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<html><head><meta http-equiv="content-type" content="text/html; charset=utf-8"/><title>4.6 Symbols</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="icons.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="tocviewsublistbottom" style="display: block;" id="tocview_1"><table cellspacing="0" cellpadding="0"><tr><td align="right">4.1 </td><td><a href="booleans.html" class="tocviewlink" 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="" class="tocviewselflink" 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><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._symbol~3f%29%29" class="tocsublink" data-pltdoc="x"><span class="RktSym"><span class="RktValLink">symbol?</span></span></a></td></tr><tr><td><a href="#%28def._%28%28quote._~23~25kernel%29._symbol-interned~3f%29%29" class="tocsublink" data-pltdoc="x"><span class="RktSym"><span class="RktValLink">symbol-<wbr></wbr>interned?</span></span></a></td></tr><tr><td><a href="#%28def._%28%28quote._~23~25kernel%29._symbol-unreadable~3f%29%29" class="tocsublink" data-pltdoc="x"><span class="RktSym"><span class="RktValLink">symbol-<wbr></wbr>unreadable?</span></span></a></td></tr><tr><td><a href="#%28def._%28%28quote._~23~25kernel%29._symbol-~3estring%29%29" class="tocsublink" data-pltdoc="x"><span class="RktSym"><span class="RktValLink">symbol-<wbr></wbr>>string</span></span></a></td></tr><tr><td><a href="#%28def._%28%28quote._~23~25kernel%29._string-~3esymbol%29%29" class="tocsublink" data-pltdoc="x"><span class="RktSym"><span class="RktValLink">string-<wbr></wbr>>symbol</span></span></a></td></tr><tr><td><a href="#%28def._%28%28quote._~23~25kernel%29._string-~3euninterned-symbol%29%29" class="tocsublink" data-pltdoc="x"><span class="RktSym"><span class="RktValLink">string-<wbr></wbr>>uninterned-<wbr></wbr>symbol</span></span></a></td></tr><tr><td><a href="#%28def._%28%28quote._~23~25kernel%29._string-~3eunreadable-symbol%29%29" class="tocsublink" data-pltdoc="x"><span class="RktSym"><span class="RktValLink">string-<wbr></wbr>>unreadable-<wbr></wbr>symbol</span></span></a></td></tr><tr><td><a href="#%28def._%28%28quote._~23~25kernel%29._gensym%29%29" class="tocsublink" data-pltdoc="x"><span class="RktSym"><span class="RktValLink">gensym</span></span></a></td></tr><tr><td><a href="#%28def._%28%28quote._~23~25kernel%29._symbol~3c~3f%29%29" class="tocsublink" data-pltdoc="x"><span class="RktSym"><span class="RktValLink">symbol<?</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="characters.html" title="backward to "4.5 Characters"" data-pltdoc="x">← prev</a> <a href="data.html" title="up to "4 Datatypes"" data-pltdoc="x">up</a> <a href="regexp.html" title="forward to "4.7 Regular Expressions"" data-pltdoc="x">next →</a></span> </div><h4 x-source-module="(lib "scribblings/reference/reference.scrbl")" x-part-tag=""symbols"">4.6<tt> </tt><a name="(part._symbols)"></a><a name="(idx._(gentag._159._(lib._scribblings/reference/reference..scrbl)))"></a><a name="(idx._(gentag._160._(lib._scribblings/reference/reference..scrbl)))"></a>Symbols</h4><blockquote class="refpara"><blockquote class="refcolumn"><blockquote class="refcontent"><p><span class="imageleft"><img src="finger.png" alt="+" width="24" height="24"/></span><a href="http://download.racket-lang.org/docs/6.1/html/local-redirect/index.html?doc=guide&rel=symbols.html&version=6.1" class="Sq" data-pltdoc="x">Symbols</a> in <a href="http://download.racket-lang.org/docs/6.1/html/local-redirect/index.html?doc=guide&rel=index.html&version=6.1" class="Sq" data-pltdoc="x"><span style="font-weight: bold">The Racket Guide</span></a> introduces symbols.</p></blockquote></blockquote></blockquote><p>A <a name="(tech._symbol)"></a><span style="font-style: italic">symbol</span> is like an immutable string, but symbols are
normally <a href="reader.html#%28tech._interned%29" class="techoutside" data-pltdoc="x"><span class="techinside">interned</span></a>, so that two symbols with the same
character content are normally <span class="RktSym"><a href="booleans.html#%28def._%28%28quote._~23~25kernel%29._eq~3f%29%29" class="RktValLink" data-pltdoc="x">eq?</a></span>. All symbols produced by
the default reader (see <a href="reader.html#%28part._parse-symbol%29" data-pltdoc="x">Reading Symbols</a>) are <a href="reader.html#%28tech._interned%29" class="techoutside" data-pltdoc="x"><span class="techinside">interned</span></a>.</p><p>The two procedures <span class="RktSym"><a href="#%28def._%28%28quote._~23~25kernel%29._string-~3euninterned-symbol%29%29" class="RktValLink" data-pltdoc="x">string->uninterned-symbol</a></span> and
<span class="RktSym"><a href="#%28def._%28%28quote._~23~25kernel%29._gensym%29%29" class="RktValLink" data-pltdoc="x">gensym</a></span> generate <a name="(tech._uninterned)"></a><span style="font-style: italic">uninterned</span> symbols, i.e., symbols
that are not <span class="RktSym"><a href="booleans.html#%28def._%28%28quote._~23~25kernel%29._eq~3f%29%29" class="RktValLink" data-pltdoc="x">eq?</a></span>, <span class="RktSym"><a href="booleans.html#%28def._%28%28quote._~23~25kernel%29._eqv~3f%29%29" class="RktValLink" data-pltdoc="x">eqv?</a></span>, or <span class="RktSym"><a href="booleans.html#%28def._%28%28quote._~23~25kernel%29._equal~3f%29%29" class="RktValLink" data-pltdoc="x">equal?</a></span> to any
other symbol, although they may print the same as other symbols.</p><p>The procedure <span class="RktSym"><a href="#%28def._%28%28quote._~23~25kernel%29._string-~3eunreadable-symbol%29%29" class="RktValLink" data-pltdoc="x">string->unreadable-symbol</a></span> returns an
<a name="(tech._unreadable._symbol)"></a><span style="font-style: italic">unreadable symbol</span> that is partially interned. The default
reader (see <a href="reader.html#%28part._parse-symbol%29" data-pltdoc="x">Reading Symbols</a>) never produces a unreadable
symbol, but two calls to <span class="RktSym"><a href="#%28def._%28%28quote._~23~25kernel%29._string-~3eunreadable-symbol%29%29" class="RktValLink" data-pltdoc="x">string->unreadable-symbol</a></span> with
<span class="RktSym"><a href="booleans.html#%28def._%28%28quote._~23~25kernel%29._equal~3f%29%29" class="RktValLink" data-pltdoc="x">equal?</a></span> strings produce <span class="RktSym"><a href="booleans.html#%28def._%28%28quote._~23~25kernel%29._eq~3f%29%29" class="RktValLink" data-pltdoc="x">eq?</a></span> results. An unreadable
symbol can print the same as an interned or uninterned
symbol. Unreadable symbols are useful in expansion and
compilation to avoid collisions with symbols that appear in the
source; they are usually not generated directly, but they can appear
in the result of functions like <span class="RktSym"><a href="stxcmp.html#%28def._%28%28quote._~23~25kernel%29._identifier-binding%29%29" class="RktValLink" data-pltdoc="x">identifier-binding</a></span>.</p><p>Interned and unreadable symbols are only weakly held by the internal
symbol table. This weakness can never affect the result of an
<span class="RktSym"><a href="booleans.html#%28def._%28%28quote._~23~25kernel%29._eq~3f%29%29" class="RktValLink" data-pltdoc="x">eq?</a></span>, <span class="RktSym"><a href="booleans.html#%28def._%28%28quote._~23~25kernel%29._eqv~3f%29%29" class="RktValLink" data-pltdoc="x">eqv?</a></span>, or <span class="RktSym"><a href="booleans.html#%28def._%28%28quote._~23~25kernel%29._equal~3f%29%29" class="RktValLink" data-pltdoc="x">equal?</a></span> test, but a symbol may
disappear when placed into a weak box (see <a href="weakbox.html" data-pltdoc="x">Weak Boxes</a>) used as
the key in a weak <a href="hashtables.html#%28tech._hash._table%29" class="techoutside" data-pltdoc="x"><span class="techinside">hash table</span></a> (see <a href="hashtables.html" data-pltdoc="x">Hash Tables</a>), or
used as an ephemeron key (see <a href="ephemerons.html" data-pltdoc="x">Ephemerons</a>).</p><p>See <a href="reader.html#%28part._parse-symbol%29" data-pltdoc="x">Reading Symbols</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
symbols and <a href="printing.html#%28part._print-symbol%29" data-pltdoc="x">Printing Symbols</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 symbols.</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)._symbol~3f))"></a><span title="Provided from: racket/base, racket | Package: base"><span class="RktSym"><a href="#%28def._%28%28quote._~23~25kernel%29._symbol~3f%29%29" class="RktValDef RktValLink" data-pltdoc="x">symbol?</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="booleans.html#%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
a symbol, <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._symbol~3f%29%29" class="RktValLink" data-pltdoc="x">symbol?</a></span><span class="hspace"> </span><span class="RktVal">'</span><span class="RktVal">Apple</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._symbol~3f%29%29" class="RktValLink" data-pltdoc="x">symbol?</a></span><span class="hspace"> </span><span class="RktVal">10</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)._symbol-interned~3f))"></a><span title="Provided from: racket/base, racket | Package: base"><span class="RktSym"><a href="#%28def._%28%28quote._~23~25kernel%29._symbol-interned~3f%29%29" class="RktValDef RktValLink" data-pltdoc="x">symbol-interned?</a></span></span><span class="hspace"> </span><span class="RktVar">sym</span><span class="RktPn">)</span><span class="hspace"> </span>→<span class="hspace"> </span><span class="RktSym"><a href="booleans.html#%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">sym</span><span class="hspace"> </span>:<span class="hspace"> </span><span class="RktSym"><a href="#%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="RktVal">#t</span> if <span class="RktVar">sym</span> is
<a href="reader.html#%28tech._interned%29" class="techoutside" data-pltdoc="x"><span class="techinside">interned</span></a>, <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._symbol-interned~3f%29%29" class="RktValLink" data-pltdoc="x">symbol-interned?</a></span><span class="hspace"> </span><span class="RktVal">'</span><span class="RktVal">Apple</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._symbol-interned~3f%29%29" class="RktValLink" data-pltdoc="x">symbol-interned?</a></span><span class="hspace"> </span><span class="RktPn">(</span><span class="RktSym"><a href="#%28def._%28%28quote._~23~25kernel%29._gensym%29%29" class="RktValLink" data-pltdoc="x">gensym</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._symbol-interned~3f%29%29" class="RktValLink" data-pltdoc="x">symbol-interned?</a></span><span class="hspace"> </span><span class="RktPn">(</span><span class="RktSym"><a href="#%28def._%28%28quote._~23~25kernel%29._string-~3eunreadable-symbol%29%29" class="RktValLink" data-pltdoc="x">string->unreadable-symbol</a></span><span class="hspace"> </span><span class="RktVal">"Apple"</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)._symbol-unreadable~3f))"></a><span title="Provided from: racket/base, racket | Package: base"><span class="RktSym"><a href="#%28def._%28%28quote._~23~25kernel%29._symbol-unreadable~3f%29%29" class="RktValDef RktValLink" data-pltdoc="x">symbol-unreadable?</a></span></span><span class="hspace"> </span><span class="RktVar">sym</span><span class="RktPn">)</span><span class="hspace"> </span>→<span class="hspace"> </span><span class="RktSym"><a href="booleans.html#%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">sym</span><span class="hspace"> </span>:<span class="hspace"> </span><span class="RktSym"><a href="#%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="RktVal">#t</span> if <span class="RktVar">sym</span> is
an <a href="#%28tech._unreadable._symbol%29" class="techoutside" data-pltdoc="x"><span class="techinside">unreadable symbol</span></a>, <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._symbol-unreadable~3f%29%29" class="RktValLink" data-pltdoc="x">symbol-unreadable?</a></span><span class="hspace"> </span><span class="RktVal">'</span><span class="RktVal">Apple</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._symbol-unreadable~3f%29%29" class="RktValLink" data-pltdoc="x">symbol-unreadable?</a></span><span class="hspace"> </span><span class="RktPn">(</span><span class="RktSym"><a href="#%28def._%28%28quote._~23~25kernel%29._gensym%29%29" class="RktValLink" data-pltdoc="x">gensym</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._symbol-unreadable~3f%29%29" class="RktValLink" data-pltdoc="x">symbol-unreadable?</a></span><span class="hspace"> </span><span class="RktPn">(</span><span class="RktSym"><a href="#%28def._%28%28quote._~23~25kernel%29._string-~3eunreadable-symbol%29%29" class="RktValLink" data-pltdoc="x">string->unreadable-symbol</a></span><span class="hspace"> </span><span class="RktVal">"Apple"</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)._symbol-~3estring))"></a><span title="Provided from: racket/base, racket | Package: base"><span class="RktSym"><a href="#%28def._%28%28quote._~23~25kernel%29._symbol-~3estring%29%29" class="RktValDef RktValLink" data-pltdoc="x">symbol->string</a></span></span><span class="hspace"> </span><span class="RktVar">sym</span><span class="RktPn">)</span><span class="hspace"> </span>→<span class="hspace"> </span><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></p></blockquote></td></tr><tr><td><span class="hspace"> </span><span class="RktVar">sym</span><span class="hspace"> </span>:<span class="hspace"> </span><span class="RktSym"><a href="#%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 a freshly
allocated mutable string whose characters are the same as in
<span class="RktVar">sym</span>.</div></p><p><table cellspacing="0" cellpadding="0" class="RktBlk"><tr><td><p>Example:</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._symbol-~3estring%29%29" class="RktValLink" data-pltdoc="x">symbol->string</a></span><span class="hspace"> </span><span class="RktVal">'</span><span class="RktVal">Apple</span><span class="RktPn">)</span></td></tr><tr><td><p><span class="RktRes">"Apple"</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)._string-~3esymbol))"></a><span title="Provided from: racket/base, racket | Package: base"><span class="RktSym"><a href="#%28def._%28%28quote._~23~25kernel%29._string-~3esymbol%29%29" class="RktValDef RktValLink" data-pltdoc="x">string->symbol</a></span></span><span class="hspace"> </span><span class="RktVar">str</span><span class="RktPn">)</span><span class="hspace"> </span>→<span class="hspace"> </span><span class="RktSym"><a href="#%28def._%28%28quote._~23~25kernel%29._symbol~3f%29%29" class="RktValLink" data-pltdoc="x">symbol?</a></span></p></blockquote></td></tr><tr><td><span class="hspace"> </span><span class="RktVar">str</span><span class="hspace"> </span>:<span class="hspace"> </span><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></td></tr></table></blockquote></div><div class="SIntrapara">Returns an
<a href="reader.html#%28tech._interned%29" class="techoutside" data-pltdoc="x"><span class="techinside">interned</span></a> symbol whose characters are the same as in
<span class="RktVar">str</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._string-~3esymbol%29%29" class="RktValLink" data-pltdoc="x">string->symbol</a></span><span class="hspace"> </span><span class="RktVal">"Apple"</span><span class="RktPn">)</span></td></tr><tr><td><p><span class="RktRes">'Apple</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._string-~3esymbol%29%29" class="RktValLink" data-pltdoc="x">string->symbol</a></span><span class="hspace"> </span><span class="RktVal">"1"</span><span class="RktPn">)</span></td></tr><tr><td><p><span class="RktRes">'|1|</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)._string-~3euninterned-symbol))"></a><span title="Provided from: racket/base, racket | Package: base"><span class="RktSym"><a href="#%28def._%28%28quote._~23~25kernel%29._string-~3euninterned-symbol%29%29" class="RktValDef RktValLink" data-pltdoc="x">string->uninterned-symbol</a></span></span><span class="hspace"> </span><span class="RktVar">str</span><span class="RktPn">)</span><span class="hspace"> </span>→<span class="hspace"> </span><span class="RktSym"><a href="#%28def._%28%28quote._~23~25kernel%29._symbol~3f%29%29" class="RktValLink" data-pltdoc="x">symbol?</a></span></p></blockquote></td></tr><tr><td><span class="hspace"> </span><span class="RktVar">str</span><span class="hspace"> </span>:<span class="hspace"> </span><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></td></tr></table></blockquote></div><div class="SIntrapara">Like
<span class="RktPn">(</span><span class="RktSym"><a href="#%28def._%28%28quote._~23~25kernel%29._string-~3esymbol%29%29" class="RktValLink" data-pltdoc="x">string->symbol</a></span><span class="stt"> </span><span class="RktVar">str</span><span class="RktPn">)</span>, but the resulting symbol is a new
<a href="#%28tech._uninterned%29" class="techoutside" data-pltdoc="x"><span class="techinside">uninterned</span></a> symbol. Calling <span class="RktSym"><a href="#%28def._%28%28quote._~23~25kernel%29._string-~3euninterned-symbol%29%29" class="RktValLink" data-pltdoc="x">string->uninterned-symbol</a></span>
twice with the same <span class="RktVar">str</span> returns two distinct symbols.</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._string-~3euninterned-symbol%29%29" class="RktValLink" data-pltdoc="x">string->uninterned-symbol</a></span><span class="hspace"> </span><span class="RktVal">"Apple"</span><span class="RktPn">)</span></td></tr><tr><td><p><span class="RktRes">'Apple</span></p></td></tr><tr><td><span class="stt">> </span><span class="RktPn">(</span><span class="RktSym"><a href="booleans.html#%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">a</span><span class="hspace"> </span><span class="RktPn">(</span><span class="RktSym"><a href="#%28def._%28%28quote._~23~25kernel%29._string-~3euninterned-symbol%29%29" class="RktValLink" data-pltdoc="x">string->uninterned-symbol</a></span><span class="hspace"> </span><span class="RktVal">"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><table cellspacing="0" cellpadding="0" class="RktBlk"><tr><td><span class="stt">> </span><span class="RktPn">(</span><span class="RktSym"><a href="booleans.html#%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="#%28def._%28%28quote._~23~25kernel%29._string-~3euninterned-symbol%29%29" class="RktValLink" data-pltdoc="x">string->uninterned-symbol</a></span><span class="hspace"> </span><span class="RktVal">"a"</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="#%28def._%28%28quote._~23~25kernel%29._string-~3euninterned-symbol%29%29" class="RktValLink" data-pltdoc="x">string->uninterned-symbol</a></span><span class="hspace"> </span><span class="RktVal">"a"</span><span class="RktPn">)</span><span class="RktPn">)</span></td></tr></table></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)._string-~3eunreadable-symbol))"></a><span title="Provided from: racket/base, racket | Package: base"><span class="RktSym"><a href="#%28def._%28%28quote._~23~25kernel%29._string-~3eunreadable-symbol%29%29" class="RktValDef RktValLink" data-pltdoc="x">string->unreadable-symbol</a></span></span><span class="hspace"> </span><span class="RktVar">str</span><span class="RktPn">)</span><span class="hspace"> </span>→<span class="hspace"> </span><span class="RktSym"><a href="#%28def._%28%28quote._~23~25kernel%29._symbol~3f%29%29" class="RktValLink" data-pltdoc="x">symbol?</a></span></p></blockquote></td></tr><tr><td><span class="hspace"> </span><span class="RktVar">str</span><span class="hspace"> </span>:<span class="hspace"> </span><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></td></tr></table></blockquote></div><div class="SIntrapara">Like
<span class="RktPn">(</span><span class="RktSym"><a href="#%28def._%28%28quote._~23~25kernel%29._string-~3esymbol%29%29" class="RktValLink" data-pltdoc="x">string->symbol</a></span><span class="stt"> </span><span class="RktVar">str</span><span class="RktPn">)</span>, but the resulting symbol is a new
<a href="#%28tech._unreadable._symbol%29" class="techoutside" data-pltdoc="x"><span class="techinside">unreadable symbol</span></a>. Calling <span class="RktSym"><a href="#%28def._%28%28quote._~23~25kernel%29._string-~3eunreadable-symbol%29%29" class="RktValLink" data-pltdoc="x">string->unreadable-symbol</a></span>
twice with equivalent <span class="RktVar">str</span>s returns the same symbol, but
<span class="RktSym"><a href="Reading.html#%28def._%28%28quote._~23~25kernel%29._read%29%29" class="RktValLink" data-pltdoc="x">read</a></span> never produces the symbol.</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._string-~3eunreadable-symbol%29%29" class="RktValLink" data-pltdoc="x">string->unreadable-symbol</a></span><span class="hspace"> </span><span class="RktVal">"Apple"</span><span class="RktPn">)</span></td></tr><tr><td><p><span class="RktRes">'Apple</span></p></td></tr><tr><td><span class="stt">> </span><span class="RktPn">(</span><span class="RktSym"><a href="booleans.html#%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">a</span><span class="hspace"> </span><span class="RktPn">(</span><span class="RktSym"><a href="#%28def._%28%28quote._~23~25kernel%29._string-~3eunreadable-symbol%29%29" class="RktValLink" data-pltdoc="x">string->unreadable-symbol</a></span><span class="hspace"> </span><span class="RktVal">"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><table cellspacing="0" cellpadding="0" class="RktBlk"><tr><td><span class="stt">> </span><span class="RktPn">(</span><span class="RktSym"><a href="booleans.html#%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="#%28def._%28%28quote._~23~25kernel%29._string-~3eunreadable-symbol%29%29" class="RktValLink" data-pltdoc="x">string->unreadable-symbol</a></span><span class="hspace"> </span><span class="RktVal">"a"</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="#%28def._%28%28quote._~23~25kernel%29._string-~3eunreadable-symbol%29%29" class="RktValLink" data-pltdoc="x">string->unreadable-symbol</a></span><span class="hspace"> </span><span class="RktVal">"a"</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)._gensym))"></a><span title="Provided from: racket/base, racket | Package: base"><span class="RktSym"><a href="#%28def._%28%28quote._~23~25kernel%29._gensym%29%29" class="RktValDef RktValLink" data-pltdoc="x">gensym</a></span></span><span class="hspace"> </span>[<span class="RktVar">base</span>]<span class="RktPn">)</span><span class="hspace"> </span>→<span class="hspace"> </span><span class="RktSym"><a href="#%28def._%28%28quote._~23~25kernel%29._symbol~3f%29%29" class="RktValLink" data-pltdoc="x">symbol?</a></span></p></blockquote></td></tr><tr><td><span class="hspace"> </span><span class="RktVar">base</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%2Fbase..rkt%29._or%2Fc%29%29" class="RktValLink" data-pltdoc="x">or/c</a></span><span class="hspace"> </span><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="hspace"> </span><span class="RktSym"><a href="#%28def._%28%28quote._~23~25kernel%29._symbol~3f%29%29" class="RktValLink" data-pltdoc="x">symbol?</a></span><span class="RktPn">)</span><span class="hspace"> </span>=<span class="hspace"> </span><span class="RktVal">"g"</span></td></tr></table></blockquote></div><div class="SIntrapara">Returns a
new <a href="#%28tech._uninterned%29" class="techoutside" data-pltdoc="x"><span class="techinside">uninterned</span></a> symbol with an automatically-generated name. The
optional <span class="RktVar">base</span> argument is a prefix symbol or string.</div></p><p><table cellspacing="0" cellpadding="0" class="RktBlk"><tr><td><p>Example:</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._gensym%29%29" class="RktValLink" data-pltdoc="x">gensym</a></span><span class="hspace"> </span><span class="RktVal">"apple"</span><span class="RktPn">)</span></td></tr><tr><td><p><span class="RktRes">'apple1143</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)._symbol~3c~3f))"></a><span title="Provided from: racket/base, racket | Package: base"><span class="RktSym"><a href="#%28def._%28%28quote._~23~25kernel%29._symbol~3c~3f%29%29" class="RktValDef RktValLink" data-pltdoc="x">symbol<?</a></span></span><span class="hspace"> </span><span class="RktVar">a-sym</span><span class="hspace"> </span><span class="RktVar">b-sym</span><span class="hspace"> </span><span class="RktMeta">...</span><span class="RktPn">)</span><span class="hspace"> </span>→<span class="hspace"> </span><span class="RktSym"><a href="booleans.html#%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-sym</span><span class="hspace"> </span>:<span class="hspace"> </span><span class="RktSym"><a href="#%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-sym</span><span class="hspace"> </span>:<span class="hspace"> </span><span class="RktSym"><a href="#%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="RktVal">#t</span> if the arguments are sorted, where the comparison
for each pair of symbols is the same as using
<span class="RktSym"><a href="#%28def._%28%28quote._~23~25kernel%29._symbol-~3estring%29%29" class="RktValLink" data-pltdoc="x">symbol->string</a></span> with <span class="RktSym"><a href="bytestrings.html#%28def._%28%28quote._~23~25kernel%29._string-~3ebytes%2Futf-8%29%29" class="RktValLink" data-pltdoc="x">string->bytes/utf-8</a></span> and
<span class="RktSym"><a href="bytestrings.html#%28def._%28%28quote._~23~25kernel%29._bytes~3c~3f%29%29" class="RktValLink" data-pltdoc="x">bytes<?</a></span>.</div></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="characters.html" title="backward to "4.5 Characters"" data-pltdoc="x">← prev</a> <a href="data.html" title="up to "4 Datatypes"" data-pltdoc="x">up</a> <a href="regexp.html" title="forward to "4.7 Regular Expressions"" data-pltdoc="x">next →</a></span> </div></div></div><div id="contextindicator"> </div></body></html>
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