol~3d~3f%29%29" class="tocsubnonseclink" data-pltdoc="x"><span class="RktSym"><span class="RktValLink">symbol=?</span></span></a></td></tr><tr><td><a href="#%28def._%28%28lib._racket%2Fbool..rkt%29._boolean~3d~3f%29%29" class="tocsubnonseclink" data-pltdoc="x"><span class="RktSym"><span class="RktValLink">boolean=?</span></span></a></td></tr><tr><td><a href="#%28def._%28%28lib._racket%2Fbool..rkt%29._false~3f%29%29" class="tocsubnonseclink" data-pltdoc="x"><span class="RktSym"><span class="RktValLink">false?</span></span></a></td></tr><tr><td><a href="#%28form._%28%28lib._racket%2Fbool..rkt%29._nand%29%29" class="tocsubnonseclink" data-pltdoc="x"><span class="RktSym"><span class="RktStxLink">nand</span></span></a></td></tr><tr><td><a href="#%28form._%28%28lib._racket%2Fbool..rkt%29._nor%29%29" class="tocsubnonseclink" data-pltdoc="x"><span class="RktSym"><span class="RktStxLink">nor</span></span></a></td></tr><tr><td><a href="#%28form._%28%28lib._racket%2Fbool..rkt%29._implies%29%29" class="tocsubnonseclink" data-pltdoc="x"><span class="RktSym"><span class="RktStxLink">implies</span></span></a></td></tr><tr><td><a href="#%28def._%28%28lib._racket%2Fbool..rkt%29._xor%29%29" class="tocsubnonseclink" data-pltdoc="x"><span class="RktSym"><span class="RktValLink">xor</span></span></a></td></tr></table></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, "6.1", "../");" onfocus="this.style.color="black"; this.style.textAlign="left"; if (this.value == "...search manuals...") this.value="";" onblur="if (this.value.match(/^ *$/)) { this.style.color="#888"; this.style.textAlign="center"; this.value="...search manuals..."; }"/></form> <a href="../index.html" title="up to the documentation top" data-pltdoc="x" onclick="return GotoPLTRoot("6.1");">top</a></span><span class="navright"> <a href="data.html" title="backward to "4 Datatypes"" data-pltdoc="x">← prev</a> <a href="data.html" title="up to "4 Datatypes"" data-pltdoc="x">up</a> <a href="numbers.html" title="forward to "4.2 Numbers"" data-pltdoc="x">next →</a></span> </div><h4 x-source-module="(lib "scribblings/reference/reference.scrbl")" x-part-tag=""booleans"">4.1<tt> </tt><a name="(part._booleans)"></a>Booleans and Equality</h4><p>True and false <a name="(tech._boolean)"></a><span style="font-style: italic">booleans</span> are represented by the values
<span class="RktVal">#t</span> and <span class="RktVal">#f</span>, respectively, though operations that
depend on a boolean value typically treat anything other than
<span class="RktVal">#f</span> as true. The <span class="RktVal">#t</span> value is always <span class="RktSym"><a href="#%28def._%28%28quote._~23~25kernel%29._eq~3f%29%29" class="RktValLink" data-pltdoc="x">eq?</a></span> to
itself, and <span class="RktVal">#f</span> is always <span class="RktSym"><a href="#%28def._%28%28quote._~23~25kernel%29._eq~3f%29%29" class="RktValLink" data-pltdoc="x">eq?</a></span> to itself.</p><p>See <a href="reader.html#%28part._parse-boolean%29" data-pltdoc="x">Reading Booleans</a>
for information on <span class="RktSym"><a href="Reading.html#%28def._%28%28quote._~23~25kernel%29._read%29%29" class="RktValLink" data-pltdoc="x">read</a></span>ing
booleans and <a href="printing.html#%28part._print-booleans%29" data-pltdoc="x">Printing Booleans</a>
for information on <span class="RktSym"><a href="Writing.html#%28def._%28%28quote._~23~25kernel%29._print%29%29" class="RktValLink" data-pltdoc="x">print</a></span>ing booleans.</p><p>See also <span class="RktSym"><a href="if.html#%28form._%28%28lib._racket%2Fprivate%2Fletstx-scheme..rkt%29._and%29%29" class="RktStxLink" data-pltdoc="x">and</a></span>, <span class="RktSym"><a href="if.html#%28form._%28%28lib._racket%2Fprivate%2Fletstx-scheme..rkt%29._or%29%29" class="RktStxLink" data-pltdoc="x">or</a></span>, <span class="RktSym"><a href="pairs.html#%28def._%28%28lib._racket%2Fprivate%2Fmap..rkt%29._andmap%29%29" class="RktValLink" data-pltdoc="x">andmap</a></span>, and <span class="RktSym"><a href="pairs.html#%28def._%28%28lib._racket%2Fprivate%2Fmap..rkt%29._ormap%29%29" class="RktValLink" data-pltdoc="x">ormap</a></span>.</p><p><div class="SIntrapara"><blockquote class="SVInsetFlow"><table cellspacing="0" cellpadding="0" class="boxed RBoxed"><tr><td><blockquote class="SubFlow"><div class="RBackgroundLabel SIEHidden"><div class="RBackgroundLabelInner"><p>procedure</p></div></div><p class="RForeground"><span class="RktPn">(</span><a name="(def._((quote._~23~25kernel)._boolean~3f))"></a><span title="Provided from: racket/base, racket | Package: base"><span class="RktSym"><a href="#%28def._%28%28quote._~23~25kernel%29._boolean~3f%29%29" class="RktValDef RktValLink" data-pltdoc="x">boolean?</a></span></span><span class="hspace"> </span><span class="RktVar">v</span><span class="RktPn">)</span><span class="hspace"> </span>→<span class="hspace"> </span><span class="RktSym"><a href="#%28def._%28%28quote._~23~25kernel%29._boolean~3f%29%29" class="RktValLink" data-pltdoc="x">boolean?</a></span></p></blockquote></td></tr><tr><td><span class="hspace"> </span><span class="RktVar">v</span><span class="hspace"> </span>:<span class="hspace"> </span><span class="RktSym"><a href="data-structure-contracts.html#%28def._%28%28lib._racket%2Fcontract%2Fprivate%2Fmisc..rkt%29._any%2Fc%29%29" class="RktValLink" data-pltdoc="x">any/c</a></span></td></tr></table></blockquote></div><div class="SIntrapara">Returns <span class="RktVal">#t</span> if <span class="RktVar">v</span> is <span class="RktVal">#t</span> or <span class="RktVal">#f</span>,
<span class="RktVal">#f</span> otherwise.</div></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><span class="stt">> </span><span class="RktPn">(</span><span class="RktSym"><a href="#%28def._%28%28quote._~23~25kernel%29._boolean~3f%29%29" class="RktValLink" data-pltdoc="x">boolean?</a></span><span class="hspace"> </span><span class="RktVal">#f</span><span class="RktPn">)</span></td></tr><tr><td><p><span class="RktRes">#t</span></p></td></tr><tr><td><span class="stt">> </span><span class="RktPn">(</span><span class="RktSym"><a href="#%28def._%28%28quote._~23~25kernel%29._boolean~3f%29%29" class="RktValLink" data-pltdoc="x">boolean?</a></span><span class="hspace"> </span><span class="RktVal">#t</span><span class="RktPn">)</span></td></tr><tr><td><p><span class="RktRes">#t</span></p></td></tr><tr><td><span class="stt">> </span><span class="RktPn">(</span><span class="RktSym"><a href="#%28def._%28%28quote._~23~25kernel%29._boolean~3f%29%29" class="RktValLink" data-pltdoc="x">boolean?</a></span><span class="hspace"> </span><span class="RktVal">'</span><span class="RktVal">true</span><span class="RktPn">)</span></td></tr><tr><td><p><span class="RktRes">#f</span></p></td></tr></table></blockquote></td></tr></table></p><p><div class="SIntrapara"><blockquote class="SVInsetFlow"><table cellspacing="0" cellpadding="0" class="boxed RBoxed"><tr><td><blockquote class="SubFlow"><div class="RBackgroundLabel SIEHidden"><div class="RBackgroundLabelInner"><p>procedure</p></div></div><p class="RForeground"><span class="RktPn">(</span><a name="(def._((quote._~23~25kernel)._not))"></a><span title="Provided from: racket/base, racket | Package: base"><span class="RktSym"><a href="#%28def._%28%28quote._~23~25kernel%29._not%29%29" class="RktValDef RktValLink" data-pltdoc="x">not</a></span></span><span class="hspace"> </span><span class="RktVar">v</span><span class="RktPn">)</span><span class="hspace"> </span>→<span class="hspace"> </span><span class="RktSym"><a href="#%28def._%28%28quote._~23~25kernel%29._boolean~3f%29%29" class="RktValLink" data-pltdoc="x">boolean?</a></span></p></blockquote></td></tr><tr><td><span class="hspace"> </span><span class="RktVar">v</span><span class="hspace"> </span>:<span class="hspace"> </span><span class="RktSym"><a href="data-structure-contracts.html#%28def._%28%28lib._racket%2Fcontract%2Fprivate%2Fmisc..rkt%29._any%2Fc%29%29" class="RktValLink" data-pltdoc="x">any/c</a></span></td></tr></table></blockquote></div><div class="SIntrapara">Returns <span class="RktVal">#t</span> if <span class="RktVar">v</span> is <span class="RktVal">#f</span>, <span class="RktVal">#f</span> otherwise.</div></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><span class="stt">> </span><span class="RktPn">(</span><span class="RktSym"><a href="#%28def._%28%28quote._~23~25kernel%29._not%29%29" class="RktValLink" data-pltdoc="x">not</a></span><span class="hspace"> </span><span class="RktVal">#f</span><span class="RktPn">)</span></td></tr><tr><td><p><span class="RktRes">#t</span></p></td></tr><tr><td><span class="stt">> </span><span class="RktPn">(</span><span class="RktSym"><a href="#%28def._%28%28quote._~23~25kernel%29._not%29%29" class="RktValLink" data-pltdoc="x">not</a></span><span class="hspace"> </span><span class="RktVal">#t</span><span class="RktPn">)</span></td></tr><tr><td><p><span class="RktRes">#f</span></p></td></tr><tr><td><span class="stt">> </span><span class="RktPn">(</span><span class="RktSym"><a href="#%28def._%28%28quote._~23~25kernel%29._not%29%29" class="RktValLink" data-pltdoc="x">not</a></span><span class="hspace"> </span><span class="RktVal">'</span><span class="RktVal">we-have-no-bananas</span><span class="RktPn">)</span></td></tr><tr><td><p><span class="RktRes">#f</span></p></td></tr></table></blockquote></td></tr></table></p><p><div class="SIntrapara"><blockquote class="SVInsetFlow"><table cellspacing="0" cellpadding="0" class="boxed RBoxed"><tr><td><blockquote class="SubFlow"><div class="RBackgroundLabel SIEHidden"><div class="RBackgroundLabelInner"><p>procedure</p></div></div><p class="RForeground"><span class="RktPn">(</span><a name="(def._((quote._~23~25kernel)._equal~3f))"></a><span title="Provided from: racket/base, racket | Package: base"><span class="RktSym"><a href="#%28def._%28%28quote._~23~25kernel%29._equal~3f%29%29" class="RktValDef RktValLink" data-pltdoc="x">equal?</a></span></span><span class="hspace"> </span><span class="RktVar">v1</span><span class="hspace"> </span><span class="RktVar">v2</span><span class="RktPn">)</span><span class="hspace"> </span>→<span class="hspace"> </span><span class="RktSym"><a href="#%28def._%28%28quote._~23~25kernel%29._boolean~3f%29%29" class="RktValLink" data-pltdoc="x">boolean?</a></span></p></blockquote></td></tr><tr><td><span class="hspace"> </span><span class="RktVar">v1</span><span class="hspace"> </span>:<span class="hspace"> </span><span class="RktSym"><a href="data-structure-contracts.html#%28def._%28%28lib._racket%2Fcontract%2Fprivate%2Fmisc..rkt%29._any%2Fc%29%29" class="RktValLink" data-pltdoc="x">any/c</a></span></td></tr><tr><td><span class="hspace"> </span><span class="RktVar">v2</span><span class="hspace"> </span>:<span class="hspace"> </span><span class="RktSym"><a href="data-structure-contracts.html#%28def._%28%28lib._racket%2Fcontract%2Fprivate%2Fmisc..rkt%29._any%2Fc%29%29" class="RktValLink" data-pltdoc="x">any/c</a></span></td></tr></table></blockquote></div><div class="SIntrapara">Two values are <span class="RktSym"><a href="#%28def._%28%28quote._~23~25kernel%29._equal~3f%29%29" class="RktValLink" data-pltdoc="x">equal?</a></span> if and only if they are <span class="RktSym"><a href="#%28def._%28%28quote._~23~25kernel%29._eqv~3f%29%29" class="RktValLink" data-pltdoc="x">eqv?</a></span>,
unless otherwise specified for a particular datatype.</div></p><p>Datatypes with further specification of <span class="RktSym"><a href="#%28def._%28%28quote._~23~25kernel%29._equal~3f%29%29" class="RktValLink" data-pltdoc="x">equal?</a></span> include
strings, byte strings, pairs, mutable pairs, vectors, boxes, hash
tables, and inspectable structures. In the last six cases, equality
is recursively defined; if both <span class="RktVar">v1</span> and <span class="RktVar">v2</span> contain
reference cycles, they are equal when the infinite unfoldings of the
values would be equal. See also <span class="RktSym"><a href="#%28def._%28%28lib._racket%2Fprivate%2Fbase..rkt%29._gen~3aequal%2Bhash%29%29" class="RktValLink" data-pltdoc="x">gen:equal+hash</a></span> and <span class="RktSym"><a href="chaperones.html#%28def._%28%28quote._~23~25kernel%29._prop~3aimpersonator-of%29%29" class="RktValLink" data-pltdoc="x">prop:impersonator-of</a></span>.</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><span class="stt">> </span><span class="RktPn">(</span><span class="RktSym"><a href="#%28def._%28%28quote._~23~25kernel%29._equal~3f%29%29" class="RktValLink" data-pltdoc="x">equal?</a></span><span class="hspace"> </span><span class="RktVal">'</span><span class="RktVal">yes</span><span class="hspace"> </span><span class="RktVal">'</span><span class="RktVal">yes</span><span class="RktPn">)</span></td></tr><tr><td><p><span class="RktRes">#t</span></p></td></tr><tr><td><span class="stt">> </span><span class="RktPn">(</span><span class="RktSym"><a href="#%28def._%28%28quote._~23~25kernel%29._equal~3f%29%29" class="RktValLink" data-pltdoc="x">equal?</a></span><span class="hspace"> </span><span class="RktVal">'</span><span class="RktVal">yes</span><span class="hspace"> </span><span class="RktVal">'</span><span class="RktVal">no</span><span class="RktPn">)</span></td></tr><tr><td><p><span class="RktRes">#f</span></p></td></tr><tr><td><span class="stt">> </span><span class="RktPn">(</span><span class="RktSym"><a href="#%28def._%28%28quote._~23~25kernel%29._equal~3f%29%29" class="RktValLink" data-pltdoc="x">equal?</a></span><span class="hspace"> </span><span class="RktPn">(</span><span class="RktSym"><a href="generic-numbers.html#%28def._%28%28quote._~23~25kernel%29._expt%29%29" class="RktValLink" data-pltdoc="x">expt</a></span><span class="hspace"> </span><span class="RktVal">2</span><span class="hspace"> </span><span class="RktVal">100</span><span class="RktPn">)</span><span class="hspace"> </span><span class="RktPn">(</span><span class="RktSym"><a href="generic-numbers.html#%28def._%28%28quote._~23~25kernel%29._expt%29%29" class="RktValLink" data-pltdoc="x">expt</a></span><span class="hspace"> </span><span class="RktVal">2</span><span class="hspace"> </span><span class="RktVal">100</span><span class="RktPn">)</span><span class="RktPn">)</span></td></tr><tr><td><p><span class="RktRes">#t</span></p></td></tr><tr><td><span class="stt">> </span><span class="RktPn">(</span><span class="RktSym"><a href="#%28def._%28%28quote._~23~25kernel%29._equal~3f%29%29" class="RktValLink" data-pltdoc="x">equal?</a></span><span class="hspace"> </span><span class="RktVal">2</span><span class="hspace"> </span><span class="RktVal">2.0</span><span class="RktPn">)</span></td></tr><tr><td><p><span class="RktRes">#f</span></p></td></tr><tr><td><span class="stt">> </span><span class="RktPn">(</span><span class="RktSym"><a href="#%28def._%28%28quote._~23~25kernel%29._equal~3f%29%29" class="RktValLink" data-pltdoc="x">equal?</a></span><span class="hspace"> </span><span class="RktPn">(</span><span class="RktSym"><a href="strings.html#%28def._%28%28quote._~23~25kernel%29._make-string%29%29" class="RktValLink" data-pltdoc="x">make-string</a></span><span class="hspace"> </span><span class="RktVal">3</span><span class="hspace"> </span><span class="RktVal">#\z</span><span class="RktPn">)</span><span class="hspace"> </span><span class="RktPn">(</span><span class="RktSym"><a href="strings.html#%28def._%28%28quote._~23~25kernel%29._make-string%29%29" class="RktValLink" data-pltdoc="x">make-string</a></span><span class="hspace"> </span><span class="RktVal">3</span><span class="hspace"> </span><span class="RktVal">#\z</span><span class="RktPn">)</span><span class="RktPn">)</span></td></tr><tr><td><p><span class="RktRes">#t</span></p></td></tr></table></blockquote></td></tr></table></p><p><div class="SIntrapara"><blockquote class="SVInsetFlow"><table cellspacing="0" cellpadding="0" class="boxed RBoxed"><tr><td><blockquote class="SubFlow"><div class="RBackgroundLabel SIEHidden"><div class="RBackgroundLabelInner"><p>procedure</p></div></div><p class="RForeground"><span class="RktPn">(</span><a name="(def._((quote._~23~25kernel)._eqv~3f))"></a><span title="Provided from: racket/base, racket | Package: base"><span class="RktSym"><a href="#%28def._%28%28quote._~23~25kernel%29._eqv~3f%29%29" class="RktValDef RktValLink" data-pltdoc="x">eqv?</a></span></span><span class="hspace"> </span><span class="RktVar">v1</span><span class="hspace"> </span><span class="RktVar">v2</span><span class="RktPn">)</span><span class="hspace"> </span>→<span class="hspace"> </span><span class="RktSym"><a href="#%28def._%28%28quote._~23~25kernel%29._boolean~3f%29%29" class="RktValLink" data-pltdoc="x">boolean?</a></span></p></blockquote></td></tr><tr><td><span class="hspace"> </span><span class="RktVar">v1</span><span class="hspace"> </span>:<span class="hspace"> </span><span class="RktSym"><a href="data-structure-contracts.html#%28def._%28%28lib._racket%2Fcontract%2Fprivate%2Fmisc..rkt%29._any%2Fc%29%29" class="RktValLink" data-pltdoc="x">any/c</a></span></td></tr><tr><td><span class="hspace"> </span><span class="RktVar">v2</span><span class="hspace"> </span>:<span class="hspace"> </span><span class="RktSym"><a href="data-structure-contracts.html#%28def._%28%28lib._racket%2Fcontract%2Fprivate%2Fmisc..rkt%29._any%2Fc%29%29" class="RktValLink" data-pltdoc="x">any/c</a></span></td></tr></table></blockquote></div><div class="SIntrapara">Two values are <span class="RktSym"><a href="#%28def._%28%28quote._~23~25kernel%29._eqv~3f%29%29" class="RktValLink" data-pltdoc="x">eqv?</a></span> if and only if they are <span class="RktSym"><a href="#%28def._%28%28quote._~23~25kernel%29._eq~3f%29%29" class="RktValLink" data-pltdoc="x">eq?</a></span>,
unless otherwise specified for a particular datatype.</div></p><p>The <a href="numbers.html#%28tech._number%29" class="techoutside" data-pltdoc="x"><span class="techinside">number</span></a> and <a href="characters.html#%28tech._character%29" class="techoutside" data-pltdoc="x"><span class="techinside">character</span></a> datatypes are the only ones for which
<span class="RktSym"><a href="#%28def._%28%28quote._~23~25kernel%29._eqv~3f%29%29" class="RktValLink" data-pltdoc="x">eqv?</a></span> differs from <span class="RktSym"><a href="#%28def._%28%28quote._~23~25kernel%29._eq~3f%29%29" class="RktValLink" data-pltdoc="x">eq?</a></span>.</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><span class="stt">> </span><span class="RktPn">(</span><span class="RktSym"><a href="#%28def._%28%28quote._~23~25kernel%29._eqv~3f%29%29" class="RktValLink" data-pltdoc="x">eqv?</a></span><span class="hspace"> </span><span class="RktVal">'</span><span class="RktVal">yes</span><span class="hspace"> </span><span class="RktVal">'</span><span class="RktVal">yes</span><span class="RktPn">)</span></td></tr><tr><td><p><span class="RktRes">#t</span></p></td></tr><tr><td><span class="stt">> </span><span class="RktPn">(</span><span class="RktSym"><a href="#%28def._%28%28quote._~23~25kernel%29._eqv~3f%29%29" class="RktValLink" data-pltdoc="x">eqv?</a></span><span class="hspace"> </span><span class="RktVal">'</span><span class="RktVal">yes</span><span class="hspace"> </span><span class="RktVal">'</span><span class="RktVal">no</span><span class="RktPn">)</span></td></tr><tr><td><p><span class="RktRes">#f</span></p></td></tr><tr><td><span class="stt">> </span><span class="RktPn">(</span><span class="RktSym"><a href="#%28def._%28%28quote._~23~25kernel%29._eqv~3f%29%29" class="RktValLink" data-pltdoc="x">eqv?</a></span><span class="hspace"> </span><span class="RktPn">(</span><span class="RktSym"><a href="generic-numbers.html#%28def._%28%28quote._~23~25kernel%29._expt%29%29" class="RktValLink" data-pltdoc="x">expt</a></span><span class="hspace"> </span><span class="RktVal">2</span><span class="hspace"> </span><span class="RktVal">100</span><span class="RktPn">)</span><span class="hspace"> </span><span class="RktPn">(</span><span class="RktSym"><a href="generic-numbers.html#%28def._%28%28quote._~23~25kernel%29._expt%29%29" class="RktValLink" data-pltdoc="x">expt</a></span><span class="hspace"> </span><span class="RktVal">2</span><span class="hspace"> </span><span class="RktVal">100</span><span class="RktPn">)</span><span class="RktPn">)</span></td></tr><tr><td><p><span class="RktRes">#t</span></p></td></tr><tr><td><span class="stt">> </span><span class="RktPn">(</span><span class="RktSym"><a href="#%28def._%28%28quote._~23~25kernel%29._eqv~3f%29%29" class="RktValLink" data-pltdoc="x">eqv?</a></span><span class="hspace"> </span><span class="RktVal">2</span><span class="hspace"> </span><span class="RktVal">2.0</span><span class="RktPn">)</span></td></tr><tr><td><p><span class="RktRes">#f</span></p></td></tr><tr><td><span class="stt">> </span><span class="RktPn">(</span><span class="RktSym"><a href="#%28def._%28%28quote._~23~25kernel%29._eqv~3f%29%29" class="RktValLink" data-pltdoc="x">eqv?</a></span><span class="hspace"> </span><span class="RktPn">(</span><span class="RktSym"><a href="characters.html#%28def._%28%28quote._~23~25kernel%29._integer-~3echar%29%29" class="RktValLink" data-pltdoc="x">integer->char</a></span><span class="hspace"> </span><span class="RktVal">955</span><span class="RktPn">)</span><span class="hspace"> </span><span class="RktPn">(</span><span class="RktSym"><a href="characters.html#%28def._%28%28quote._~23~25kernel%29._integer-~3echar%29%29" class="RktValLink" data-pltdoc="x">integer->char</a></span><span class="hspace"> </span><span class="RktVal">955</span><span class="RktPn">)</span><span class="RktPn">)</span></td></tr><tr><td><p><span class="RktRes">#t</span></p></td></tr><tr><td><span class="stt">> </span><span class="RktPn">(</span><span class="RktSym"><a href="#%28def._%28%28quote._~23~25kernel%29._eqv~3f%29%29" class="RktValLink" data-pltdoc="x">eqv?</a></span><span class="hspace"> </span><span class="RktPn">(</span><span class="RktSym"><a href="strings.html#%28def._%28%28quote._~23~25kernel%29._make-string%29%29" class="RktValLink" data-pltdoc="x">make-string</a></span><span class="hspace"> </span><span class="RktVal">3</span><span class="hspace"> </span><span class="RktVal">#\z</span><span class="RktPn">)</span><span class="hspace"> </span><span class="RktPn">(</span><span class="RktSym"><a href="strings.html#%28def._%28%28quote._~23~25kernel%29._make-string%29%29" class="RktValLink" data-pltdoc="x">make-string</a></span><span class="hspace"> </span><span class="RktVal">3</span><span class="hspace"> </span><span class="RktVal">#\z</span><span class="RktPn">)</span><span class="RktPn">)</span></td></tr><tr><td><p><span class="RktRes">#f</span></p></td></tr></table></blockquote></td></tr></table></p><p><div class="SIntrapara"><blockquote class="SVInsetFlow"><table cellspacing="0" cellpadding="0" class="boxed RBoxed"><tr><td><blockquote class="SubFlow"><div class="RBackgroundLabel SIEHidden"><div class="RBackgroundLabelInner"><p>procedure</p></div></div><p class="RForeground"><span class="RktPn">(</span><a name="(def._((quote._~23~25kernel)._eq~3f))"></a><span title="Provided from: racket/base, racket | Package: base"><span class="RktSym"><a href="#%28def._%28%28quote._~23~25kernel%29._eq~3f%29%29" class="RktValDef RktValLink" data-pltdoc="x">eq?</a></span></span><span class="hspace"> </span><span class="RktVar">v1</span><span class="hspace"> </span><span class="RktVar">v2</span><span class="RktPn">)</span><span class="hspace"> </span>→<span class="hspace"> </span><span class="RktSym"><a href="#%28def._%28%28quote._~23~25kernel%29._boolean~3f%29%29" class="RktValLink" data-pltdoc="x">boolean?</a></span></p></blockquote></td></tr><tr><td><span class="hspace"> </span><span class="RktVar">v1</span><span class="hspace"> </span>:<span class="hspace"> </span><span class="RktSym"><a href="data-structure-contracts.html#%28def._%28%28lib._racket%2Fcontract%2Fprivate%2Fmisc..rkt%29._any%2Fc%29%29" class="RktValLink" data-pltdoc="x">any/c</a></span></td></tr><tr><td><span class="hspace"> </span><span class="RktVar">v2</span><span class="hspace"> </span>:<span class="hspace"> </span><span class="RktSym"><a href="data-structure-contracts.html#%28def._%28%28lib._racket%2Fcontract%2Fprivate%2Fmisc..rkt%29._any%2Fc%29%29" class="RktValLink" data-pltdoc="x">any/c</a></span></td></tr></table></blockquote></div><div class="SIntrapara">Return <span class="RktVal">#t</span> if <span class="RktVar">v1</span> and <span class="RktVar">v2</span> refer to the same
object, <span class="RktVal">#f</span> otherwise. See also <a href="eval-model.html#%28part._model-eq%29" data-pltdoc="x">Object Identity and Comparisons</a>.</div></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><span class="stt">> </span><span class="RktPn">(</span><span class="RktSym"><a href="#%28def._%28%28quote._~23~25kernel%29._eq~3f%29%29" class="RktValLink" data-pltdoc="x">eq?</a></span><span class="hspace"> </span><span class="RktVal">'</span><span class="RktVal">yes</span><span class="hspace"> </span><span class="RktVal">'</span><span class="RktVal">yes</span><span class="RktPn">)</span></td></tr><tr><td><p><span class="RktRes">#t</span></p></td></tr><tr><td><span class="stt">> </span><span class="RktPn">(</span><span class="RktSym"><a href="#%28def._%28%28quote._~23~25kernel%29._eq~3f%29%29" class="RktValLink" data-pltdoc="x">eq?</a></span><span class="hspace"> </span><span class="RktVal">'</span><span class="RktVal">yes</span><span class="hspace"> </span><span class="RktVal">'</span><span class="RktVal">no</span><span class="RktPn">)</span></td></tr><tr><td><p><span class="RktRes">#f</span></p></td></tr><tr><td><span class="stt">> </span><span class="RktPn">(</span><span class="RktSym"><a href="let.html#%28form._%28%28lib._racket%2Fprivate%2Fletstx-scheme..rkt%29._let%29%29" class="RktStxLink" data-pltdoc="x">let</a></span><span class="hspace"> </span><span class="RktPn">(</span><span class="RktPn">[</span><span class="RktSym">v</span><span class="hspace"> </span><span class="RktPn">(</span><span class="RktSym"><a href="mpairs.html#%28def._%28%28quote._~23~25kernel%29._mcons%29%29" class="RktValLink" data-pltdoc="x">mcons</a></span><span class="hspace"> </span><span class="RktVal">1</span><span class="hspace"> </span><span class="RktVal">2</span><span class="RktPn">)</span><span class="RktPn">]</span><span class="RktPn">)</span><span class="hspace"> </span><span class="RktPn">(</span><span class="RktSym"><a href="#%28def._%28%28quote._~23~25kernel%29._eq~3f%29%29" class="RktValLink" data-pltdoc="x">eq?</a></span><span class="hspace"> </span><span class="RktSym">v</span><span class="hspace"> </span><span class="RktSym">v</span><span class="RktPn">)</span><span class="RktPn">)</span></td></tr><tr><td><p><span class="RktRes">#t</span></p></td></tr><tr><td><span class="stt">> </span><span class="RktPn">(</span><span class="RktSym"><a href="#%28def._%28%28quote._~23~25kernel%29._eq~3f%29%29" class="RktValLink" data-pltdoc="x">eq?</a></span><span class="hspace"> </span><span class="RktPn">(</span><span class="RktSym"><a href="mpairs.html#%28def._%28%28quote._~23~25kernel%29._mcons%29%29" class="RktValLink" data-pltdoc="x">mcons</a></span><span class="hspace"> </span><span class="RktVal">1</span><span class="hspace"> </span><span class="RktVal">2</span><span class="RktPn">)</span><span class="hspace"> </span><span class="RktPn">(</span><span class="RktSym"><a href="mpairs.html#%28def._%28%28quote._~23~25kernel%29._mcons%29%29" class="RktValLink" data-pltdoc="x">mcons</a></span><span class="hspace"> </span><span class="RktVal">1</span><span class="hspace"> </span><span class="RktVal">2</span><span class="RktPn">)</span><span class="RktPn">)</span></td></tr><tr><td><p><span class="RktRes">#f</span></p></td></tr><tr><td><span class="stt">> </span><span class="RktPn">(</span><span class="RktSym"><a href="#%28def._%28%28quote._~23~25kernel%29._eq~3f%29%29" class="RktValLink" data-pltdoc="x">eq?</a></span><span class="hspace"> </span><span class="RktPn">(</span><span class="RktSym"><a href="strings.html#%28def._%28%28quote._~23~25kernel%29._make-string%29%29" class="RktValLink" data-pltdoc="x">make-string</a></span><span class="hspace"> </span><span class="RktVal">3</span><span class="hspace"> </span><span class="RktVal">#\z</span><span class="RktPn">)</span><span class="hspace"> </span><span class="RktPn">(</span><span class="RktSym"><a href="strings.html#%28def._%28%28quote._~23~25kernel%29._make-string%29%29" class="RktValLink" data-pltdoc="x">make-string</a></span><span class="hspace"> </span><span class="RktVal">3</span><span class="hspace"> </span><span class="RktVal">#\z</span><span class="RktPn">)</span><span class="RktPn">)</span></td></tr><tr><td><p><span class="RktRes">#f</span></p></td></tr></table></blockquote></td></tr></table></p><p><div class="SIntrapara"><blockquote class="SVInsetFlow"><table cellspacing="0" cellpadding="0" class="boxed RBoxed"><tr><td><blockquote class="SubFlow"><div class="RBackgroundLabel SIEHidden"><div class="RBackgroundLabelInner"><p>procedure</p></div></div><p class="RForeground"><span class="RktPn">(</span><a name="(def._((quote._~23~25kernel)._equal~3f/recur))"></a><span title="Provided from: racket/base, racket | Package: base"><span class="RktSym"><a href="#%28def._%28%28quote._~23~25kernel%29._equal~3f%2Frecur%29%29" class="RktValDef RktValLink" data-pltdoc="x">equal?/recur</a></span></span><span class="hspace"> </span><span class="RktVar">v1</span><span class="hspace"> </span><span class="RktVar">v2</span><span class="hspace"> </span><span class="RktVar">recur-proc</span><span class="RktPn">)</span><span class="hspace"> </span>→<span class="hspace"> </span><span class="RktSym"><a href="#%28def._%28%28quote._~23~25kernel%29._boolean~3f%29%29" class="RktValLink" data-pltdoc="x">boolean?</a></span></p></blockquote></td></tr><tr><td><span class="hspace"> </span><span class="RktVar">v1</span><span class="hspace"> </span>:<span class="hspace"> </span><span class="RktSym"><a href="data-structure-contracts.html#%28def._%28%28lib._racket%2Fcontract%2Fprivate%2Fmisc..rkt%29._any%2Fc%29%29" class="RktValLink" data-pltdoc="x">any/c</a></span></td></tr><tr><td><span class="hspace"> </span><span class="RktVar">v2</span><span class="hspace"> </span>:<span class="hspace"> </span><span class="RktSym"><a href="data-structure-contracts.html#%28def._%28%28lib._racket%2Fcontract%2Fprivate%2Fmisc..rkt%29._any%2Fc%29%29" class="RktValLink" data-pltdoc="x">any/c</a></span></td></tr><tr><td><span class="hspace"> </span><span class="RktVar">recur-proc</span><span class="hspace"> </span>:<span class="hspace"> </span><span class="RktPn">(</span><span class="RktSym"><a href="data-structure-contracts.html#%28def._%28%28lib._racket%2Fcontract%2Fprivate%2Fmisc..rkt%29._any%2Fc%29%29" class="RktValLink" data-pltdoc="x">any/c</a></span><span class="hspace"> </span><span class="RktSym"><a href="data-structure-contracts.html#%28def._%28%28lib._racket%2Fcontract%2Fprivate%2Fmisc..rkt%29._any%2Fc%29%29" class="RktValLink" data-pltdoc="x">any/c</a></span><span class="hspace"> </span><span class="RktSym"><a href="function-contracts.html#%28form._%28%28lib._racket%2Fcontract%2Fbase..rkt%29._-~3e%29%29" class="RktStxLink" data-pltdoc="x"><span class="nobreak">-></span></a></span><span class="hspace"> </span><span class="RktSym"><a href="data-structure-contracts.html#%28def._%28%28lib._racket%2Fcontract%2Fprivate%2Fmisc..rkt%29._any%2Fc%29%29" class="RktValLink" data-pltdoc="x">any/c</a></span><span class="RktPn">)</span></td></tr></table></blockquote></div><div class="SIntrapara">Like <span class="RktSym"><a href="#%28def._%28%28quote._~23~25kernel%29._equal~3f%29%29" class="RktValLink" data-pltdoc="x">equal?</a></span>, but using <span class="RktVar">recur-proc</span> for recursive
comparisons (which means that reference cycles are not handled
automatically). Non-<span class="RktVal">#f</span> results from <span class="RktVar">recur-proc</span> are
converted to <span class="RktVal">#t</span> before being returned by
<span class="RktSym"><a href="#%28def._%28%28quote._~23~25kernel%29._equal~3f%2Frecur%29%29" class="RktValLink" data-pltdoc="x">equal?/recur</a></span>.</div></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><span class="stt">> </span><span class="RktPn">(</span><span class="RktSym"><a href="#%28def._%28%28quote._~23~25kernel%29._equal~3f%2Frecur%29%29" class="RktValLink" data-pltdoc="x">equal?/recur</a></span><span class="hspace"> </span><span class="RktVal">1</span><span class="hspace"> </span><span class="RktVal">1</span><span class="hspace"> </span><span class="RktPn">(</span><span class="RktSym"><a href="lambda.html#%28form._%28%28lib._racket%2Fprivate%2Fbase..rkt%29._lambda%29%29" class="RktStxLink" data-pltdoc="x">lambda</a></span><span class="hspace"> </span><span class="RktPn">(</span><span class="RktSym">a</span><span class="hspace"> </span><span class="RktSym">b</span><span class="RktPn">)</span><span class="hspace"> </span><span class="RktVal">#f</span><span class="RktPn">)</span><span class="RktPn">)</span></td></tr><tr><td><p><span class="RktRes">#t</span></p></td></tr><tr><td><span class="stt">> </span><span class="RktPn">(</span><span class="RktSym"><a href="#%28def._%28%28quote._~23~25kernel%29._equal~3f%2Frecur%29%29" class="RktValLink" data-pltdoc="x">equal?/recur</a></span><span class="hspace"> </span><span class="RktVal">'</span><span class="RktVal">(</span><span class="RktVal">1</span><span class="RktVal">)</span><span class="hspace"> </span><span class="RktVal">'</span><span class="RktVal">(</span><span class="RktVal">1</span><span class="RktVal">)</span><span class="hspace"> </span><span class="RktPn">(</span><span class="RktSym"><a href="lambda.html#%28form._%28%28lib._racket%2Fprivate%2Fbase..rkt%29._lambda%29%29" class="RktStxLink" data-pltdoc="x">lambda</a></span><span class="hspace"> </span><span class="RktPn">(</span><span class="RktSym">a</span><span class="hspace"> </span><span class="RktSym">b</span><span class="RktPn">)</span><span class="hspace"> </span><span class="RktVal">#f</span><span class="RktPn">)</span><span class="RktPn">)</span></td></tr><tr><td><p><span class="RktRes">#f</span></p></td></tr><tr><td><table cellspacing="0" cellpadding="0" class="RktBlk"><tr><td><span class="stt">> </span><span class="RktPn">(</span><span class="RktSym"><a href="#%28def._%28%28quote._~23~25kernel%29._equal~3f%2Frecur%29%29" class="RktValLink" data-pltdoc="x">equal?/recur</a></span><span class="hspace"> </span><span class="RktVal">'</span><span class="RktVal">#</span><span class="RktVal">(</span><span class="RktVal">1</span><span class="hspace"> </span><span class="RktVal">1</span><span class="hspace"> </span><span class="RktVal">1</span><span class="RktVal">)</span><span class="hspace"> </span><span class="RktVal">'</span><span class="RktVal">#</span><span class="RktVal">(</span><span class="RktVal">1</span><span class="hspace"> </span><span class="RktVal">1.2</span><span class="hspace"> </span><span class="RktVal">3/4</span><span class="RktVal">)</span></td></tr><tr><td><span class="hspace"> </span><span class="hspace"> </span><span class="RktPn">(</span><span class="RktSym"><a href="lambda.html#%28form._%28%28lib._racket%2Fprivate%2Fbase..rkt%29._lambda%29%29" class="RktStxLink" data-pltdoc="x">lambda</a></span><span class="hspace"> </span><span class="RktPn">(</span><span class="RktSym">a</span><span class="hspace"> </span><span class="RktSym">b</span><span class="RktPn">)</span><span class="hspace"> </span><span class="RktPn">(</span><span class="RktSym"><a href="generic-numbers.html#%28def._%28%28quote._~23~25kernel%29._~3c~3d%29%29" class="RktValLink" data-pltdoc="x"><=</a></span><span class="hspace"> </span><span class="RktPn">(</span><span class="RktSym"><a href="generic-numbers.html#%28def._%28%28quote._~23~25kernel%29._abs%29%29" class="RktValLink" data-pltdoc="x">abs</a></span><span class="hspace"> </span><span class="RktPn">(</span><span class="RktSym"><a href="generic-numbers.html#%28def._%28%28quote._~23~25kernel%29._-%29%29" class="RktValLink" data-pltdoc="x"><span class="nobreak">-</span></a></span><span class="hspace"> </span><span class="RktSym">a</span><span class="hspace"> </span><span class="RktSym">b</span><span class="RktPn">)</span><span class="RktPn">)</span><span class="hspace"> </span><span class="RktVal">0.25</span><span class="RktPn">)</span><span class="RktPn">)</span><span class="RktPn">)</span></td></tr></table></td></tr><tr><td><p><span class="RktRes">#t</span></p></td></tr></table></blockquote></td></tr></table></p><p><div class="SIntrapara"><blockquote class="SVInsetFlow"><table cellspacing="0" cellpadding="0" class="boxed RBoxed"><tr><td><blockquote class="SubFlow"><div class="RBackgroundLabel SIEHidden"><div class="RBackgroundLabelInner"><p>procedure</p></div></div><p class="RForeground"><span class="RktPn">(</span><a name="(def._((quote._~23~25kernel)._immutable~3f))"></a><span title="Provided from: racket/base, racket | Package: base"><span class="RktSym"><a href="#%28def._%28%28quote._~23~25kernel%29._immutable~3f%29%29" class="RktValDef RktValLink" data-pltdoc="x">immutable?</a></span></span><span class="hspace"> </span><span class="RktVar">v</span><span class="RktPn">)</span><span class="hspace"> </span>→<span class="hspace"> </span><span class="RktSym"><a href="#%28def._%28%28quote._~23~25kernel%29._boolean~3f%29%29" class="RktValLink" data-pltdoc="x">boolean?</a></span></p></blockquote></td></tr><tr><td><span class="hspace"> </span><span class="RktVar">v</span><span class="hspace"> </span>:<span class="hspace"> </span><span class="RktSym"><a href="data-structure-contracts.html#%28def._%28%28lib._racket%2Fcontract%2Fprivate%2Fmisc..rkt%29._any%2Fc%29%29" class="RktValLink" data-pltdoc="x">any/c</a></span></td></tr></table></blockquote></div><div class="SIntrapara">Returns <span class="RktVal">#t</span> if <span class="RktVar">v</span> is an immutable <a href="strings.html#%28tech._string%29" class="techoutside" data-pltdoc="x"><span class="techinside">string</span></a>,
<a href="bytestrings.html#%28tech._byte._string%29" class="techoutside" data-pltdoc="x"><span class="techinside">byte string</span></a>, <a href="vectors.html#%28tech._vector%29" class="techoutside" data-pltdoc="x"><span class="techinside">vector</span></a>, <a href="hashtables.html#%28tech._hash._table%29" class="techoutside" data-pltdoc="x"><span class="techinside">hash table</span></a>, or box,
<span class="RktVal">#f</span> otherwise.</div></p><p>Note that <span class="RktSym"><a href="#%28def._%28%28quote._~23~25kernel%29._immutable~3f%29%29" class="RktValLink" data-pltdoc="x">immutable?</a></span> is not a general predicate for
immutability (despite its name). It works only for a handful of
datatypes for which a single predicate—<wbr></wbr><span class="RktSym"><a href="strings.html#%28def._%28%28quote._~23~25kernel%29._string~3f%29%29" class="RktValLink" data-pltdoc="x">string?</a></span>,
<span class="RktSym"><a href="vectors.html#%28def._%28%28quote._~23~25kernel%29._vector~3f%29%29" class="RktValLink" data-pltdoc="x">vector?</a></span>, etc<span class="Sendabbrev">.</span>—<wbr></wbr>recognizes both mutable and immutable variants
of the datatype. In particular, <span class="RktSym"><a href="#%28def._%28%28quote._~23~25kernel%29._immutable~3f%29%29" class="RktValLink" data-pltdoc="x">immutable?</a></span> produces
<span class="RktVal">#f</span> for a <a href="pairs.html#%28tech._pair%29" class="techoutside" data-pltdoc="x"><span class="techinside">pair</span></a>, even though pairs are immutable, since
<span class="RktSym"><a href="pairs.html#%28def._%28%28quote._~23~25kernel%29._pair~3f%29%29" class="RktValLink" data-pltdoc="x">pair?</a></span> implies immutability.</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><span class="stt">> </span><span class="RktPn">(</span><span class="RktSym"><a href="#%28def._%28%28quote._~23~25kernel%29._immutable~3f%29%29" class="RktValLink" data-pltdoc="x">immutable?</a></span><span class="hspace"> </span><span class="RktVal">'</span><span class="RktVal">hello</span><span class="RktPn">)</span></td></tr><tr><td><p><span class="RktRes">#f</span></p></td></tr><tr><td><span class="stt">> </span><span class="RktPn">(</span><span class="RktSym"><a href="#%28def._%28%28quote._~23~25kernel%29._immutable~3f%29%29" class="RktValLink" data-pltdoc="x">immutable?</a></span><span class="hspace"> </span><span class="RktVal">"a string"</span><span class="RktPn">)</span></td></tr><tr><td><p><span class="RktRes">#t</span></p></td></tr><tr><td><span class="stt">> </span><span class="RktPn">(</span><span class="RktSym"><a href="#%28def._%28%28quote._~23~25kernel%29._immutable~3f%29%29" class="RktValLink" data-pltdoc="x">immutable?</a></span><span class="hspace"> </span><span class="RktPn">(</span><span class="RktSym"><a href="boxes.html#%28def._%28%28quote._~23~25kernel%29._box%29%29" class="RktValLink" data-pltdoc="x">box</a></span><span class="hspace"> </span><span class="RktVal">5</span><span class="RktPn">)</span><span class="RktPn">)</span></td></tr><tr><td><p><span class="RktRes">#f</span></p></td></tr><tr><td><span class="stt">> </span><span class="RktPn">(</span><span class="RktSym"><a href="#%28def._%28%28quote._~23~25kernel%29._immutable~3f%29%29" class="RktValLink" data-pltdoc="x">immutable?</a></span><span class="hspace"> </span><span class="RktVal">#</span><span class="RktVal">(</span><span class="RktVal">0</span><span class="hspace"> </span><span class="RktVal">1</span><span class="hspace"> </span><span class="RktVal">2</span><span class="hspace"> </span><span class="RktVal">3</span><span class="RktVal">)</span><span class="RktPn">)</span></td></tr><tr><td><p><span class="RktRes">#t</span></p></td></tr><tr><td><span class="stt">> </span><span class="RktPn">(</span><span class="RktSym"><a href="#%28def._%28%28quote._~23~25kernel%29._immutable~3f%29%29" class="RktValLink" data-pltdoc="x">immutable?</a></span><span class="hspace"> </span><span class="RktPn">(</span><span class="RktSym"><a href="hashtables.html#%28def._%28%28quote._~23~25kernel%29._make-hash%29%29" class="RktValLink" data-pltdoc="x">make-hash</a></span><span class="RktPn">)</span><span class="RktPn">)</span></td></tr><tr><td><p><span class="RktRes">#f</span></p></td></tr><tr><td><span class="stt">> </span><span class="RktPn">(</span><span class="RktSym"><a href="#%28def._%28%28quote._~23~25kernel%29._immutable~3f%29%29" class="RktValLink" data-pltdoc="x">immutable?</a></span><span class="hspace"> </span><span class="RktPn">(</span><span class="RktSym"><a href="hashtables.html#%28def._%28%28quote._~23~25kernel%29._make-immutable-hash%29%29" class="RktValLink" data-pltdoc="x">make-immutable-hash</a></span><span class="hspace"> </span><span class="RktVal">'</span><span class="RktVal">(</span><span class="RktVal">[</span><span class="RktVal">a</span><span class="hspace"> </span><span class="RktVal">b</span><span class="RktVal">]</span><span class="RktVal">)</span><span class="RktPn">)</span><span class="RktPn">)</span></td></tr><tr><td><p><span class="RktRes">#t</span></p></td></tr></table></blockquote></td></tr></table></p><p><div class="SIntrapara"><blockquote class="SVInsetFlow"><table cellspacing="0" cellpadding="0" class="boxed RBoxed"><tr><td><blockquote class="SubFlow"><div class="RBackgroundLabel SIEHidden"><div class="RBackgroundLabelInner"><p>value</p></div></div><p class="RForeground"><a name="(def._((lib._racket/private/base..rkt)._gen~3aequal+hash))"></a><span title="Provided from: racket/base, racket | Package: base"><span class="RktSym"><a href="#%28def._%28%28lib._racket%2Fprivate%2Fbase..rkt%29._gen~3aequal%2Bhash%29%29" class="RktValDef RktValLink" data-pltdoc="x">gen:equal+hash</a></span></span><span class="hspace"> </span>:<span class="hspace"> </span><span class="RktSym"><a href="data-structure-contracts.html#%28def._%28%28lib._racket%2Fcontract%2Fprivate%2Fmisc..rkt%29._any%2Fc%29%29" class="RktValLink" data-pltdoc="x">any/c</a></span></p></blockquote></td></tr></table></blockquote></div><div class="SIntrapara">A <a href="struct-generics.html#%28tech._generic._interface%29" class="techoutside" data-pltdoc="x"><span class="techinside">generic interface</span></a> (see <a href="struct-generics.html" data-pltdoc="x">Generic Interfaces</a>) that
supplies an equality predicate and hashing functions for a structure
type. The following methods must be implemented:</div></p><ul><li><p><span class="RktVar">equal-proc</span><span class="stt"> </span><span class="RktSym">:</span><span class="stt"> </span><span class="RktPn">(</span><span class="RktSym"><a href="function-contracts.html#%28form._%28%28lib._racket%2Fcontract%2Fbase..rkt%29._-~3e%29%29" class="RktStxLink" data-pltdoc="x"><span class="nobreak">-></span></a></span><span class="stt"> </span><span class="RktSym"><a href="data-structure-contracts.html#%28def._%28%28lib._racket%2Fcontract%2Fprivate%2Fmisc..rkt%29._any%2Fc%29%29" class="RktValLink" data-pltdoc="x">any/c</a></span><span class="stt"> </span><span class="RktSym"><a href="data-structure-contracts.html#%28def._%28%28lib._racket%2Fcontract%2Fprivate%2Fmisc..rkt%29._any%2Fc%29%29" class="RktValLink" data-pltdoc="x">any/c</a></span><span class="stt"> </span><span class="RktPn">(</span><span class="RktSym"><a href="function-contracts.html#%28form._%28%28lib._racket%2Fcontract%2Fbase..rkt%29._-~3e%29%29" class="RktStxLink" data-pltdoc="x"><span class="nobreak">-></span></a></span><span class="stt"> </span><span class="RktSym"><a href="data-structure-contracts.html#%28def._%28%28lib._racket%2Fcontract%2Fprivate%2Fmisc..rkt%29._any%2Fc%29%29" class="RktValLink" data-pltdoc="x">any/c</a></span><span class="stt"> </span><span class="RktSym"><a href="data-structure-contracts.html#%28def._%28%28lib._racket%2Fcontract%2Fprivate%2Fmisc..rkt%29._any%2Fc%29%29" class="RktValLink" data-pltdoc="x">any/c</a></span><span class="stt"> </span><span class="RktSym"><a href="#%28def._%28%28quote._~23~25kernel%29._boolean~3f%29%29" class="RktValLink" data-pltdoc="x">boolean?</a></span><span class="RktPn">)</span><span class="stt"> </span><span class="RktSym"><a href="data-structure-contracts.html#%28def._%28%28lib._racket%2Fcontract%2Fprivate%2Fmisc..rkt%29._any%2Fc%29%29" class="RktValLink" data-pltdoc="x">any/c</a></span><span class="RktPn">)</span> —<wbr></wbr> tests whether the first two
arguments are equal, where both values are instances of the
structure type to which the generic interface is associated
(or a subtype of the structure type).</p><p>The third argument is an <span class="RktSym"><a href="#%28def._%28%28quote._~23~25kernel%29._equal~3f%29%29" class="RktValLink" data-pltdoc="x">equal?</a></span> predicate to use for
recursive equality checks; use the given predicate instead of
<span class="RktSym"><a href="#%28def._%28%28quote._~23~25kernel%29._equal~3f%29%29" class="RktValLink" data-pltdoc="x">equal?</a></span> to ensure that data cycles are handled
properly and to work with <span class="RktSym"><a href="#%28def._%28%28quote._~23~25kernel%29._equal~3f%2Frecur%29%29" class="RktValLink" data-pltdoc="x">equal?/recur</a></span> (but beware
that an arbitrary function can be provided to
<span class="RktSym"><a href="#%28def._%28%28quote._~23~25kernel%29._equal~3f%2Frecur%29%29" class="RktValLink" data-pltdoc="x">equal?/recur</a></span> for recursive checks, which means that
arguments provided to the predicate might be exposed to
arbitrary code).</p><p>The <span class="RktVar">equal-proc</span> is called for a pair of structures
only when they are not <span class="RktSym"><a href="#%28def._%28%28quote._~23~25kernel%29._eq~3f%29%29" class="RktValLink" data-pltdoc="x">eq?</a></span>, and only when they both
have a <span class="RktSym"><a href="#%28def._%28%28lib._racket%2Fprivate%2Fbase..rkt%29._gen~3aequal%2Bhash%29%29" class="RktValLink" data-pltdoc="x">gen:equal+hash</a></span> value inherited from the same
structure type. With this strategy, the order in which
<span class="RktSym"><a href="#%28def._%28%28quote._~23~25kernel%29._equal~3f%29%29" class="RktValLink" data-pltdoc="x">equal?</a></span> receives two structures does not matter. It
also means that, by default, a structure sub-type inherits the
equality predicate of its parent, if any.</p></li><li><p><span class="RktVar">hash-proc</span><span class="stt"> </span><span class="RktSym">:</span><span class="stt"> </span><span class="RktPn">(</span><span class="RktSym"><a href="function-contracts.html#%28form._%28%28lib._racket%2Fcontract%2Fbase..rkt%29._-~3e%29%29" class="RktStxLink" data-pltdoc="x"><span class="nobreak">-></span></a></span><span class="stt"> </span><span class="RktSym"><a href="data-structure-contracts.html#%28def._%28%28lib._racket%2Fcontract%2Fprivate%2Fmisc..rkt%29._any%2Fc%29%29" class="RktValLink" data-pltdoc="x">any/c</a></span><span class="stt"> </span><span class="RktPn">(</span><span class="RktSym"><a href="function-contracts.html#%28form._%28%28lib._racket%2Fcontract%2Fbase..rkt%29._-~3e%29%29" class="RktStxLink" data-pltdoc="x"><span class="nobreak">-></span></a></span><span class="stt"> </span><span class="RktSym"><a href="data-structure-contracts.html#%28def._%28%28lib._racket%2Fcontract%2Fprivate%2Fmisc..rkt%29._any%2Fc%29%29" class="RktValLink" data-pltdoc="x">any/c</a></span><span class="stt"> </span><span class="RktSym"><a href="number-types.html#%28def._%28%28quote._~23~25kernel%29._exact-integer~3f%29%29" class="RktValLink" data-pltdoc="x">exact-integer?</a></span><span class="RktPn">)</span><span class="stt"> </span><span class="RktSym"><a href="number-types.html#%28def._%28%28quote._~23~25kernel%29._exact-integer~3f%29%29" class="RktValLink" data-pltdoc="x">exact-integer?</a></span><span class="RktPn">)</span> —<wbr></wbr> computes a hash code for the given
structure, like <span class="RktSym"><a href="hashtables.html#%28def._%28%28quote._~23~25kernel%29._equal-hash-code%29%29" class="RktValLink" data-pltdoc="x">equal-hash-code</a></span>. The first argument is
an instance of the structure type (or one of its subtypes) to
which the generic interface is associated.</p><p>The second argument is an <span class="RktSym"><a href="hashtables.html#%28def._%28%28quote._~23~25kernel%29._equal-hash-code%29%29" class="RktValLink" data-pltdoc="x">equal-hash-code</a></span>-like
procedure to use for recursive hash-code computation; use the
given procedure instead of <span class="RktSym"><a href="hashtables.html#%28def._%28%28quote._~23~25kernel%29._equal-hash-code%29%29" class="RktValLink" data-pltdoc="x">equal-hash-code</a></span> to ensure
that data cycles are handled properly.</p></li><li><p><span class="RktVar">hash2-proc</span><span class="stt"> </span><span class="RktSym">:</span><span class="stt"> </span><span class="RktPn">(</span><span class="RktSym"><a href="function-contracts.html#%28form._%28%28lib._racket%2Fcontract%2Fbase..rkt%29._-~3e%29%29" class="RktStxLink" data-pltdoc="x"><span class="nobreak">-></span></a></span><span class="stt"> </span><span class="RktSym"><a href="data-structure-contracts.html#%28def._%28%28lib._racket%2Fcontract%2Fprivate%2Fmisc..rkt%29._any%2Fc%29%29" class="RktValLink" data-pltdoc="x">any/c</a></span><span class="stt"> </span><span class="RktPn">(</span><span class="RktSym"><a href="function-contracts.html#%28form._%28%28lib._racket%2Fcontract%2Fbase..rkt%29._-~3e%29%29" class="RktStxLink" data-pltdoc="x"><span class="nobreak">-></span></a></span><span class="stt"> </span><span class="RktSym"><a href="data-structure-contracts.html#%28def._%28%28lib._racket%2Fcontract%2Fprivate%2Fmisc..rkt%29._any%2Fc%29%29" class="RktValLink" data-pltdoc="x">any/c</a></span><span class="stt"> </span><span class="RktSym"><a href="number-types.html#%28def._%28%28quote._~23~25kernel%29._exact-integer~3f%29%29" class="RktValLink" data-pltdoc="x">exact-integer?</a></span><span class="RktPn">)</span><span class="stt"> </span><span class="RktSym"><a href="number-types.html#%28def._%28%28quote._~23~25kernel%29._exact-integer~3f%29%29" class="RktValLink" data-pltdoc="x">exact-integer?</a></span><span class="RktPn">)</span> —<wbr></wbr> computes a secondary hash code for the
given structure. This procedure is like <span class="RktVar">hash-proc</span>,
but analogous to <span class="RktSym"><a href="hashtables.html#%28def._%28%28quote._~23~25kernel%29._equal-secondary-hash-code%29%29" class="RktValLink" data-pltdoc="x">equal-secondary-hash-code</a></span>.</p></li></ul><p>Take care to ensure that <span class="RktVar">hash-proc</span> and <span class="RktVar">hash2-proc</span>
are consistent with <span class="RktVar">equal-proc</span>. Specifically,
<span class="RktVar">hash-proc</span> and <span class="RktVar">hash2-proc</span> should produce the same
value for any two structures for which <span class="RktVar">equal-proc</span> produces a
true value.</p><p>When a structure type has no <span class="RktSym"><a href="#%28def._%28%28lib._racket%2Fprivate%2Fbase..rkt%29._gen~3aequal%2Bhash%29%29" class="RktValLink" data-pltdoc="x">gen:equal+hash</a></span> implementation, then
transparent structures (i.e., structures with an <a href="inspectors.html#%28tech._inspector%29" class="techoutside" data-pltdoc="x"><span class="techinside">inspector</span></a> that
is controlled by the current <a href="inspectors.html#%28tech._inspector%29" class="techoutside" data-pltdoc="x"><span class="techinside">inspector</span></a>) are <span class="RktSym"><a href="#%28def._%28%28quote._~23~25kernel%29._equal~3f%29%29" class="RktValLink" data-pltdoc="x">equal?</a></span>
when they are instances of the same structure type (not counting
sub-types), and when they have <span class="RktSym"><a href="#%28def._%28%28quote._~23~25kernel%29._equal~3f%29%29" class="RktValLink" data-pltdoc="x">equal?</a></span> field values. For
transparent structures, <span class="RktSym"><a href="hashtables.html#%28def._%28%28quote._~23~25kernel%29._equal-hash-code%29%29" class="RktValLink" data-pltdoc="x">equal-hash-code</a></span> and
<span class="RktSym"><a href="hashtables.html#%28def._%28%28quote._~23~25kernel%29._equal-secondary-hash-code%29%29" class="RktValLink" data-pltdoc="x">equal-secondary-hash-code</a></span> derive hash code using the field
values. For opaque structure types, <span class="RktSym"><a href="#%28def._%28%28quote._~23~25kernel%29._equal~3f%29%29" class="RktValLink" data-pltdoc="x">equal?</a></span> is the same as
<span class="RktSym"><a href="#%28def._%28%28quote._~23~25kernel%29._eq~3f%29%29" class="RktValLink" data-pltdoc="x">eq?</a></span>, and <span class="RktSym"><a href="hashtables.html#%28def._%28%28quote._~23~25kernel%29._equal-hash-code%29%29" class="RktValLink" data-pltdoc="x">equal-hash-code</a></span> and
<span class="RktSym"><a href="hashtables.html#%28def._%28%28quote._~23~25kernel%29._equal-secondary-hash-code%29%29" class="RktValLink" data-pltdoc="x">equal-secondary-hash-code</a></span> results are based only on
<span class="RktSym"><a href="hashtables.html#%28def._%28%28quote._~23~25kernel%29._eq-hash-code%29%29" class="RktValLink" data-pltdoc="x">eq-hash-code</a></span>. If a structure has a <span class="RktSym"><a href="chaperones.html#%28def._%28%28quote._~23~25kernel%29._prop~3aimpersonator-of%29%29" class="RktValLink" data-pltdoc="x">prop:impersonator-of</a></span>
property, then the <span class="RktSym"><a href="chaperones.html#%28def._%28%28quote._~23~25kernel%29._prop~3aimpersonator-of%29%29" class="RktValLink" data-pltdoc="x">prop:impersonator-of</a></span> property takes precedence over
<span class="RktSym"><a href="#%28def._%28%28lib._racket%2Fprivate%2Fbase..rkt%29._gen~3aequal%2Bhash%29%29" class="RktValLink" data-pltdoc="x">gen:equal+hash</a></span> if the property value’s procedure returns a
non-<span class="RktVal">#f</span> value when applied to the structure.</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">> </span><span class="RktPn">(</span><span class="RktSym"><a href="define.html#%28form._%28%28lib._racket%2Fprivate%2Fbase..rkt%29._define%29%29" class="RktStxLink" data-pltdoc="x">define</a></span><span class="hspace"> </span><span class="RktPn">(</span><span class="RktSym">farm=?</span><span class="hspace"> </span><span class="RktSym">farm1</span><span class="hspace"> </span><span class="RktSym">farm2</span><span class="hspace"> </span><span class="RktSym">recursive-equal?</span><span class="RktPn">)</span></td></tr><tr><td><span class="hspace"> </span><span class="hspace"> </span><span class="RktPn">(</span><span class="RktSym"><a href="if.html#%28form._%28%28lib._racket%2Fprivate%2Fletstx-scheme..rkt%29._and%29%29" class="RktStxLink" data-pltdoc="x">and</a></span><span class="hspace"> </span><span class="RktPn">(</span><span class="RktSym"><a href="generic-numbers.html#%28def._%28%28quote._~23~25kernel%29._~3d%29%29" class="RktValLink" data-pltdoc="x">=</a></span><span class="hspace"> </span><span class="RktPn">(</span><span class="RktSym">farm-apples</span><span class="hspace"> </span><span class="RktSym">farm1</span><span class="RktPn">)</span></td></tr><tr><td><span class="hspace"> </span><span class="hspace"> </span><span class="RktPn">(</span><span class="RktSym">farm-apples</span><span class="hspace"> </span><span class="RktSym">farm2</span><span class="RktPn">)</span><span class="RktPn">)</span></td></tr><tr><td><span class="hspace"> </span><span class="hspace"> </span><span class="RktPn">(</span><span class="RktSym"><a href="generic-numbers.html#%28def._%28%28quote._~23~25kernel%29._~3d%29%29" class="RktValLink" data-pltdoc="x">=</a></span><span class="hspace"> </span><span class="RktPn">(</span><span class="RktSym">farm-oranges</span><span class="hspace"> </span><span class="RktSym">farm1</span><span class="RktPn">)</span></td></tr><tr><td><span class="hspace"> </span><span class="hspace"> </span><span class="RktPn">(</span><span class="RktSym">farm-oranges</span><span class="hspace"> </span><span class="RktSym">farm2</span><span class="RktPn">)</span><span class="RktPn">)</span></td></tr><tr><td><span class="hspace"> </span><span class="hspace"> </span><span class="RktPn">(</span><span class="RktSym"><a href="generic-numbers.html#%28def._%28%28quote._~23~25kernel%29._~3d%29%29" class="RktValLink" data-pltdoc="x">=</a></span><span class="hspace"> </span><span class="RktPn">(</span><span class="RktSym">farm-sheep</span><span class="hspace"> </span><span class="RktSym">farm1</span><span class="RktPn">)</span></td></tr><tr><td><span class="hspace"> </span><span class="hspace"> </span><span class="RktPn">(</span><span class="RktSym">farm-sheep</span><span class="hspace"> </span><span class="RktSym">farm2</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><table cellspacing="0" cellpadding="0" class="RktBlk"><tr><td><span class="stt">> </span><span class="RktPn">(</span><span class="RktSym"><a href="define.html#%28form._%28%28lib._racket%2Fprivate%2Fbase..rkt%29._define%29%29" class="RktStxLink" data-pltdoc="x">define</a></span><span class="hspace"> </span><span class="RktPn">(</span><span class="RktSym">farm-hash-1</span><span class="hspace"> </span><span class="RktSym">farm</span><span class="hspace"> </span><span class="RktSym">recursive-equal-hash</span><span class="RktPn">)</span></td></tr><tr><td><span class="hspace"> </span><span class="hspace"> </span><span class="RktPn">(</span><span class="RktSym"><a href="generic-numbers.html#%28def._%28%28quote._~23~25kernel%29._%2B%29%29" class="RktValLink" data-pltdoc="x">+</a></span><span class="hspace"> </span><span class="RktPn">(</span><span class="RktSym"><a href="generic-numbers.html#%28def._%28%28quote._~23~25kernel%29._%2A%29%29" class="RktValLink" data-pltdoc="x">*</a></span><span class="hspace"> </span><span class="RktVal">10000</span><span class="hspace"> </span><span class="RktPn">(</span><span class="RktSym">farm-apples</span><span class="hspace"> </span><span class="RktSym">farm</span><span class="RktPn">)</span><span class="RktPn">)</span></td></tr><tr><td><span class="hspace"> </span><span class="hspace"> </span><span class="RktPn">(</span><span class="RktSym"><a href="generic-numbers.html#%28def._%28%28quote._~23~25kernel%29._%2A%29%29" class="RktValLink" data-pltdoc="x">*</a></span><span class="hspace"> </span><span class="RktVal">100</span><span class="hspace"> </span><span class="RktPn">(</span><span class="RktSym">farm-oranges</span><span class="hspace"> </span><span class="RktSym">farm</span><span class="RktPn">)</span><span class="RktPn">)</span></td></tr><tr><td><span class="hspace"> </span><span class="hspace"> </span><span class="RktPn">(</span><span class="RktSym"><a href="generic-numbers.html#%28def._%28%28quote._~23~25kernel%29._%2A%29%29" class="RktValLink" data-pltdoc="x">*</a></span><span class="hspace"> </span><span class="RktVal">1</span><span class="hspace"> </span><span class="RktPn">(</span><span class="RktSym">farm-sheep</span><span class="hspace"> </span><span class="RktSym">farm</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><table cellspacing="0" cellpadding="0" class="RktBlk"><tr><td><span class="stt">> </span><span class="RktPn">(</span><span class="RktSym"><a href="define.html#%28form._%28%28lib._racket%2Fprivate%2Fbase..rkt%29._define%29%29" class="RktStxLink" data-pltdoc="x">define</a></span><span class="hspace"> </span><span class="RktPn">(</span><span class="RktSym">farm-hash-2</span><span class="hspace"> </span><span class="RktSym">farm</span><span class="hspace"> </span><span class="RktSym">recursive-equal-hash</span><span class="RktPn">)</span></td></tr><tr><td><span class="hspace"> </span><span class="hspace"> </span><span class="RktPn">(</span><span class="RktSym"><a href="generic-numbers.html#%28def._%28%28quote._~23~25kernel%29._%2B%29%29" class="RktValLink" data-pltdoc="x">+</a></span><span class="hspace"> </span><span class="RktPn">(</span><span class="RktSym"><a href="generic-numbers.html#%28def._%28%28quote._~23~25kernel%29._%2A%29%29" class="RktValLink" data-pltdoc="x">*</a></span><span class="hspace"> </span><span class="RktVal">10000</span><span class="hspace"> </span><span class="RktPn">(</span><span class="RktSym">farm-sheep</span><span class="hspace"> </span><span class="RktSym">farm</span><span class="RktPn">)</span><span class="RktPn">)</span></td></tr><tr><td><span class="hspace"> </span><span class="hspace"> </span><span class="RktPn">(</span><span class="RktSym"><a href="generic-numbers.html#%28def._%28%28quote._~23~25kernel%29._%2A%29%29" class="RktValLink" data-pltdoc="x">*</a></span><span class="hspace"> </span><span class="RktVal">100</span><span class="hspace"> </span><span class="RktPn">(</span><span class="RktSym">farm-apples</span><span class="hspace"> </span><span class="RktSym">farm</span><span class="RktPn">)</span><span class="RktPn">)</span></td></tr><tr><td><span class="hspace"> </span><span class="hspace"> </span><span class="RktPn">(</span><span class="RktSym"><a href="generic-numbers.html#%28def._%28%28quote._~23~25kernel%29._%2A%29%29" class="RktValLink" data-pltdoc="x">*</a></span><span class="hspace"> </span><span class="RktVal">1</span><span class="hspace"> </span><span class="RktPn">(</span><span class="RktSym">farm-oranges</span><span class="hspace"> </span><span class="RktSym">farm</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><table cellspacing="0" cellpadding="0" class="RktBlk"><tr><td><span class="stt">> </span><span class="RktPn">(</span><span class="RktSym"><a href="define-struct.html#%28form._%28%28lib._racket%2Fprivate%2Fbase..rkt%29._define-struct%29%29" class="RktStxLink" data-pltdoc="x">define-struct</a></span><span class="hspace"> </span><span class="RktSym">farm</span><span class="hspace"> </span><span class="RktPn">(</span><span class="RktSym">apples</span><span class="hspace"> </span><span class="RktSym">oranges</span><span class="hspace"> </span><span class="RktSym">sheep</span><span class="RktPn">)</span></td></tr><tr><td><span class="hspace"> </span><span class="hspace"> </span><span class="RktPn">#:methods</span><span class="hspace"> </span><span class="RktSym"><a href="#%28def._%28%28lib._racket%2Fprivate%2Fbase..rkt%29._gen~3aequal%2Bhash%29%29" class="RktValLink" data-pltdoc="x">gen:equal+hash</a></span></td></tr><tr><td><span class="hspace"> </span><span class="hspace"> </span><span class="RktPn">[</span><span class="RktPn">(</span><span class="RktSym"><a href="define.html#%28form._%28%28lib._racket%2Fprivate%2Fbase..rkt%29._define%29%29" class="RktStxLink" data-pltdoc="x">define</a></span><span class="hspace"> </span><span class="RktSym">equal-proc</span><span class="hspace"> </span><span class="RktSym">farm=?</span><span class="RktPn">)</span></td></tr><tr><td><span class="hspace"> </span><span class="hspace"> </span><span class="RktPn">(</span><span class="RktSym"><a href="define.html#%28form._%28%28lib._racket%2Fprivate%2Fbase..rkt%29._define%29%29" class="RktStxLink" data-pltdoc="x">define</a></span><span class="hspace"> </span><span class="RktSym">hash-proc</span><span class="hspace"> </span><span class="RktSym">farm-hash-1</span><span class="RktPn">)</span></td></tr><tr><td><span class="hspace"> </span><span class="hspace"> </span><span class="RktPn">(</span><span class="RktSym"><a href="define.html#%28form._%28%28lib._racket%2Fprivate%2Fbase..rkt%29._define%29%29" class="RktStxLink" data-pltdoc="x">define</a></span><span class="hspace"> </span><span class="RktSym">hash2-proc</span><span class="hspace"> </span><span class="RktSym">farm-hash-2</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">> </span><span class="RktPn">(</span><span class="RktSym"><a href="define.html#%28form._%28%28lib._racket%2Fprivate%2Fbase..rkt%29._define%29%29" class="RktStxLink" data-pltdoc="x">define</a></span><span class="hspace"> </span><span class="RktSym">east</span><span class="hspace"> </span><span class="RktPn">(</span><span class="RktSym">make-farm</span><span class="hspace"> </span><span class="RktVal">5</span><span class="hspace"> </span><span class="RktVal">2</span><span class="hspace"> </span><span class="RktVal">20</span><span class="RktPn">)</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">> </span><span class="RktPn">(</span><span class="RktSym"><a href="define.html#%28form._%28%28lib._racket%2Fprivate%2Fbase..rkt%29._define%29%29" class="RktStxLink" data-pltdoc="x">define</a></span><span class="hspace"> </span><span class="RktSym">west</span><span class="hspace"> </span><span class="RktPn">(</span><span class="RktSym">make-farm</span><span class="hspace"> </span><span class="RktVal">18</span><span class="hspace"> </span><span class="RktVal">6</span><span class="hspace"> </span><span class="RktVal">14</span><span class="RktPn">)</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">> </span><span class="RktPn">(</span><span class="RktSym"><a href="define.html#%28form._%28%28lib._racket%2Fprivate%2Fbase..rkt%29._define%29%29" class="RktStxLink" data-pltdoc="x">define</a></span><span class="hspace"> </span><span class="RktSym">north</span><span class="hspace"> </span><span class="RktPn">(</span><span class="RktSym">make-farm</span><span class="hspace"> </span><span class="RktVal">5</span><span class="hspace"> </span><span class="RktVal">20</span><span class="hspace"> </span><span class="RktVal">20</span><span class="RktPn">)</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">> </span><span class="RktPn">(</span><span class="RktSym"><a href="define.html#%28form._%28%28lib._racket%2Fprivate%2Fbase..rkt%29._define%29%29" class="RktStxLink" data-pltdoc="x">define</a></span><span class="hspace"> </span><span class="RktSym">south</span><span class="hspace"> </span><span class="RktPn">(</span><span class="RktSym">make-farm</span><span class="hspace"> </span><span class="RktVal">18</span><span class="hspace"> </span><span class="RktVal">6</span><span class="hspace"> </span><span class="RktVal">14</span><span class="RktPn">)</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">> </span><span class="RktPn">(</span><span class="RktSym"><a href="#%28def._%28%28quote._~23~25kernel%29._equal~3f%29%29" class="RktValLink" data-pltdoc="x">equal?</a></span><span class="hspace"> </span><span class="RktSym">east</span><span class="hspace"> </span><span class="RktSym">west</span><span class="RktPn">)</span></td></tr><tr><td><p><span class="RktRes">#f</span></p></td></tr><tr><td><span class="stt">> </span><span class="RktPn">(</span><span class="RktSym"><a href="#%28def._%28%28quote._~23~25kernel%29._equal~3f%29%29" class="RktValLink" data-pltdoc="x">equal?</a></span><span class="hspace"> </span><span class="RktSym">east</span><span class="hspace"> </span><span class="RktSym">north</span><span class="RktPn">)</span></td></tr><tr><td><p><span class="RktRes">#f</span></p></td></tr><tr><td><span class="stt">> </span><span class="RktPn">(</span><span class="RktSym"><a href="#%28def._%28%28quote._~23~25kernel%29._equal~3f%29%29" class="RktValLink" data-pltdoc="x">equal?</a></span><span class="hspace"> </span><span class="RktSym">west</span><span class="hspace"> </span><span class="RktSym">south</span><span class="RktPn">)</span></td></tr><tr><td><p><span class="RktRes">#t</span></p></td></tr></table></blockquote></td></tr></table></p><p><div class="SIntrapara"><blockquote class="SVInsetFlow"><table cellspacing="0" cellpadding="0" class="boxed RBoxed"><tr><td><blockquote class="SubFlow"><div class="RBackgroundLabel SIEHidden"><div class="RBackgroundLabelInner"><p>value</p></div></div><p class="RForeground"><a name="(def._((quote._~23~25kernel)._prop~3aequal+hash))"></a><span title="Provided from: racket/base, racket | Package: base"><span class="RktSym"><a href="#%28def._%28%28quote._~23~25kernel%29._prop~3aequal%2Bhash%29%29" class="RktValDef RktValLink" data-pltdoc="x">prop:equal+hash</a></span></span><span class="hspace"> </span>:<span class="hspace"> </span><span class="RktSym"><a href="structprops.html#%28def._%28%28quote._~23~25kernel%29._struct-type-property~3f%29%29" class="RktValLink" data-pltdoc="x">struct-type-property?</a></span></p></blockquote></td></tr></table></blockquote></div><div class="SIntrapara">A deprecated <a href="structprops.html#%28tech._structure._type._property%29" class="techoutside" data-pltdoc="x"><span class="techinside">structure type property</span></a> (see <a href="structprops.html" data-pltdoc="x">Structure Type Properties</a>)
that supplies an equality predicate and hashing functions for a structure
type. The <span class="RktSym"><a href="#%28def._%28%28lib._racket%2Fprivate%2Fbase..rkt%29._gen~3aequal%2Bhash%29%29" class="RktValLink" data-pltdoc="x">gen:equal+hash</a></span> <a href="struct-generics.html#%28tech._generic._interface%29" class="techoutside" data-pltdoc="x"><span class="techinside">generic interface</span></a> should be used,
instead. A <span class="RktSym"><a href="#%28def._%28%28quote._~23~25kernel%29._prop~3aequal%2Bhash%29%29" class="RktValLink" data-pltdoc="x">prop:equal+hash</a></span> property value is a list of
three procedures that correspond to the methods of <span class="RktSym"><a href="#%28def._%28%28lib._racket%2Fprivate%2Fbase..rkt%29._gen~3aequal%2Bhash%29%29" class="RktValLink" data-pltdoc="x">gen:equal+hash</a></span>.</div></p><h5 x-source-module="(lib "scribblings/reference/reference.scrbl")" x-part-tag=""Boolean_Aliases"">4.1.1<tt> </tt><a name="(part._.Boolean_.Aliases)"></a><a name="(mod-path._racket/bool)"></a>Boolean Aliases</h5><p><div class="SIntrapara"><table cellspacing="0" cellpadding="0" class="defmodule"><tr><td align="left"><span class="hspace"> </span><span class="RktPn">(</span><span class="RktSym"><a href="require.html#%28form._%28%28lib._racket%2Fprivate%2Fbase..rkt%29._require%29%29" class="RktStxLink" data-pltdoc="x">require</a></span><span class="stt"> </span><a href="#%28mod-path._racket%2Fbool%29" class="RktModLink" data-pltdoc="x"><span class="RktSym">racket/bool</span></a><span class="RktPn">)</span></td><td align="right"><span class="RpackageSpec"><span class="Smaller"> package:</span> <span class="stt">base</span></span></td></tr></table></div><div class="SIntrapara">The bindings documented in this section are provided by the <a href="#%28mod-path._racket%2Fbool%29" class="RktModLink" data-pltdoc="x"><span class="RktSym">racket/bool</span></a> and <a href="index.html" class="RktModLink" data-pltdoc="x"><span class="RktSym">racket</span></a> libraries, but not <a href="index.html" class="RktModLink" data-pltdoc="x"><span class="RktSym">racket/base</span></a>.</div></p><p><div class="SIntrapara"><blockquote class="SVInsetFlow"><table cellspacing="0" cellpadding="0" class="boxed RBoxed"><tr><td><blockquote class="SubFlow"><div class="RBackgroundLabel SIEHidden"><div class="RBackgroundLabelInner"><p>value</p></div></div><p class="RForeground"><a name="(def._((lib._racket/bool..rkt)._true))"></a><span title="Provided from: racket/bool, racket | Package: base"><span class="RktSym"><a href="#%28def._%28%28lib._racket%2Fbool..rkt%29._true%29%29" class="RktValDef RktValLink" data-pltdoc="x">true</a></span></span><span class="hspace"> </span>:<span class="hspace"> </span><span class="RktSym"><a href="#%28def._%28%28quote._~23~25kernel%29._boolean~3f%29%29" class="RktValLink" data-pltdoc="x">boolean?</a></span></p></blockquote></td></tr></table></blockquote></div><div class="SIntrapara">An alias for <span class="RktVal">#t</span>.</div></p><p><div class="SIntrapara"><blockquote class="SVInsetFlow"><table cellspacing="0" cellpadding="0" class="boxed RBoxed"><tr><td><blockquote class="SubFlow"><div class="RBackgroundLabel SIEHidden"><div class="RBackgroundLabelInner"><p>value</p></div></div><p class="RForeground"><a name="(def._((lib._racket/bool..rkt)._false))"></a><span title="Provided from: racket/bool, racket | Package: base"><span class="RktSym"><a href="#%28def._%28%28lib._racket%2Fbool..rkt%29._false%29%29" class="RktValDef RktValLink" data-pltdoc="x">false</a></span></span><span class="hspace"> </span>:<span class="hspace"> </span><span class="RktSym"><a href="#%28def._%28%28quote._~23~25kernel%29._boolean~3f%29%29" class="RktValLink" data-pltdoc="x">boolean?</a></span></p></blockquote></td></tr></table></blockquote></div><div class="SIntrapara">An alias for <span class="RktVal">#f</span>.</div></p><p><div class="SIntrapara"><blockquote class="SVInsetFlow"><table cellspacing="0" cellpadding="0" class="boxed RBoxed"><tr><td><blockquote class="SubFlow"><div class="RBackgroundLabel SIEHidden"><div class="RBackgroundLabelInner"><p>procedure</p></div></div><p class="RForeground"><span class="RktPn">(</span><a name="(def._((lib._racket/bool..rkt)._symbol~3d~3f))"></a><span title="Provided from: racket/bool, racket | Package: base"><span class="RktSym"><a href="#%28def._%28%28lib._racket%2Fbool..rkt%29._symbol~3d~3f%29%29" class="RktValDef RktValLink" data-pltdoc="x">symbol=?</a></span></span><span class="hspace"> </span><span class="RktVar">a</span><span class="hspace"> </span><span class="RktVar">b</span><span class="RktPn">)</span><span class="hspace"> </span>→<span class="hspace"> </span><span class="RktSym"><a href="#%28def._%28%28quote._~23~25kernel%29._boolean~3f%29%29" class="RktValLink" data-pltdoc="x">boolean?</a></span></p></blockquote></td></tr><tr><td><span class="hspace"> </span><span class="RktVar">a</span><span class="hspace"> </span>:<span class="hspace"> </span><span class="RktSym"><a href="symbols.html#%28def._%28%28quote._~23~25kernel%29._symbol~3f%29%29" class="RktValLink" data-pltdoc="x">symbol?</a></span></td></tr><tr><td><span class="hspace"> </span><span class="RktVar">b</span><span class="hspace"> </span>:<span class="hspace"> </span><span class="RktSym"><a href="symbols.html#%28def._%28%28quote._~23~25kernel%29._symbol~3f%29%29" class="RktValLink" data-pltdoc="x">symbol?</a></span></td></tr></table></blockquote></div><div class="SIntrapara">Returns <span class="RktPn">(</span><span class="RktSym"><a href="#%28def._%28%28quote._~23~25kernel%29._equal~3f%29%29" class="RktValLink" data-pltdoc="x">equal?</a></span><span class="stt"> </span><span class="RktVar">a</span><span class="stt"> </span><span class="RktVar">b</span><span class="RktPn">)</span> (if <span class="RktVar">a</span> and <span class="RktVar">b</span> are symbols).</div></p><p><div class="SIntrapara"><blockquote class="SVInsetFlow"><table cellspacing="0" cellpadding="0" class="boxed RBoxed"><tr><td><blockquote class="SubFlow"><div class="RBackgroundLabel SIEHidden"><div class="RBackgroundLabelInner"><p>procedure</p></div></div><p class="RForeground"><span class="RktPn">(</span><a name="(def._((lib._racket/bool..rkt)._boolean~3d~3f))"></a><span title="Provided from: racket/bool, racket | Package: base"><span class="RktSym"><a href="#%28def._%28%28lib._racket%2Fbool..rkt%29._boolean~3d~3f%29%29" class="RktValDef RktValLink" data-pltdoc="x">boolean=?</a></span></span><span class="hspace"> </span><span class="RktVar">a</span><span class="hspace"> </span><span class="RktVar">b</span><span class="RktPn">)</span><span class="hspace"> </span>→<span class="hspace"> </span><span class="RktSym"><a href="#%28def._%28%28quote._~23~25kernel%29._boolean~3f%29%29" class="RktValLink" data-pltdoc="x">boolean?</a></span></p></blockquote></td></tr><tr><td><span class="hspace"> </span><span class="RktVar">a</span><span class="hspace"> </span>:<span class="hspace"> </span><span class="RktSym"><a href="#%28def._%28%28quote._~23~25kernel%29._boolean~3f%29%29" class="RktValLink" data-pltdoc="x">boolean?</a></span></td></tr><tr><td><span class="hspace"> </span><span class="RktVar">b</span><span class="hspace"> </span>:<span class="hspace"> </span><span class="RktSym"><a href="#%28def._%28%28quote._~23~25kernel%29._boolean~3f%29%29" class="RktValLink" data-pltdoc="x">boolean?</a></span></td></tr></table></blockquote></div><div class="SIntrapara">Returns <span class="RktPn">(</span><span class="RktSym"><a href="#%28def._%28%28quote._~23~25kernel%29._equal~3f%29%29" class="RktValLink" data-pltdoc="x">equal?</a></span><span class="stt"> </span><span class="RktVar">a</span><span class="stt"> </span><span class="RktVar">b</span><span class="RktPn">)</span> (if <span class="RktVar">a</span> and <span class="RktVar">b</span> are booleans).</div></p><p><div class="SIntrapara"><blockquote class="SVInsetFlow"><table cellspacing="0" cellpadding="0" class="boxed RBoxed"><tr><td><blockquote class="SubFlow"><div class="RBackgroundLabel SIEHidden"><div class="RBackgroundLabelInner"><p>procedure</p></div></div><p class="RForeground"><span class="RktPn">(</span><a name="(def._((lib._racket/bool..rkt)._false~3f))"></a><span title="Provided from: racket/bool, racket | Package: base"><span class="RktSym"><a href="#%28def._%28%28lib._racket%2Fbool..rkt%29._false~3f%29%29" class="RktValDef RktValLink" data-pltdoc="x">false?</a></span></span><span class="hspace"> </span><span class="RktVar">v</span><span class="RktPn">)</span><span class="hspace"> </span>→<span class="hspace"> </span><span class="RktSym"><a href="#%28def._%28%28quote._~23~25kernel%29._boolean~3f%29%29" class="RktValLink" data-pltdoc="x">boolean?</a></span></p></blockquote></td></tr><tr><td><span class="hspace"> </span><span class="RktVar">v</span><span class="hspace"> </span>:<span class="hspace"> </span><span class="RktSym"><a href="data-structure-contracts.html#%28def._%28%28lib._racket%2Fcontract%2Fprivate%2Fmisc..rkt%29._any%2Fc%29%29" class="RktValLink" data-pltdoc="x">any/c</a></span></td></tr></table></blockquote></div><div class="SIntrapara">Returns <span class="RktPn">(</span><span class="RktSym"><a href="#%28def._%28%28quote._~23~25kernel%29._not%29%29" class="RktValLink" data-pltdoc="x">not</a></span><span class="stt"> </span><span class="RktVar">v</span><span class="RktPn">)</span>.</div></p><p><div class="SIntrapara"><blockquote class="SVInsetFlow"><table cellspacing="0" cellpadding="0" class="boxed RBoxed"><tr><td><blockquote class="SubFlow"><div class="RBackgroundLabel SIEHidden"><div class="RBackgroundLabelInner"><p>syntax</p></div></div><p class="RForeground"><span class="RktPn">(</span><a name="(form._((lib._racket/bool..rkt)._nand))"></a><span title="Provided from: racket/bool, racket | Package: base"><span class="RktSym"><a href="#%28form._%28%28lib._racket%2Fbool..rkt%29._nand%29%29" class="RktStxDef RktStxLink" data-pltdoc="x">nand</a></span></span><span class="hspace"> </span><span class="RktVar">expr</span><span class="hspace"> </span><span class="RktMeta">...</span><span class="RktPn">)</span></p></blockquote></td></tr></table></blockquote></div><div class="SIntrapara">Same as <span class="RktPn">(</span><span class="RktSym"><a href="#%28def._%28%28quote._~23~25kernel%29._not%29%29" class="RktValLink" data-pltdoc="x">not</a></span><span class="stt"> </span><span class="RktPn">(</span><span class="RktSym"><a href="if.html#%28form._%28%28lib._racket%2Fprivate%2Fletstx-scheme..rkt%29._and%29%29" class="RktStxLink" data-pltdoc="x">and</a></span><span class="stt"> </span><span class="RktVar">expr</span><span class="stt"> </span><span class="RktMeta"><a href="stx-patterns.html#%28form._%28%28lib._racket%2Fprivate%2Fstxcase-scheme..rkt%29._......%29%29" class="RktStxLink" data-pltdoc="x">...</a></span><span class="RktPn">)</span><span class="RktPn">)</span>.</div></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><span class="stt">> </span><span class="RktPn">(</span><span class="RktSym"><a href="#%28form._%28%28lib._racket%2Fbool..rkt%29._nand%29%29" class="RktStxLink" data-pltdoc="x">nand</a></span><span class="hspace"> </span><span class="RktVal">#f</span><span class="hspace"> </span><span class="RktVal">#t</span><span class="RktPn">)</span></td></tr><tr><td><p><span class="RktRes">#t</span></p></td></tr><tr><td><span class="stt">> </span><span class="RktPn">(</span><span class="RktSym"><a href="#%28form._%28%28lib._racket%2Fbool..rkt%29._nand%29%29" class="RktStxLink" data-pltdoc="x">nand</a></span><span class="hspace"> </span><span class="RktVal">#f</span><span class="hspace"> </span><span class="RktPn">(</span><span class="RktSym"><a href="exns.html#%28def._%28%28quote._~23~25kernel%29._error%29%29" class="RktValLink" data-pltdoc="x">error</a></span><span class="hspace"> </span><span class="RktVal">'</span><span class="RktVal">ack</span><span class="hspace"> </span><span class="RktVal">"we don't get here"</span><span class="RktPn">)</span><span class="RktPn">)</span></td></tr><tr><td><p><span class="RktRes">#t</span></p></td></tr></table></blockquote></td></tr></table></p><p><div class="SIntrapara"><blockquote class="SVInsetFlow"><table cellspacing="0" cellpadding="0" class="boxed RBoxed"><tr><td><blockquote class="SubFlow"><div class="RBackgroundLabel SIEHidden"><div class="RBackgroundLabelInner"><p>syntax</p></div></div><p class="RForeground"><span class="RktPn">(</span><a name="(form._((lib._racket/bool..rkt)._nor))"></a><span title="Provided from: racket/bool, racket | Package: base"><span class="RktSym"><a href="#%28form._%28%28lib._racket%2Fbool..rkt%29._nor%29%29" class="RktStxDef RktStxLink" data-pltdoc="x">nor</a></span></span><span class="hspace"> </span><span class="RktVar">expr</span><span class="hspace"> </span><span class="RktMeta">...</span><span class="RktPn">)</span></p></blockquote></td></tr></table></blockquote></div><div class="SIntrapara">Same as <span class="RktPn">(</span><span class="RktSym"><a href="#%28def._%28%28quote._~23~25kernel%29._not%29%29" class="RktValLink" data-pltdoc="x">not</a></span><span class="stt"> </span><span class="RktPn">(</span><span class="RktSym"><a href="if.html#%28form._%28%28lib._racket%2Fprivate%2Fletstx-scheme..rkt%29._or%29%29" class="RktStxLink" data-pltdoc="x">or</a></span><span class="stt"> </span><span class="RktVar">expr</span><span class="stt"> </span><span class="RktMeta"><a href="stx-patterns.html#%28form._%28%28lib._racket%2Fprivate%2Fstxcase-scheme..rkt%29._......%29%29" class="RktStxLink" data-pltdoc="x">...</a></span><span class="RktPn">)</span><span class="RktPn">)</span>.</div></p><p>In the two argument case, returns <span class="RktVal">#t</span> if neither of the
arguments is a true value.</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><span class="stt">> </span><span class="RktPn">(</span><span class="RktSym"><a href="#%28form._%28%28lib._racket%2Fbool..rkt%29._nor%29%29" class="RktStxLink" data-pltdoc="x">nor</a></span><span class="hspace"> </span><span class="RktVal">#f</span><span class="hspace"> </span><span class="RktVal">#t</span><span class="RktPn">)</span></td></tr><tr><td><p><span class="RktRes">#f</span></p></td></tr><tr><td><span class="stt">> </span><span class="RktPn">(</span><span class="RktSym"><a href="#%28form._%28%28lib._racket%2Fbool..rkt%29._nor%29%29" class="RktStxLink" data-pltdoc="x">nor</a></span><span class="hspace"> </span><span class="RktVal">#t</span><span class="hspace"> </span><span class="RktPn">(</span><span class="RktSym"><a href="exns.html#%28def._%28%28quote._~23~25kernel%29._error%29%29" class="RktValLink" data-pltdoc="x">error</a></span><span class="hspace"> </span><span class="RktVal">'</span><span class="RktVal">ack</span><span class="hspace"> </span><span class="RktVal">"we don't get here"</span><span class="RktPn">)</span><span class="RktPn">)</span></td></tr><tr><td><p><span class="RktRes">#f</span></p></td></tr></table></blockquote></td></tr></table></p><p><div class="SIntrapara"><blockquote class="SVInsetFlow"><table cellspacing="0" cellpadding="0" class="boxed RBoxed"><tr><td><blockquote class="SubFlow"><div class="RBackgroundLabel SIEHidden"><div class="RBackgroundLabelInner"><p>syntax</p></div></div><p class="RForeground"><span class="RktPn">(</span><a name="(form._((lib._racket/bool..rkt)._implies))"></a><span title="Provided from: racket/bool, racket | Package: base"><span class="RktSym"><a href="#%28form._%28%28lib._racket%2Fbool..rkt%29._implies%29%29" class="RktStxDef RktStxLink" data-pltdoc="x">implies</a></span></span><span class="hspace"> </span><span class="RktVar">expr1</span><span class="hspace"> </span><span class="RktVar">expr2</span><span class="RktPn">)</span></p></blockquote></td></tr></table></blockquote></div><div class="SIntrapara">Checks to be sure that the first
expression implies the second.</div></p><p>Same as <span class="RktPn">(</span><span class="RktSym"><a href="if.html#%28form._%28%28quote._~23~25kernel%29._if%29%29" class="RktStxLink" data-pltdoc="x">if</a></span><span class="stt"> </span><span class="RktVar">expr1</span><span class="stt"> </span><span class="RktVar">expr2</span><span class="stt"> </span><span class="RktVal">#t</span><span class="RktPn">)</span>.</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><span class="stt">> </span><span class="RktPn">(</span><span class="RktSym"><a href="#%28form._%28%28lib._racket%2Fbool..rkt%29._implies%29%29" class="RktStxLink" data-pltdoc="x">implies</a></span><span class="hspace"> </span><span class="RktVal">#f</span><span class="hspace"> </span><span class="RktVal">#t</span><span class="RktPn">)</span></td></tr><tr><td><p><span class="RktRes">#t</span></p></td></tr><tr><td><span class="stt">> </span><span class="RktPn">(</span><span class="RktSym"><a href="#%28form._%28%28lib._racket%2Fbool..rkt%29._implies%29%29" class="RktStxLink" data-pltdoc="x">implies</a></span><span class="hspace"> </span><span class="RktVal">#f</span><span class="hspace"> </span><span class="RktVal">#f</span><span class="RktPn">)</span></td></tr><tr><td><p><span class="RktRes">#t</span></p></td></tr><tr><td><span class="stt">> </span><span class="RktPn">(</span><span class="RktSym"><a href="#%28form._%28%28lib._racket%2Fbool..rkt%29._implies%29%29" class="RktStxLink" data-pltdoc="x">implies</a></span><span class="hspace"> </span><span class="RktVal">#t</span><span class="hspace"> </span><span class="RktVal">#f</span><span class="RktPn">)</span></td></tr><tr><td><p><span class="RktRes">#f</span></p></td></tr><tr><td><span class="stt">> </span><span class="RktPn">(</span><span class="RktSym"><a href="#%28form._%28%28lib._racket%2Fbool..rkt%29._implies%29%29" class="RktStxLink" data-pltdoc="x">implies</a></span><span class="hspace"> </span><span class="RktVal">#f</span><span class="hspace"> </span><span class="RktPn">(</span><span class="RktSym"><a href="exns.html#%28def._%28%28quote._~23~25kernel%29._error%29%29" class="RktValLink" data-pltdoc="x">error</a></span><span class="hspace"> </span><span class="RktVal">'</span><span class="RktVal">ack</span><span class="hspace"> </span><span class="RktVal">"we don't get here"</span><span class="RktPn">)</span><span class="RktPn">)</span></td></tr><tr><td><p><span class="RktRes">#t</span></p></td></tr></table></blockquote></td></tr></table></p><p><div class="SIntrapara"><blockquote class="SVInsetFlow"><table cellspacing="0" cellpadding="0" class="boxed RBoxed"><tr><td><blockquote class="SubFlow"><div class="RBackgroundLabel SIEHidden"><div class="RBackgroundLabelInner"><p>procedure</p></div></div><p class="RForeground"><span class="RktPn">(</span><a name="(def._((lib._racket/bool..rkt)._xor))"></a><span title="Provided from: racket/bool, racket | Package: base"><span class="RktSym"><a href="#%28def._%28%28lib._racket%2Fbool..rkt%29._xor%29%29" class="RktValDef RktValLink" data-pltdoc="x">xor</a></span></span><span class="hspace"> </span><span class="RktVar">b1</span><span class="hspace"> </span><span class="RktVar">b2</span><span class="RktPn">)</span><span class="hspace"> </span>→<span class="hspace"> </span><span class="RktSym"><a href="data-structure-contracts.html#%28form._%28%28lib._racket%2Fcontract%2Fprivate%2Fmisc..rkt%29._any%29%29" class="RktStxLink" data-pltdoc="x">any</a></span></p></blockquote></td></tr><tr><td><span class="hspace"> </span><span class="RktVar">b1</span><span class="hspace"> </span>:<span class="hspace"> </span><span class="RktSym"><a href="data-structure-contracts.html#%28def._%28%28lib._racket%2Fcontract%2Fprivate%2Fmisc..rkt%29._any%2Fc%29%29" class="RktValLink" data-pltdoc="x">any/c</a></span></td></tr><tr><td><span class="hspace"> </span><span class="RktVar">b2</span><span class="hspace"> </span>:<span class="hspace"> </span><span class="RktSym"><a href="data-structure-contracts.html#%28def._%28%28lib._racket%2Fcontract%2Fprivate%2Fmisc..rkt%29._any%2Fc%29%29" class="RktValLink" data-pltdoc="x">any/c</a></span></td></tr></table></blockquote></div><div class="SIntrapara">Returns the exclusive or of <span class="RktVar">b1</span> and <span class="RktVar">b2</span>.</div></p><p>If exactly one of <span class="RktVar">b1</span> and <span class="RktVar">b2</span> is
not <span class="RktVal">#f</span>, then return it. Otherwise, returns
<span class="RktVal">#f</span>.</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><span class="stt">> </span><span class="RktPn">(</span><span class="RktSym"><a href="#%28def._%28%28lib._racket%2Fbool..rkt%29._xor%29%29" class="RktValLink" data-pltdoc="x">xor</a></span><span class="hspace"> </span><span class="RktVal">11</span><span class="hspace"> </span><span class="RktVal">#f</span><span class="RktPn">)</span></td></tr><tr><td><p><span class="RktRes">11</span></p></td></tr><tr><td><span class="stt">> </span><span class="RktPn">(</span><span class="RktSym"><a href="#%28def._%28%28lib._racket%2Fbool..rkt%29._xor%29%29" class="RktValLink" data-pltdoc="x">xor</a></span><span class="hspace"> </span><span class="RktVal">#f</span><span class="hspace"> </span><span class="RktVal">22</span><span class="RktPn">)</span></td></tr><tr><td><p><span class="RktRes">22</span></p></td></tr><tr><td><span class="stt">> </span><span class="RktPn">(</span><span class="RktSym"><a href="#%28def._%28%28lib._racket%2Fbool..rkt%29._xor%29%29" class="RktValLink" data-pltdoc="x">xor</a></span><span class="hspace"> </span><span class="RktVal">11</span><span class="hspace"> </span><span class="RktVal">22</span><span class="RktPn">)</span></td></tr><tr><td><p><span class="RktRes">#f</span></p></td></tr><tr><td><span class="stt">> </span><span class="RktPn">(</span><span class="RktSym"><a href="#%28def._%28%28lib._racket%2Fbool..rkt%29._xor%29%29" class="RktValLink" data-pltdoc="x">xor</a></span><span class="hspace"> </span><span class="RktVal">#f</span><span class="hspace"> </span><span class="RktVal">#f</span><span class="RktPn">)</span></td></tr><tr><td><p><span class="RktRes">#f</span></p></td></tr></table></blockquote></td></tr></table></p><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, "6.1", "../");" onfocus="this.style.color="black"; this.style.textAlign="left"; if (this.value == "...search manuals...") this.value="";" onblur="if (this.value.match(/^ *$/)) { this.style.color="#888"; this.style.textAlign="center"; this.value="...search manuals..."; }"/></form> <a href="../index.html" title="up to the documentation top" data-pltdoc="x" onclick="return GotoPLTRoot("6.1");">top</a></span><span class="navright"> <a href="data.html" title="backward to "4 Datatypes"" data-pltdoc="x">← prev</a> <a href="data.html" title="up to "4 Datatypes"" data-pltdoc="x">up</a> <a href="numbers.html" title="forward to "4.2 Numbers"" data-pltdoc="x">next →</a></span> </div></div></div><div id="contextindicator"> </div></body></html>
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