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<html><head><meta http-equiv="content-type" content="text/html; charset=utf-8"/><title>13.7.1 Readtables</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="tocviewlink" 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="tocviewselflink" 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>13 </td><td><a href="input-and-output.html" class="tocviewlink" data-pltdoc="x">Input and Output</a></td></tr></table><div class="tocviewsublist" style="display: none;" id="tocview_1"><table cellspacing="0" cellpadding="0"><tr><td align="right">13.1 </td><td><a href="ports.html" class="tocviewlink" data-pltdoc="x">Ports</a></td></tr><tr><td align="right">13.2 </td><td><a href="Byte_and_String_Input.html" class="tocviewlink" data-pltdoc="x">Byte and String Input</a></td></tr><tr><td align="right">13.3 </td><td><a href="Byte_and_String_Output.html" class="tocviewlink" data-pltdoc="x">Byte and String Output</a></td></tr><tr><td align="right">13.4 </td><td><a href="Reading.html" class="tocviewlink" data-pltdoc="x">Reading</a></td></tr><tr><td align="right">13.5 </td><td><a href="Writing.html" class="tocviewlink" data-pltdoc="x">Writing</a></td></tr><tr><td align="right">13.6 </td><td><a href="pretty-print.html" class="tocviewlink" data-pltdoc="x">Pretty Printing</a></td></tr><tr><td align="right">13.7 </td><td><a href="Reader_Extension.html" class="tocviewselflink" data-pltdoc="x">Reader Extension</a></td></tr><tr><td align="right">13.8 </td><td><a href="Printer_Extension.html" class="tocviewlink" data-pltdoc="x">Printer Extension</a></td></tr><tr><td align="right">13.9 </td><td><a href="serialization.html" class="tocviewlink" data-pltdoc="x">Serialization</a></td></tr><tr><td align="right">13.10 </td><td><a href="fasl.html" class="tocviewlink" data-pltdoc="x">Fast-<wbr></wbr>Load Serialization</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>13.7 </td><td><a href="Reader_Extension.html" class="tocviewlink" data-pltdoc="x">Reader Extension</a></td></tr></table><div class="tocviewsublistbottom" style="display: block;" id="tocview_2"><table cellspacing="0" cellpadding="0"><tr><td align="right">13.7.1 </td><td><a href="" class="tocviewselflink" data-pltdoc="x">Readtables</a></td></tr><tr><td align="right">13.7.2 </td><td><a href="reader-procs.html" class="tocviewlink" data-pltdoc="x">Reader-<wbr></wbr>Extension Procedures</a></td></tr><tr><td align="right">13.7.3 </td><td><a href="special-comments.html" class="tocviewlink" data-pltdoc="x">Special Comments</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._readtable~3f%29%29" class="tocsublink" data-pltdoc="x"><span class="RktSym"><span class="RktValLink">readtable?</span></span></a></td></tr><tr><td><a href="#%28def._%28%28quote._~23~25kernel%29._make-readtable%29%29" class="tocsublink" data-pltdoc="x"><span class="RktSym"><span class="RktValLink">make-<wbr></wbr>readtable</span></span></a></td></tr><tr><td><a href="#%28def._%28%28quote._~23~25kernel%29._readtable-mapping%29%29" class="tocsublink" data-pltdoc="x"><span class="RktSym"><span class="RktValLink">readtable-<wbr></wbr>mapping</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, "6.7", "../");" 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("6.7");">top</a></span><span class="navright"> <a href="Reader_Extension.html" title="backward to "13.7 Reader Extension"" data-pltdoc="x">← prev</a> <a href="Reader_Extension.html" title="up to "13.7 Reader Extension"" data-pltdoc="x">up</a> <a href="reader-procs.html" title="forward to "13.7.2 Reader-Extension Procedures"" data-pltdoc="x">next →</a></span> </div><h5 x-source-module="(lib "scribblings/reference/reference.scrbl")" x-source-pkg="racket-doc" x-part-tag=""readtables"">13.7.1<tt> </tt><a name="(part._readtables)"></a>Readtables</h5><p>The dispatch table in <a href="reader.html#%28part._default-readtable-dispatch%29" data-pltdoc="x">Delimiters and Dispatch</a>
corresponds to the default <a name="(tech._readtable)"></a><span style="font-style: italic">readtable</span>. By creating a new
readtable and installing it via the <span class="RktSym"><a href="Reading.html#%28def._%28%28quote._~23~25kernel%29._current-readtable%29%29" class="RktValLink" data-pltdoc="x">current-readtable</a></span>
parameter, the reader’s behavior can be extended.</p><p>A readtable is consulted at specific times by the reader:</p><ul><li><p>when looking for the start of a datum;</p></li><li><p>when determining how to parse a datum that starts with
<span class="RktInBG"><span class="hspace"></span><span class="RktIn">#</span><span class="hspace"></span></span>;</p></li><li><p>when looking for a delimiter to terminate a symbol or number;</p></li><li><p>when looking for an opener (such as <span class="RktInBG"><span class="hspace"></span><span class="RktIn">(</span><span class="hspace"></span></span>), closer (such
as <span class="RktInBG"><span class="hspace"></span><span class="RktIn">)</span><span class="hspace"></span></span>), or <span class="RktInBG"><span class="hspace"></span><span class="RktIn">.</span><span class="hspace"></span></span> after the first character parsed as
a sequence for a pair, list, vector, or hash table; or</p></li><li><p>when looking for an opener after <span class="RktInBG"><span class="hspace"></span><span class="RktIn">#</span><span class="hspace"></span></span><span class="sroman">‹<span style="font-style: italic">n</span>›</span> in a
vector of specified length <span class="sroman">‹<span style="font-style: italic">n</span>›</span>.</p></li></ul><p>The readtable is ignored at other times. In particular, after parsing
a character that is mapped to the default behavior of <span class="RktInBG"><span class="hspace"></span><span class="RktIn">;</span><span class="hspace"></span></span>, the
readtable is ignored until the comment’s terminating newline is
discovered. Similarly, the readtable does not affect string parsing
until a closing double-quote is found. Meanwhile, if a character is
mapped to the default behavior of <span class="RktInBG"><span class="hspace"></span><span class="RktIn">(</span><span class="hspace"></span></span>, then it starts sequence
that is closed by any character that is mapped to a closing parenthesis
<span class="RktInBG"><span class="hspace"></span><span class="RktIn">)</span><span class="hspace"></span></span>. An apparent exception is that the default parsing of
<span class="RktInBG"><span class="hspace"></span><span class="RktIn">|</span><span class="hspace"></span></span> quotes a symbol until a matching character is found, but
the parser is simply using the character that started the quote; it
does not consult the readtable.</p><p>For many contexts, <span class="RktVal">#f</span> identifies the default readtable. In
particular, <span class="RktVal">#f</span> is the initial value for the
<span class="RktSym"><a href="Reading.html#%28def._%28%28quote._~23~25kernel%29._current-readtable%29%29" class="RktValLink" data-pltdoc="x">current-readtable</a></span> parameter, which causes the reader to
behave as described in <a href="reader.html" data-pltdoc="x">The Reader</a>.</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)._readtable~3f))"></a><span title="Provided from: racket/base, racket | Package: base"><span class="RktSym"><a href="#%28def._%28%28quote._~23~25kernel%29._readtable~3f%29%29" class="RktValDef RktValLink" data-pltdoc="x">readtable?</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 readtable, <span class="RktVal">#f</span>
otherwise.</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><table cellspacing="0" cellpadding="0" class="prototype RForeground"><tr><td valign="top"><span class="RktPn">(</span><a name="(def._((quote._~23~25kernel)._make-readtable))"></a><span title="Provided from: racket/base, racket | Package: base"><span class="RktSym"><a href="#%28def._%28%28quote._~23~25kernel%29._make-readtable%29%29" class="RktValDef RktValLink" data-pltdoc="x">make-readtable</a></span></span></td><td valign="top"><span class="hspace"> </span></td><td valign="top"><span class="RktVar">readtable</span></td><td valign="top"><span class="hspace"> </span></td><td valign="top"><span class="hspace"> </span></td><td valign="top"><span class="hspace"> </span></td><td valign="top"><span class="hspace"> </span></td></tr><tr><td valign="top"><span class="hspace"> </span></td><td valign="top"><span class="hspace"> </span></td><td valign="top"><span class="RktVar">key</span></td><td valign="top"><span class="hspace"> </span></td><td valign="top"><span class="hspace"> </span></td><td valign="top"><span class="hspace"> </span></td><td valign="top"><span class="hspace"> </span></td></tr><tr><td valign="top"><span class="hspace"> </span></td><td valign="top"><span class="hspace"> </span></td><td valign="top"><span class="RktVar">mode</span></td><td valign="top"><span class="hspace"> </span></td><td valign="top"><span class="hspace"> </span></td><td valign="top"><span class="hspace"> </span></td><td valign="top"><span class="hspace"> </span></td></tr><tr><td valign="top"><span class="hspace"> </span></td><td valign="top"><span class="hspace"> </span></td><td valign="top"><span class="RktVar">action</span><span class="hspace"> </span><span class="RktMeta">...+</span><span class="RktPn">)</span></td><td valign="top"><span class="hspace"> </span></td><td valign="top">→</td><td valign="top"><span class="hspace"> </span></td><td valign="top"><span class="RktSym"><a href="#%28def._%28%28quote._~23~25kernel%29._readtable~3f%29%29" class="RktValLink" data-pltdoc="x">readtable?</a></span></td></tr></table></blockquote></td></tr><tr><td><span class="hspace"> </span><span class="RktVar">readtable</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="#%28def._%28%28quote._~23~25kernel%29._readtable~3f%29%29" class="RktValLink" data-pltdoc="x">readtable?</a></span><span class="hspace"> </span><span class="RktVal">#f</span><span class="RktPn">)</span></td></tr><tr><td><span class="hspace"> </span><span class="RktVar">key</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="characters.html#%28def._%28%28quote._~23~25kernel%29._char~3f%29%29" class="RktValLink" data-pltdoc="x">char?</a></span><span class="hspace"> </span><span class="RktVal">#f</span><span class="RktPn">)</span></td></tr><tr><td><table cellspacing="0" cellpadding="0" class="argcontract"><tr><td valign="top"><span class="hspace"> </span></td><td valign="top"><span class="RktVar">mode</span></td><td valign="top"><span class="hspace"> </span></td><td valign="top">:</td><td valign="top"><span class="hspace"> </span></td><td valign="top"><table cellspacing="0" cellpadding="0" class="RktBlk"><tr><td><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="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="RktVal">'</span><span class="RktVal">terminating-macro</span></td></tr><tr><td><span class="hspace"> </span><span class="RktVal">'</span><span class="RktVal">non-terminating-macro</span></td></tr><tr><td><span class="hspace"> </span><span class="RktVal">'</span><span class="RktVal">dispatch-macro</span><span class="RktPn">)</span></td></tr><tr><td><span class="hspace"> </span><span class="RktSym"><a href="characters.html#%28def._%28%28quote._~23~25kernel%29._char~3f%29%29" class="RktValLink" data-pltdoc="x">char?</a></span><span class="RktPn">)</span></td></tr></table></td></tr></table></td></tr><tr><td><table cellspacing="0" cellpadding="0" class="argcontract"><tr><td valign="top"><span class="hspace"> </span></td><td valign="top"><span class="RktVar">action</span></td><td valign="top"><span class="hspace"> </span></td><td valign="top">:</td><td valign="top"><span class="hspace"> </span></td><td valign="top"><table cellspacing="0" cellpadding="0" class="RktBlk"><tr><td><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="procedures.html#%28def._%28%28quote._~23~25kernel%29._procedure~3f%29%29" class="RktValLink" data-pltdoc="x">procedure?</a></span></td></tr><tr><td><span class="hspace"> </span><span class="RktSym"><a href="#%28def._%28%28quote._~23~25kernel%29._readtable~3f%29%29" class="RktValLink" data-pltdoc="x">readtable?</a></span><span class="RktPn">)</span></td></tr></table></td></tr></table></td></tr></table></blockquote></div><div class="SIntrapara">Creates a new readtable that is like <span class="RktVar">readtable</span> (which can be
<span class="RktVal">#f</span>), except that the reader’s behavior is modified for each
<span class="RktVar">key</span> according to the given <span class="RktVar">mode</span> and
<span class="RktVar">action</span>. The <span class="RktSym">...+</span> for <span class="RktSym"><a href="#%28def._%28%28quote._~23~25kernel%29._make-readtable%29%29" class="RktValLink" data-pltdoc="x">make-readtable</a></span> applies
to all three of <span class="RktVar">key</span>, <span class="RktVar">mode</span>, and <span class="RktVar">action</span>; in
other words, the total number of arguments to <span class="RktSym"><a href="#%28def._%28%28quote._~23~25kernel%29._make-readtable%29%29" class="RktValLink" data-pltdoc="x">make-readtable</a></span>
must be <span style="font-style: italic"></span>1<span style="font-style: italic"></span> modulo <span style="font-style: italic"></span>3<span style="font-style: italic"></span>.</div></p><p>The possible combinations for <span class="RktVar">key</span>, <span class="RktVar">mode</span>, and
<span class="RktVar">action</span> are as follows:</p><ul><li><p><span class="RktVar">char</span><span class="stt"> </span><a name="(idx._(gentag._239._(lib._scribblings/reference/reference..scrbl)))"></a><span class="RktVal">'</span><span class="RktVal">terminating-macro</span><span class="stt"> </span><span class="RktVar">proc</span> —<wbr></wbr> causes
<span class="RktVar">char</span> to be parsed as a delimiter, and an
unquoted/uncommented <span class="RktVar">char</span> in the input string triggers a
call to the <a name="(tech._reader._macro)"></a><span style="font-style: italic">reader macro</span> <span class="RktVar">proc</span>; the activity of
<span class="RktVar">proc</span> is described further below. Conceptually, characters
like <span class="RktInBG"><span class="hspace"></span><span class="RktIn">;</span><span class="hspace"></span></span>, <span class="RktInBG"><span class="hspace"></span><span class="RktIn">(</span><span class="hspace"></span></span>, and <span class="RktInBG"><span class="hspace"></span><span class="RktIn">)</span><span class="hspace"></span></span> are mapped to
terminating reader macros in the default readtable.</p></li><li><p><span class="RktVar">char</span><span class="stt"> </span><a name="(idx._(gentag._240._(lib._scribblings/reference/reference..scrbl)))"></a><span class="RktVal">'</span><span class="RktVal">non-terminating-macro</span><span class="stt"> </span><span class="RktVar">proc</span> —<wbr></wbr> like
the <span class="RktVal">'</span><span class="RktVal">terminating-macro</span> variant, but <span class="RktVar">char</span> is not
treated as a delimiter, so it can be used in the middle of an
identifier or number. Conceptually, <span class="RktInBG"><span class="hspace"></span><span class="RktIn">#</span><span class="hspace"></span></span> is mapped to a
non-terminating macro in the default readtable.</p></li><li><p><span class="RktVar">char</span><span class="stt"> </span><a name="(idx._(gentag._241._(lib._scribblings/reference/reference..scrbl)))"></a><span class="RktVal">'</span><span class="RktVal">dispatch-macro</span><span class="stt"> </span><span class="RktVar">proc</span> —<wbr></wbr> like the
<span class="RktVal">'</span><span class="RktVal">non-terminating-macro</span> variant, but for <span class="RktVar">char</span> only
when it follows a <span class="RktInBG"><span class="hspace"></span><span class="RktIn">#</span><span class="hspace"></span></span> (or, more precisely, when the character
follows one that has been mapped to the behavior of <span class="RktInBG"><span class="hspace"></span><span class="RktIn">#</span><span class="hspace"></span></span>
in the default readtable).</p></li><li><p><span class="RktVar">char</span><span class="stt"> </span><span class="RktVar">like-char</span><span class="stt"> </span><span class="RktVar">readtable</span> —<wbr></wbr> causes
<span class="RktVar">char</span> to be parsed in the same way that <span class="RktVar">like-char</span>
is parsed in <span class="RktVar">readtable</span>, where <span class="RktVar">readtable</span> can be
<span class="RktVal">#f</span> to indicate the default readtable. Mapping a character to
the same actions as <span class="RktInBG"><span class="hspace"></span><span class="RktIn">|</span><span class="hspace"></span></span> in the default reader means that the
character starts quoting for symbols, and the same character
terminates the quote; in contrast, mapping a character to the same
action as a <span class="RktInBG"><span class="hspace"></span><span class="RktIn">"</span><span class="hspace"></span></span> means that the character starts a string, but
the string is still terminated with a closing <span class="RktInBG"><span class="hspace"></span><span class="RktIn">"</span><span class="hspace"></span></span>. Finally,
mapping a character to an action in the default readtable means that
the character’s behavior is sensitive to parameters that affect the
original character; for example, mapping a character to the same
action as a curly brace <span class="RktInBG"><span class="hspace"></span><span class="RktIn">{</span><span class="hspace"></span></span> in the default readtable means
that the character is disallowed when the
<span class="RktSym"><a href="Reading.html#%28def._%28%28quote._~23~25kernel%29._read-curly-brace-as-paren%29%29" class="RktValLink" data-pltdoc="x">read-curly-brace-as-paren</a></span> parameter is set to <span class="RktVal">#f</span>.</p></li><li><p><span class="RktVal">#f</span><span class="stt"> </span><a name="(idx._(gentag._242._(lib._scribblings/reference/reference..scrbl)))"></a><span class="RktVal">'</span><span class="RktVal">non-terminating-macro</span><span class="stt"> </span><span class="RktVar">proc</span> —<wbr></wbr>
replaces the macro used to parse characters with no specific mapping:
i.e., the characters (other than <span class="RktInBG"><span class="hspace"></span><span class="RktIn">#</span><span class="hspace"></span></span> or <span class="RktInBG"><span class="hspace"></span><span class="RktIn">|</span><span class="hspace"></span></span>) that can
start a symbol or number with the default readtable.</p></li></ul><p>If multiple <span class="RktVal">'</span><span class="RktVal">dispatch-macro</span> mappings are provided for a
single <span class="RktVar">char</span>, all but the last one are ignored. Similarly, if
multiple non-<span class="RktVal">'</span><span class="RktVal">dispatch-macro</span> mappings are provided for a
single <span class="RktVar">char</span>, all but the last one are ignored.</p><p>A reader macro <span class="RktVar">proc</span> must accept six arguments, and it can
optionally accept two arguments. The first two arguments are always
the character that triggered the reader macro and the input port for
reading. When the reader macro is triggered by <span class="RktSym"><a href="Reading.html#%28def._%28%28quote._~23~25kernel%29._read-syntax%29%29" class="RktValLink" data-pltdoc="x">read-syntax</a></span>
(or <span class="RktSym"><a href="Reading.html#%28def._%28%28quote._~23~25kernel%29._read-syntax%2Frecursive%29%29" class="RktValLink" data-pltdoc="x">read-syntax/recursive</a></span>), the procedure is passed four
additional arguments that represent a source location for
already-consumed character(s): the source name, a line number or
<span class="RktVal">#f</span>, a column number or <span class="RktVal">#f</span>, and a position or
<span class="RktVal">#f</span>. When the reader macro is triggered by <span class="RktSym"><a href="Reading.html#%28def._%28%28quote._~23~25kernel%29._read%29%29" class="RktValLink" data-pltdoc="x">read</a></span> (or
<span class="RktSym"><a href="Reading.html#%28def._%28%28quote._~23~25kernel%29._read%2Frecursive%29%29" class="RktValLink" data-pltdoc="x">read/recursive</a></span>), the procedure is passed only two arguments
if it accepts two arguments, otherwise it is passed six arguments
where the last four are all <span class="RktVal">#f</span>. See <a href="reader-procs.html" data-pltdoc="x">Reader-Extension Procedures</a>
for information on the procedure’s results.</p><p>A reader macro normally reads characters from the given input port to
produce a value to be used as the “reader macro-expansion” of the
consumed characters. The reader macro might produce a special-comment
value (see <a href="special-comments.html" data-pltdoc="x">Special Comments</a>) to cause the consumed
character to be treated as whitespace, and it might use
<span class="RktSym"><a href="Reading.html#%28def._%28%28quote._~23~25kernel%29._read%2Frecursive%29%29" class="RktValLink" data-pltdoc="x">read/recursive</a></span> or <span class="RktSym"><a href="Reading.html#%28def._%28%28quote._~23~25kernel%29._read-syntax%2Frecursive%29%29" class="RktValLink" data-pltdoc="x">read-syntax/recursive</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)._readtable-mapping))"></a><span title="Provided from: racket/base, racket | Package: base"><span class="RktSym"><a href="#%28def._%28%28quote._~23~25kernel%29._readtable-mapping%29%29" class="RktValDef RktValLink" data-pltdoc="x">readtable-mapping</a></span></span><span class="hspace"> </span><span class="RktVar">readtable</span><span class="hspace"> </span><span class="RktVar">char</span><span class="RktPn">)</span></p></blockquote></td></tr><tr><td><table cellspacing="0" cellpadding="0" class="prototype"><tr><td valign="top"><span class="hspace"> </span></td><td valign="top">→</td><td valign="top"><span class="hspace"> </span></td><td valign="top"><table cellspacing="0" cellpadding="0"><tr><td><table cellspacing="0" cellpadding="0" class="RktBlk"><tr><td><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="characters.html#%28def._%28%28quote._~23~25kernel%29._char~3f%29%29" class="RktValLink" data-pltdoc="x">char?</a></span></td></tr><tr><td><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="RktVal">'</span><span class="RktVal">terminating-macro</span></td></tr><tr><td><span class="hspace"> </span><span class="RktVal">'</span><span class="RktVal">non-terminating-macro</span><span class="RktPn">)</span><span class="RktPn">)</span></td></tr></table></td></tr><tr><td><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="RktVal">#f</span><span class="hspace"> </span><span class="RktSym"><a href="procedures.html#%28def._%28%28quote._~23~25kernel%29._procedure~3f%29%29" class="RktValLink" data-pltdoc="x">procedure?</a></span><span class="RktPn">)</span></td></tr><tr><td><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="RktVal">#f</span><span class="hspace"> </span><span class="RktSym"><a href="procedures.html#%28def._%28%28quote._~23~25kernel%29._procedure~3f%29%29" class="RktValLink" data-pltdoc="x">procedure?</a></span><span class="RktPn">)</span></td></tr></table></td></tr></table></td></tr><tr><td><span class="hspace"> </span><span class="RktVar">readtable</span><span class="hspace"> </span>:<span class="hspace"> </span><span class="RktSym"><a href="#%28def._%28%28quote._~23~25kernel%29._readtable~3f%29%29" class="RktValLink" data-pltdoc="x">readtable?</a></span></td></tr><tr><td><span class="hspace"> </span><span class="RktVar">char</span><span class="hspace"> </span>:<span class="hspace"> </span><span class="RktSym"><a href="characters.html#%28def._%28%28quote._~23~25kernel%29._char~3f%29%29" class="RktValLink" data-pltdoc="x">char?</a></span></td></tr></table></blockquote></div><div class="SIntrapara">Produces information about the mappings in <span class="RktVar">readtable</span> for
<span class="RktVar">char</span>. The result is three values:</div></p><ul><li><p>either a character (mapping to the same behavior as the
character in the default readtable), <span class="RktVal">'</span><span class="RktVal">terminating-macro</span>, or
<span class="RktVal">'</span><span class="RktVal">non-terminating-macro</span>; this result reports the main (i.e.,
non-<span class="RktVal">'</span><span class="RktVal">dispatch-macro</span>) mapping for <span class="RktVar">char</span>. When the result
is a character, then <span class="RktVar">char</span> is mapped to the same behavior as the
returned character in the default readtable.</p></li><li><p>either <span class="RktVal">#f</span> or a reader-macro procedure; the result is a
procedure when the first result is <span class="RktVal">'</span><span class="RktVal">terminating-macro</span> or
<span class="RktVal">'</span><span class="RktVal">non-terminating-macro</span>.</p></li><li><p>either <span class="RktVal">#f</span> or a reader-macro procedure; the result is a
procedure when the character has a <span class="RktVal">'</span><span class="RktVal">dispatch-macro</span> mapping in
<span class="RktVar">readtable</span> to override the default dispatch behavior.</p></li></ul><p>Note that reader-macro procedures for the default readtable are not
directly accessible. To invoke default behaviors, use
<span class="RktSym"><a href="Reading.html#%28def._%28%28quote._~23~25kernel%29._read%2Frecursive%29%29" class="RktValLink" data-pltdoc="x">read/recursive</a></span> or <span class="RktSym"><a href="Reading.html#%28def._%28%28quote._~23~25kernel%29._read-syntax%2Frecursive%29%29" class="RktValLink" data-pltdoc="x">read-syntax/recursive</a></span> with a
character and the <span class="RktVal">#f</span> readtable.</p><p><div class="SIntrapara">Examples:</div><div class="SIntrapara"><blockquote class="SCodeFlow"><table cellspacing="0" cellpadding="0" class="RktBlk"><tr><td><span class="RktCmt">;</span><span class="RktCmt"> </span><span class="RktCmt">Provides </span><span class="RktSym">raise-read-error</span><span class="RktCmt"> and </span><span class="RktSym">raise-read-eof-error</span></td></tr><tr><td><span class="stt">> </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="hspace"> </span><span class="RktSym">syntax/readerr</span><span class="RktPn">)</span></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">skip-whitespace</span><span class="hspace"> </span><span class="RktSym">port</span><span class="RktPn">)</span></td></tr><tr><td><span class="hspace"> </span><span class="hspace"> </span><span class="RktCmt">;</span><span class="RktCmt"> </span><span class="RktCmt">Skips whitespace characters, sensitive to the current</span></td></tr><tr><td><span class="hspace"> </span><span class="hspace"> </span><span class="RktCmt">;</span><span class="RktCmt"> </span><span class="RktCmt">readtable</span><span class="RktCmt">'</span><span class="RktCmt">s definition of whitespace</span></td></tr><tr><td><span class="hspace"> </span><span class="hspace"> </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">ch</span><span class="hspace"> </span><span class="RktPn">(</span><span class="RktSym"><a href="Byte_and_String_Input.html#%28def._%28%28quote._~23~25kernel%29._peek-char%29%29" class="RktValLink" data-pltdoc="x">peek-char</a></span><span class="hspace"> </span><span class="RktSym">port</span><span class="RktPn">)</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="when_unless.html#%28form._%28%28lib._racket%2Fprivate%2Fletstx-scheme..rkt%29._unless%29%29" class="RktStxLink" data-pltdoc="x">unless</a></span><span class="hspace"> </span><span class="RktPn">(</span><span class="RktSym"><a href="port-ops.html#%28def._%28%28quote._~23~25kernel%29._eof-object~3f%29%29" class="RktValLink" data-pltdoc="x">eof-object?</a></span><span class="hspace"> </span><span class="RktSym">ch</span><span class="RktPn">)</span></td></tr><tr><td><span class="hspace"> </span><span class="hspace"> </span><span class="RktCmt">;</span><span class="RktCmt"> </span><span class="RktCmt">Consult current readtable:</span></td></tr><tr><td><span class="hspace"> </span><span class="hspace"> </span><span class="RktPn">(</span><span class="RktSym"><a href="let.html#%28form._%28%28quote._~23~25kernel%29._let-values%29%29" class="RktStxLink" data-pltdoc="x">let-values</a></span><span class="hspace"> </span><span class="RktPn">(</span><span class="RktPn">[</span><span class="RktPn">(</span><span class="RktSym">like-ch/sym</span><span class="hspace"> </span><span class="RktSym">proc</span><span class="hspace"> </span><span class="RktSym">dispatch-proc</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._readtable-mapping%29%29" class="RktValLink" data-pltdoc="x">readtable-mapping</a></span><span class="hspace"> </span><span class="RktPn">(</span><span class="RktSym"><a href="Reading.html#%28def._%28%28quote._~23~25kernel%29._current-readtable%29%29" class="RktValLink" data-pltdoc="x">current-readtable</a></span><span class="RktPn">)</span><span class="hspace"> </span><span class="RktSym">ch</span><span class="RktPn">)</span><span class="RktPn">]</span><span class="RktPn">)</span></td></tr><tr><td><span class="hspace"> </span><span class="hspace"> </span><span class="RktCmt">;</span><span class="RktCmt"> </span><span class="RktCmt">If like-ch/sym is whitespace, then ch is whitespace</span></td></tr><tr><td><span class="hspace"> </span><span class="hspace"> </span><span class="RktPn">(</span><span class="RktSym"><a href="when_unless.html#%28form._%28%28lib._racket%2Fprivate%2Fletstx-scheme..rkt%29._when%29%29" class="RktStxLink" data-pltdoc="x">when</a></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="characters.html#%28def._%28%28quote._~23~25kernel%29._char~3f%29%29" class="RktValLink" data-pltdoc="x">char?</a></span><span class="hspace"> </span><span class="RktSym">like-ch/sym</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="characters.html#%28def._%28%28quote._~23~25kernel%29._char-whitespace~3f%29%29" class="RktValLink" data-pltdoc="x">char-whitespace?</a></span><span class="hspace"> </span><span class="RktSym">like-ch/sym</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="Byte_and_String_Input.html#%28def._%28%28quote._~23~25kernel%29._read-char%29%29" class="RktValLink" data-pltdoc="x">read-char</a></span><span class="hspace"> </span><span class="RktSym">port</span><span class="RktPn">)</span></td></tr><tr><td><span class="hspace"> </span><span class="hspace"> </span><span class="RktPn">(</span><span class="RktSym">skip-whitespace</span><span class="hspace"> </span><span class="RktSym">port</span><span class="RktPn">)</span><span class="RktPn">)</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" 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">skip-comments</span><span class="hspace"> </span><span class="RktSym">read-one</span><span class="hspace"> </span><span class="RktSym">port</span><span class="hspace"> </span><span class="RktSym">src</span><span class="RktPn">)</span></td></tr><tr><td><span class="hspace"> </span><span class="hspace"> </span><span class="RktCmt">;</span><span class="RktCmt"> </span><span class="RktCmt">Recursive read, but skip comments and detect EOF</span></td></tr><tr><td><span class="hspace"> </span><span class="hspace"> </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="RktSym">loop</span><span class="hspace"> </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="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">read-one</span><span class="RktPn">)</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="if.html#%28form._%28%28lib._racket%2Fprivate%2Fletstx-scheme..rkt%29._cond%29%29" class="RktStxLink" data-pltdoc="x">cond</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="special-comments.html#%28def._%28%28quote._~23~25kernel%29._special-comment~3f%29%29" class="RktValLink" data-pltdoc="x">special-comment?</a></span><span class="hspace"> </span><span class="RktSym">v</span><span class="RktPn">)</span><span class="hspace"> </span><span class="RktPn">(</span><span class="RktSym">loop</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="RktPn">(</span><span class="RktSym"><a href="port-ops.html#%28def._%28%28quote._~23~25kernel%29._eof-object~3f%29%29" class="RktValLink" data-pltdoc="x">eof-object?</a></span><span class="hspace"> </span><span class="RktSym">v</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="let.html#%28form._%28%28quote._~23~25kernel%29._let-values%29%29" class="RktStxLink" data-pltdoc="x">let-values</a></span><span class="hspace"> </span><span class="RktPn">(</span><span class="RktPn">[</span><span class="RktPn">(</span><span class="RktSym">l</span><span class="hspace"> </span><span class="RktSym">c</span><span class="hspace"> </span><span class="RktSym">p</span><span class="RktPn">)</span><span class="hspace"> </span><span class="RktPn">(</span><span class="RktSym"><a href="linecol.html#%28def._%28%28quote._~23~25kernel%29._port-next-location%29%29" class="RktValLink" data-pltdoc="x">port-next-location</a></span><span class="hspace"> </span><span class="RktSym">port</span><span class="RktPn">)</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">raise-read-eof-error</span></td></tr><tr><td><span class="hspace"> </span><span class="hspace"> </span><span class="RktVal">"unexpected EOF in tuple"</span><span class="hspace"> </span><span class="RktSym">src</span><span class="hspace"> </span><span class="RktSym">l</span><span class="hspace"> </span><span class="RktSym">c</span><span class="hspace"> </span><span class="RktSym">p</span><span class="hspace"> </span><span class="RktVal">1</span><span class="RktPn">)</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="if.html#%28form._%28%28lib._racket%2Fprivate%2Fletstx-scheme..rkt%29._else%29%29" class="RktStxLink" data-pltdoc="x">else</a></span><span class="hspace"> </span><span class="RktSym">v</span><span class="RktPn">]</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" 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">parse</span><span class="hspace"> </span><span class="RktSym">port</span><span class="hspace"> </span><span class="RktSym">read-one</span><span class="hspace"> </span><span class="RktSym">src</span><span class="RktPn">)</span></td></tr><tr><td><span class="hspace"> </span><span class="hspace"> </span><span class="RktCmt">;</span><span class="RktCmt"> </span><span class="RktCmt">First, check for empty tuple</span></td></tr><tr><td><span class="hspace"> </span><span class="hspace"> </span><span class="RktPn">(</span><span class="RktSym">skip-whitespace</span><span class="hspace"> </span><span class="RktSym">port</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%28quote._~23~25kernel%29._if%29%29" class="RktStxLink" data-pltdoc="x">if</a></span><span class="hspace"> </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="hspace"> </span><span class="RktPn">(</span><span class="RktSym"><a href="Byte_and_String_Input.html#%28def._%28%28quote._~23~25kernel%29._peek-char%29%29" class="RktValLink" data-pltdoc="x">peek-char</a></span><span class="hspace"> </span><span class="RktSym">port</span><span class="RktPn">)</span><span class="RktPn">)</span></td></tr><tr><td><span class="hspace"> </span><span class="hspace"> </span><span class="RktSym"><a href="pairs.html#%28def._%28%28quote._~23~25kernel%29._null%29%29" class="RktValLink" data-pltdoc="x">null</a></span></td></tr><tr><td><span class="hspace"> </span><span class="hspace"> </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">elem</span><span class="hspace"> </span><span class="RktPn">(</span><span class="RktSym">read-one</span><span class="RktPn">)</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="if.html#%28form._%28%28quote._~23~25kernel%29._if%29%29" class="RktStxLink" data-pltdoc="x">if</a></span><span class="hspace"> </span><span class="RktPn">(</span><span class="RktSym"><a href="special-comments.html#%28def._%28%28quote._~23~25kernel%29._special-comment~3f%29%29" class="RktValLink" data-pltdoc="x">special-comment?</a></span><span class="hspace"> </span><span class="RktSym">elem</span><span class="RktPn">)</span></td></tr><tr><td><span class="hspace"> </span><span class="hspace"> </span><span class="RktCmt">;</span><span class="RktCmt"> </span><span class="RktCmt">Found a comment, so look for > again</span></td></tr><tr><td><span class="hspace"> </span><span class="hspace"> </span><span class="RktPn">(</span><span class="RktSym">parse</span><span class="hspace"> </span><span class="RktSym">port</span><span class="hspace"> </span><span class="RktSym">read-one</span><span class="hspace"> </span><span class="RktSym">src</span><span class="RktPn">)</span></td></tr><tr><td><span class="hspace"> </span><span class="hspace"> </span><span class="RktCmt">;</span><span class="RktCmt"> </span><span class="RktCmt">Non-empty tuple:</span></td></tr><tr><td><span class="hspace"> </span><span class="hspace"> </span><span class="RktPn">(</span><span class="RktSym"><a href="pairs.html#%28def._%28%28quote._~23~25kernel%29._cons%29%29" class="RktValLink" data-pltdoc="x">cons</a></span><span class="hspace"> </span><span class="RktSym">elem</span></td></tr><tr><td><span class="hspace"> </span><span class="hspace"> </span><span class="RktPn">(</span><span class="RktSym">parse-nonempty</span><span class="hspace"> </span><span class="RktSym">port</span><span class="hspace"> </span><span class="RktSym">read-one</span><span class="hspace"> </span><span class="RktSym">src</span><span class="RktPn">)</span><span class="RktPn">)</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" 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">parse-nonempty</span><span class="hspace"> </span><span class="RktSym">port</span><span class="hspace"> </span><span class="RktSym">read-one</span><span class="hspace"> </span><span class="RktSym">src</span><span class="RktPn">)</span></td></tr><tr><td><span class="hspace"> </span><span class="hspace"> </span><span class="RktCmt">;</span><span class="RktCmt"> </span><span class="RktCmt">Need a comma or closer</span></td></tr><tr><td><span class="hspace"> </span><span class="hspace"> </span><span class="RktPn">(</span><span class="RktSym">skip-whitespace</span><span class="hspace"> </span><span class="RktSym">port</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="case.html#%28form._%28%28lib._racket%2Fprivate%2Fmore-scheme..rkt%29._case%29%29" class="RktStxLink" data-pltdoc="x">case</a></span><span class="hspace"> </span><span class="RktPn">(</span><span class="RktSym"><a href="Byte_and_String_Input.html#%28def._%28%28quote._~23~25kernel%29._peek-char%29%29" class="RktValLink" data-pltdoc="x">peek-char</a></span><span class="hspace"> </span><span class="RktSym">port</span><span class="RktPn">)</span></td></tr><tr><td><span class="hspace"> </span><span class="hspace"> </span><span class="RktPn">[</span><span class="RktPn">(</span><span class="RktVal">#\></span><span class="RktPn">)</span><span class="hspace"> </span><span class="RktPn">(</span><span class="RktSym"><a href="Byte_and_String_Input.html#%28def._%28%28quote._~23~25kernel%29._read-char%29%29" class="RktValLink" data-pltdoc="x">read-char</a></span><span class="hspace"> </span><span class="RktSym">port</span><span class="RktPn">)</span></td></tr><tr><td><span class="hspace"> </span><span class="hspace"> </span><span class="RktCmt">;</span><span class="RktCmt"> </span><span class="RktCmt">Done</span></td></tr><tr><td><span class="hspace"> </span><span class="hspace"> </span><span class="RktSym"><a href="pairs.html#%28def._%28%28quote._~23~25kernel%29._null%29%29" class="RktValLink" data-pltdoc="x">null</a></span><span class="RktPn">]</span></td></tr><tr><td><span class="hspace"> </span><span class="hspace"> </span><span class="RktPn">[</span><span class="RktPn">(</span><span class="RktVal">#\,</span><span class="RktPn">)</span><span class="hspace"> </span><span class="RktPn">(</span><span class="RktSym"><a href="Byte_and_String_Input.html#%28def._%28%28quote._~23~25kernel%29._read-char%29%29" class="RktValLink" data-pltdoc="x">read-char</a></span><span class="hspace"> </span><span class="RktSym">port</span><span class="RktPn">)</span></td></tr><tr><td><span class="hspace"> </span><span class="hspace"> </span><span class="RktCmt">;</span><span class="RktCmt"> </span><span class="RktCmt">Read next element and recur</span></td></tr><tr><td><span class="hspace"> </span><span class="hspace"> </span><span class="RktPn">(</span><span class="RktSym"><a href="pairs.html#%28def._%28%28quote._~23~25kernel%29._cons%29%29" class="RktValLink" data-pltdoc="x">cons</a></span><span class="hspace"> </span><span class="RktPn">(</span><span class="RktSym">skip-comments</span><span class="hspace"> </span><span class="RktSym">read-one</span><span class="hspace"> </span><span class="RktSym">port</span><span class="hspace"> </span><span class="RktSym">src</span><span class="RktPn">)</span></td></tr><tr><td><span class="hspace"> </span><span class="hspace"> </span><span class="RktPn">(</span><span class="RktSym">parse-nonempty</span><span class="hspace"> </span><span class="RktSym">port</span><span class="hspace"> </span><span class="RktSym">read-one</span><span class="hspace"> </span><span class="RktSym">src</span><span class="RktPn">)</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="if.html#%28form._%28%28lib._racket%2Fprivate%2Fletstx-scheme..rkt%29._else%29%29" class="RktStxLink" data-pltdoc="x">else</a></span></td></tr><tr><td><span class="hspace"> </span><span class="hspace"> </span><span class="RktCmt">;</span><span class="RktCmt"> </span><span class="RktCmt">Either a comment or an error; grab location (in case</span></td></tr><tr><td><span class="hspace"> </span><span class="hspace"> </span><span class="RktCmt">;</span><span class="RktCmt"> </span><span class="RktCmt">of error) and read recursively to detect comments</span></td></tr><tr><td><span class="hspace"> </span><span class="hspace"> </span><span class="RktPn">(</span><span class="RktSym"><a href="let.html#%28form._%28%28quote._~23~25kernel%29._let-values%29%29" class="RktStxLink" data-pltdoc="x">let-values</a></span><span class="hspace"> </span><span class="RktPn">(</span><span class="RktPn">[</span><span class="RktPn">(</span><span class="RktSym">l</span><span class="hspace"> </span><span class="RktSym">c</span><span class="hspace"> </span><span class="RktSym">p</span><span class="RktPn">)</span><span class="hspace"> </span><span class="RktPn">(</span><span class="RktSym"><a href="linecol.html#%28def._%28%28quote._~23~25kernel%29._port-next-location%29%29" class="RktValLink" data-pltdoc="x">port-next-location</a></span><span class="hspace"> </span><span class="RktSym">port</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="RktPn">(</span><span class="RktSym">v</span><span class="RktPn">)</span><span class="hspace"> </span><span class="RktPn">(</span><span class="RktSym">read-one</span><span class="RktPn">)</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="if.html#%28form._%28%28lib._racket%2Fprivate%2Fletstx-scheme..rkt%29._cond%29%29" class="RktStxLink" data-pltdoc="x">cond</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="special-comments.html#%28def._%28%28quote._~23~25kernel%29._special-comment~3f%29%29" class="RktValLink" data-pltdoc="x">special-comment?</a></span><span class="hspace"> </span><span class="RktSym">v</span><span class="RktPn">)</span></td></tr><tr><td><span class="hspace"> </span><span class="hspace"> </span><span class="RktCmt">;</span><span class="RktCmt"> </span><span class="RktCmt">It was a comment, so try again</span></td></tr><tr><td><span class="hspace"> </span><span class="hspace"> </span><span class="RktPn">(</span><span class="RktSym">parse-nonempty</span><span class="hspace"> </span><span class="RktSym">port</span><span class="hspace"> </span><span class="RktSym">read-one</span><span class="hspace"> </span><span class="RktSym">src</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="if.html#%28form._%28%28lib._racket%2Fprivate%2Fletstx-scheme..rkt%29._else%29%29" class="RktStxLink" data-pltdoc="x">else</a></span></td></tr><tr><td><span class="hspace"> </span><span class="hspace"> </span><span class="RktCmt">;</span><span class="RktCmt"> </span><span class="RktCmt">Wasn</span><span class="RktCmt">'</span><span class="RktCmt">t a comment, comma, or closer; error</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="if.html#%28form._%28%28quote._~23~25kernel%29._if%29%29" class="RktStxLink" data-pltdoc="x">if</a></span><span class="hspace"> </span><span class="RktPn">(</span><span class="RktSym"><a href="port-ops.html#%28def._%28%28quote._~23~25kernel%29._eof-object~3f%29%29" class="RktValLink" data-pltdoc="x">eof-object?</a></span><span class="hspace"> </span><span class="RktSym">v</span><span class="RktPn">)</span></td></tr><tr><td><span class="hspace"> </span><span class="hspace"> </span><span class="RktSym">raise-read-eof-error</span></td></tr><tr><td><span class="hspace"> </span><span class="hspace"> </span><span class="RktSym">raise-read-error</span><span class="RktPn">)</span></td></tr><tr><td><span class="hspace"> </span><span class="hspace"> </span><span class="RktVal">"expected `,' or `>'"</span><span class="hspace"> </span><span class="RktSym">src</span><span class="hspace"> </span><span class="RktSym">l</span><span class="hspace"> </span><span class="RktSym">c</span><span class="hspace"> </span><span class="RktSym">p</span><span class="hspace"> </span><span class="RktVal">1</span><span class="RktPn">)</span><span class="RktPn">]</span><span class="RktPn">)</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" 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">make-delims-table</span><span class="RktPn">)</span></td></tr><tr><td><span class="hspace"> </span><span class="hspace"> </span><span class="RktCmt">;</span><span class="RktCmt"> </span><span class="RktCmt">Table to use for recursive reads to disallow delimiters</span></td></tr><tr><td><span class="hspace"> </span><span class="hspace"> </span><span class="RktCmt">;</span><span class="RktCmt"> </span><span class="RktCmt"> (except those in sub-expressions)</span></td></tr><tr><td><span class="hspace"> </span><span class="hspace"> </span><span class="RktPn">(</span><span class="RktSym"><a href="let.html#%28form._%28%28lib._racket%2Fprivate%2Fletstx-scheme..rkt%29._letrec%29%29" class="RktStxLink" data-pltdoc="x">letrec</a></span><span class="hspace"> </span><span class="RktPn">(</span><span class="RktPn">[</span><span class="RktSym">misplaced-delimiter</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%28quote._~23~25kernel%29._case-lambda%29%29" class="RktStxLink" data-pltdoc="x">case-lambda</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">ch</span><span class="hspace"> </span><span class="RktSym">port</span><span class="RktPn">)</span><span class="hspace"> </span><span class="RktPn">(</span><span class="RktSym">misplaced-delimiter</span><span class="hspace"> </span><span class="RktSym">ch</span><span class="hspace"> </span><span class="RktSym">port</span><span class="hspace"> </span><span class="RktVal">#f</span><span class="hspace"> </span><span class="RktVal">#f</span><span class="hspace"> </span><span class="RktVal">#f</span><span class="hspace"> </span><span class="RktVal">#f</span><span class="RktPn">)</span><span class="RktPn">]</span></td></tr><tr><td><span class="hspace"> </span><span class="hspace"> </span><span class="RktPn">[</span><span class="RktPn">(</span><span class="RktSym">ch</span><span class="hspace"> </span><span class="RktSym">port</span><span class="hspace"> </span><span class="RktSym">src</span><span class="hspace"> </span><span class="RktSym">line</span><span class="hspace"> </span><span class="RktSym">col</span><span class="hspace"> </span><span class="RktSym">pos</span><span class="RktPn">)</span></td></tr><tr><td><span class="hspace"> </span><span class="hspace"> </span><span class="RktPn">(</span><span class="RktSym">raise-read-error</span></td></tr><tr><td><span class="hspace"> </span><span class="hspace"> </span><span class="RktPn">(</span><span class="RktSym"><a href="Writing.html#%28def._%28%28quote._~23~25kernel%29._format%29%29" class="RktValLink" data-pltdoc="x">format</a></span><span class="hspace"> </span><span class="RktVal">"misplaced `~a' in tuple"</span><span class="hspace"> </span><span class="RktSym">ch</span><span class="RktPn">)</span></td></tr><tr><td><span class="hspace"> </span><span class="hspace"> </span><span class="RktSym">src</span><span class="hspace"> </span><span class="RktSym">line</span><span class="hspace"> </span><span class="RktSym">col</span><span class="hspace"> </span><span class="RktSym">pos</span><span class="hspace"> </span><span class="RktVal">1</span><span class="RktPn">)</span><span class="RktPn">]</span><span class="RktPn">)</span><span class="RktPn">]</span><span class="RktPn">)</span></td></tr><tr><td><span class="hspace"> </span><span class="hspace"> </span><span class="RktPn">(</span><span class="RktSym"><a href="#%28def._%28%28quote._~23~25kernel%29._make-readtable%29%29" class="RktValLink" data-pltdoc="x">make-readtable</a></span><span class="hspace"> </span><span class="RktPn">(</span><span class="RktSym"><a href="Reading.html#%28def._%28%28quote._~23~25kernel%29._current-readtable%29%29" class="RktValLink" data-pltdoc="x">current-readtable</a></span><span class="RktPn">)</span></td></tr><tr><td><span class="hspace"> </span><span class="hspace"> </span><span class="RktVal">#\,</span><span class="hspace"> </span><span class="RktVal">'</span><span class="RktVal">terminating-macro</span><span class="hspace"> </span><span class="RktSym">misplaced-delimiter</span></td></tr><tr><td><span class="hspace"> </span><span class="hspace"> </span><span class="RktVal">#\></span><span class="hspace"> </span><span class="RktVal">'</span><span class="RktVal">terminating-macro</span><span class="hspace"> </span><span class="RktSym">misplaced-delimiter</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" 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">wrap</span><span class="hspace"> </span><span class="RktSym">l</span><span class="RktPn">)</span></td></tr><tr><td><span class="hspace"> </span><span class="hspace"> </span><span class="RktVal">`</span><span class="RktVal">(</span><span class="RktVal">make-tuple</span><span class="hspace"> </span><span class="RktVal">(</span><span class="RktVal">list</span><span class="hspace"> </span><span class="RktRdr">,@</span><span class="RktSym">l</span><span class="RktVal">)</span><span class="RktVal">)</span><span class="RktPn">)</span></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="RktSym">parse-open-tuple</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%28quote._~23~25kernel%29._case-lambda%29%29" class="RktStxLink" data-pltdoc="x">case-lambda</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">ch</span><span class="hspace"> </span><span class="RktSym">port</span><span class="RktPn">)</span></td></tr><tr><td><span class="hspace"> </span><span class="hspace"> </span><span class="RktCmt">;</span><span class="RktCmt"> </span><span class="RktCmt">‘</span><span class="RktCmt">read</span><span class="RktCmt">'</span><span class="RktCmt"> mode</span></td></tr><tr><td><span class="hspace"> </span><span class="hspace"> </span><span class="RktPn">(</span><span class="RktSym">wrap</span><span class="hspace"> </span><span class="RktPn">(</span><span class="RktSym">parse</span><span class="hspace"> </span><span class="RktSym">port</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="RktPn">)</span></td></tr><tr><td><span class="hspace"> </span><span class="hspace"> </span><span class="RktPn">(</span><span class="RktSym"><a href="Reading.html#%28def._%28%28quote._~23~25kernel%29._read%2Frecursive%29%29" class="RktValLink" data-pltdoc="x">read/recursive</a></span><span class="hspace"> </span><span class="RktSym">port</span><span class="hspace"> </span><span class="RktVal">#f</span></td></tr><tr><td><span class="hspace"> </span><span class="hspace"> </span><span class="RktPn">(</span><span class="RktSym">make-delims-table</span><span class="RktPn">)</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="inspectors.html#%28def._%28%28quote._~23~25kernel%29._object-name%29%29" class="RktValLink" data-pltdoc="x">object-name</a></span><span class="hspace"> </span><span class="RktSym">port</span><span class="RktPn">)</span><span class="RktPn">)</span><span class="RktPn">)</span><span class="RktPn">]</span></td></tr><tr><td><span class="hspace"> </span><span class="hspace"> </span><span class="RktPn">[</span><span class="RktPn">(</span><span class="RktSym">ch</span><span class="hspace"> </span><span class="RktSym">port</span><span class="hspace"> </span><span class="RktSym">src</span><span class="hspace"> </span><span class="RktSym">line</span><span class="hspace"> </span><span class="RktSym">col</span><span class="hspace"> </span><span class="RktSym">pos</span><span class="RktPn">)</span></td></tr><tr><td><span class="hspace"> </span><span class="hspace"> </span><span class="RktCmt">;</span><span class="RktCmt"> </span><span class="RktCmt">‘</span><span class="RktCmt">read-syntax</span><span class="RktCmt">'</span><span class="RktCmt"> mode</span></td></tr><tr><td><span class="hspace"> </span><span class="hspace"> </span><span class="RktPn">(</span><span class="RktSym"><a href="stxops.html#%28def._%28%28quote._~23~25kernel%29._datum-~3esyntax%29%29" class="RktValLink" data-pltdoc="x">datum->syntax</a></span></td></tr><tr><td><span class="hspace"> </span><span class="hspace"> </span><span class="RktVal">#f</span></td></tr><tr><td><span class="hspace"> </span><span class="hspace"> </span><span class="RktPn">(</span><span class="RktSym">wrap</span><span class="hspace"> </span><span class="RktPn">(</span><span class="RktSym">parse</span><span class="hspace"> </span><span class="RktSym">port</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="RktPn">)</span></td></tr><tr><td><span class="hspace"> </span><span class="hspace"> </span><span class="RktPn">(</span><span class="RktSym"><a href="Reading.html#%28def._%28%28quote._~23~25kernel%29._read-syntax%2Frecursive%29%29" class="RktValLink" data-pltdoc="x">read-syntax/recursive</a></span><span class="hspace"> </span><span class="RktSym">src</span><span class="hspace"> </span><span class="RktSym">port</span><span class="hspace"> </span><span class="RktVal">#f</span></td></tr><tr><td><span class="hspace"> </span><span class="hspace"> </span><span class="RktPn">(</span><span class="RktSym">make-delims-table</span><span class="RktPn">)</span><span class="RktPn">)</span><span class="RktPn">)</span></td></tr><tr><td><span class="hspace"> </span><span class="hspace"> </span><span class="RktSym">src</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="let.html#%28form._%28%28quote._~23~25kernel%29._let-values%29%29" class="RktStxLink" data-pltdoc="x">let-values</a></span><span class="hspace"> </span><span class="RktPn">(</span><span class="RktPn">[</span><span class="RktPn">(</span><span class="RktSym">l</span><span class="hspace"> </span><span class="RktSym">c</span><span class="hspace"> </span><span class="RktSym">p</span><span class="RktPn">)</span><span class="hspace"> </span><span class="RktPn">(</span><span class="RktSym"><a href="linecol.html#%28def._%28%28quote._~23~25kernel%29._port-next-location%29%29" class="RktValLink" data-pltdoc="x">port-next-location</a></span><span class="hspace"> </span><span class="RktSym">port</span><span class="RktPn">)</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="pairs.html#%28def._%28%28quote._~23~25kernel%29._list%29%29" class="RktValLink" data-pltdoc="x">list</a></span><span class="hspace"> </span><span class="RktSym">src</span><span class="hspace"> </span><span class="RktSym">line</span><span class="hspace"> </span><span class="RktSym">col</span><span class="hspace"> </span><span class="RktSym">pos</span><span class="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="RktSym">pos</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">p</span><span class="hspace"> </span><span class="RktSym">pos</span><span class="RktPn">)</span><span class="RktPn">)</span><span class="RktPn">)</span><span class="RktPn">)</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" 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="RktSym">tuple-readtable</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._make-readtable%29%29" class="RktValLink" data-pltdoc="x">make-readtable</a></span><span class="hspace"> </span><span class="RktVal">#f</span><span class="hspace"> </span><span class="RktVal">#\<</span><span class="hspace"> </span><span class="RktVal">'</span><span class="RktVal">terminating-macro</span><span class="hspace"> </span><span class="RktSym">parse-open-tuple</span><span class="RktPn">)</span><span class="RktPn">)</span></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="parameters.html#%28form._%28%28lib._racket%2Fprivate%2Fmore-scheme..rkt%29._parameterize%29%29" class="RktStxLink" data-pltdoc="x">parameterize</a></span><span class="hspace"> </span><span class="RktPn">(</span><span class="RktPn">[</span><span class="RktSym"><a href="Reading.html#%28def._%28%28quote._~23~25kernel%29._current-readtable%29%29" class="RktValLink" data-pltdoc="x">current-readtable</a></span><span class="hspace"> </span><span class="RktSym">tuple-readtable</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="Reading.html#%28def._%28%28quote._~23~25kernel%29._read%29%29" class="RktValLink" data-pltdoc="x">read</a></span><span class="hspace"> </span><span class="RktPn">(</span><span class="RktSym"><a href="stringport.html#%28def._%28%28quote._~23~25kernel%29._open-input-string%29%29" class="RktValLink" data-pltdoc="x">open-input-string</a></span><span class="hspace"> </span><span class="RktVal">"<1 , 2 , \"a\">"</span><span class="RktPn">)</span><span class="RktPn">)</span><span class="RktPn">)</span></td></tr></table></td></tr><tr><td><p><span class="RktRes">'(make-tuple (list 1 2 "a"))</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="parameters.html#%28form._%28%28lib._racket%2Fprivate%2Fmore-scheme..rkt%29._parameterize%29%29" class="RktStxLink" data-pltdoc="x">parameterize</a></span><span class="hspace"> </span><span class="RktPn">(</span><span class="RktPn">[</span><span class="RktSym"><a href="Reading.html#%28def._%28%28quote._~23~25kernel%29._current-readtable%29%29" class="RktValLink" data-pltdoc="x">current-readtable</a></span><span class="hspace"> </span><span class="RktSym">tuple-readtable</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="Reading.html#%28def._%28%28quote._~23~25kernel%29._read%29%29" class="RktValLink" data-pltdoc="x">read</a></span><span class="hspace"> </span><span class="RktPn">(</span><span class="RktSym"><a href="stringport.html#%28def._%28%28quote._~23~25kernel%29._open-input-string%29%29" class="RktValLink" data-pltdoc="x">open-input-string</a></span></td></tr><tr><td><span class="hspace"> </span><span class="hspace"> </span><span class="RktVal">"< #||# 1 #||# , #||# 2 #||# , #||# \"a\" #||# >"</span><span class="RktPn">)</span><span class="RktPn">)</span><span class="RktPn">)</span></td></tr></table></td></tr><tr><td><p><span class="RktRes">'(make-tuple (list 1 2 "a"))</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="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">tuple-readtable+</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._make-readtable%29%29" class="RktValLink" data-pltdoc="x">make-readtable</a></span><span class="hspace"> </span><span class="RktSym">tuple-readtable</span></td></tr><tr><td><span class="hspace"> </span><span class="hspace"> </span><span class="RktVal">#\*</span><span class="hspace"> </span><span class="RktVal">'</span><span class="RktVal">terminating-macro</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="RktSym">a</span></td></tr><tr><td><span class="hspace"> </span><span class="hspace"> </span><span class="RktPn">(</span><span class="RktSym"><a href="special-comments.html#%28def._%28%28quote._~23~25kernel%29._make-special-comment%29%29" class="RktValLink" data-pltdoc="x">make-special-comment</a></span><span class="hspace"> </span><span class="RktVal">#f</span><span class="RktPn">)</span><span class="RktPn">)</span></td></tr><tr><td><span class="hspace"> </span><span class="hspace"> </span><span class="RktVal">#\_</span><span class="hspace"> </span><span class="RktVal">#\space</span><span class="hspace"> </span><span class="RktVal">#f</span><span class="RktPn">)</span><span class="RktPn">)</span></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="parameters.html#%28form._%28%28lib._racket%2Fprivate%2Fmore-scheme..rkt%29._parameterize%29%29" class="RktStxLink" data-pltdoc="x">parameterize</a></span><span class="hspace"> </span><span class="RktPn">(</span><span class="RktPn">[</span><span class="RktSym"><a href="Reading.html#%28def._%28%28quote._~23~25kernel%29._current-readtable%29%29" class="RktValLink" data-pltdoc="x">current-readtable</a></span><span class="hspace"> </span><span class="RktSym">tuple-readtable+</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="Reading.html#%28def._%28%28quote._~23~25kernel%29._read%29%29" class="RktValLink" data-pltdoc="x">read</a></span><span class="hspace"> </span><span class="RktPn">(</span><span class="RktSym"><a href="stringport.html#%28def._%28%28quote._~23~25kernel%29._open-input-string%29%29" class="RktValLink" data-pltdoc="x">open-input-string</a></span><span class="hspace"> </span><span class="RktVal">"< * 1 __,__</span><span class="hspace"> </span><span class="RktVal">2 __,__ * \"a\" * >"</span><span class="RktPn">)</span><span class="RktPn">)</span><span class="RktPn">)</span></td></tr></table></td></tr><tr><td><p><span class="RktRes">'(make-tuple (list 1 2 "a"))</span></p></td></tr></table></blockquote></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, "6.7", "../");" 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