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<html><head><meta http-equiv="content-type" content="text/html; charset=utf-8"/><meta name="viewport" content="width=device-width, initial-scale=0.8"/><title>10.2 Exceptions</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">The Racket Reference</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="tocviewselflink" 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><t
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model. It is based on a proposal by Friedman, Haynes, and Dybvig
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[<a href="doc-bibliography.html#%28cite._.Friedman95%29" data-pltdoc="x">Friedman95</a>].</p><p>Whenever a primitive error occurs in Racket, an exception is
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raised. The value that is passed to the current <a href="eval-model.html#%28tech._exception._handler%29" class="techoutside" data-pltdoc="x"><span class="techinside">exception
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handler</span></a> for a primitive error is always an instance of the
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<span class="RktSym"><a href="exns.html#%28def._%28%28lib._racket%2Fprivate%2Fbase..rkt%29._exn%29%29" class="RktValLink" data-pltdoc="x">exn</a></span> structure type. Every <span class="RktSym"><a href="exns.html#%28def._%28%28lib._racket%2Fprivate%2Fbase..rkt%29._exn%29%29" class="RktValLink" data-pltdoc="x">exn</a></span> structure value has a
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<span class="RktSym">message</span> field that is a string, the primitive error message.
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The default exception handler recognizes exception values with the
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<span class="RktSym"><a href="exns.html#%28def._%28%28quote._~23~25kernel%29._exn~3f%29%29" class="RktValLink" data-pltdoc="x">exn?</a></span> predicate and passes the error message to the current
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<a href="exns.html#%28tech._error._display._handler%29" class="techoutside" data-pltdoc="x"><span class="techinside">error display handler</span></a> (see <span class="RktSym"><a href="exns.html#%28def._%28%28quote._~23~25kernel%29._error-display-handler%29%29" class="RktValLink" data-pltdoc="x">error-display-handler</a></span>).</p><p>Primitive procedures that accept a procedure argument with a
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particular required arity (e.g., <span class="RktSym"><a href="file-ports.html#%28def._%28%28lib._racket%2Fprivate%2Fbase..rkt%29._call-with-input-file%29%29" class="RktValLink" data-pltdoc="x">call-with-input-file</a></span>,
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<span class="RktSym"><a href="cont.html#%28def._%28%28lib._racket%2Fprivate%2Fmore-scheme..rkt%29._call%2Fcc%29%29" class="RktValLink" data-pltdoc="x">call/cc</a></span>) check the argument’s arity immediately, raising
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<span class="RktSym"><a href="exns.html#%28def._%28%28lib._racket%2Fprivate%2Fbase..rkt%29._exn~3afail~3acontract%29%29" class="RktValLink" data-pltdoc="x">exn:fail:contract</a></span> if the arity is incorrect.</p><h5 x-source-module="(lib "scribblings/reference/reference.scrbl")" x-source-pkg="racket-doc" x-part-tag=""err-msg-conventions"">10.2.1<tt> </tt><a name="(part._err-msg-conventions)"></a>Error Message Conventions</h5><p>Racket’s <a name="(tech._error._message._convention)"></a><span style="font-style: italic">error message convention</span> is to produce error
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messages with the following shape:</p><blockquote class="SCodeFlow"><table cellspacing="0" cellpadding="0" class="RktBlk"><tr><td><span class="sroman">‹<span style="font-style: italic">srcloc</span>›</span><span class="RktSym">:</span><span class="hspace"> </span><span class="sroman">‹<span style="font-style: italic">name</span>›</span><span class="RktSym">:</span><span class="hspace"> </span><span class="sroman">‹<span style="font-style: italic">message</span>›</span><span class="stt">;</span></td></tr><tr><td><span class="hspace"> </span><span class="sroman">‹<span style="font-style: italic">continued-message</span>›</span><span class="hspace"> </span><span class="RktSym"><a href="stx-patterns.html#%28form._%28%28lib._racket%2Fprivate%2Fstxcase-scheme..rkt%29._......%29%29" class="RktStxLink" data-pltdoc="x">...</a></span></td></tr><tr><td><span class="hspace"> </span><span class="sroman">‹<span style="font-style: italic">field</span>›</span><span class="RktSym">:</span><span class="hspace"> </span><span class="sroman">‹<span style="font-style: italic">detail</span>›</span></td></tr><tr><td><span class="hspace"> </span><span class="RktSym"><a href="stx-patterns.html#%28form._%28%28lib._racket%2Fprivate%2Fstxcase-scheme..rkt%29._......%29%29" class="RktStxLink" data-pltdoc="x">...</a></span></td></tr></table></blockquote><p>The message starts with an optional source location, <span class="sroman">‹<span style="font-style: italic">srcloc</span>›</span>,
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which is followed by a colon and space when present. The message
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continues with an optional <span class="sroman">‹<span style="font-style: italic">name</span>›</span> that usually identifies the
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complaining function, syntactic form, or other entity, but may also
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refer to an entity being complained about; the <span class="sroman">‹<span style="font-style: italic">name</span>›</span> is also
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followed by a colon and space when present.</p><p>The <span class="sroman">‹<span style="font-style: italic">message</span>›</span> should be relatively short, and it should be
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largely independent of specific values that triggered the error. More
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detailed explanation that requires multiple lines should continue with
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each line indented by a single space, in which case <span class="sroman">‹<span style="font-style: italic">message</span>›</span>
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should end in a semi-colon (but the semi-colon should be omitted if
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<span class="sroman">‹<span style="font-style: italic">continued-message</span>›</span> is not present). Message text should be
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lowercase—<wbr></wbr>using semi-colons to separate sentences if needed,
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although long explanations may be better deferred to extra fields.</p><p>Specific values that triggered the error or other helpful information
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should appear in separate <span class="sroman">‹<span style="font-style: italic">field</span>›</span> lines, each of which is
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indented by two spaces. If a <span class="sroman">‹<span style="font-style: italic">detail</span>›</span> is especially long or
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takes multiple lines, it should start on its own line after the
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<span class="sroman">‹<span style="font-style: italic">field</span>›</span> label, and each of its lines should be indented by
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three spaces. Field names should be all lowercase.</p><p>A <span class="sroman">‹<span style="font-style: italic">field</span>›</span> name should end with <span class="RktInBG"><span class="hspace"></span><span class="RktIn">...</span><span class="hspace"></span></span> if the field
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provides relatively detailed information that might be distracting in
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common cases but useful in others. For example, when a contract
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failure is reported for a particular argument of a function, other
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arguments to the function might be shown in an “other arguments...”
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field. The intent is that fields whose names end in <span class="RktInBG"><span class="hspace"></span><span class="RktIn">...</span><span class="hspace"></span></span>
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might be hidden by default in an environment such as DrRacket.</p><p>Make <span class="sroman">‹<span style="font-style: italic">field</span>›</span> names as short as possible, relying on
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<span class="sroman">‹<span style="font-style: italic">message</span>›</span> or <span class="sroman">‹<span style="font-style: italic">continued message</span>›</span> text to clarify the
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meaning for a field. For example, prefer “given” to “given turtle”
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as a field name, where <span class="sroman">‹<span style="font-style: italic">message</span>›</span> is something like “given
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turtle is too sleepy” to clarify that “given” refers to a turtle.</p><h5 x-source-module="(lib "scribblings/reference/reference.scrbl")" x-source-pkg="racket-doc" x-part-tag=""errorproc"">10.2.2<tt> </tt><a name="(part._errorproc)"></a>Raising Exceptions</h5><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)._raise))"></a><span title="Provided from: racket/base, racket | Package: base"><span class="RktSym"><a href="exns.html#%28def._%28%28quote._~23~25kernel%29._raise%29%29" class="RktValDef RktValLink" data-pltdoc="x">raise</a></span></span><span class="hspace"> </span><span class="RktVar">v</span><span class="hspace"> </span><span class="RktOpt">[</span><span class="RktVar">barrier?</span><span class="RktOpt">]</span><span class="RktPn">)</span><span class="hspace"> </span>→<span class="hspace"> </span><span class="RktSym"><a href="data-structure-contracts.html#%28form._%28%28lib._racket%2Fcontract%2Fprivate%2Fmisc..rkt%29._any%29%29" class="RktStxLink" data-pltdoc="x">any</a></span></p></blockquote></td></tr><tr><td><span class="hspace"> </span><span class="RktVar">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><tr><td><span class="hspace"> </span><span class="RktVar">barrier?</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><span class="hspace"> </span>=<span class="hspace"> </span><span class="RktVal">#t</span></td></tr></table></blockquote></div><div class="SIntrapara">Raises an exception, where <span class="RktVar">v</span> represents the exception being
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raised. The <span class="RktVar">v</span> argument can be anything; it is passed to the
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current <a href="eval-model.html#%28tech._exception._handler%29" class="techoutside" data-pltdoc="x"><span class="techinside">exception handler</span></a>.</div></p><p>If <span class="RktVar">barrier?</span> is true, then the call to the <a href="eval-model.html#%28tech._exception._handler%29" class="techoutside" data-pltdoc="x"><span class="techinside">exception
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handler</span></a> is protected by a <a href="eval-model.html#%28tech._continuation._barrier%29" class="techoutside" data-pltdoc="x"><span class="techinside">continuation barrier</span></a>, so that
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multiple returns/escapes are impossible. All exceptions raised by
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<a href="index.html" class="RktModLink" data-pltdoc="x"><span class="RktSym">racket</span></a> functions effectively use <span class="RktSym"><a href="exns.html#%28def._%28%28quote._~23~25kernel%29._raise%29%29" class="RktValLink" data-pltdoc="x">raise</a></span> with a
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<span class="RktVal">#t</span> value for <span class="RktVar">barrier?</span>.</p><p>Breaks are disabled from the time the exception is raised until the
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exception handler obtains control, and the handler itself is
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<span class="RktSym"><a href="breakhandler.html#%28form._%28%28lib._racket%2Fprivate%2Fmore-scheme..rkt%29._parameterize-break%29%29" class="RktStxLink" data-pltdoc="x">parameterize-break</a></span>ed to disable breaks initially; see
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<a href="breakhandler.html" data-pltdoc="x">Breaks</a> for more information on breaks.</p><p><div class="SIntrapara">Examples:</div><div class="SIntrapara"><blockquote class="SCodeFlow"><table cellspacing="0" cellpadding="0" class="RktBlk"><tr><td><table cellspacing="0" cellpadding="0" class="RktBlk"><tr><td><span class="stt">> </span><span class="RktPn">(</span><span class="RktSym"><a href="exns.html#%28form._%28%28lib._racket%2Fprivate%2Fmore-scheme..rkt%29._with-handlers%29%29" class="RktStxLink" data-pltdoc="x">with-handlers</a></span><span class="hspace"> </span><span class="RktPn">(</span><span class="RktPn">[</span><span class="RktSym"><a href="number-types.html#%28def._%28%28quote._~23~25kernel%29._number~3f%29%29" class="RktValLink" data-pltdoc="x">number?</a></span><span class="hspace"> </span><span class="RktPn">(</span><span class="RktSym"><a href="lambda.html#%28form._%28%28lib._racket%2Fprivate%2Fbase..rkt%29._lambda%29%29" class="RktStxLink" data-pltdoc="x">lambda</a></span><span class="hspace"> </span><span class="RktPn">(</span><span class="RktSym">n</span><span class="RktPn">)</span></td></tr><tr><td><span class="hspace"> </span><span class="hspace"> </span><span class="RktPn">(</span><span class="RktSym"><a href="generic-numbers.html#%28def._%28%28quote._~23~25kernel%29._%2B%29%29" class="RktValLink" data-pltdoc="x">+</a></span><span class="hspace"> </span><span class="RktSym">n</span><span class="hspace"> </span><span class="RktVal">5</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="exns.html#%28def._%28%28quote._~23~25kernel%29._raise%29%29" class="RktValLink" data-pltdoc="x">raise</a></span><span class="hspace"> </span><span class="RktVal">18</span><span class="hspace"> </span><span class="RktVal">#t</span><span class="RktPn">)</span><span class="RktPn">)</span></td></tr></table></td></tr><tr><td><p><span class="RktRes">23</span></p></td></tr><tr><td><span class="stt">> </span><span class="RktPn">(</span><span class="RktSym"><a href="define-struct.html#%28form._%28%28lib._racket%2Fprivate%2Fbase..rkt%29._struct%29%29" class="RktStxLink" data-pltdoc="x">struct</a></span><span class="hspace"> </span><span class="RktSym">my-exception</span><span class="hspace"> </span><span class="RktSym"><a href="exns.html#%28def._%28%28lib._racket%2Fprivate%2Fbase..rkt%29._exn~3afail~3auser%29%29" class="RktValLink" data-pltdoc="x">exn:fail:user</a></span><span class="hspace"> </span><span class="RktPn">(</span><span class="RktPn">)</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="exns.html#%28form._%28%28lib._racket%2Fprivate%2Fmore-scheme..rkt%29._with-handlers%29%29" class="RktStxLink" data-pltdoc="x">with-handlers</a></span><span class="hspace"> </span><span class="RktPn">(</span><span class="RktPn">[</span><span class="RktSym">my-exception?</span><span class="hspace"> </span><span class="RktPn">(</span><span class="RktSym"><a href="lambda.html#%28form._%28%28lib._racket%2Fprivate%2Fbase..rkt%29._lambda%29%29" class="RktStxLink" data-pltdoc="x">lambda</a></span><span class="hspace"> </span><span class="RktPn">(</span><span class="RktSym">e</span><span class="RktPn">)</span></td></tr><tr><td><span class="hspace"> </span><span class="hspace"> </span><span class="RktVal">#f</span><span class="RktPn">)<
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string. The different forms produce the error string in different
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ways:</div></p><ul><li><p><span class="RktPn">(</span><span class="RktSym"><a href="exns.html#%28def._%28%28quote._~23~25kernel%29._error%29%29" class="RktValLink" data-pltdoc="x">error</a></span><span class="stt"> </span><span class="RktVar">message-sym</span><span class="RktPn">)</span> creates a message string by concatenating
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<span class="RktVal">"error: "</span> with the string form of <span class="RktVar">message-sym</span>. Use this
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form sparingly.</p></li><li><p><span class="RktPn">(</span><span class="RktSym"><a href="exns.html#%28def._%28%28quote._~23~25kernel%29._error%29%29" class="RktValLink" data-pltdoc="x">error</a></span><span class="stt"> </span><span class="RktVar">message-str</span><span class="stt"> </span><span class="RktVar">v</span><span class="stt"> </span><span class="RktSym"><a href="stx-patterns.html#%28form._%28%28lib._racket%2Fprivate%2Fstxcase-scheme..rkt%29._......%29%29" class="RktStxLink" data-pltdoc="x">...</a></span><span class="RktPn">)</span> creates a message string by
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concatenating <span class="RktVar">message-str</span> with string versions of the <span class="RktVar">v</span>s
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(as produced by the current error value conversion handler; see
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<span class="RktSym"><a href="exns.html#%28def._%28%28quote._~23~25kernel%29._error-value-~3estring-handler%29%29" class="RktValLink" data-pltdoc="x">error-value->string-handler</a></span>). A space is inserted before
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each <span class="RktVar">v</span>. Use this form sparingly, because it does not conform
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well to Racket’s <a href="exns.html#%28tech._error._message._convention%29" class="techoutside" data-pltdoc="x"><span class="techinside">error message conventions</span></a>; consider
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<span class="RktSym"><a href="exns.html#%28def._%28%28quote._~23~25kernel%29._raise-arguments-error%29%29" class="RktValLink" data-pltdoc="x">raise-arguments-error</a></span>, instead. </p></li><li><p><span class="RktPn">(</span><span class="RktSym"><a href="exns.html#%28def._%28%28quote._~23~25kernel%29._error%29%29" class="RktValLink" data-pltdoc="x">error</a></span><span class="stt"> </span><span class="RktVar">who-sym</span><span class="stt"> </span><span class="RktVar">format-str</span><span class="stt"> </span><span class="RktVar">v</span><span class="stt"> </span><span class="RktSym"><a href="stx-patterns.html#%28form._%28%28lib._racket%2Fprivate%2Fstxcase-scheme..rkt%29._......%29%29" class="RktStxLink" data-pltdoc="x">...</a></span><span class="RktPn">)</span> creates a
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message string equivalent to the string created by</p><blockquote class="SCodeFlow"><p><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="RktPn">(</span><span class="RktSym"><a href="strings.html#%28def._%28%28quote._~23~25kernel%29._string-append%29%29" class="RktValLink" data-pltdoc="x">string-append</a></span><span class="hspace"> </span><span class="RktVal">"~s: "</span><span class="hspace"> </span><span class="RktVar">format-str</span><span class="RktPn">)</span><span class="hspace"> </span><span class="RktVar">who-sym</span><span class="hspace"> </span><span class="RktVar">v</span><span class="hspace"> </span><span class="RktSym"><a href="stx-patterns.html#%28form._%28%28lib._racket%2Fprivate%2Fstxcase-scheme..rkt%29._......%29%29" class="RktStxLink" data-pltdoc="x">...</a></span><span class="RktPn">)</span></p></blockquote><p>When possible, use functions such as <span class="RktSym"><a href="exns.html#%28def._%28%28quote._~23~25kernel%29._raise-argument-error%29%29" class="RktValLink" data-pltdoc="x">raise-argument-error</a></span>,
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||
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instead, which construct messages that follow Racket’s <a href="exns.html#%28tech._error._message._convention%29" class="techoutside" data-pltdoc="x"><span class="techinside">error message
|
||
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conventions</span></a>.</p></li></ul><p>In all cases, the constructed message string is passed to
|
||
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<span class="RktSym"><a href="exns.html#%28def._%28%28lib._racket%2Fprivate%2Fbase..rkt%29._make-exn~3afail%29%29" class="RktValLink" data-pltdoc="x">make-exn:fail</a></span>, and the resulting exception is raised.</p><p><div class="SIntrapara">Examples:</div><div class="SIntrapara"><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="exns.html#%28def._%28%28quote._~23~25kernel%29._error%29%29" class="RktValLink" data-pltdoc="x">error</a></span><span class="hspace"> </span><span class="RktVal">'</span><span class="RktVal">failed</span><span class="RktPn">)</span></td></tr><tr><td><p><span class="RktErr">error: failed</span></p></td></tr><tr><td><span class="stt">> </span><span class="RktPn">(</span><span class="RktSym"><a href="exns.html#%28def._%28%28quote._~23~25kernel%29._error%29%29" class="RktValLink" data-pltdoc="x">error</a></span><span class="hspace"> </span><span class="RktVal">"failed"</span><span class="hspace"> </span><span class="RktVal">23</span><span class="hspace"> </span><span class="RktVal">'</span><span class="RktVal">pizza</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="RktVal">1</span><span class="hspace"> </span><span class="RktVal">2</span><span class="hspace"> </span><span class="RktVal">3</span><span class="RktPn">)</span><span class="RktPn">)</span></td></tr><tr><td><p><span class="RktErr">failed 23 'pizza '(1 2 3)</span></p></td></tr><tr><td><span class="stt">> </span><span class="RktPn">(</span><span class="RktSym"><a href="exns.html#%28def._%28%28quote._~23~25kernel%29._error%29%29" class="RktValLink" data-pltdoc="x">error</a></span><span class="hspace"> </span><span class="RktVal">'</span><span class="RktVal">method-a</span><span class="hspace"> </span><span class="RktVal">"failed because ~a"</span><span class="hspace"> </span><span class="RktVal">"no argument supplied"</span><span class="RktPn">)</span></td></tr><tr><td><p><span class="RktErr">method-a: failed because no argument supplied</span></p></td></tr></table></blockquote></div></p><p><div class="SIntrapara"><blockquote class="SVInsetFlow"><table cellspacing="0" cellpadding="0" class="boxed RBoxed"><tr><td><blockquote class="SubFlow"><div class="RBackgroundLabel SIEHidden"><div class="RBackgroundLabelInner"><p>procedure</p></div></div><p class="RForeground"><span class="RktPn">(</span><a name="(def._((quote._~23~25kernel)._raise-user-error))"></a><span title="Provided from: racket/base, racket | Package: base"><span class="RktSym"><a href="exns.html#%28def._%28%28quote._~23~25kernel%29._raise-user-error%29%29" class="RktValDef RktValLink" data-pltdoc="x">raise-user-error</a></span></span><span class="hspace"> </span><span class="RktVar">message-sym</span><span class="RktPn">)</span><span class="hspace"> </span>→<span class="hspace"> </span><span class="RktSym"><a href="data-structure-contracts.html#%28form._%28%28lib._racket%2Fcontract%2Fprivate%2Fmisc..rkt%29._any%29%29" class="RktStxLink" data-pltdoc="x">any</a></span></p></blockquote></td></tr><tr><td><span class="hspace"> </span><span class="RktVar">message-sym</span><span class="hspace"> </span>:<span class="hspace"> </span><span class="RktSym"><a href="symbols.html#%28def._%28%28quote._~23~25kernel%29._symbol~3f%29%29" class="RktValLink" data-pltdoc="x">symbol?</a></span></td></tr><tr><td><span class="RktPn">(</span><span title="Provided from: racket/base, racket | Package: base"><span class="RktSym"><a href="exns.html#%28def._%28%28quote._~23~25kernel%29._raise-user-error%29%29" class="RktValDef RktValLink" data-pltdoc="x">raise-user-error</a></span></span><span class="hspace"> </span><span class="RktVar">message-str</span><span class="hspace"> </
|
||
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<span class="RktSym"><a href="exns.html#%28def._%28%28lib._racket%2Fprivate%2Fbase..rkt%29._make-exn~3afail~3auser%29%29" class="RktValLink" data-pltdoc="x">make-exn:fail:user</a></span> instead of <span class="RktSym"><a href="exns.html#%28def._%28%28lib._racket%2Fprivate%2Fbase..rkt%29._make-exn~3afail%29%29" class="RktValLink" data-pltdoc="x">make-exn:fail</a></span>. The
|
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default <a href="exns.html#%28tech._error._display._handler%29" class="techoutside" data-pltdoc="x"><span class="techinside">error display handler</span></a> does not show a “stack trace” for
|
||
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<span class="RktSym"><a href="exns.html#%28def._%28%28lib._racket%2Fprivate%2Fbase..rkt%29._exn~3afail~3auser%29%29" class="RktValLink" data-pltdoc="x">exn:fail:user</a></span> exceptions (see <a href="contmarks.html" data-pltdoc="x">Continuation Marks</a>), so
|
||
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<span class="RktSym"><a href="exns.html#%28def._%28%28quote._~23~25kernel%29._raise-user-error%29%29" class="RktValLink" data-pltdoc="x">raise-user-error</a></span> should be used for errors that are intended
|
||
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for end users.</div></p><p><div class="SIntrapara"><blockquote class="SVInsetFlow"><table cellspacing="0" cellpadding="0" class="boxed RBoxed"><tr><td><blockquote class="SubFlow"><div class="RBackgroundLabel SIEHidden"><div class="RBackgroundLabelInner"><p>procedure</p></div></div><p class="RForeground"><span class="RktPn">(</span><a name="(def._((quote._~23~25kernel)._raise-argument-error))"></a><span title="Provided from: racket/base, racket | Package: base"><span class="RktSym"><a href="exns.html#%28def._%28%28quote._~23~25kernel%29._raise-argument-error%29%29" class="RktValDef RktValLink" data-pltdoc="x">raise-argument-error</a></span></span><span class="hspace"> </span><span class="RktVar">name</span><span class="hspace"> </span><span class="RktVar">expected</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="data-structure-contracts.html#%28form._%28%28lib._racket%2Fcontract%2Fprivate%2Fmisc..rkt%29._any%29%29" class="RktStxLink" data-pltdoc="x">any</a></span></p></blockquote></td></tr><tr><td><span class="hspace"> </span><span class="RktVar">name</span><span class="hspace"> </span>:<span class="hspace"> </span><span class="RktSym"><a href="symbols.html#%28def._%28%28quote._~23~25kernel%29._symbol~3f%29%29" class="RktValLink" data-pltdoc="x">symbol?</a></span></td></tr><tr><td><span class="hspace"> </span><span class="RktVar">expected</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><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><tr><td><table cellspacing="0" cellpadding="0" class="prototype"><tr><td valign="top"><span class="RktPn">(</span><span title="Provided from: racket/base, racket | Package: base"><span class="RktSym"><a href="exns.html#%28def._%28%28quote._~23~25kernel%29._raise-argument-error%29%29" class="RktValDef RktValLink" data-pltdoc="x">raise-argument-error</a></span></span></td><td valign="top"><span class="hspace"> </span></td><td valign="top"><span class="RktVar">name</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">expected</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">bad-pos</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">v</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 h
|
||
|
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an exception. The <span class="RktVar">name</span> argument is used as the source
|
||
|
|
procedure’s name in the error message. The <span class="RktVar">expected</span> argument
|
||
|
|
is used as a description of the expected contract (i.e., as a string,
|
||
|
|
but the string is intended to contain a contract expression).</div></p><p>In the first form, <span class="RktVar">v</span> is the value received by the procedure
|
||
|
|
that does not have the expected type.</p><p>In the second form, the bad argument is indicated by an index
|
||
|
|
<span class="RktVar">bad-pos</span> (counting from <span style="font-style: italic"></span>0<span style="font-style: italic"></span>), and all of the original
|
||
|
|
arguments <span class="RktVar">v</span> are provided (in order). The resulting error
|
||
|
|
message names the bad argument and also lists the other arguments. If
|
||
|
|
<span class="RktVar">bad-pos</span> is not less than the number of <span class="RktVar">v</span>s, the
|
||
|
|
<span class="RktSym"><a href="exns.html#%28def._%28%28lib._racket%2Fprivate%2Fbase..rkt%29._exn~3afail~3acontract%29%29" class="RktValLink" data-pltdoc="x">exn:fail:contract</a></span> exception is raised.</p><p>The error message generated by <span class="RktSym"><a href="exns.html#%28def._%28%28quote._~23~25kernel%29._raise-argument-error%29%29" class="RktValLink" data-pltdoc="x">raise-argument-error</a></span> is
|
||
|
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adjusted via <span class="RktSym"><a href="exns.html#%28def._%28%28quote._~23~25kernel%29._error-contract-~3eadjusted-string%29%29" class="RktValLink" data-pltdoc="x">error-contract->adjusted-string</a></span> and then
|
||
|
|
<span class="RktSym"><a href="exns.html#%28def._%28%28quote._~23~25kernel%29._error-message-~3eadjusted-string%29%29" class="RktValLink" data-pltdoc="x">error-message->adjusted-string</a></span> using the default
|
||
|
|
<span class="RktVal">'</span><span class="RktVal">racket</span> realm.</p><p><div class="SIntrapara">Examples:</div><div class="SIntrapara"><blockquote class="SCodeFlow"><table cellspacing="0" cellpadding="0" class="RktBlk"><tr><td><table cellspacing="0" cellpadding="0" class="RktBlk"><tr><td><span class="stt">> </span><span class="RktPn">(</span><span class="RktSym"><a href="define.html#%28form._%28%28lib._racket%2Fprivate%2Fbase..rkt%29._define%29%29" class="RktStxLink" data-pltdoc="x">define</a></span><span class="hspace"> </span><span class="RktPn">(</span><span class="RktSym">feed-machine</span><span class="hspace"> </span><span class="RktSym">bits</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._not%29%29" class="RktValLink" data-pltdoc="x">not</a></span><span class="hspace"> </span><span class="RktPn">(</span><span class="RktSym"><a href="number-types.html#%28def._%28%28quote._~23~25kernel%29._integer~3f%29%29" class="RktValLink" data-pltdoc="x">integer?</a></span><span class="hspace"> </span><span class="RktSym">bits</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="exns.html#%28def._%28%28quote._~23~25kernel%29._raise-argument-error%29%29" class="RktValLink" data-pltdoc="x">raise-argument-error</a></span><span class="hspace"> </span><span class="RktVal">'</span><span class="RktVal">feed-machine</span><span class="hspace"> </span><span class="RktVal">"integer?"</span><span class="hspace"> </span><span class="RktSym">bits</span><span class="RktPn">)</span></td></tr><tr><td><span class="hspace"> </span><span class="hspace"> </span><span class="RktVal">"fed the machine"</span><span class="RktPn">)</span><span class="RktPn">)</span></td></tr></table></td></tr><tr><td><span class="stt">> </span><span class="RktPn">(</span><span class="RktSym">feed-machine</span><span class="hspace"> </span><span class="RktVal">'</span><span class="RktVal">turkey</span><span class="RktPn">)</span></td></tr><tr><td><p><span class="RktErr">feed-machine: contract violation</span></p></td></tr><tr><td><p><span class="RktErr"></span><span class="hspace"> </span><span class="RktErr">expected: integer?</span></p></td></tr><tr><td><p><span class="RktErr"></span><span class="hspace"> </span><span class="RktErr">given: 'turkey</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="RktPn">(</span><span class="RktSym">feed-cow</span><span class="hspace"> </span><span class="RktSym">animal</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._not%29%29" class="RktValLink" data-pltdoc="x">not</a></span><span class="hspace"> </span><span class="RktPn">(</span><span class="RktSym"><a href="Equality.html#%28def._%28%28quote._~23~25kernel%29._eq~3f%29%29" class="RktValLink" data-pltdoc="x">eq?</a></span><span c
|
||
|
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for error-message adjustments.</div></p><p class="SHistory">Added in version 8.4.0.2 of package <span class="stt">base</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)._raise-result-error))"></a><span title="Provided from: racket/base, racket | Package: base"><span class="RktSym"><a href="exns.html#%28def._%28%28quote._~23~25kernel%29._raise-result-error%29%29" class="RktValDef RktValLink" data-pltdoc="x">raise-result-error</a></span></span><span class="hspace"> </span><span class="RktVar">name</span><span class="hspace"> </span><span class="RktVar">expected</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="data-structure-contracts.html#%28form._%28%28lib._racket%2Fcontract%2Fprivate%2Fmisc..rkt%29._any%29%29" class="RktStxLink" data-pltdoc="x">any</a></span></p></blockquote></td></tr><tr><td><span class="hspace"> </span><span class="RktVar">name</span><span class="hspace"> </span>:<span class="hspace"> </span><span class="RktSym"><a href="symbols.html#%28def._%28%28quote._~23~25kernel%29._symbol~3f%29%29" class="RktValLink" data-pltdoc="x">symbol?</a></span></td></tr><tr><td><span class="hspace"> </span><span class="RktVar">expected</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><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><tr><td><table cellspacing="0" cellpadding="0" class="prototype"><tr><td valign="top"><span class="RktPn">(</span><span title="Provided from: racket/base, racket | Package: base"><span class="RktSym"><a href="exns.html#%28def._%28%28quote._~23~25kernel%29._raise-result-error%29%29" class="RktValDef RktValLink" data-pltdoc="x">raise-result-error</a></span></span></td><td valign="top"><span class="hspace"> </span></td><td valign="top"><span class="RktVar">name</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">expected</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">bad-pos</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">v</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><t
|
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|
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as a “result” instead of an “argument.”</div></p><p><div class="SIntrapara"><blockquote class="SVInsetFlow"><table cellspacing="0" cellpadding="0" class="boxed RBoxed"><tr><td><blockquote class="SubFlow"><div class="RBackgroundLabel SIEHidden"><div class="RBackgroundLabelInner"><p>procedure</p></div></div><p class="RForeground"><span class="RktPn">(</span><a name="(def._((quote._~23~25kernel)._raise-result-error*))"></a><span title="Provided from: racket/base, racket | Package: base"><span class="RktSym"><a href="exns.html#%28def._%28%28quote._~23~25kernel%29._raise-result-error%2A%29%29" class="RktValDef RktValLink" data-pltdoc="x">raise-result-error*</a></span></span><span class="hspace"> </span><span class="RktVar">name</span><span class="hspace"> </span><span class="RktVar">realm</span><span class="hspace"> </span><span class="RktVar">expected</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="data-structure-contracts.html#%28form._%28%28lib._racket%2Fcontract%2Fprivate%2Fmisc..rkt%29._any%29%29" class="RktStxLink" data-pltdoc="x">any</a></span></p></blockquote></td></tr><tr><td><span class="hspace"> </span><span class="RktVar">name</span><span class="hspace"> </span>:<span class="hspace"> </span><span class="RktSym"><a href="symbols.html#%28def._%28%28quote._~23~25kernel%29._symbol~3f%29%29" class="RktValLink" data-pltdoc="x">symbol?</a></span></td></tr><tr><td><span class="hspace"> </span><span class="RktVar">realm</span><span class="hspace"> </span>:<span class="hspace"> </span><span class="RktSym"><a href="symbols.html#%28def._%28%28quote._~23~25kernel%29._symbol~3f%29%29" class="RktValLink" data-pltdoc="x">symbol?</a></span></td></tr><tr><td><span class="hspace"> </span><span class="RktVar">expected</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><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><tr><td><table cellspacing="0" cellpadding="0" class="prototype"><tr><td valign="top"><span class="RktPn">(</span><span title="Provided from: racket/base, racket | Package: base"><span class="RktSym"><a href="exns.html#%28def._%28%28quote._~23~25kernel%29._raise-result-error%2A%29%29" class="RktValDef RktValLink" data-pltdoc="x">raise-result-error*</a></span></span></td><td valign="top"><span class="hspace"> </span></td><td valign="top"><span class="RktVar">name</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">realm</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">expected</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
|
||
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for error-message adjustments.</div></p><p class="SHistory">Added in version 8.4.0.2 of package <span class="stt">base</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><table cellspacing="0" cellpadding="0" class="prototype RForeground"><tr><td valign="top"><span class="RktPn">(</span><a name="(def._((quote._~23~25kernel)._raise-arguments-error))"></a><span title="Provided from: racket/base, racket | Package: base"><span class="RktSym"><a href="exns.html#%28def._%28%28quote._~23~25kernel%29._raise-arguments-error%29%29" class="RktValDef RktValLink" data-pltdoc="x">raise-arguments-error</a></span></span></td><td valign="top"><span class="hspace"> </span></td><td valign="top"><span class="RktVar">name</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">message</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">field</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">v</span><span class="hspace"> </span><span class="RktMeta">...</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="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="data-structure-contracts.html#%28form._%28%28lib._racket%2Fcontract%2Fprivate%2Fmisc..rkt%29._any%29%29" class="RktStxLink" data-pltdoc="x">any</a></span></td></tr></table></blockquote></td></tr><tr><td><span class="hspace"> </span><span class="RktVar">name</span><span class="hspace"> </span>:<span class="hspace"> </span><span class="RktSym"><a href="symbols.html#%28def._%28%28quote._~23~25kernel%29._symbol~3f%29%29" class="RktValLink" data-pltdoc="x">symbol?</a></span></td></tr><tr><td><span class="hspace"> </span><span class="RktVar">message</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><tr><td><span class="hspace"> </span><span class="RktVar">field</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><tr><td><span class="hspace"> </span><span class="RktVar">v</span><span class="hspace"> </span>:<span class="hspace"> </sp
|
||
|
|
an exception. The <span class="RktVar">name</span> is used as the source procedure’s
|
||
|
|
name in the error message. The <span class="RktVar">message</span> is the error
|
||
|
|
message; if <span class="RktVar">message</span> contains newline characters, each extra line should be
|
||
|
|
suitably indented (with one extra space at the start of each line), but it should not end with a newline character.
|
||
|
|
Each <span class="RktVar">field</span> must have a corresponding <span class="RktVar">v</span>,
|
||
|
|
and the two are rendered on their own
|
||
|
|
line in the error message; each <span class="RktVar">v</span> is formatted
|
||
|
|
using the error value conversion handler (see
|
||
|
|
<span class="RktSym"><a href="exns.html#%28def._%28%28quote._~23~25kernel%29._error-value-~3estring-handler%29%29" class="RktValLink" data-pltdoc="x">error-value->string-handler</a></span>), unless <span class="RktVar">v</span> is a
|
||
|
|
<a href="exns.html#%28tech._unquoted._printing._string%29" class="techoutside" data-pltdoc="x"><span class="techinside">unquoted-printing string</span></a>, in which case the string content is
|
||
|
|
<span class="RktSym"><a href="Writing.html#%28def._%28%28quote._~23~25kernel%29._display%29%29" class="RktValLink" data-pltdoc="x">display</a></span>ed without using the error value conversion handler.</div></p><p>The error message generated by <span class="RktSym"><a href="exns.html#%28def._%28%28quote._~23~25kernel%29._raise-result-error%29%29" class="RktValLink" data-pltdoc="x">raise-result-error</a></span> is adjusted
|
||
|
|
via <span class="RktSym"><a href="exns.html#%28def._%28%28quote._~23~25kernel%29._error-contract-~3eadjusted-string%29%29" class="RktValLink" data-pltdoc="x">error-contract->adjusted-string</a></span> and then
|
||
|
|
<span class="RktSym"><a href="exns.html#%28def._%28%28quote._~23~25kernel%29._error-message-~3eadjusted-string%29%29" class="RktValLink" data-pltdoc="x">error-message->adjusted-string</a></span> using the default
|
||
|
|
<span class="RktVal">'</span><span class="RktVal">racket</span> realm.</p><p><div class="SIntrapara">Example:</div><div class="SIntrapara"><blockquote class="SCodeFlow"><table cellspacing="0" cellpadding="0" class="RktBlk"><tr><td><table cellspacing="0" cellpadding="0" class="RktBlk"><tr><td><span class="stt">> </span><span class="RktPn">(</span><span class="RktSym"><a href="exns.html#%28def._%28%28quote._~23~25kernel%29._raise-arguments-error%29%29" class="RktValLink" data-pltdoc="x">raise-arguments-error</a></span><span class="hspace"> </span><span class="RktVal">'</span><span class="RktVal">eat</span></td></tr><tr><td><span class="hspace"> </span><span class="hspace"> </span><span class="RktVal">"fish is smaller than its given meal"</span></td></tr><tr><td><span class="hspace"> </span><span class="hspace"> </span><span class="RktVal">"fish"</span><span class="hspace"> </span><span class="RktVal">12</span></td></tr><tr><td><span class="hspace"> </span><span class="hspace"> </span><span class="RktVal">"meal"</span><span class="hspace"> </span><span class="RktVal">13</span><span class="RktPn">)</span></td></tr></table></td></tr><tr><td><p><span class="RktErr">eat: fish is smaller than its given meal</span></p></td></tr><tr><td><p><span class="RktErr"></span><span class="hspace"> </span><span class="RktErr">fish: 12</span></p></td></tr><tr><td><p><span class="RktErr"></span><span class="hspace"> </span><span class="RktErr">meal: 13</span></p></td></tr></table></blockquote></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)._raise-arguments-error*))"></a><span title="Provided from: racket/base, racket | Package: base"><span class="RktSym"><a href="exns.html#%28def._%28%28quote._~23~25kernel%29._raise-arguments-error%2A%29%29" class="RktValDef RktValLink" data-pltdoc="x">raise-arguments-error*</a></span></span></td><td valign="top"><span class="hspace"> </span></td><td valign="top"><span class="RktVar">name</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">realm</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">message</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">field</span></td><td valign="top"><span class="hspace"> </span></td><td valign="top"><span clas
|
||
|
|
for error-message adjustments.</div></p><p class="SHistory">Added in version 8.4.0.2 of package <span class="stt">base</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><table cellspacing="0" cellpadding="0" class="prototype RForeground"><tr><td valign="top"><span class="RktPn">(</span><a name="(def._((quote._~23~25kernel)._raise-range-error))"></a><span title="Provided from: racket/base, racket | Package: base"><span class="RktSym"><a href="exns.html#%28def._%28%28quote._~23~25kernel%29._raise-range-error%29%29" class="RktValDef RktValLink" data-pltdoc="x">raise-range-error</a></span></span></td><td valign="top"><span class="hspace"> </span></td><td valign="top"><span class="RktVar">name</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">type-description</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">index-prefix</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">index</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">in-value</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">lower-bound</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">upper-bound</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><span class="RktOpt">[</span></td><td valign="top"><span class="RktVar">alt-lower-bound</span><span class="RktOpt">]</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="data-structure-contracts.html#%28form._%28%28l
|
||
|
|
an exception to report an out-of-range error. The <span class="RktVar">type-description</span>
|
||
|
|
string describes the value for which the index is meant to select an element,
|
||
|
|
and <span class="RktVar">index-prefix</span> is a prefix for the word “index.” The <span class="RktVar">index</span>
|
||
|
|
argument is the rejected index. The <span class="RktVar">in-value</span> argument is the value
|
||
|
|
for which the index was meant. The <span class="RktVar">lower-bound</span> and <span class="RktVar">upper-bound</span>
|
||
|
|
arguments specify the valid range of indices, inclusive; if <span class="RktVar">upper-bound</span>
|
||
|
|
is below <span class="RktVar">lower-bound</span>, the value is characterized as “empty.” If <span class="RktVar">alt-lower-bound</span>
|
||
|
|
is not <span class="RktVal">#f</span>, and if <span class="RktVar">index</span> is between <span class="RktVar">alt-lower-bound</span>
|
||
|
|
and <span class="RktVar">upper-bound</span>, then the error is report as <span class="RktVar">index</span> being less
|
||
|
|
than the “starting” index <span class="RktVar">lower-bound</span>.</div></p><p>Since <span class="RktVar">upper-bound</span> is inclusive, a typical value is <span class="emph">one
|
||
|
|
less than</span> the size of a collection—<wbr></wbr>for example, <span class="RktPn">(</span><span class="RktSym"><a href="generic-numbers.html#%28def._%28%28quote._~23~25kernel%29._sub1%29%29" class="RktValLink" data-pltdoc="x">sub1</a></span><span class="stt"> </span><span class="RktPn">(</span><span class="RktSym"><a href="vectors.html#%28def._%28%28quote._~23~25kernel%29._vector-length%29%29" class="RktValLink" data-pltdoc="x">vector-length</a></span><span class="stt"> </span><span class="RktVar">vec</span><span class="RktPn">)</span><span class="RktPn">)</span>, <span class="RktPn">(</span><span class="RktSym"><a href="generic-numbers.html#%28def._%28%28quote._~23~25kernel%29._sub1%29%29" class="RktValLink" data-pltdoc="x">sub1</a></span><span class="stt"> </span><span class="RktPn">(</span><span class="RktSym"><a href="pairs.html#%28def._%28%28quote._~23~25kernel%29._length%29%29" class="RktValLink" data-pltdoc="x">length</a></span><span class="stt"> </span><span class="RktVar">lst</span><span class="RktPn">)</span><span class="RktPn">)</span>, and so on.</p><p>The error message generated by <span class="RktSym"><a href="exns.html#%28def._%28%28quote._~23~25kernel%29._raise-range-error%29%29" class="RktValLink" data-pltdoc="x">raise-range-error</a></span> is adjusted
|
||
|
|
via <span class="RktSym"><a href="exns.html#%28def._%28%28quote._~23~25kernel%29._error-message-~3eadjusted-string%29%29" class="RktValLink" data-pltdoc="x">error-message->adjusted-string</a></span> using the default
|
||
|
|
<span class="RktVal">'</span><span class="RktVal">racket</span> realm.</p><p><div class="SIntrapara">Examples:</div><div class="SIntrapara"><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="exns.html#%28def._%28%28quote._~23~25kernel%29._raise-range-error%29%29" class="RktValLink" data-pltdoc="x">raise-range-error</a></span><span class="hspace"> </span><span class="RktVal">'</span><span class="RktVal">vector-ref</span><span class="hspace"> </span><span class="RktVal">"vector"</span><span class="hspace"> </span><span class="RktVal">"starting "</span><span class="hspace"> </span><span class="RktVal">5</span><span class="hspace"> </span><span class="RktVal">#</span><span class="RktVal">(</span><span class="RktVal">1</span><span class="hspace"> </span><span class="RktVal">2</span><span class="hspace"> </span><span class="RktVal">3</span><span class="hspace"> </span><span class="RktVal">4</span><span class="RktVal">)</span><span class="hspace"> </span><span class="RktVal">0</span><span class="hspace"> </span><span class="RktVal">3</span><span class="RktPn">)</span></td></tr><tr><td><p><span class="RktErr">vector-ref: starting index is out of range</span></p></td></tr><tr><td><p><span class="RktErr"></span><span class="hspace"> </span><span class="RktErr">starting index: 5</span></p></td></tr><tr><td><p><span class="RktErr"></span><span class="hspace"> </span><span class="RktErr">valid range: [0, 3]</span></p></td></tr><tr><td><p><span class="RktErr"></span><span class="hspace"> </span><span class="RktErr">vector: '#(1 2 3 4)</span></p></td></tr><tr><td><span class="stt">> </span><span class="RktPn">(</span><span class="RktSym"><a href="exns.html#%28def._%28%28quote._~23~25kernel%29._raise-range-error%29%29" class="RktValLink" data-pltdoc="x">raise-range-error</a></span><span class="hspace"> </span><span class="RktVal">'</span><span class="RktVal">vector-ref</span><span class="hspace"> </span><span class="RktVal">"vector"</span><span class="hspace"> </span><span class="RktVal">"ending "</span><span class="hspace"> </span><span class="RktVal">5</span><span class="hspace"> </span><span class="RktVal">#</span><span class="RktVal">(</span><span class="RktVal">1</span><span class="hspace"> </span><span class="RktVal">2</span><span class="hspace"> </span><span class="RktVal">3</span><span class="hspace"> </span><span class="RktVal">4</span><span class="RktVal">)</span><span class="hspace"> </span><span class="RktVal">0</span><span class="hspace"> </span><span class="RktVal">3</span><span class="RktPn">)</span></td></tr><tr><td><p><span class="RktErr">vector-ref: ending index is out of range</span></p></td></tr><tr><td><p><span class="RktErr"></span><span class="hspace"> </span><span class="RktErr">ending index: 5</span></p></td></tr><tr><td><p><span class="RktErr"></span><span class="hspace"> </span><span class="RktErr">valid range: [0, 3]</span></p></td></tr><tr><td><p><span class="RktErr"></span><span class="hspace"> </span><span class="RktErr">vector: '#(1 2 3 4)</span></p></td></tr><tr><td><span class="stt">> </span><span class="RktPn">(</span><span class="RktSym"><a href="exns.html#%28def._%28%28quote._~23~25kernel%29._raise-range-error%29%29" class="RktValLink" data-pltdoc="x">raise-range-error</a></span><span class="hspace"> </span><span class="RktVal">'</span><span class="RktVal">vector-ref</span><span class="hspace"> </span><span class="RktVal">"vector"</span><span class="hspace"> </span><span class="RktVal">""</span><span class="hspace"> </span><span class="RktVal">3</span><span class="hspace"> </span><span class="RktVal">#</span><span class="RktVal">(</span><span class="RktVal">)</span><span class="hspace"> </span><span class="RktVal">0</span><span class="hspace"> </span><span class="RktVal
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for error-message adjustments.</div></p><p class="SHistory">Added in version 8.4.0.2 of package <span class="stt">base</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)._raise-type-error))"></a><span title="Provided from: racket/base, racket | Package: base"><span class="RktSym"><a href="exns.html#%28def._%28%28quote._~23~25kernel%29._raise-type-error%29%29" class="RktValDef RktValLink" data-pltdoc="x">raise-type-error</a></span></span><span class="hspace"> </span><span class="RktVar">name</span><span class="hspace"> </span><span class="RktVar">expected</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="data-structure-contracts.html#%28form._%28%28lib._racket%2Fcontract%2Fprivate%2Fmisc..rkt%29._any%29%29" class="RktStxLink" data-pltdoc="x">any</a></span></p></blockquote></td></tr><tr><td><span class="hspace"> </span><span class="RktVar">name</span><span class="hspace"> </span>:<span class="hspace"> </span><span class="RktSym"><a href="symbols.html#%28def._%28%28quote._~23~25kernel%29._symbol~3f%29%29" class="RktValLink" data-pltdoc="x">symbol?</a></span></td></tr><tr><td><span class="hspace"> </span><span class="RktVar">expected</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><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><tr><td><span class="RktPn">(</span><span title="Provided from: racket/base, racket | Package: base"><span class="RktSym"><a href="exns.html#%28def._%28%28quote._~23~25kernel%29._raise-type-error%29%29" class="RktValDef RktValLink" data-pltdoc="x">raise-type-error</a></span></span><span class="hspace"> </span><span class="RktVar">name</span><span class="hspace"> </span><span class="RktVar">expected</span><span class="hspace"> </span><span class="RktVar">bad-pos</span><span class="hspace"> </span><span class="RktVar">v</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="data-structure-contracts.html#%28form._%28%28lib._racket%2Fcontract%2Fprivate%2Fmisc..rkt%29._any%29%29" class="RktStxLink" data-pltdoc="x">any</a></span></td></tr><tr><td><span class="hspace"> </span><span class="RktVar">name</span><span class="hspace"> </span>:<span class="hspace"> </span><span class="RktSym"><a href="symbols.html#%28def._%28%28quote._~23~25kernel%29._symbol~3f%29%29" class="RktValLink" data-pltdoc="x">symbol?</a></span></td></tr><tr><td><span class="hspace"> </span><span class="RktVar">expected</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><tr><td><span class="hspace"> </span><span class="RktVar">bad-pos</span><span class="hspace"> </span>:<span class="hspace"> </span><span class="RktSym"><a href="number-types.html#%28def._%28%28quote._~23~25kernel%29._exact-nonnegative-integer~3f%29%29" class="RktValLink" data-pltdoc="x">exact-nonnegative-int
|
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conventions, and where <span class="RktVar">expected</span> is used as a “type”
|
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description instead of a contract expression. Use <span class="RktSym"><a href="exns.html#%28def._%28%28quote._~23~25kernel%29._raise-argument-error%29%29" class="RktValLink" data-pltdoc="x">raise-argument-error</a></span>
|
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or <span class="RktSym"><a href="exns.html#%28def._%28%28quote._~23~25kernel%29._raise-result-error%29%29" class="RktValLink" data-pltdoc="x">raise-result-error</a></span>, instead.</div></p><p>The error message generated by <span class="RktSym"><a href="exns.html#%28def._%28%28quote._~23~25kernel%29._raise-type-error%29%29" class="RktValLink" data-pltdoc="x">raise-type-error</a></span> is adjusted
|
||
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via <span class="RktSym"><a href="exns.html#%28def._%28%28quote._~23~25kernel%29._error-message-~3eadjusted-string%29%29" class="RktValLink" data-pltdoc="x">error-message->adjusted-string</a></span> using the default
|
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<span class="RktVal">'</span><span class="RktVal">racket</span> realm.</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)._raise-mismatch-error))"></a><span title="Provided from: racket/base, racket | Package: base"><span class="RktSym"><a href="exns.html#%28def._%28%28quote._~23~25kernel%29._raise-mismatch-error%29%29" class="RktValDef RktValLink" data-pltdoc="x">raise-mismatch-error</a></span></span></td><td valign="top"><span class="hspace"> </span></td><td valign="top"><span class="RktVar">name</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">message</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">v</span><span class="hspace"> </span><span class="RktMeta">...+</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="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="data-structure-contracts.html#%28form._%28%28lib._racket%2Fcontract%2Fprivate%2Fmisc..rkt%29._any%29%29" class="RktStxLink" data-pltdoc="x">any</a></span></td></tr></table></blockquote></td></tr><tr><td><span class="hspace"> </span><span class="RktVar">name</span><span class="hspace"> </span>:<span class="hspace"> </span><span class="RktSym"><a href="symbols.html#%28def._%28%28quote._~23~25kernel%29._symbol~3f%29%29" class="RktValLink" data-pltdoc="x">symbol?</a></span></td></tr><tr><td><span class="hspace"> </span><span class="RktVar">message</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><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">Similar to <span class="RktSym"><a href="exns.html#%28def._%28%28quote._~23~25kernel%29._raise-arguments-error%29%29" class="RktValLink" data-pltdoc="x">raise-arguments-error</a></span>, but using Racket’s old
|
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formatting conventions, with a required <span class="RktVar">v</span> immediately
|
||
|
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after the first <span class="RktVar">message</span> string, and with further <span class="RktVar">message</span>
|
||
|
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strings that are spliced into the message without line breaks or
|
||
|
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space. Use <span class="RktSym"><a href="exns.html#%28def._%28%28quote._~23~25kernel%29._raise-arguments-error%29%29" class="RktValLink" data-pltdoc="x">raise-arguments-error</a></span>, instead.</div></p><p>The error message generated by <span class="RktSym"><a href="exns.html#%28def._%28%28quote._~23~25kernel%29._raise-mismatch-error%29%29" class="RktValLink" data-pltdoc="x">raise-mismatch-error</a></span> is adjusted
|
||
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via <span class="RktSym"><a href="exns.html#%28def._%28%28quote._~23~25kernel%29._error-message-~3eadjusted-string%29%29" class="RktValLink" data-pltdoc="x">error-message->adjusted-string</a></span> using the default
|
||
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<span class="RktVal">'</span><span class="RktVal">racket</span> realm.</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)._raise-arity-error))"></a><span title="Provided from: racket/base, racket | Package: base"><span class="RktSym"><a href="exns.html#%28def._%28%28quote._~23~25kernel%29._raise-arity-error%29%29" class="RktValDef RktValLink" data-pltdoc="x">raise-arity-error</a></span></span><span class="hspace"> </span><span class="RktVar">name</span><span class="hspace"> </span><span class="RktVar">arity-v</span><span class="hspace"> </span><span class="RktVar">arg-v</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="data-structure-contracts.html#%28form._%28%28lib._racket%2Fcontract%2Fprivate%2Fmisc..rkt%29._any%29%29" class="RktStxLink" data-pltdoc="x">any</a></span></p></blockquote></td></tr><tr><td><span class="hspace"> </span><span class="RktVar">name</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="symbols.html#%28def._%28%28quote._~23~25kernel%29._symbol~3f%29%29" class="RktValLink" data-pltdoc="x">symbol?</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><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">arity-v</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="number-types.html#%28def._%28%28quote._~23~25kernel%29._exact-nonnegative-integer~3f%29%29" class="RktValLink" data-pltdoc="x">exact-nonnegative-integer?</a></span></td></tr><tr><td><span class="hspace"> </span><span class="RktSym"><a href="procedures.html#%28def._%28%28quote._~23~25kernel%29._arity-at-least~3f%29%29" class="RktValLink" data-pltdoc="x">arity-at-least?</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._listof%29%29" class="RktValLink" data-pltdoc="x">listof</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="RktSym"><a href="number-types.html#%28def._%28%28quote._~23~25kernel%29._exact-nonnegative-integer~3f%29%29" class="RktValLink" data-pltdoc="x">exact-nonnegative-integer?</a></span></td></tr><tr><td><span class="hspace"> </span><span class="RktSym"><a h
|
||
|
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it as an exception. The <span class="RktVar">name</span> is used for the source
|
||
|
|
procedure’s name in the error message.</div></p><p>The <span class="RktVar">arity-v</span> value must
|
||
|
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be a possible result from <span class="RktSym"><a href="procedures.html#%28def._%28%28quote._~23~25kernel%29._procedure-arity%29%29" class="RktValLink" data-pltdoc="x">procedure-arity</a></span>, except
|
||
|
|
that it does not have to be normalized (see <span class="RktSym"><a href="procedures.html#%28def._%28%28quote._~23~25kernel%29._procedure-arity~3f%29%29" class="RktValLink" data-pltdoc="x">procedure-arity?</a></span> for
|
||
|
|
the details of normalized arities); <span class="RktSym"><a href="exns.html#%28def._%28%28quote._~23~25kernel%29._raise-arity-error%29%29" class="RktValLink" data-pltdoc="x">raise-arity-error</a></span>
|
||
|
|
will normalize the arity and use the normalized form in the error message.
|
||
|
|
If <span class="RktVar">name</span> is a procedure, its actual arity is
|
||
|
|
ignored.</p><p>The <span class="RktVar">arg-v</span> arguments are the actual supplied
|
||
|
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arguments, which are shown in the error message (using the error value
|
||
|
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conversion handler; see <span class="RktSym"><a href="exns.html#%28def._%28%28quote._~23~25kernel%29._error-value-~3estring-handler%29%29" class="RktValLink" data-pltdoc="x">error-value->string-handler</a></span>); also,
|
||
|
|
the number of supplied <span class="RktVar">arg-v</span>s is explicitly mentioned in the
|
||
|
|
message.</p><p>The error message generated by <span class="RktSym"><a href="exns.html#%28def._%28%28quote._~23~25kernel%29._raise-arity-error%29%29" class="RktValLink" data-pltdoc="x">raise-arity-error</a></span> is adjusted
|
||
|
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via <span class="RktSym"><a href="exns.html#%28def._%28%28quote._~23~25kernel%29._error-message-~3eadjusted-string%29%29" class="RktValLink" data-pltdoc="x">error-message->adjusted-string</a></span> using the default
|
||
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<span class="RktVal">'</span><span class="RktVal">racket</span> realm.</p><p><div class="SIntrapara">Example:</div><div class="SIntrapara"><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="exns.html#%28def._%28%28quote._~23~25kernel%29._raise-arity-error%29%29" class="RktValLink" data-pltdoc="x">raise-arity-error</a></span><span class="hspace"> </span><span class="RktVal">'</span><span class="RktVal">unite</span><span class="hspace"> </span><span class="RktPn">(</span><span class="RktSym"><a href="procedures.html#%28def._%28%28lib._racket%2Fprivate%2Fbase..rkt%29._arity-at-least%29%29" class="RktValLink" data-pltdoc="x">arity-at-least</a></span><span class="hspace"> </span><span class="RktVal">13</span><span class="RktPn">)</span><span class="hspace"> </span><span class="RktVal">"Virginia"</span><span class="hspace"> </span><span class="RktVal">"Maryland"</span><span class="RktPn">)</span></td></tr><tr><td><p><span class="RktErr">unite: arity mismatch;</span></p></td></tr><tr><td><p><span class="RktErr"></span><span class="hspace"> </span><span class="RktErr">the expected number of arguments does not match the given</span></p></td></tr><tr><td><p><span class="RktErr">number</span></p></td></tr><tr><td><p><span class="RktErr"></span><span class="hspace"> </span><span class="RktErr">expected: at least 13</span></p></td></tr><tr><td><p><span class="RktErr"></span><span class="hspace"> </span><span class="RktErr">given: 2</span></p></td></tr><tr><td><p><span class="RktErr"></span><span class="hspace"> </span><span class="RktErr">arguments...:</span></p></td></tr><tr><td><p><span class="RktErr"></span><span class="hspace"> </span><span class="RktErr"></span><span class="hspace"> </span><span class="RktErr">"Virginia"</span></p></td></tr><tr><td><p><span class="RktErr"></span><span class="hspace"> </span><span class="RktErr"></span><span class="hspace"> </span><span class="RktErr">"Maryland"</span></p></td></tr></table></blockquote></div></p><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)._raise-arity-error*))"></a><span title="Provided from: racket/base, racket | Package: base"><span class="RktSym"><a href="exns.html#%28def._%28%28quote._~23~25kernel%29._raise-arity-error%2A%29%29" class="RktValDef RktValLink" data-pltdoc="x">raise-arity-error*</a></span></span></td><td valign="top"><span class="hspace"> </span></td><td valign="top"><span class="RktVar">name</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">realm</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">arity-v</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
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||
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for error-message adjustments.</p><p class="SHistory">Added in version 8.4.0.2 of package <span class="stt">base</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)._raise-arity-mask-error))"></a><span title="Provided from: racket/base, racket | Package: base"><span class="RktSym"><a href="exns.html#%28def._%28%28quote._~23~25kernel%29._raise-arity-mask-error%29%29" class="RktValDef RktValLink" data-pltdoc="x">raise-arity-mask-error</a></span></span><span class="hspace"> </span><span class="RktVar">name</span><span class="hspace"> </span><span class="RktVar">mask</span><span class="hspace"> </span><span class="RktVar">arg-v</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="data-structure-contracts.html#%28form._%28%28lib._racket%2Fcontract%2Fprivate%2Fmisc..rkt%29._any%29%29" class="RktStxLink" data-pltdoc="x">any</a></span></p></blockquote></td></tr><tr><td><span class="hspace"> </span><span class="RktVar">name</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="symbols.html#%28def._%28%28quote._~23~25kernel%29._symbol~3f%29%29" class="RktValLink" data-pltdoc="x">symbol?</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><span class="RktPn">)</span></td></tr><tr><td><span class="hspace"> </span><span class="RktVar">mask</span><span class="hspace"> </span>:<span class="hspace"> </span><span class="RktSym"><a href="number-types.html#%28def._%28%28quote._~23~25kernel%29._exact-integer~3f%29%29" class="RktValLink" data-pltdoc="x">exact-integer?</a></span></td></tr><tr><td><span class="hspace"> </span><span class="RktVar">arg-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">The same as <span class="RktSym"><a href="exns.html#%28def._%28%28quote._~23~25kernel%29._raise-arity-error%29%29" class="RktValLink" data-pltdoc="x">raise-arity-error</a></span>, but using the arity representation
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||
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described with <span class="RktSym"><a href="procedures.html#%28def._%28%28quote._~23~25kernel%29._procedure-arity-mask%29%29" class="RktValLink" data-pltdoc="x">procedure-arity-mask</a></span>.</div></p><p class="SHistory">Added in version 7.0.0.11 of package <span class="stt">base</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><table cellspacing="0" cellpadding="0" class="prototype RForeground"><tr><td valign="top"><span class="RktPn">(</span><a name="(def._((quote._~23~25kernel)._raise-arity-mask-error*))"></a><span title="Provided from: racket/base, racket | Package: base"><span class="RktSym"><a href="exns.html#%28def._%28%28quote._~23~25kernel%29._raise-arity-mask-error%2A%29%29" class="RktValDef RktValLink" data-pltdoc="x">raise-arity-mask-error*</a></span></span></td><td valign="top"><span class="hspace"> </span></td><td valign="top"><span class="RktVar">name</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">realm</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">mask</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">arg-v</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="data-structure-contracts.html#%28form._%28%28lib._racket%2Fcontract%2Fprivate%2Fmisc..rkt%29._any%29%29" class="RktStxLink" data-pltdoc="x">any</a></span></td></tr></table></blockquote></td></tr><tr><td><span class="hspace"> </span><span class="RktVar">name</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="symbols.html#%28def._%28%28quote._~23~25kernel%29._symbol~3f%29%29" class="RktValLink" data-pltdoc="x">symbol?</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><span class="RktPn">)</span></td></tr><tr><td><span class="hspace"> </span><span class="RktVar">realm</span><span class="hspace"> </span>:<span class="hspace"> </span><span class="RktSym"><a href="symbols.html#%28def._%28%28quote._~23~25kernel%29._symbol~3f%29%29" class="RktValLink" data-pltdoc="x">symbol?</a></span></td></tr><tr><td><span class="hspace"> </span><span class="RktVar">mask</span><span class="hspace"> </span>:<span class="hspace"> </span><span class="RktSym"><a href="number-types.html#%28def._%28%28quote._~2
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for error-message adjustments.</div></p><p class="SHistory">Added in version 8.4.0.2 of package <span class="stt">base</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><table cellspacing="0" cellpadding="0" class="prototype RForeground"><tr><td valign="top"><span class="RktPn">(</span><a name="(def._((quote._~23~25kernel)._raise-result-arity-error))"></a><span title="Provided from: racket/base, racket | Package: base"><span class="RktSym"><a href="exns.html#%28def._%28%28quote._~23~25kernel%29._raise-result-arity-error%29%29" class="RktValDef RktValLink" data-pltdoc="x">raise-result-arity-error</a></span></span></td><td valign="top"><span class="hspace"> </span></td><td valign="top"><span class="RktVar">name</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">arity-v</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">detail-str</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">result-v</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="data-structure-contracts.html#%28form._%28%28lib._racket%2Fcontract%2Fprivate%2Fmisc..rkt%29._any%29%29" class="RktStxLink" data-pltdoc="x">any</a></span></td></tr></table></blockquote></td></tr><tr><td><span class="hspace"> </span><span class="RktVar">name</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="symbols.html#%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">#f</span><span class="RktPn">)</span></td></tr><tr><td><span class="hspace"> </span><span class="RktVar">arity-v</span><span class="hspace"> </span>:<span class="hspace"> </span><span class="RktSym"><a href="number-types.html#%28def._%28%28quote._~23~25kernel%29._exact-nonnegative-integer~3f%29%29" class="RktValLink" data-pltdoc="x">exact-nonnegative-integer?</a></span></td></tr><tr><td><span class="hspace"> </span><span class="RktVar">detail-str</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._
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instead of an “argument” mismatch. The <span class="RktVar">name</span> argument can be
|
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<span class="RktVal">#f</span> to omit an initial source for the error. The
|
||
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<span class="RktVar">detail-str</span> argument, if non-<span class="RktVal">#f</span>, should be a string
|
||
|
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that starts with a newline, since it is added near the end of the
|
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generated error message.</div></p><p>The error message generated by <span class="RktSym"><a href="exns.html#%28def._%28%28quote._~23~25kernel%29._raise-result-arity-error%29%29" class="RktValLink" data-pltdoc="x">raise-result-arity-error</a></span> is
|
||
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adjusted via <span class="RktSym"><a href="exns.html#%28def._%28%28quote._~23~25kernel%29._error-message-~3eadjusted-string%29%29" class="RktValLink" data-pltdoc="x">error-message->adjusted-string</a></span> using the default
|
||
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<span class="RktVal">'</span><span class="RktVal">racket</span> realm.</p><p><div class="SIntrapara">Example:</div><div class="SIntrapara"><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="exns.html#%28def._%28%28quote._~23~25kernel%29._raise-result-arity-error%29%29" class="RktValLink" data-pltdoc="x">raise-result-arity-error</a></span><span class="hspace"> </span><span class="RktVal">'</span><span class="RktVal">let-values</span><span class="hspace"> </span><span class="RktVal">2</span><span class="hspace"> </span><span class="RktVal">"\n</span><span class="hspace"> </span><span class="RktVal">in: example"</span><span class="hspace"> </span><span class="RktVal">'</span><span class="RktVal">a</span><span class="hspace"> </span><span class="RktVal">2.0</span><span class="hspace"> </span><span class="RktVal">"three"</span><span class="RktPn">)</span></td></tr><tr><td><p><span class="RktErr">let-values: result arity mismatch;</span></p></td></tr><tr><td><p><span class="RktErr"></span><span class="hspace"> </span><span class="RktErr">expected number of values not received</span></p></td></tr><tr><td><p><span class="RktErr"></span><span class="hspace"> </span><span class="RktErr">expected: 2</span></p></td></tr><tr><td><p><span class="RktErr"></span><span class="hspace"> </span><span class="RktErr">received: 3</span></p></td></tr><tr><td><p><span class="RktErr"></span><span class="hspace"> </span><span class="RktErr">in: example</span></p></td></tr><tr><td><p><span class="RktErr"></span><span class="hspace"> </span><span class="RktErr">arguments...:</span></p></td></tr><tr><td><p><span class="RktErr"></span><span class="hspace"> </span><span class="RktErr"></span><span class="hspace"> </span><span class="RktErr">'a</span></p></td></tr><tr><td><p><span class="RktErr"></span><span class="hspace"> </span><span class="RktErr"></span><span class="hspace"> </span><span class="RktErr">2.0</span></p></td></tr><tr><td><p><span class="RktErr"></span><span class="hspace"> </span><span class="RktErr"></span><span class="hspace"> </span><span class="RktErr">"three"</span></p></td></tr></table></blockquote></div></p><p class="SHistory">Added in version 6.90.0.26 of package <span class="stt">base</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><table cellspacing="0" cellpadding="0" class="prototype RForeground"><tr><td valign="top"><span class="RktPn">(</span><a name="(def._((quote._~23~25kernel)._raise-result-arity-error*))"></a><span title="Provided from: racket/base, racket | Package: base"><span class="RktSym"><a href="exns.html#%28def._%28%28quote._~23~25kernel%29._raise-result-arity-error%2A%29%29" class="RktValDef RktValLink" data-pltdoc="x">raise-result-arity-error*</a></span></span></td><td valign="top"><span class="hspace"> </span></td><td valign="top"><span class="RktVar">name</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">realm</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 cl
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for error-message adjustments.</div></p><p class="SHistory">Added in version 8.4.0.2 of package <span class="stt">base</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><table cellspacing="0" cellpadding="0" class="prototype RForeground"><tr><td valign="top"><span class="RktPn">(</span><a name="(def._((lib._racket/private/base..rkt)._raise-syntax-error))"></a><span title="Provided from: racket/base, racket | Package: base"><span class="RktSym"><a href="exns.html#%28def._%28%28lib._racket%2Fprivate%2Fbase..rkt%29._raise-syntax-error%29%29" class="RktValDef RktValLink" data-pltdoc="x">raise-syntax-error</a></span></span></td><td valign="top"><span class="hspace"> </span></td><td valign="top"><span class="RktVar">name</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">message</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><span class="RktOpt">[</span></td><td valign="top"><span class="RktVar">expr</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">sub-expr</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">extra-sources</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">message-suffix</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="RktPn">#:exn</span><span class="hspace"> </span><span class="RktVar">exn</span><span class="RktOpt">]</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="data-structure-contracts.html#%28form._%28%28lib._racket%2Fcontract%2Fprivate%2Fmisc..rkt%29._any%29%29" class="RktStxLink" data-pltdoc="x">any</a></span></td></tr></table></blockquote></td></tr><tr><td><span class="hspace"> </span><span class="RktVar">name</span><span class="hspace"> </span>:<span class="hspace"> </span><span class="RktPn">(</span><span
|
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exception. Macros use this procedure to report syntax errors.</div></p><p>The <span class="RktVar">name</span> argument is usually <span class="RktVal">#f</span> when <span class="RktVar">expr</span>
|
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is provided; it is described in more detail below. The
|
||
|
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<span class="RktVar">message</span> is used as the main body of the error message; if
|
||
|
|
<span class="RktVar">message</span> contains newline characters, each new line should be
|
||
|
|
suitably indented (with one space at the start), and it should not end with a newline character.</p><p>The optional <span class="RktVar">expr</span> argument is the erroneous source syntax
|
||
|
|
object or S-expression (but the expression <span class="RktVal">#f</span> cannot be
|
||
|
|
represented by itself; it must be wrapped as a <a href="syntax-model.html#%28tech._syntax._object%29" class="techoutside" data-pltdoc="x"><span class="techinside">syntax
|
||
|
|
object</span></a>). The optional <span class="RktVar">sub-expr</span> argument is a syntax object
|
||
|
|
or S-expression (again, <span class="RktVal">#f</span> cannot represent itself) within
|
||
|
|
<span class="RktVar">expr</span> that more precisely locates the error. Both may appear
|
||
|
|
in the generated error-message text if
|
||
|
|
<span class="RktSym"><a href="exns.html#%28def._%28%28quote._~23~25kernel%29._error-print-source-location%29%29" class="RktValLink" data-pltdoc="x">error-print-source-location</a></span> is <span class="RktVal">#t</span>. Source location
|
||
|
|
information in the error-message text is similarly extracted from
|
||
|
|
<span class="RktVar">sub-expr</span> or <span class="RktVar">expr</span> when at least one is a syntax
|
||
|
|
object and <span class="RktSym"><a href="exns.html#%28def._%28%28quote._~23~25kernel%29._error-print-source-location%29%29" class="RktValLink" data-pltdoc="x">error-print-source-location</a></span> is <span class="RktVal">#t</span>.</p><p>If <span class="RktVar">sub-expr</span> is provided and not <span class="RktVal">#f</span>, it is used (in
|
||
|
|
syntax form) for the <span class="RktSym">exprs</span> field of the generated exception
|
||
|
|
record, else the <span class="RktVar">expr</span> is used if provided and not
|
||
|
|
<span class="RktVal">#f</span>. In either case, the syntax object is <span class="RktSym"><a href="pairs.html#%28def._%28%28quote._~23~25kernel%29._cons%29%29" class="RktValLink" data-pltdoc="x">cons</a></span>ed onto
|
||
|
|
<span class="RktVar">extra-sources</span> to produce the <span class="RktSym">exprs</span> field, or
|
||
|
|
<span class="RktVar">extra-sources</span> is used directly for <span class="RktSym">exprs</span> if neither
|
||
|
|
<span class="RktVar">expr</span> nor <span class="RktVar">sub-expr</span> is provided and not <span class="RktVal">#f</span>.
|
||
|
|
The <span class="RktVar">extra-sources</span> argument is also used directly for
|
||
|
|
<span class="RktSym">exprs</span> in the unusual case that the <span class="RktVar">sub-expr</span> or
|
||
|
|
<span class="RktVar">expr</span> that would be included in <span class="RktSym">exprs</span> cannot be
|
||
|
|
converted to a syntax object (because it contains a cycle).</p><p>The form name used in the generated error message is determined
|
||
|
|
through a combination of the <span class="RktVar">name</span>, <span class="RktVar">expr</span>, and
|
||
|
|
<span class="RktVar">sub-expr</span> arguments:</p><ul><li><p>When <span class="RktVar">name</span> is <span class="RktVal">#f</span>, and when <span class="RktVar">expr</span> is
|
||
|
|
either an identifier or a syntax pair containing an identifier as
|
||
|
|
its first element, then the form name from the error message is the
|
||
|
|
identifier’s symbol.</p></li><li><p>When <span class="RktVar">name</span> is <span class="RktVal">#f</span> and when <span class="RktVar">expr</span> is not
|
||
|
|
an identifier or a syntax pair containing an identifier as its
|
||
|
|
first element, then the form name in the error message is
|
||
|
|
<span class="RktVal">"?"</span>.</p></li><li><p>When <span class="RktVar">name</span> is a symbol, then the symbol
|
||
|
|
is used as the form name in the generated error message.</p></li></ul><p>The <span class="RktVar">message-suffix</span> string is appended to the end of the error
|
||
|
|
message. If not <span class="RktVal">""</span>, it should normally start with a newline
|
||
|
|
and two spaces to add extra fields to the message (see
|
||
|
|
<a href="exns.html#%28part._err-msg-conventions%29" data-pltdoc="x">Error Message Conventions</a>).</p><p>If specified, <span class="RktVar">exn</span> should be a constructor or function that
|
||
|
|
has the same signature as the <span class="RktSym"><a href="exns.html#%28def._%28%28lib._racket%2Fprivate%2Fbase..rkt%29._exn~3afail~3asyntax%29%29" class="RktValLink" data-pltdoc="x">exn:fail:syntax</a></span> constructor.</p><p><div class="SIntrapara">Examples:</div><div class="SIntrapara"><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="exns.html#%28def._%28%28lib._racket%2Fprivate%2Fbase..rkt%29._raise-syntax-error%29%29" class="RktValLink" data-pltdoc="x">raise-syntax-error</a></span><span class="hspace"> </span><span class="RktVal">#f</span><span class="hspace"> </span><span class="RktVal">"bad syntax"</span><span class="hspace"> </span><span class="RktVal">'</span><span class="RktVal">(</span><span class="RktVal">bad</span><span class="hspace"> </span><span class="RktVal">syntax</span><span class="RktVal">)</span><span class="RktPn">)</span></td></tr><tr><td><p><span class="RktErr">?: bad syntax</span></p></td></tr><tr><td><p><span class="RktErr"></span><span class="hspace"> </span><span class="RktErr">in: (bad syntax)</span></p></td></tr><tr><td><span class="stt">> </span><span class="RktPn">(</span><span class="RktSym"><a href="exns.html#%28def._%28%28lib._racket%2Fprivate%2Fbase..rkt%29._raise-syntax-error%29%29" class="RktValLink" data-pltdoc="x">raise-syntax-error</a></span><span class="hspace"> </span><span class="RktVal">#f</span><span class="hspace"> </span><span class="RktVal">"unbound identifier"</span><span class="hspace"> </span><span class="RktVal">'</span><span class="RktVal">unbound-id</span><span class="hspace"> </span><span class="RktPn">#:exn</span><span class="hspace"> </span><span class="RktSym"><a href="exns.html#%28def._%28%28lib._racket%2Fprivate%2Fbase..rkt%29._exn~3afail~3asyntax~3aunbound%29%29" class="RktValLink" data-pltdoc="x">exn:fail:syntax:unbound</a></span><span class="RktPn">)</span></td></tr><tr><td><p><span class="RktErr">?: unbound identifier</span></p></td></tr><tr><td><p><span class="RktErr"></span><span class="hspace"> </span><span class="RktErr">in: unbound-id</span></p></td></tr></table></blockquote></div></p><p class="SHistory">Changed in version 6.90.0.18 of package <span class="stt">base</span>: Added the <span class="RktVar">message-suffix</span> optional argument.<br/>Changed in version 8.4.0.6: Added the <span class="RktVar">exn</span> optional argument.</p><p><div class="SIntrapara"><blockquote class="SVInsetFlow"><table cellspacing="0" cellpadding="0" class="boxed RBoxed"><tr><td><table cellspacing="0" cellpadding="0" class="together"><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)._unquoted-printing-string~3f))"></a><span title="Provided from: racket/base, racket | Package: base"><span class="RktSym"><a href="exns.html#%28def._%28%28quote._~23~25kernel%29._unquoted-printing-string~3f%29%29" class="RktValDef RktValLink" data-pltdoc="x">unquoted-printing-string?</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></td></tr><tr><td><table cellspacing="0" cellpadding="0" class="together"><tr><td><blockquote class="SubFlow"><div class="RBackgr
|
||
|
|
<span class="RktSym"><a href="Writing.html#%28def._%28%28quote._~23~25kernel%29._print%29%29" class="RktValLink" data-pltdoc="x">print</a></span>s, <span class="RktSym"><a href="Writing.html#%28def._%28%28quote._~23~25kernel%29._write%29%29" class="RktValLink" data-pltdoc="x">write</a></span>s, and <span class="RktSym"><a href="Writing.html#%28def._%28%28quote._~23~25kernel%29._display%29%29" class="RktValLink" data-pltdoc="x">display</a></span>s the same way
|
||
|
|
that the string <span class="RktSym"><a href="Writing.html#%28def._%28%28quote._~23~25kernel%29._display%29%29" class="RktValLink" data-pltdoc="x">display</a></span>s. An <a href="exns.html#%28tech._unquoted._printing._string%29" class="techoutside" data-pltdoc="x"><span class="techinside">unquoted-printing string</span></a>
|
||
|
|
is especially useful with <span class="RktSym"><a href="exns.html#%28def._%28%28quote._~23~25kernel%29._raise-arguments-error%29%29" class="RktValLink" data-pltdoc="x">raise-arguments-error</a></span> to serve as a
|
||
|
|
field “value” that causes literal text to be printed as the field
|
||
|
|
content.</div></p><p>The <span class="RktSym"><a href="exns.html#%28def._%28%28quote._~23~25kernel%29._unquoted-printing-string~3f%29%29" class="RktValLink" data-pltdoc="x">unquoted-printing-string?</a></span> procedure returns <span class="RktVal">#t</span>
|
||
|
|
if <span class="RktVar">v</span> is a <a href="exns.html#%28tech._unquoted._printing._string%29" class="techoutside" data-pltdoc="x"><span class="techinside">unquoted-printing string</span></a>, <span class="RktVal">#f</span>
|
||
|
|
otherwise. The <span class="RktSym"><a href="exns.html#%28def._%28%28quote._~23~25kernel%29._unquoted-printing-string%29%29" class="RktValLink" data-pltdoc="x">unquoted-printing-string</a></span> creates a
|
||
|
|
<a href="exns.html#%28tech._unquoted._printing._string%29" class="techoutside" data-pltdoc="x"><span class="techinside">unquoted-printing string</span></a> value that encapsulates the string
|
||
|
|
<span class="RktVar">s</span>, and <span class="RktSym"><a href="exns.html#%28def._%28%28quote._~23~25kernel%29._unquoted-printing-string-value%29%29" class="RktValLink" data-pltdoc="x">unquoted-printing-string-value</a></span> returns the
|
||
|
|
string within a <a href="exns.html#%28tech._unquoted._printing._string%29" class="techoutside" data-pltdoc="x"><span class="techinside">unquoted-printing string</span></a>.</p><p class="SHistory">Added in version 6.10.0.2 of package <span class="stt">base</span>.</p><h5 x-source-module="(lib "scribblings/reference/reference.scrbl")" x-source-pkg="racket-doc" x-part-tag=""Handling_Exceptions"">10.2.3<tt> </tt><a name="(part._.Handling_.Exceptions)"></a>Handling Exceptions</h5><p><div class="SIntrapara"><blockquote class="SVInsetFlow"><table cellspacing="0" cellpadding="0" class="boxed RBoxed"><tr><td><blockquote class="SubFlow"><div class="RBackgroundLabel SIEHidden"><div class="RBackgroundLabelInner"><p>procedure</p></div></div><p class="RForeground"><span class="RktPn">(</span><a name="(def._((lib._racket/private/more-scheme..rkt)._call-with-exception-handler))"></a><span title="Provided from: racket/base, racket | Package: base"><span class="RktSym"><a href="exns.html#%28def._%28%28lib._racket%2Fprivate%2Fmore-scheme..rkt%29._call-with-exception-handler%29%29" class="RktValDef RktValLink" data-pltdoc="x">call-with-exception-handler</a></span></span><span class="hspace"> </span><span class="RktVar">f</span><span class="hspace"> </span><span class="RktVar">thunk</span><span class="RktPn">)</span><span class="hspace"> </span>→<span class="hspace"> </span><span class="RktSym"><a href="data-structure-contracts.html#%28form._%28%28lib._racket%2Fcontract%2Fprivate%2Fmisc..rkt%29._any%29%29" class="RktStxLink" data-pltdoc="x">any</a></span></p></blockquote></td></tr><tr><td><span class="hspace"> </span><span class="RktVar">f</span><span class="hspace"> </span>:<span class="hspace"> </span><span class="RktPn">(</span><span class="RktSym"><a href="data-structure-contracts.html#%28def._%28%28lib._racket%2Fcontract%2Fprivate%2Fmisc..rkt%29._any%2Fc%29%29" class="RktValLink" data-pltdoc="x">any/c</a></span><span class="hspace"> </span><span class="RktPn">. </span><span class="RktSym"><a href="function-contracts.html#%28form._%28%28lib._racket%2Fcontract%2Fbase..rkt%29._-~3e%29%29" class="RktStxLink" data-pltdoc="x"><span class="nobreak">-></span></a></span><span class="RktPn"> .</span><span class="hspace"> </span><span class="RktSym"><a href="data-structure-contracts.html#%28form._%28%28lib._racket%2Fcontract%2Fprivate%2Fmisc..rkt%29._any%29%29" class="RktStxLink" data-pltdoc="x">any</a></span><span class="RktPn">)</span></td></tr><tr><td><span class="hspace"> </span><span class="RktVar">thunk</span><span class="hspace"> </span>:<span class="hspace"> </span><span class="RktPn">(</span><span class="RktSym"><a href="function-contracts.html#%28form._%28%28lib._racket%2Fcontract%2Fbase..rkt%29._-~3e%29%29" class="RktStxLink" data-pltdoc="x"><span class="nobreak">-></span></a></span><span class="hspace"> </span><span class="RktSym"><a href="data-structure-contracts.html#%28form._%28%28lib._racket%2Fcontract%2Fprivate%2Fmisc..rkt%29._any%29%29" class="RktStxLink" data-pltdoc="x">any</a></span><span class="RktPn">)</span></td></tr></table></blockquote></div><div class="SIntrapara">Installs <span class="RktVar">f</span> as the <a href="eval-model.html#%28tech._exception._handler%29" class="techoutside" data-pltdoc="x"><span class="techinside">exception handler</span></a> for the
|
||
|
|
<a href="eval-model.html#%28tech._dynamic._extent%29" class="techoutside" data-pltdoc="x"><span class="techinside">dynamic extent</span></a> of the call to <span class="RktVar">thunk</span>. If an exception
|
||
|
|
is raised during the evaluation of <span class="RktVar">thunk</span> (in an extension of
|
||
|
|
the current continuation that does not have its own exception
|
||
|
|
handler), then <span class="RktVar">f</span> is applied to the <span class="RktSym"><a href="exns.html#%28def._%28%28quote._~23~25kernel%29._raise%29%29" class="RktValLink" data-pltdoc="x">raise</a></span>d value in
|
||
|
|
the continuation of the <span class="RktSym"><a href="exns.html#%28def._%28%28quote._~23~25kernel%29._raise%29%29" class="RktValLink" data-pltdoc="x">raise</a></span> call (but the continuation is
|
||
|
|
normally extended
|
||
|
|
with a <a href="eval-model.html#%28tech._continuation._barrier%29" class="techoutside" data-pltdoc="x"><span class="techinside">continuation barrier</span></a>; see <a href="eval-model.html#%28part._prompt-model%29" data-pltdoc="x">Prompts, Delimited Continuations, and Barriers</a> and
|
||
|
|
<span class="RktSym"><a href="exns.html#%28def._%28%28quote._~23~25kernel%29._raise%29%29" class="RktValLink" data-pltdoc="x">raise</a></span>).</div></p><p>Any procedure that takes one argument can be an exception handler.
|
||
|
|
Normally, an exception handler escapes from the context of the
|
||
|
|
<span class="RktSym"><a href="exns.html#%28def._%28%28quote._~23~25kernel%29._raise%29%29" class="RktValLink" data-pltdoc="x">raise</a></span> call via <span class="RktSym"><a href="cont.html#%28def._%28%28quote._~23~25kernel%29._abort-current-continuation%29%29" class="RktValLink" data-pltdoc="x">abort-current-continuation</a></span> or some other escape
|
||
|
|
mechanism. To propagate an exception to the “previous” exception
|
||
|
|
handler—<wbr></wbr>that is, the exception handler associated with the rest of
|
||
|
|
the continuation after the point where the called exception handler
|
||
|
|
was associated with the continuation—<wbr></wbr>an exception handler can simply
|
||
|
|
return a result instead of escaping, in which case the <span class="RktSym"><a href="exns.html#%28def._%28%28quote._~23~25kernel%29._raise%29%29" class="RktValLink" data-pltdoc="x">raise</a></span> call
|
||
|
|
propagates the value to the previous exception handler (still in the
|
||
|
|
dynamic extent of the call to <span class="RktSym"><a href="exns.html#%28def._%28%28quote._~23~25kernel%29._raise%29%29" class="RktValLink" data-pltdoc="x">raise</a></span>, and under the same
|
||
|
|
barrier, if any). If an exception handler returns a result and no
|
||
|
|
previous handler is available, the <a href="exns.html#%28tech._uncaught._exception._handler%29" class="techoutside" data-pltdoc="x"><span class="techinside">uncaught-exception handler</span></a>
|
||
|
|
is used.</p><p>A call to an exception handler is <span class="RktSym"><a href="breakhandler.html#%28form._%28%28lib._racket%2Fprivate%2Fmore-scheme..rkt%29._parameterize-break%29%29" class="RktStxLink" data-pltdoc="x">parameterize-break</a></span>ed to
|
||
|
|
disable breaks, and it is wrapped with
|
||
|
|
<span class="RktSym"><a href="exns.html#%28def._%28%28lib._racket%2Fprivate%2Fmore-scheme..rkt%29._call-with-exception-handler%29%29" class="RktValLink" data-pltdoc="x">call-with-exception-handler</a></span> to install an exception handler
|
||
|
|
that reports both the original and newly raised exceptions via the
|
||
|
|
<a href="exns.html#%28tech._error._display._handler%29" class="techoutside" data-pltdoc="x"><span class="techinside">error display handler</span></a> and then escapes via the <a href="exns.html#%28tech._error._escape._handler%29" class="techoutside" data-pltdoc="x"><span class="techinside">error
|
||
|
|
escape handler</span></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>parameter</p></div></div><p class="RForeground"><span class="RktPn">(</span><a name="(def._((quote._~23~25kernel)._uncaught-exception-handler))"></a><span title="Provided from: racket/base, racket | Package: base"><span class="RktSym"><a href="exns.html#%28def._%28%28quote._~23~25kernel%29._uncaught-exception-handler%29%29" class="RktValDef RktValLink" data-pltdoc="x">uncaught-exception-handler</a></span></span><span class="RktPn"></span><span class="RktPn">)</span><span class="hspace"> </span>→<span class="hspace"> </span><span class="RktPn">(</span><span class="RktSym"><a href="data-structure-contracts.html#%28def._%28%28lib._racket%2Fcontract%2Fprivate%2Fmisc..rkt%29._any%2Fc%29%29" class="RktValLink" data-pltdoc="x">any/c</a></span><span class="hspace"> </span><span class="RktPn">. </span><span class="RktSym"><a href="function-contracts.html#%28form._%28%28lib._racket%2Fcontract%2Fbase..rkt%29._-~3e%29%29" class="RktStxLink" data-pltdoc="x"><span class="nobreak">-></span></a></span><span class="RktPn"> .</span><span class="hspace"> </span><span class="RktSym"><a href="data-structure-contracts.html#%28form._%28%28lib._racket%2Fcontract%2Fprivate%2Fmisc..rkt%29._any%29%29" class="RktStxLink" data-pltdoc="x">any</a></span><span class="RktPn">)</span></p></blockquote></td></tr><tr><td><span class="RktPn">(</span><span title="Provided from: racket/base, racket | Package: base"><span class="RktSym"><a href="exns.html#%28def._%28%28quote._~23~25kernel%29._uncaught-exception-handler%29%29" class="RktValDef RktValLink" data-pltdoc="x">uncaught-exception-handler</a></span></span><span class="hspace"> </span><span class="RktVar">f</span><span class="RktPn">)</span><span class="hspace"> </span>→<span class="hspace"> </span><span class="RktSym"><a href="void.html#%28def._%28%28quote._~23~25kernel%29._void~3f%29%29" class="RktValLink" data-pltdoc="x">void?</a></span></td></tr><tr><td><span class="hspace"> </span><span class="RktVar">f</span><span class="hspace"> </span>:<span class="hspace"> </span><span class="RktPn">(</span><span class="RktSym"><a href="data-structure-contracts.html#%28def._%28%28lib._racket%2Fcontract%2Fprivate%2Fmisc..rkt%29._any%2Fc%29%29" class="RktValLink" data-pltdoc="x">any/c</a></span><span class="hspace"> </span><span class="RktPn">. </span><span class="RktSym"><a href="function-contracts.html#%28form._%28%28lib._racket%2Fcontract%2Fbase..rkt%29._-~3e%29%29" class="RktStxLink" data-pltdoc="x"><span class="nobreak">-></span></a></span><span class="RktPn"> .</span><span class="hspace"> </span><span class="RktSym"><a href="data-structure-contracts.html#%28form._%28%28lib._racket%2Fcontract%2Fprivate%2Fmisc..rkt%29._any%29%29" class="RktStxLink" data-pltdoc="x">any</a></span><span class="RktPn">)</span></td></tr></table></blockquote></div><div class="SIntrapara">A <a href="eval-model.html#%28tech._parameter%29" class="techoutside" data-pltdoc="x"><span class="techinside">parameter</span></a> that determines an <a name="(tech._uncaught._exception._handler)"></a><span style="font-style: italic">uncaught-exception handler</span> used by
|
||
|
|
<span class="RktSym"><a href="exns.html#%28def._%28%28quote._~23~25kernel%29._raise%29%29" class="RktValLink" data-pltdoc="x">raise</a></span> when the relevant continuation has no exception handler
|
||
|
|
installed with <span class="RktSym"><a href="exns.html#%28def._%28%28lib._racket%2Fprivate%2Fmore-scheme..rkt%29._call-with-exception-handler%29%29" class="RktValLink" data-pltdoc="x">call-with-exception-handler</a></span> or
|
||
|
|
<span class="RktSym"><a href="exns.html#%28form._%28%28lib._racket%2Fprivate%2Fmore-scheme..rkt%29._with-handlers%29%29" class="RktStxLink" data-pltdoc="x">with-handlers</a></span>. Unlike exception handlers installed with
|
||
|
|
<span class="RktSym"><a href="exns.html#%28def._%28%28lib._racket%2Fprivate%2Fmore-scheme..rkt%29._call-with-exception-handler%29%29" class="RktValLink" data-pltdoc="x">call-with-exception-handler</a></span>, the uncaught-exception
|
||
|
|
handler must not return a value when called by <span class="RktSym"><a href="exns.html#%28def._%28%28quote._~23~25kernel%29._raise%29%29" class="RktValLink" data-pltdoc="x">raise</a></span>; if
|
||
|
|
it returns, an exception is raised (to be handled by an exception
|
||
|
|
handler that reports both the original and newly raised exception).</div></p><p>The default uncaught-exception handler prints an error message using
|
||
|
|
the current <a href="exns.html#%28tech._error._display._handler%29" class="techoutside" data-pltdoc="x"><span class="techinside">error display handler</span></a> (see <span class="RktSym"><a href="exns.html#%28def._%28%28quote._~23~25kernel%29._error-display-handler%29%29" class="RktValLink" data-pltdoc="x">error-display-handler</a></span>),
|
||
|
|
unless the argument to the handler is an instance of <span class="RktSym"><a href="exns.html#%28def._%28%28lib._racket%2Fprivate%2Fbase..rkt%29._exn~3abreak~3ahang-up%29%29" class="RktValLink" data-pltdoc="x">exn:break:hang-up</a></span>.
|
||
|
|
If the argument to the handler is an instance of <span class="RktSym"><a href="exns.html#%28def._%28%28lib._racket%2Fprivate%2Fbase..rkt%29._exn~3abreak~3ahang-up%29%29" class="RktValLink" data-pltdoc="x">exn:break:hang-up</a></span>
|
||
|
|
or <span class="RktSym"><a href="exns.html#%28def._%28%28lib._racket%2Fprivate%2Fbase..rkt%29._exn~3abreak~3aterminate%29%29" class="RktValLink" data-pltdoc="x">exn:break:terminate</a></span>, the default uncaught-exception handler
|
||
|
|
then calls the <a href="Exiting.html#%28tech._exit._handler%29" class="techoutside" data-pltdoc="x"><span class="techinside">exit handler</span></a> with <span class="RktVal">1</span>, which normally exits
|
||
|
|
or escapes. For any argument, the default uncaught-exception handler
|
||
|
|
then escapes by calling the current <a href="exns.html#%28tech._error._escape._handler%29" class="techoutside" data-pltdoc="x"><span class="techinside">error escape handler</span></a> (see
|
||
|
|
<span class="RktSym"><a href="exns.html#%28def._%28%28quote._~23~25kernel%29._error-escape-handler%29%29" class="RktValLink" data-pltdoc="x">error-escape-handler</a></span>). The call to each handler is
|
||
|
|
<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>d to set <span class="RktSym"><a href="exns.html#%28def._%28%28quote._~23~25kernel%29._error-display-handler%29%29" class="RktValLink" data-pltdoc="x">error-display-handler</a></span> to the
|
||
|
|
default <a href="exns.html#%28tech._error._display._handler%29" class="techoutside" data-pltdoc="x"><span class="techinside">error display handler</span></a>, and it is <span class="RktSym"><a href="breakhandler.html#%28form._%28%28lib._racket%2Fprivate%2Fmore-scheme..rkt%29._parameterize-break%29%29" class="RktStxLink" data-pltdoc="x">parameterize-break</a></span>ed
|
||
|
|
to disable breaks. The call to the <a href="exns.html#%28tech._error._escape._handler%29" class="techoutside" data-pltdoc="x"><span class="techinside">error escape handler</span></a> is further
|
||
|
|
parameterized to set <span class="RktSym"><a href="exns.html#%28def._%28%28quote._~23~25kernel%29._error-escape-handler%29%29" class="RktValLink" data-pltdoc="x">error-escape-handler</a></span> to the default
|
||
|
|
<a href="exns.html#%28tech._error._escape._handler%29" class="techoutside" data-pltdoc="x"><span class="techinside">error escape handler</span></a>; if the <a href="exns.html#%28tech._error._escape._handler%29" class="techoutside" data-pltdoc="x"><span class="techinside">error escape handler</span></a> returns, then
|
||
|
|
the default <a href="exns.html#%28tech._error._escape._handler%29" class="techoutside" data-pltdoc="x"><span class="techinside">error escape handler</span></a> is called.</p><p>When the current <a href="exns.html#%28tech._error._display._handler%29" class="techoutside" data-pltdoc="x"><span class="techinside">error display handler</span></a> is the default handler, then the
|
||
|
|
error-display call is parameterized to install an emergency error
|
||
|
|
display handler that logs an error (see <span class="RktSym"><a href="logging.html#%28form._%28%28lib._racket%2Fprivate%2Fmore-scheme..rkt%29._log-error%29%29" class="RktStxLink" data-pltdoc="x">log-error</a></span>) and never
|
||
|
|
fails.</p><p><div class="SIntrapara"><blockquote class="SVInsetFlow"><table cellspacing="0" cellpadding="0" class="boxed RBoxed"><tr><td><blockquote class="SubFlow"><div class="RBackgroundLabel SIEHidden"><div class="RBackgroundLabelInner"><p>syntax</p></div></div><table cellspacing="0" cellpadding="0" class="RktBlk RForeground"><tr><td><span class="RktPn">(</span><a name="(form._((lib._racket/private/more-scheme..rkt)._with-handlers))"></a><span title="Provided from: racket/base, racket | Package: base"><span class="RktSym"><a href="exns.html#%28form._%28%28lib._racket%2Fprivate%2Fmore-scheme..rkt%29._with-handlers%29%29" class="RktStxDef RktStxLink" data-pltdoc="x">with-handlers</a></span></span><span class="hspace"> </span><span class="RktPn">(</span><span class="RktPn">[</span><span class="RktVar">pred-expr</span><span class="hspace"> </span><span class="RktVar">handler-expr</span><span class="RktPn">]</span><span class="hspace"> </span><span class="RktMeta">...</span><span class="RktPn">)</span></td></tr><tr><td><span class="hspace"> </span><span class="RktVar">body</span><span class="hspace"> </span><span class="RktMeta">...+</span><span class="RktPn">)</span></td></tr></table></blockquote></td></tr></table></blockquote></div><div class="SIntrapara">Evaluates each <span class="RktVar">pred-expr</span> and <span class="RktVar">handler-expr</span> in the
|
||
|
|
order that they are specified, and then evaluates the <span class="RktVar">body</span>s
|
||
|
|
with a new exception handler during its dynamic extent.</div></p><p>The new exception handler processes an exception only if one of the
|
||
|
|
<span class="RktVar">pred-expr</span> procedures returns a true value when applied to the
|
||
|
|
exception, otherwise the exception handler is invoked from the
|
||
|
|
continuation of the <span class="RktSym"><a href="exns.html#%28form._%28%28lib._racket%2Fprivate%2Fmore-scheme..rkt%29._with-handlers%29%29" class="RktStxLink" data-pltdoc="x">with-handlers</a></span> expression (by raising the
|
||
|
|
exception again). If an exception is handled by one of the
|
||
|
|
<span class="RktVar">handler-expr</span> procedures, the result of the entire
|
||
|
|
<span class="RktSym"><a href="exns.html#%28form._%28%28lib._racket%2Fprivate%2Fmore-scheme..rkt%29._with-handlers%29%29" class="RktStxLink" data-pltdoc="x">with-handlers</a></span> expression is the return value of the handler.</p><p>When an exception is raised during the evaluation of <span class="RktVar">body</span>s,
|
||
|
|
each predicate procedure <span class="RktVar">pred-expr</span> is applied to the
|
||
|
|
exception value; if a predicate returns a true value, the
|
||
|
|
corresponding <span class="RktVar">handler-expr</span> procedure is invoked with the
|
||
|
|
exception as an argument. The predicates are tried in the order that
|
||
|
|
they are specified.</p><p>Before any predicate or handler procedure is invoked, the continuation
|
||
|
|
of the entire <span class="RktSym"><a href="exns.html#%28form._%28%28lib._racket%2Fprivate%2Fmore-scheme..rkt%29._with-handlers%29%29" class="RktStxLink" data-pltdoc="x">with-handlers</a></span> expression is restored, but also
|
||
|
|
<span class="RktSym"><a href="breakhandler.html#%28form._%28%28lib._racket%2Fprivate%2Fmore-scheme..rkt%29._parameterize-break%29%29" class="RktStxLink" data-pltdoc="x">parameterize-break</a></span>ed to disable breaks. Thus, breaks are
|
||
|
|
disabled by default during the predicate and handler procedures (see
|
||
|
|
<a href="breakhandler.html" data-pltdoc="x">Breaks</a>), and the exception handler is the one from
|
||
|
|
the continuation of the <span class="RktSym"><a href="exns.html#%28form._%28%28lib._racket%2Fprivate%2Fmore-scheme..rkt%29._with-handlers%29%29" class="RktStxLink" data-pltdoc="x">with-handlers</a></span> expression.</p><p>The <span class="RktSym"><a href="exns.html#%28def._%28%28quote._~23~25kernel%29._exn~3afail~3f%29%29" class="RktValLink" data-pltdoc="x">exn:fail?</a></span> procedure is useful as a handler predicate to
|
||
|
|
catch all error exceptions. Avoid using <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="stt"> </span><span class="RktPn">(</span><span class="RktSym">x</span><span class="RktPn">)</span><span class="stt"> </span><span class="RktVal">#t</span><span class="RktPn">)</span> as a
|
||
|
|
predicate, because the <span class="RktSym"><a href="exns.html#%28def._%28%28lib._racket%2Fprivate%2Fbase..rkt%29._exn~3abreak%29%29" class="RktValLink" data-pltdoc="x">exn:break</a></span> exception typically should
|
||
|
|
not be caught (unless it will be re-raised to cooperatively
|
||
|
|
break). Beware, also, of catching and discarding exceptions, because
|
||
|
|
discarding an error message can make debugging unnecessarily
|
||
|
|
difficult; instead of discarding an error message, consider logging it
|
||
|
|
via <span class="RktSym"><a href="logging.html#%28form._%28%28lib._racket%2Fprivate%2Fmore-scheme..rkt%29._log-error%29%29" class="RktStxLink" data-pltdoc="x">log-error</a></span> or a logging form created by
|
||
|
|
<span class="RktSym"><a href="logging.html#%28form._%28%28lib._racket%2Fprivate%2Fmore-scheme..rkt%29._define-logger%29%29" class="RktStxLink" data-pltdoc="x">define-logger</a></span>.</p><p><div class="SIntrapara">Examples:</div><div class="SIntrapara"><blockquote class="SCodeFlow"><table cellspacing="0" cellpadding="0" class="RktBlk"><tr><td><table cellspacing="0" cellpadding="0" class="RktBlk"><tr><td><span class="stt">> </span><span class="RktPn">(</span><span class="RktSym"><a href="exns.html#%28form._%28%28lib._racket%2Fprivate%2Fmore-scheme..rkt%29._with-handlers%29%29" class="RktStxLink" data-pltdoc="x">with-handlers</a></span><span class="hspace"> </span><span class="RktPn">(</span><span class="RktPn">[</span><span class="RktSym"><a href="exns.html#%28def._%28%28quote._~23~25kernel%29._exn~3afail~3asyntax~3f%29%29" class="RktValLink" data-pltdoc="x">exn:fail:syntax?</a></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._~ce~bb%29%29" class="RktStxLink" data-pltdoc="x">λ</a></span><span class="hspace"> </span><span class="RktPn">(</span><span class="RktSym">e</span><span class="RktPn">)</span><span class="hspace"> </span><span class="RktPn">(</span><span class="RktSym"><a href="Writing.html#%28def._%28%28lib._racket%2Fprivate%2Fmisc..rkt%29._displayln%29%29" class="RktValLink" data-pltdoc="x">displayln</a></span><span class="hspace"> </span><span class="RktVal">"got a syntax error"</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="exns.html#%28def._%28%28lib._racket%2Fprivate%2Fbase..rkt%29._raise-syntax-error%29%29" class="RktValLink" data-pltdoc="x">raise-syntax-error</a></span><span class="hspace"> </span><span class="RktVal">#f</span><span class="hspace"> </span><span class="RktVal">"a syntax error"</span><span class="RktPn">)</span><span class="RktPn">)</span></td></tr></table></td></tr><tr><td><p><span class="RktOut">got a syntax error</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="exns.html#%28form._%28%28lib._racket%2Fprivate%2Fmore-scheme..rkt%29._with-handlers%29%29" class="RktStxLink" data-pltdoc="x">with-handlers</a></span><span class="hspace"> </span><span class="RktPn">(</span><span class="RktPn">[</span><span class="RktSym"><a href="exns.html#%28def._%28%28quote._~23~25kernel%29._exn~3afail~3asyntax~3f%29%29" class="RktValLink" data-pltdoc="x">exn:fail:syntax?</a></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._~ce~bb%29%29" class="RktStxLink" data-pltdoc="x">λ</a></span><span class="hspace"> </span><span class="RktPn">(</span><span class="RktSym">e</span><span class="RktPn">)</span><span class="hspace"> </span><span class="RktPn">(</span><span class="RktSym"><a href="Writing.html#%28def._%28%28lib._racket%2Fprivate%2Fmisc..rkt%29._displayln%29%29" class="RktValLink" data-pltdoc="x">displayln</a></span><span class="hspace"> </span><span class="RktVal">"got a syntax error"</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">[</s
|
||
|
|
is called, breaks are not explicitly disabled, and the handler call is
|
||
|
|
in tail position with respect to the <span class="RktSym"><a href="exns.html#%28form._%28%28lib._racket%2Fprivate%2Fmore-scheme..rkt%29._with-handlers%2A%29%29" class="RktStxLink" data-pltdoc="x">with-handlers*</a></span> form.</div></p><h5 x-source-module="(lib "scribblings/reference/reference.scrbl")" x-source-pkg="racket-doc" x-part-tag=""Configuring_Default_Handling"">10.2.4<tt> </tt><a name="(part._.Configuring_.Default_.Handling)"></a>Configuring Default Handling</h5><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>parameter</p></div></div><p class="RForeground"><span class="RktPn">(</span><a name="(def._((quote._~23~25kernel)._error-escape-handler))"></a><span title="Provided from: racket/base, racket | Package: base"><span class="RktSym"><a href="exns.html#%28def._%28%28quote._~23~25kernel%29._error-escape-handler%29%29" class="RktValDef RktValLink" data-pltdoc="x">error-escape-handler</a></span></span><span class="RktPn"></span><span class="RktPn">)</span><span class="hspace"> </span>→<span class="hspace"> </span><span class="RktPn">(</span><span class="RktSym"><a href="function-contracts.html#%28form._%28%28lib._racket%2Fcontract%2Fbase..rkt%29._-~3e%29%29" class="RktStxLink" data-pltdoc="x"><span class="nobreak">-></span></a></span><span class="hspace"> </span><span class="RktSym"><a href="data-structure-contracts.html#%28form._%28%28lib._racket%2Fcontract%2Fprivate%2Fmisc..rkt%29._any%29%29" class="RktStxLink" data-pltdoc="x">any</a></span><span class="RktPn">)</span></p></blockquote></td></tr><tr><td><span class="RktPn">(</span><span title="Provided from: racket/base, racket | Package: base"><span class="RktSym"><a href="exns.html#%28def._%28%28quote._~23~25kernel%29._error-escape-handler%29%29" class="RktValDef RktValLink" data-pltdoc="x">error-escape-handler</a></span></span><span class="hspace"> </span><span class="RktVar">proc</span><span class="RktPn">)</span><span class="hspace"> </span>→<span class="hspace"> </span><span class="RktSym"><a href="void.html#%28def._%28%28quote._~23~25kernel%29._void~3f%29%29" class="RktValLink" data-pltdoc="x">void?</a></span></td></tr><tr><td><span class="hspace"> </span><span class="RktVar">proc</span><span class="hspace"> </span>:<span class="hspace"> </span><span class="RktPn">(</span><span class="RktSym"><a href="function-contracts.html#%28form._%28%28lib._racket%2Fcontract%2Fbase..rkt%29._-~3e%29%29" class="RktStxLink" data-pltdoc="x"><span class="nobreak">-></span></a></span><span class="hspace"> </span><span class="RktSym"><a href="data-structure-contracts.html#%28form._%28%28lib._racket%2Fcontract%2Fprivate%2Fmisc..rkt%29._any%29%29" class="RktStxLink" data-pltdoc="x">any</a></span><span class="RktPn">)</span></td></tr></table></blockquote></div><div class="SIntrapara">A parameter for the <a name="(tech._error._escape._handler)"></a><span style="font-style: italic">error escape handler</span>, which takes no
|
||
|
|
arguments and escapes from the dynamic context of an exception. The
|
||
|
|
default error escape handler escapes using
|
||
|
|
<span class="RktPn">(</span><span class="RktSym"><a href="cont.html#%28def._%28%28quote._~23~25kernel%29._abort-current-continuation%29%29" class="RktValLink" data-pltdoc="x">abort-current-continuation</a></span><span class="stt"> </span><span class="RktPn">(</span><span class="RktSym"><a href="cont.html#%28def._%28%28quote._~23~25kernel%29._default-continuation-prompt-tag%29%29" class="RktValLink" data-pltdoc="x">default-continuation-prompt-tag</a></span><span class="RktPn">)</span><span class="stt"> </span><span class="RktSym"><a href="void.html#%28def._%28%28quote._~23~25kernel%29._void%29%29" class="RktValLink" data-pltdoc="x">void</a></span><span class="RktPn">)</span>.</div></p><p>The error escape handler is normally called directly by an exception
|
||
|
|
handler, in a <a href="eval-model.html#%28tech._parameterization%29" class="techoutside" data-pltdoc="x"><span class="techinside">parameterization</span></a> that sets the <a href="exns.html#%28tech._error._display._handler%29" class="techoutside" data-pltdoc="x"><span class="techinside">error
|
||
|
|
display handler</span></a> and <a href="exns.html#%28tech._error._escape._handler%29" class="techoutside" data-pltdoc="x"><span class="techinside">error escape handler</span></a> to the default
|
||
|
|
handlers, and it is normally <span class="RktSym"><a href="breakhandler.html#%28form._%28%28lib._racket%2Fprivate%2Fmore-scheme..rkt%29._parameterize-break%29%29" class="RktStxLink" data-pltdoc="x">parameterize-break</a></span>ed to disable
|
||
|
|
breaks. To escape from a run-time error in a different context, use
|
||
|
|
<span class="RktSym"><a href="exns.html#%28def._%28%28quote._~23~25kernel%29._raise%29%29" class="RktValLink" data-pltdoc="x">raise</a></span> or <span class="RktSym"><a href="exns.html#%28def._%28%28quote._~23~25kernel%29._error%29%29" class="RktValLink" data-pltdoc="x">error</a></span>.</p><p>Due to a <a href="eval-model.html#%28tech._continuation._barrier%29" class="techoutside" data-pltdoc="x"><span class="techinside">continuation barrier</span></a> around exception-handling calls,
|
||
|
|
an error escape handler cannot invoke a full continuation that was
|
||
|
|
created prior to the exception, but it can abort to a prompt (see
|
||
|
|
<span class="RktSym"><a href="cont.html#%28def._%28%28quote._~23~25kernel%29._call-with-continuation-prompt%29%29" class="RktValLink" data-pltdoc="x">call-with-continuation-prompt</a></span>) or invoke an escape
|
||
|
|
continuation (see <span class="RktSym"><a href="cont.html#%28def._%28%28quote._~23~25kernel%29._call-with-escape-continuation%29%29" class="RktValLink" data-pltdoc="x">call-with-escape-continuation</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>parameter</p></div></div><p class="RForeground"><span class="RktPn">(</span><a name="(def._((quote._~23~25kernel)._error-display-handler))"></a><span title="Provided from: racket/base, racket | Package: base"><span class="RktSym"><a href="exns.html#%28def._%28%28quote._~23~25kernel%29._error-display-handler%29%29" class="RktValDef RktValLink" data-pltdoc="x">error-display-handler</a></span></span><span class="RktPn"></span><span class="RktPn">)</span><span class="hspace"> </span>→<span class="hspace"> </span><span class="RktPn">(</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="data-structure-contracts.html#%28def._%28%28lib._racket%2Fcontract%2Fprivate%2Fmisc..rkt%29._any%2Fc%29%29" class="RktValLink" data-pltdoc="x">any/c</a></span><span class="hspace"> </span><span class="RktPn">. </span><span class="RktSym"><a href="function-contracts.html#%28form._%28%28lib._racket%2Fcontract%2Fbase..rkt%29._-~3e%29%29" class="RktStxLink" data-pltdoc="x"><span class="nobreak">-></span></a></span><span class="RktPn"> .</span><span class="hspace"> </span><span class="RktSym"><a href="data-structure-contracts.html#%28form._%28%28lib._racket%2Fcontract%2Fprivate%2Fmisc..rkt%29._any%29%29" class="RktStxLink" data-pltdoc="x">any</a></span><span class="RktPn">)</span></p></blockquote></td></tr><tr><td><span class="RktPn">(</span><span title="Provided from: racket/base, racket | Package: base"><span class="RktSym"><a href="exns.html#%28def._%28%28quote._~23~25kernel%29._error-display-handler%29%29" class="RktValDef RktValLink" data-pltdoc="x">error-display-handler</a></span></span><span class="hspace"> </span><span class="RktVar">proc</span><span class="RktPn">)</span><span class="hspace"> </span>→<span class="hspace"> </span><span class="RktSym"><a href="void.html#%28def._%28%28quote._~23~25kernel%29._void~3f%29%29" class="RktValLink" data-pltdoc="x">void?</a></span></td></tr><tr><td><span class="hspace"> </span><span class="RktVar">proc</span><span class="hspace"> </span>:<span class="hspace"> </span><span class="RktPn">(</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="data-structure-contracts.html#%28def._%28%28lib._racket%2Fcontract%2Fprivate%2Fmisc..rkt%29._any%2Fc%29%29" class="RktValLink" data-pltdoc="x">any/c</a></span><span class="hspace"> </span><span class="RktPn">. </span><span class="RktSym"><a href="function-contracts.html#%28form._%28%28lib._racket%2Fcontract%2Fbase..rkt%29._-~3e%29%29" class="RktStxLink" data-pltdoc="x"><span class="nobreak">-></span></a></span><span class="RktPn"> .</span><span class="hspace"> </span><span class="RktSym"><a href="data-structure-contracts.html#%28form._%28%28lib._racket%2Fcontract%2Fprivate%2Fmisc..rkt%29._any%29%29" class="RktStxLink" data-pltdoc="x">any</a></span><span class="RktPn">)</span></td></tr></table></blockquote></div><div class="SIntrapara">A parameter for the <a name="(tech._error._display._handler)"></a><span style="font-style: italic">error display handler</span>, which is called
|
||
|
|
by the default exception handler with an error message and the
|
||
|
|
exception value. More generally, the handler’s first argument is a
|
||
|
|
string to print as an error message, and the second is a value
|
||
|
|
representing a raised exception. An error display handler can
|
||
|
|
print errors in different ways, but it should always print to the
|
||
|
|
current error port.</div></p><p>The default error display handler <span class="RktSym"><a href="Writing.html#%28def._%28%28quote._~23~25kernel%29._display%29%29" class="RktValLink" data-pltdoc="x">display</a></span>s its first argument
|
||
|
|
to the current error port (determined by the
|
||
|
|
<span class="RktSym"><a href="port-ops.html#%28def._%28%28quote._~23~25kernel%29._current-error-port%29%29" class="RktValLink" data-pltdoc="x">current-error-port</a></span> parameter) and extracts a stack trace (see
|
||
|
|
<span class="RktSym"><a href="contmarks.html#%28def._%28%28quote._~23~25kernel%29._continuation-mark-set-~3econtext%29%29" class="RktValLink" data-pltdoc="x">continuation-mark-set->context</a></span>) to display from the second
|
||
|
|
argument if it is an <span class="RktSym"><a href="exns.html#%28def._%28%28lib._racket%2Fprivate%2Fbase..rkt%29._exn%29%29" class="RktValLink" data-pltdoc="x">exn</a></span> value but not an
|
||
|
|
<span class="RktSym"><a href="exns.html#%28def._%28%28lib._racket%2Fprivate%2Fbase..rkt%29._exn~3afail~3auser%29%29" class="RktValLink" data-pltdoc="x">exn:fail:user</a></span> value.</p><blockquote class="refpara"><blockquote class="refcolumn"><blockquote class="refcontent"><p>The default error display handler in DrRacket also uses
|
||
|
|
the second argument to highlight source locations.</p></blockquote></blockquote></blockquote><p>To report a run-time error, use <span class="RktSym"><a href="exns.html#%28def._%28%28quote._~23~25kernel%29._raise%29%29" class="RktValLink" data-pltdoc="x">raise</a></span> or procedures like
|
||
|
|
<span class="RktSym"><a href="exns.html#%28def._%28%28quote._~23~25kernel%29._error%29%29" class="RktValLink" data-pltdoc="x">error</a></span>, instead of calling the error display handler
|
||
|
|
directly.</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>parameter</p></div></div><p class="RForeground"><span class="RktPn">(</span><a name="(def._((quote._~23~25kernel)._error-print-width))"></a><span title="Provided from: racket/base, racket | Package: base"><span class="RktSym"><a href="exns.html#%28def._%28%28quote._~23~25kernel%29._error-print-width%29%29" class="RktValDef RktValLink" data-pltdoc="x">error-print-width</a></span></span><span class="RktPn"></span><span class="RktPn">)</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._and%2Fc%29%29" class="RktValLink" data-pltdoc="x">and/c</a></span><span class="hspace"> </span><span class="RktSym"><a href="number-types.html#%28def._%28%28quote._~23~25kernel%29._exact-integer~3f%29%29" class="RktValLink" data-pltdoc="x">exact-integer?</a></span><span class="hspace"> </span><span class="RktPn">(</span><span class="RktSym"><a href="data-structure-contracts.html#%28def._%28%28lib._racket%2Fcontract%2Fprivate%2Fmisc..rkt%29._~3e~3d%2Fc%29%29" class="RktValLink" data-pltdoc="x">>=/c</a></span><span class="hspace"> </span><span class="RktVal">3</span><span class="RktPn">)</span><span class="RktPn">)</span></p></blockquote></td></tr><tr><td><span class="RktPn">(</span><span title="Provided from: racket/base, racket | Package: base"><span class="RktSym"><a href="exns.html#%28def._%28%28quote._~23~25kernel%29._error-print-width%29%29" class="RktValDef RktValLink" data-pltdoc="x">error-print-width</a></span></span><span class="hspace"> </span><span class="RktVar">width</span><span class="RktPn">)</span><span class="hspace"> </span>→<span class="hspace"> </span><span class="RktSym"><a href="void.html#%28def._%28%28quote._~23~25kernel%29._void~3f%29%29" class="RktValLink" data-pltdoc="x">void?</a></span></td></tr><tr><td><span class="hspace"> </span><span class="RktVar">width</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._and%2Fc%29%29" class="RktValLink" data-pltdoc="x">and/c</a></span><span class="hspace"> </span><span class="RktSym"><a href="number-types.html#%28def._%28%28quote._~23~25kernel%29._exact-integer~3f%29%29" class="RktValLink" data-pltdoc="x">exact-integer?</a></span><span class="hspace"> </span><span class="RktPn">(</span><span class="RktSym"><a href="data-structure-contracts.html#%28def._%28%28lib._racket%2Fcontract%2Fprivate%2Fmisc..rkt%29._~3e~3d%2Fc%29%29" class="RktValLink" data-pltdoc="x">>=/c</a></span><span class="hspace"> </span><span class="RktVal">3</span><span class="RktPn">)</span><span class="RktPn">)</span></td></tr></table></blockquote></div><div class="SIntrapara">A parameter whose value is used as the maximum number of characters
|
||
|
|
used to print a Racket value that is embedded in a primitive error
|
||
|
|
message.</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>parameter</p></div></div><p class="RForeground"><span class="RktPn">(</span><a name="(def._((quote._~23~25kernel)._error-print-context-length))"></a><span title="Provided from: racket/base, racket | Package: base"><span class="RktSym"><a href="exns.html#%28def._%28%28quote._~23~25kernel%29._error-print-context-length%29%29" class="RktValDef RktValLink" data-pltdoc="x">error-print-context-length</a></span></span><span class="RktPn"></span><span class="RktPn">)</span><span class="hspace"> </span>→<span class="hspace"> </span><span class="RktSym"><a href="number-types.html#%28def._%28%28quote._~23~25kernel%29._exact-nonnegative-integer~3f%29%29" class="RktValLink" data-pltdoc="x">exact-nonnegative-integer?</a></span></p></blockquote></td></tr><tr><td><span class="RktPn">(</span><span title="Provided from: racket/base, racket | Package: base"><span class="RktSym"><a href="exns.html#%28def._%28%28quote._~23~25kernel%29._error-print-context-length%29%29" class="RktValDef RktValLink" data-pltdoc="x">error-print-context-length</a></span></span><span class="hspace"> </span><span class="RktVar">cnt</span><span class="RktPn">)</span><span class="hspace"> </span>→<span class="hspace"> </span><span class="RktSym"><a href="void.html#%28def._%28%28quote._~23~25kernel%29._void~3f%29%29" class="RktValLink" data-pltdoc="x">void?</a></span></td></tr><tr><td><span class="hspace"> </span><span class="RktVar">cnt</span><span class="hspace"> </span>:<span class="hspace"> </span><span class="RktSym"><a href="number-types.html#%28def._%28%28quote._~23~25kernel%29._exact-nonnegative-integer~3f%29%29" class="RktValLink" data-pltdoc="x">exact-nonnegative-integer?</a></span></td></tr></table></blockquote></div><div class="SIntrapara">A parameter whose value is used by the default <a href="exns.html#%28tech._error._display._handler%29" class="techoutside" data-pltdoc="x"><span class="techinside">error display handler</span></a>
|
||
|
|
as the maximum number of lines of context (or “stack trace”) to
|
||
|
|
print; a single “...” line is printed if more lines are available
|
||
|
|
after the first <span class="RktVar">cnt</span> lines. A <span class="RktVal">0</span> value for
|
||
|
|
<span class="RktVar">cnt</span> disables context printing entirely.</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>parameter</p></div></div><p class="RForeground"><span class="RktPn">(</span><a name="(def._((quote._~23~25kernel)._error-print-source-location))"></a><span title="Provided from: racket/base, racket | Package: base"><span class="RktSym"><a href="exns.html#%28def._%28%28quote._~23~25kernel%29._error-print-source-location%29%29" class="RktValDef RktValLink" data-pltdoc="x">error-print-source-location</a></span></span><span class="RktPn"></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="RktPn">(</span><span title="Provided from: racket/base, racket | Package: base"><span class="RktSym"><a href="exns.html#%28def._%28%28quote._~23~25kernel%29._error-print-source-location%29%29" class="RktValDef RktValLink" data-pltdoc="x">error-print-source-location</a></span></span><span class="hspace"> </span><span class="RktVar">include?</span><span class="RktPn">)</span><span class="hspace"> </span>→<span class="hspace"> </span><span class="RktSym"><a href="void.html#%28def._%28%28quote._~23~25kernel%29._void~3f%29%29" class="RktValLink" data-pltdoc="x">void?</a></span></td></tr><tr><td><span class="hspace"> </span><span class="RktVar">include?</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">A <a href="eval-model.html#%28tech._parameter%29" class="techoutside" data-pltdoc="x"><span class="techinside">parameter</span></a> that controls whether read and syntax error messages
|
||
|
|
include source information, such as the source line and column or the
|
||
|
|
expression. This parameter also controls the error message when a
|
||
|
|
module-defined variable is accessed before its definition is executed;
|
||
|
|
the parameter determines whether the message includes a module
|
||
|
|
name. Only the message field of an <span class="RktSym"><a href="exns.html#%28def._%28%28lib._racket%2Fprivate%2Fbase..rkt%29._exn~3afail~3aread%29%29" class="RktValLink" data-pltdoc="x">exn:fail:read</a></span>,
|
||
|
|
<span class="RktSym"><a href="exns.html#%28def._%28%28lib._racket%2Fprivate%2Fbase..rkt%29._exn~3afail~3asyntax%29%29" class="RktValLink" data-pltdoc="x">exn:fail:syntax</a></span>, or <span class="RktSym"><a href="exns.html#%28def._%28%28lib._racket%2Fprivate%2Fbase..rkt%29._exn~3afail~3acontract~3avariable%29%29" class="RktValLink" data-pltdoc="x">exn:fail:contract:variable</a></span>
|
||
|
|
structure is affected by the parameter. The default is <span class="RktVal">#t</span>.</div></p><p><div class="SIntrapara"><blockquote class="SVInsetFlow"><table cellspacing="0" cellpadding="0" class="boxed RBoxed"><tr><td><blockquote class="SubFlow"><div class="RBackgroundLabel SIEHidden"><div class="RBackgroundLabelInner"><p>parameter</p></div></div><p class="RForeground"><span class="RktPn">(</span><a name="(def._((quote._~23~25kernel)._error-value-~3estring-handler))"></a><span title="Provided from: racket/base, racket | Package: base"><span class="RktSym"><a href="exns.html#%28def._%28%28quote._~23~25kernel%29._error-value-~3estring-handler%29%29" class="RktValDef RktValLink" data-pltdoc="x">error-value->string-handler</a></span></span><span class="RktPn"></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" class="RktBlk"><tr><td><span class="RktPn">(</span><span class="RktSym"><a href="data-structure-contracts.html#%28def._%28%28lib._racket%2Fcontract%2Fprivate%2Fmisc..rkt%29._any%2Fc%29%29" class="RktValLink" data-pltdoc="x">any/c</a></span><span class="hspace"> </span><span class="RktSym"><a href="number-types.html#%28def._%28%28quote._~23~25kernel%29._exact-nonnegative-integer~3f%29%29" class="RktValLink" data-pltdoc="x">exact-nonnegative-integer?</a></span></td></tr><tr><td><span class="hspace"> </span><span class="RktPn">. </span><span class="RktSym"><a href="function-contracts.html#%28form._%28%28lib._racket%2Fcontract%2Fbase..rkt%29._-~3e%29%29" class="RktStxLink" data-pltdoc="x"><span class="nobreak">-></span></a></span><span class="RktPn"> .</span></td></tr><tr><td><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="RktPn">)</span></td></tr></table></td></tr></table></td></tr><tr><td><span class="RktPn">(</span><span title="Provided from: racket/base, racket | Package: base"><span class="RktSym"><a href="exns.html#%28def._%28%28quote._~23~25kernel%29._error-value-~3estring-handler%29%29" class="RktValDef RktValLink" data-pltdoc="x">error-value->string-handler</a></span></span><span class="hspace"> </span><span class="RktVar">proc</span><span class="RktPn">)</span><span class="hspace"> </span>→<span class="hspace"> </span><span class="RktSym"><a href="void.html#%28def._%28%28quote._~23~25kernel%29._void~3f%29%29" class="RktValLink" data-pltdoc="x">void?</a></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">proc</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%2Fprivate%2Fmisc..rkt%29._any%2Fc%29%29" class="RktValLink" data-pltdoc="x">any/c</a></span><span class="hspace"> </span><span class="RktSym"><a href="number-types.html#%28def._%28%28quote._~23~25kernel%29._exact-nonnegative-integer~3f%29%29" class="RktValLink" data-pltdoc="x">exact-nonnegative-integer?</a></span></td></tr><tr><td><span class="hspace"> </span><span class="RktPn">. </span><span class="RktSym"><a href="function-contracts.html#%28form._%28%28lib._racket%2Fcontract%2Fbase..rkt%29._-~3e%29%29" class="RktStxLink" data-pltdoc="x"><span class="nobreak">-></span></a></span><span class="RktPn"> .</span></td></tr><tr><td><span class="hspace"> 
|
||
|
|
handler</span>, which is used to print a Racket value that is embedded in a
|
||
|
|
primitive error message.</div></p><p>The integer argument to the handler specifies the maximum number of
|
||
|
|
characters that should be used to represent the value in the resulting
|
||
|
|
string. The default error value conversion handler <span class="RktSym"><a href="Writing.html#%28def._%28%28quote._~23~25kernel%29._print%29%29" class="RktValLink" data-pltdoc="x">print</a></span>s
|
||
|
|
the value into a string (using the current <a href="Writing.html#%28tech._global._port._print._handler%29" class="techoutside" data-pltdoc="x"><span class="techinside">global port print
|
||
|
|
handler</span></a>; see <span class="RktSym"><a href="Writing.html#%28def._%28%28quote._~23~25kernel%29._global-port-print-handler%29%29" class="RktValLink" data-pltdoc="x">global-port-print-handler</a></span>). If the printed form
|
||
|
|
is too long, the printed form is truncated and the last three
|
||
|
|
characters of the return string are set to “...”.</p><p>If the string returned by an error value conversion handler is longer
|
||
|
|
than requested, the string is destructively “truncated” by setting
|
||
|
|
the first extra position in the string to the null character. If a
|
||
|
|
non-string is returned, then the string <span class="RktVal">"..."</span> is used. If a
|
||
|
|
primitive error string needs to be generated before the handler has
|
||
|
|
returned, the default error value conversion handler is used.</p><p>Calls to an error value conversion handler are <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>d
|
||
|
|
to re-install the default error value conversion handler, and to
|
||
|
|
enable printing of unreadable values (see <span class="RktSym"><a href="Writing.html#%28def._%28%28quote._~23~25kernel%29._print-unreadable%29%29" class="RktValLink" data-pltdoc="x">print-unreadable</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>parameter</p></div></div><p class="RForeground"><span class="RktPn">(</span><a name="(def._((quote._~23~25kernel)._error-syntax-~3estring-handler))"></a><span title="Provided from: racket/base, racket | Package: base"><span class="RktSym"><a href="exns.html#%28def._%28%28quote._~23~25kernel%29._error-syntax-~3estring-handler%29%29" class="RktValDef RktValLink" data-pltdoc="x">error-syntax->string-handler</a></span></span><span class="RktPn"></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" class="RktBlk"><tr><td><span class="RktPn">(</span><span class="RktSym"><a href="data-structure-contracts.html#%28def._%28%28lib._racket%2Fcontract%2Fprivate%2Fmisc..rkt%29._any%2Fc%29%29" class="RktValLink" data-pltdoc="x">any/c</a></span><span class="hspace"> </span><span class="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="number-types.html#%28def._%28%28quote._~23~25kernel%29._exact-nonnegative-integer~3f%29%29" class="RktValLink" data-pltdoc="x">exact-nonnegative-integer?</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="RktPn">. </span><span class="RktSym"><a href="function-contracts.html#%28form._%28%28lib._racket%2Fcontract%2Fbase..rkt%29._-~3e%29%29" class="RktStxLink" data-pltdoc="x"><span class="nobreak">-></span></a></span><span class="RktPn"> .</span></td></tr><tr><td><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="RktPn">)</span></td></tr></table></td></tr></table></td></tr><tr><td><span class="RktPn">(</span><span title="Provided from: racket/base, racket | Package: base"><span class="RktSym"><a href="exns.html#%28def._%28%28quote._~23~25kernel%29._error-syntax-~3estring-handler%29%29" class="RktValDef RktValLink" data-pltdoc="x">error-syntax->string-handler</a></span></span><span class="hspace"> </span><span class="RktVar">proc</span><span class="RktPn">)</span><span class="hspace"> </span>→<span class="hspace"> </span><span class="RktSym"><a href="void.html#%28def._%28%28quote._~23~25kernel%29._void~3f%29%29" class="RktValLink" data-pltdoc="x">void?</a></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">proc</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%2Fprivate%2Fmisc..rkt%29._any%2Fc%29%29" class="RktValLink" data-pltdoc="x">any/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._
|
||
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conversion handler</span>, which is used to print a syntax form that is
|
||
|
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embedded in an error message, such as from <span class="RktSym"><a href="exns.html#%28def._%28%28lib._racket%2Fprivate%2Fbase..rkt%29._raise-syntax-error%29%29" class="RktValLink" data-pltdoc="x">raise-syntax-error</a></span>
|
||
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when <span class="RktSym"><a href="exns.html#%28def._%28%28quote._~23~25kernel%29._error-print-source-location%29%29" class="RktValLink" data-pltdoc="x">error-print-source-location</a></span> is <span class="RktVal">#t</span>.</div></p><p>The arguments to the handler are analogous to the arguments for a
|
||
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<a href="exns.html#%28tech._error._value._conversion._handler%29" class="techoutside" data-pltdoc="x"><span class="techinside">error value conversion handler</span></a> as configured with
|
||
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<span class="RktSym"><a href="exns.html#%28def._%28%28quote._~23~25kernel%29._error-value-~3estring-handler%29%29" class="RktValLink" data-pltdoc="x">error-value->string-handler</a></span>, except that <span class="RktVal">#f</span> can be
|
||
|
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provided instead of an integer for the length, meaning that the
|
||
|
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printed form should not be truncated. The first argument is normally a
|
||
|
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<a href="syntax-model.html#%28tech._syntax._object%29" class="techoutside" data-pltdoc="x"><span class="techinside">syntax object</span></a>, but in the same way that
|
||
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<span class="RktSym"><a href="exns.html#%28def._%28%28lib._racket%2Fprivate%2Fbase..rkt%29._raise-syntax-error%29%29" class="RktValLink" data-pltdoc="x">raise-syntax-error</a></span> accepts other S-expressions, the error
|
||
|
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syntax conversion handler must also handle representations that are
|
||
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not syntax objects.</p><p class="SHistory">Added in version 8.2.0.8 of package <span class="stt">base</span>.</p><h5 x-source-module="(lib "scribblings/reference/reference.scrbl")" x-source-pkg="racket-doc" x-part-tag=""Built-in_Exception_Types"">10.2.5<tt> </tt><a name="(part._.Built-in_.Exception_.Types)"></a>Built-in Exception Types</h5><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>struct</p></div></div><table cellspacing="0" cellpadding="0" class="RForeground"><tr><td><span class="RktPn">(</span><span class="RktSym"><a href="define-struct.html#%28form._%28%28lib._racket%2Fprivate%2Fbase..rkt%29._struct%29%29" class="RktStxLink" data-pltdoc="x">struct</a></span></td><td><span class="hspace"> </span></td><td><a name="(def._((quote._~23~25kernel)._exn-continuation-marks))"></a><a name="(def._((quote._~23~25kernel)._exn-message))"></a><a name="(def._((lib._racket/private/base..rkt)._make-exn))"></a><a name="(def._((quote._~23~25kernel)._exn~3f))"></a><a name="(def._((quote._~23~25kernel)._struct~3aexn))"></a><a name="(def._((lib._racket/private/base..rkt)._exn))"></a><span title="Provided from: racket/base, racket | Package: base"><span class="RktSym"><a href="exns.html#%28def._%28%28lib._racket%2Fprivate%2Fbase..rkt%29._exn%29%29" class="RktValDef RktValLink" data-pltdoc="x">exn</a></span></span><span class="hspace"> </span><span class="RktPn">(</span><span class="RktSym">message</span><span class="stt"> </span><span class="RktSym">continuation-marks</span><span class="RktPn">)</span></td></tr></table></blockquote></td></tr><tr><td><span class="hspace"> </span><span class="RktPn">#:extra-constructor-name</span><span class="hspace"> </span><span class="RktSym"><a href="exns.html#%28def._%28%28lib._racket%2Fprivate%2Fbase..rkt%29._make-exn%29%29" class="RktValLink" data-pltdoc="x">make-exn</a></span></td></tr><tr><td><span class="hspace"> </span><span class="RktPn">#:transparent</span><span class="RktPn">)</span></td></tr><tr><td><span class="hspace"> </span><span class="RktSym">message</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><tr><td><span class="hspace"> </span><span class="RktSym">continuation-marks</span><span class="hspace"> </span>:<span class="hspace"> </span><span class="RktSym"><a href="contmarks.html#%28def._%28%28quote._~23~25kernel%29._continuation-mark-set~3f%29%29" class="RktValLink" data-pltdoc="x">continuation-mark-set?</a></span></td></tr></table></blockquote></div><div class="SIntrapara">The base <a href="structures.html#%28tech._structure._type%29" class="techoutside" data-pltdoc="x"><span class="techinside">structure type</span></a> for exceptions. The <span class="RktSym">message</span>
|
||
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field contains an error message, and the <span class="RktSym"><a href="contmarks.html#%28def._%28%28quote._~23~25kernel%29._continuation-marks%29%29" class="RktValLink" data-pltdoc="x">continuation-marks</a></span>
|
||
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field contains the value produced by <span class="RktPn">(</span><span class="RktSym"><a href="contmarks.html#%28def._%28%28quote._~23~25kernel%29._current-continuation-marks%29%29" class="RktValLink" data-pltdoc="x">current-continuation-marks</a></span><span class="RktPn">)</span>
|
||
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immediately before the exception was raised.</div></p><p>Exceptions raised by Racket form a hierarchy under <span class="RktSym"><a href="exns.html#%28def._%28%28lib._racket%2Fprivate%2Fbase..rkt%29._exn%29%29" class="RktValLink" data-pltdoc="x">exn</a></span>:</p><blockquote class="SCodeFlow"><table cellspacing="0" cellpadding="0" class="RktBlk"><tr><td><span class="RktSym"><a href="exns.html#%28def._%28%28lib._racket%2Fprivate%2Fbase..rkt%29._exn%29%29" class="RktValLink" data-pltdoc="x">exn</a></span></td></tr><tr><td><span class="hspace"> </span><span class="RktSym"><a href="exns.html#%28def._%28%28lib._racket%2Fprivate%2Fbase..rkt%29._exn~3afail%29%29" class="RktValLink" data-pltdoc="x">exn:fail</a></span></td></tr><tr><td><span class="hspace"> </span><span class="RktSym"><a href="exns.html#%28def._%28%28lib._racket%2Fprivate%2Fbase..rkt%29._exn~3afail~3acontract%29%29" class="RktValLink" data-pltdoc="x">exn:fail:contract</a></span></td></tr><tr><td><span class="hspace"> </span><span class="RktSym"><a href="exns.html#%28def._%28%28lib._racket%2Fprivate%2Fbase..rkt%29._exn~3afail~3acontract~3aarity%29%29" class="RktValLink" data-pltdoc="x">exn:fail:contract:arity</a></span></td></tr><tr><td><span class="hspace"> </span><span class="RktSym"><a href="exns.html#%28def._%28%28lib._racket%2Fprivate%2Fbase..rkt%29._exn~3afail~3acontract~3adivide-by-zero%29%29" class="RktValLink" data-pltdoc="x">exn:fail:contract:divide-by-zero</a></span></td></tr><tr><td><span class="hspace"> </span><span class="RktSym"><a href="exns.html#%28def._%28%28lib._racket%2Fprivate%2Fbase..rkt%29._exn~3afail~3acontract~3anon-fixnum-result%29%29" class="RktValLink" data-pltdoc="x">exn:fail:contract:non-fixnum-result</a></span></td></tr><tr><td><span class="hspace"> </span><span class="RktSym"><a href="exns.html#%28def._%28%28lib._racket%2Fprivate%2Fbase..rkt%29._exn~3afail~3acontract~3acontinuation%29%29" class="RktValLink" data-pltdoc="x">exn:fail:contract:continuation</a></span></td></tr><tr><td><span class="hspace"> </span><span class="RktSym"><a href="exns.html#%28def._%28%28lib._racket%2Fprivate%2Fbase..rkt%29._exn~3afail~3acontract~3avariable%29%29" class="RktValLink" data-pltdoc="x">exn:fail:contract:variable</a></span></td></tr><tr><td><span class="hspace"> </span><span class="RktSym"><a href="exns.html#%28def._%28%28lib._racket%2Fprivate%2Fbase..rkt%29._exn~3afail~3asyntax%29%29" class="RktValLink" data-pltdoc="x">exn:fail:syntax</a></span></td></tr><tr><td><span class="hspace"> </span><span class="RktSym"><a href="exns.html#%28def._%28%28lib._racket%2Fprivate%2Fbase..rkt%29._exn~3afail~3asyntax~3aunbound%29%29" class="RktValLink" data-pltdoc="x">exn:fail:syntax:unbound</a></span></td></tr><tr><td><span class="hspace"> </span><span class="RktSym"><a href="exns.html#%28def._%28%28lib._racket%2Fprivate%2Fbase..rkt%29._exn~3afail~3asyntax~3amissing-module%29%29" class="RktValLink" data-pltdoc="x">exn:fail:syntax:missing-module</a></span></td></tr><tr><td><span class="hspace"> </span><span class="RktSym"><a href="exns.html#%28def._%28%28lib._racket%2Fprivate%2Fbase..rkt%29._exn~3afail~3aread%29%29" class="RktValLink" data-pltdoc="x">exn:fail:read</a></span></td></tr><tr><td><span class="hspace"> </span><span class="RktSym"><a href="exns.html#%28def._%28%28lib._racket%2Fprivate%2Fbase..rkt%29._exn~3afail~3aread~3aeof%29%29" class="RktValLink" data-pltdoc="x">exn:fail:read:eof</a></span></td></tr><tr><td><span class="hspace"> </span><span class="RktSym"><a href="exns.html#%28def._%28%28lib._racket%2Fprivate%2Fbase..rkt%29._exn~3afail~3aread~3anon-char%29%29" class="RktValLink" data-pltdoc="x">exn:fail:read:non-char</a></span></td></tr><tr><td><span class="h
|
||
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|
<span class="RktSym"><a href="exns.html#%28def._%28%28lib._racket%2Fprivate%2Fbase..rkt%29._exn~3abreak%29%29" class="RktValLink" data-pltdoc="x">exn:break</a></span>.</div></p><p><div class="SIntrapara"><blockquote class="SVInsetFlow"><table cellspacing="0" cellpadding="0" class="boxed RBoxed"><tr><td><blockquote class="SubFlow"><div class="RBackgroundLabel SIEHidden"><div class="RBackgroundLabelInner"><p>struct</p></div></div><table cellspacing="0" cellpadding="0" class="RForeground"><tr><td><span class="RktPn">(</span><span class="RktSym"><a href="define-struct.html#%28form._%28%28lib._racket%2Fprivate%2Fbase..rkt%29._struct%29%29" class="RktStxLink" data-pltdoc="x">struct</a></span></td><td><span class="hspace"> </span></td><td><a name="(def._((lib._racket/private/base..rkt)._make-exn~3afail~3acontract))"></a><a name="(def._((quote._~23~25kernel)._exn~3afail~3acontract~3f))"></a><a name="(def._((quote._~23~25kernel)._struct~3aexn~3afail~3acontract))"></a><a name="(def._((lib._racket/private/base..rkt)._exn~3afail~3acontract))"></a><span title="Provided from: racket/base, racket | Package: base"><span class="RktSym"><a href="exns.html#%28def._%28%28lib._racket%2Fprivate%2Fbase..rkt%29._exn~3afail~3acontract%29%29" class="RktValDef RktValLink" data-pltdoc="x">exn:fail:contract</a></span></span><span class="hspace"> </span><span class="RktSym"><a href="exns.html#%28def._%28%28lib._racket%2Fprivate%2Fbase..rkt%29._exn~3afail%29%29" class="RktValLink" data-pltdoc="x">exn:fail</a></span><span class="hspace"> </span><span class="RktPn">(</span><span class="RktPn">)</span></td></tr></table></blockquote></td></tr><tr><td><span class="hspace"> </span><span class="RktPn">#:extra-constructor-name</span><span class="hspace"> </span><span class="RktSym"><a href="exns.html#%28def._%28%28lib._racket%2Fprivate%2Fbase..rkt%29._make-exn~3afail~3acontract%29%29" class="RktValLink" data-pltdoc="x">make-exn:fail:contract</a></span></td></tr><tr><td><span class="hspace"> </span><span class="RktPn">#:transparent</span><span class="RktPn">)</span></td></tr></table></blockquote></div><div class="SIntrapara">Raised for errors from the inappropriate run-time use of a function or
|
||
|
|
syntactic form.</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>struct</p></div></div><table cellspacing="0" cellpadding="0" class="RForeground"><tr><td><span class="RktPn">(</span><span class="RktSym"><a href="define-struct.html#%28form._%28%28lib._racket%2Fprivate%2Fbase..rkt%29._struct%29%29" class="RktStxLink" data-pltdoc="x">struct</a></span></td><td><span class="hspace"> </span></td><td><a name="(def._((lib._racket/private/base..rkt)._make-exn~3afail~3acontract~3aarity))"></a><a name="(def._((quote._~23~25kernel)._exn~3afail~3acontract~3aarity~3f))"></a><a name="(def._((quote._~23~25kernel)._struct~3aexn~3afail~3acontract~3aarity))"></a><a name="(def._((lib._racket/private/base..rkt)._exn~3afail~3acontract~3aarity))"></a><span title="Provided from: racket/base, racket | Package: base"><span class="RktSym"><a href="exns.html#%28def._%28%28lib._racket%2Fprivate%2Fbase..rkt%29._exn~3afail~3acontract~3aarity%29%29" class="RktValDef RktValLink" data-pltdoc="x">exn:fail:contract:arity</a></span></span><span class="hspace"> </span><span class="RktSym"><a href="exns.html#%28def._%28%28lib._racket%2Fprivate%2Fbase..rkt%29._exn~3afail~3acontract%29%29" class="RktValLink" data-pltdoc="x">exn:fail:contract</a></span><span class="hspace"> </span><span class="RktPn">(</span><span class="RktPn">)</span></td></tr></table></blockquote></td></tr><tr><td><span class="hspace"> </span><span class="RktPn">#:extra-constructor-name</span><span class="hspace"> </span><span class="RktSym"><a href="exns.html#%28def._%28%28lib._racket%2Fprivate%2Fbase..rkt%29._make-exn~3afail~3acontract~3aarity%29%29" class="RktValLink" data-pltdoc="x">make-exn:fail:contract:arity</a></span></td></tr><tr><td><span class="hspace"> </span><span class="RktPn">#:transparent</span><span class="RktPn">)</span></td></tr></table></blockquote></div><div class="SIntrapara">Raised when a procedure is applied to the wrong number of arguments.</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>struct</p></div></div><table cellspacing="0" cellpadding="0" class="RForeground"><tr><td><span class="RktPn">(</span><span class="RktSym"><a href="define-struct.html#%28form._%28%28lib._racket%2Fprivate%2Fbase..rkt%29._struct%29%29" class="RktStxLink" data-pltdoc="x">struct</a></span></td><td><span class="hspace"> </span></td><td><a name="(def._((lib._racket/private/base..rkt)._make-exn~3afail~3acontract~3adivide-by-zero))"></a><a name="(def._((quote._~23~25kernel)._exn~3afail~3acontract~3adivide-by-zero~3f))"></a><a name="(def._((quote._~23~25kernel)._struct~3aexn~3afail~3acontract~3adivide-by-zero))"></a><a name="(def._((lib._racket/private/base..rkt)._exn~3afail~3acontract~3adivide-by-zero))"></a><span title="Provided from: racket/base, racket | Package: base"><span class="RktSym"><a href="exns.html#%28def._%28%28lib._racket%2Fprivate%2Fbase..rkt%29._exn~3afail~3acontract~3adivide-by-zero%29%29" class="RktValDef RktValLink" data-pltdoc="x">exn:fail:contract:divide-by-zero</a></span></span><span class="hspace"> </span><span class="RktSym"><a href="exns.html#%28def._%28%28lib._racket%2Fprivate%2Fbase..rkt%29._exn~3afail~3acontract%29%29" class="RktValLink" data-pltdoc="x">exn:fail:contract</a></span><span class="hspace"> </span><span class="RktPn">(</span><span class="RktPn">)</span></td></tr></table></blockquote></td></tr><tr><td><span class="hspace"> </span><span class="RktPn">#:extra-constructor-name</span></td></tr><tr><td><span class="hspace"> </span><span class="RktSym"><a href="exns.html#%28def._%28%28lib._racket%2Fprivate%2Fbase..rkt%29._make-exn~3afail~3acontract~3adivi
|
||
|
|
continuation barrier.</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>struct</p></div></div><table cellspacing="0" cellpadding="0" class="RForeground"><tr><td><span class="RktPn">(</span><span class="RktSym"><a href="define-struct.html#%28form._%28%28lib._racket%2Fprivate%2Fbase..rkt%29._struct%29%29" class="RktStxLink" data-pltdoc="x">struct</a></span></td><td><span class="hspace"> </span></td><td><a name="(def._((quote._~23~25kernel)._exn~3afail~3acontract~3avariable-id))"></a><a name="(def._((lib._racket/private/base..rkt)._make-exn~3afail~3acontract~3avariable))"></a><a name="(def._((quote._~23~25kernel)._exn~3afail~3acontract~3avariable~3f))"></a><a name="(def._((quote._~23~25kernel)._struct~3aexn~3afail~3acontract~3avariable))"></a><a name="(def._((lib._racket/private/base..rkt)._exn~3afail~3acontract~3avariable))"></a><span title="Provided from: racket/base, racket | Package: base"><span class="RktSym"><a href="exns.html#%28def._%28%28lib._racket%2Fprivate%2Fbase..rkt%29._exn~3afail~3acontract~3avariable%29%29" class="RktValDef RktValLink" data-pltdoc="x">exn:fail:contract:variable</a></span></span><span class="hspace"> </span><span class="RktSym"><a href="exns.html#%28def._%28%28lib._racket%2Fprivate%2Fbase..rkt%29._exn~3afail~3acontract%29%29" class="RktValLink" data-pltdoc="x">exn:fail:contract</a></span><span class="hspace"> </span><span class="RktPn">(</span><span class="RktSym">id</span><span class="RktPn">)</span></td></tr></table></blockquote></td></tr><tr><td><span class="hspace"> </span><span class="RktPn">#:extra-constructor-name</span><span class="hspace"> </span><span class="RktSym"><a href="exns.html#%28def._%28%28lib._racket%2Fprivate%2Fbase..rkt%29._make-exn~3afail~3acontract~3avariable%29%29" class="RktValLink" data-pltdoc="x">make-exn:fail:contract:variable</a></span></td></tr><tr><td><span class="hspace"> </span><span class="RktPn">#:transparent</span><span class="RktPn">)</span></td></tr><tr><td><span class="hspace"> </span><span class="RktSym">id</span><span class="hspace"> </span>:<span class="hspace"> </span><span class="RktSym"><a href="symbols.html#%28def._%28%28quote._~23~25kernel%29._symbol~3f%29%29" class="RktValLink" data-pltdoc="x">symbol?</a></span></td></tr></table></blockquote></div><div class="SIntrapara">Raised for a reference to a not-yet-defined <a href="eval-model.html#%28tech._top._level._variable%29" class="techoutside" data-pltdoc="x"><span class="techinside">top-level variable</span></a>
|
||
|
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or <a href="eval-model.html#%28tech._module._level._variable%29" class="techoutside" data-pltdoc="x"><span class="techinside">module-level variable</span></a>.</div></p><p><div class="SIntrapara"><blockquote class="SVInsetFlow"><table cellspacing="0" cellpadding="0" class="boxed RBoxed"><tr><td><blockquote class="SubFlow"><div class="RBackgroundLabel SIEHidden"><div class="RBackgroundLabelInner"><p>struct</p></div></div><table cellspacing="0" cellpadding="0" class="RForeground"><tr><td><span class="RktPn">(</span><span class="RktSym"><a href="define-struct.html#%28form._%28%28lib._racket%2Fprivate%2Fbase..rkt%29._struct%29%29" class="RktStxLink" data-pltdoc="x">struct</a></span></td><td><span class="hspace"> </span></td><td><a name="(def._((quote._~23~25kernel)._exn~3afail~3asyntax-exprs))"></a><a name="(def._((lib._racket/private/base..rkt)._make-exn~3afail~3asyntax))"></a><a name="(def._((quote._~23~25kernel)._exn~3afail~3asyntax~3f))"></a><a name="(def._((quote._~23~25kernel)._struct~3aexn~3afail~3asyntax))"></a><a name="(def._((lib._racket/private/base..rkt)._exn~3afail~3asyntax))"></a><span title="Provided from: racket/base, racket | Package: base"><span class="RktSym"><a href="exns.html#%28def._%28%28lib._racket%2Fprivate%2Fbase..rkt%29._exn~3afail~3asyntax%29%29" class="RktValDef RktValLink" data-pltdoc="x">exn:fail:syntax</a></span></span><span class="hspace"> </span><span class="RktSym"><a href="exns.html#%28def._%28%28lib._racket%2Fprivate%2Fbase..rkt%29._exn~3afail%29%29" class="RktValLink" data-pltdoc="x">exn:fail</a></span><span class="hspace"> </span><span class="RktPn">(</span><span class="RktSym">exprs</span><span class="RktPn">)</span></td></tr></table></blockquote></td></tr><tr><td><span class="hspace"> </span><span class="RktPn">#:extra-constructor-name</span><span class="hspace"> </span><span class="RktSym"><a href="exns.html#%28def._%28%28lib._racket%2Fprivate%2Fbase..rkt%29._make-exn~3afail~3asyntax%29%29" class="RktValLink" data-pltdoc="x">make-exn:fail:syntax</a></span></td></tr><tr><td><span class="hspace"> </span><span class="RktPn">#:transparent</span><span class="RktPn">)</span></td></tr><tr><td><span class="hspace"> </span><span class="RktSym">exprs</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._listof%29%29" class="RktValLink" data-pltdoc="x">listof</a></span><span class="hspace"> </span><span class="RktSym"><a href="stxops.html#%28def._%28%28quote._~23~25kernel%29._syntax~3f%29%29" class="RktValLink" data-pltdoc="x">syntax?</a></span><span class="RktPn">)</span></td></tr></table></blockquote></div><div class="SIntrapara">Raised for a syntax error that is not a <span class="RktSym"><a href="Reading.html#%28def._%28%28quote._~23~25kernel%29._read%29%29" class="RktValLink" data-pltdoc="x">read</a></span> error. The
|
||
|
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<span class="RktSym">exprs</span> indicate the relevant source expressions,
|
||
|
|
least-specific to most-specific.</div></p><p>This structure type implements the <span class="RktSym"><a href="exns.html#%28def._%28%28quote._~23~25kernel%29._prop~3aexn~3asrclocs%29%29" class="RktValLink" data-pltdoc="x">prop:exn:srclocs</a></span> property.</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>struct</p></div></div><table cellspacing="0" cellpadding="0" class="RForeground"><tr><td><span class="RktPn">(</span><span class="RktSym"><a href="define-struct.html#%28form._%28%28lib._racket%2Fprivate%2Fbase..rkt%29._struct%29%29" class="RktStxLink" data-pltdoc="x">struct</a></span></td><td><span class="hspace"> </span></td><td><a name="(def._((lib._racket/private/base..rkt)._make-exn~3afail~3asyntax~3aunbound))"></a><a name="(def._((quote._~23~25kernel)._exn~3afail~3asyntax~3aunbound~3f))"></a><a name="(def._((quote._~23~25kernel)._struct~3aexn~3afail~3asyntax~3aunbound))"></a><a name="(def._((lib._racket/private/base..rkt)._exn~3afail~3asyntax~3aunbound))"></a><span title="Provided from: racket/base, racket | Package: base"><span class="RktSym"><a href="exns.html#%28def._%28%28lib._racket%2Fprivate%2Fbase..rkt%29._exn~3afail~3asyntax~3aunbound%29%29" class="RktValDef RktValLink" data-pltdoc="x">exn:fail:syntax:unbound</a></span></span><span class="hspace"> </span><span class="RktSym"><a href="exns.html#%28def._%28%28lib._racket%2Fprivate%2Fbase..rkt%29._exn~3afail~3asyntax%29%29" class="RktValLink" data-pltdoc="x">exn:fail:syntax</a></span><span class="hspace"> </span><span class="RktPn">(</span><span class="RktPn">)</span></td></tr></table></blockquote></td></tr><tr><td><span class="hspace"> </span><span class="RktPn">#:extra-constructor-name</span><span class="hspace"> </span><span class="RktSym"><a href="exns.html#%28def._%28%28lib._racket%2Fprivate%2Fbase..rkt%29._make-exn~3afail~3asyntax~3aunbound%29%29" class="RktValLink" data-pltdoc="x">make-exn:fail:syntax:unbound</a></span></td></tr><tr><td><span class="hspace"> </span><span class="RktPn">#:transparent</span><span class="RktPn">)</span></td></tr></table></blockquote></div><div class="SIntrapara">Raised by <span class="RktSym"><a href="__top.html#%28form._%28%28quote._~23~25kernel%29._~23~25top%29%29" class="RktStxLink" data-pltdoc="x">#%top</a></span> or <span class="RktSym"><a href="set_.html#%28form._%28%28quote._~23~25kernel%29._set%21%29%29" class="RktStxLink" data-pltdoc="x">set!</a></span> for an
|
||
|
|
unbound identifier within a module.</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>struct</p></div></div><table cellspacing="0" cellpadding="0" class="RForeground"><tr><td><span class="RktPn">(</span><span class="RktSym"><a href="define-struct.html#%28form._%28%28lib._racket%2Fprivate%2Fbase..rkt%29._struct%29%29" class="RktStxLink" data-pltdoc="x">struct</a></span></td><td><span class="hspace"> </span></td><td><a name="(def._((quote._~23~25kernel)._exn~3afail~3asyntax~3amissing-module-path))"></a><a name="(def._((lib._racket/private/base..rkt)._make-exn~3afail~3asyntax~3amissing-module))"></a><a name="(def._((quote._~23~25kernel)._exn~3afail~3asyntax~3amissing-module~3f))"></a><a name="(def._((quote._~23~25kernel)._struct~3aexn~3afail~3asyntax~3amissing-module))"></a><a name="(def._((lib._racket/private/base..rkt)._exn~3afail~3asyntax~3amissing-module))"></a><span title="Provided from: racket/base, racket | Package: base"><span class="RktSym"><a href="exns.html#%28def._%28%28lib._racket%2Fprivate%2Fbase..rkt%29._exn~3afail~3asyntax~3amissing-module%29%29" class="RktValDef RktValLink" data-pltdoc="x">exn:fail:syntax:missing-module</a></span></span><span class="hspace"> </span><span class="RktSym"><a href="exns.html#%28def._%28%28lib._racket%2Fprivate%2Fbase..rkt%29._exn~3afail~3asyntax%29%29" class="RktValLink" data-pltdoc="x">exn:fail:syntax</a></span><span class="hspace"> </span><span class="RktPn">(</span><span class="RktSym">path</span><span class="RktPn">)</span></td></tr></table></blockquote></td></tr><tr><td><span class="hspace"> </span><span class="RktPn">#:extra-constructor-name</span><span class="hspace"> </span><span class="RktSym"><a href="exns.html#%28def._%28%28lib._racket%2Fprivate%2Fbase..rkt%29._make-exn~3afail~3asyntax~3amissing-module%29%29" class="RktValLink" data-pltdoc="x">make-exn:fail:syntax:missing-module</a></span></td></tr><tr><td><span class="hspace"> </span><span class="RktPn">#:transparent</span><span class="RktPn">)</span></td></tr><tr><td><span class="hspace"> </span><span class="RktSym">path</span><span class="hspace"> </span>:<span class="hspace"> </span><span class="RktSym"><a href="Module_Names_and_Loading.html#%28def._%28%28quote._~23~25kernel%29._module-path~3f%29%29" class="RktValLink" data-pltdoc="x">module-path?</a></span></td></tr></table></blockquote></div><div class="SIntrapara">Raised by the default <a href="Module_Names_and_Loading.html#%28tech._module._name._resolver%29" class="techoutside" data-pltdoc="x"><span class="techinside">module name resolver</span></a> or default
|
||
|
|
<a href="eval.html#%28tech._load._handler%29" class="techoutside" data-pltdoc="x"><span class="techinside">load handler</span></a> to report a module path—<wbr></wbr>a reported in the
|
||
|
|
<span class="RktSym">path</span> field—<wbr></wbr>whose implementation file cannot be
|
||
|
|
found.</div></p><p>The default <a href="Module_Names_and_Loading.html#%28tech._module._name._resolver%29" class="techoutside" data-pltdoc="x"><span class="techinside">module name resolver</span></a> raises this exception only
|
||
|
|
when it is given a syntax object as its second argument, and the
|
||
|
|
default <a href="eval.html#%28tech._load._handler%29" class="techoutside" data-pltdoc="x"><span class="techinside">load handler</span></a> raises this exception only when the value
|
||
|
|
of <span class="RktSym"><a href="Module_Names_and_Loading.html#%28def._%28%28quote._~23~25kernel%29._current-module-path-for-load%29%29" class="RktValLink" data-pltdoc="x">current-module-path-for-load</a></span> is a syntax object (in which
|
||
|
|
case both the <span class="RktSym">exprs</span> field and the <span class="RktSym">path</span> field
|
||
|
|
are determined by the syntax object).</p><p>This structure type implements the <span class="RktSym"><a href="exns.html#%28def._%28%28quote._~23~25kernel%29._prop~3aexn~3amissing-module%29%29" class="RktValLink" data-pltdoc="x">prop:exn:missing-module</a></span> property.</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>struct</p></div></div><table cellspacing="0" cellpadding="0" class="RForeground"><tr><td><span class="RktPn">(</span><span class="RktSym"><a href="define-struct.html#%28form._%28%28lib._racket%2Fprivate%2Fbase..rkt%29._struct%29%29" class="RktStxLink" data-pltdoc="x">struct</a></span></td><td><span class="hspace"> </span></td><td><a name="(def._((quote._~23~25kernel)._exn~3afail~3aread-srclocs))"></a><a name="(def._((lib._racket/private/base..rkt)._make-exn~3afail~3aread))"></a><a name="(def._((quote._~23~25kernel)._exn~3afail~3aread~3f))"></a><a name="(def._((quote._~23~25kernel)._struct~3aexn~3afail~3aread))"></a><a name="(def._((lib._racket/private/base..rkt)._exn~3afail~3aread))"></a><span title="Provided from: racket/base, racket | Package: base"><span class="RktSym"><a href="exns.html#%28def._%28%28lib._racket%2Fprivate%2Fbase..rkt%29._exn~3afail~3aread%29%29" class="RktValDef RktValLink" data-pltdoc="x">exn:fail:read</a></span></span><span class="hspace"> </span><span class="RktSym"><a href="exns.html#%28def._%28%28lib._racket%2Fprivate%2Fbase..rkt%29._exn~3afail%29%29" class="RktValLink" data-pltdoc="x">exn:fail</a></span><span class="hspace"> </span><span class="RktPn">(</span><span class="RktSym">srclocs</span><span class="RktPn">)</span></td></tr></table></blockquote></td></tr><tr><td><span class="hspace"> </span><span class="RktPn">#:extra-constructor-name</span><span class="hspace"> </span><span class="RktSym"><a href="exns.html#%28def._%28%28lib._racket%2Fprivate%2Fbase..rkt%29._make-exn~3afail~3aread%29%29" class="RktValLink" data-pltdoc="x">make-exn:fail:read</a></span></td></tr><tr><td><span class="hspace"> </span><span class="RktPn">#:transparent</span><span class="RktPn">)</span></td></tr><tr><td><span class="hspace"> </span><span class="RktSym">srclocs</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._listof%29%29" class="RktValLink" data-pltdoc="x">listof</a></span><span class="hspace"> </span><span class="RktSym"><a href="exns.html#%28def._%28%28quote._~23~25kernel%29._srcloc~3f%29%29" class="RktValLink" data-pltdoc="x">srcloc?</a></span><span class="RktPn">)</span></td></tr></table></blockquote></div><div class="SIntrapara">Raised for a <span class="RktSym"><a href="Reading.html#%28def._%28%28quote._~23~25kernel%29._read%29%29" class="RktValLink" data-pltdoc="x">read</a></span> error. The <span class="RktSym">srclocs</span> indicate the
|
||
|
|
relevant source expressions.</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>struct</p></div></div><table cellspacing="0" cellpadding="0" class="RForeground"><tr><td><span class="RktPn">(</span><span class="RktSym"><a href="define-struct.html#%28form._%28%28lib._racket%2Fprivate%2Fbase..rkt%29._struct%29%29" class="RktStxLink" data-pltdoc="x">struct</a></span></td><td><span class="hspace"> </span></td><td><a name="(def._((lib._racket/private/base..rkt)._make-exn~3afail~3aread~3aeof))"></a><a name="(def._((quote._~23~25kernel)._exn~3afail~3aread~3aeof~3f))"></a><a name="(def._((quote._~23~25kernel)._struct~3aexn~3afail~3aread~3aeof))"></a><a name="(def._((lib._racket/private/base..rkt)._exn~3afail~3aread~3aeof))"></a><span title="Provided from: racket/base, racket | Package: base"><span class="RktSym"><a href="exns.html#%28def._%28%28lib._racket%2Fprivate%2Fbase..rkt%29._exn~3afail~3aread~3aeof%29%29" class="RktValDef RktValLink" data-pltdoc="x">exn:fail:read:eof</a></span></span><span class="hspace"> </span><span class="RktSym"><a href="exns.html#%28def._%28%28lib._racket%2Fprivate%2Fbase..rkt%29._exn~3afail~3aread%29%29" class="RktValLink" data-pltdoc="x">exn:fail:read</a></span><span class="hspace"> </span><span class="RktPn">(</span><span class="RktPn">)</span></td></tr></table></blockquote></td></tr><tr><td><span class="hspace"> </span><span class="RktPn">#:extra-constructor-name</span><span class="hspace"> </span><span class="RktSym"><a href="exns.html#%28def._%28%28lib._racket%2Fprivate%2Fbase..rkt%29._make-exn~3afail~3aread~3aeof%29%29" class="RktValLink" data-pltdoc="x">make-exn:fail:read:eof</a></span></td></tr><tr><td><span class="hspace"> </span><span class="RktPn">#:transparent</span><span class="RktPn">)</span></td></tr></table></blockquote></div><div class="SIntrapara">Raised for a <span class="RktSym"><a href="Reading.html#%28def._%28%28quote._~23~25kernel%29._read%29%29" class="RktValLink" data-pltdoc="x">read</a></span> error, specifically when the error is due
|
||
|
|
to an unexpected end-of-file.</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>struct</p></div></div><table cellspacing="0" cellpadding="0" class="RForeground"><tr><td><span class="RktPn">(</span><span class="RktSym"><a href="define-struct.html#%28form._%28%28lib._racket%2Fprivate%2Fbase..rkt%29._struct%29%29" class="RktStxLink" data-pltdoc="x">struct</a></span></td><td><span class="hspace"> </span></td><td><a name="(def._((lib._racket/private/base..rkt)._make-exn~3afail~3aread~3anon-char))"></a><a name="(def._((quote._~23~25kernel)._exn~3afail~3aread~3anon-char~3f))"></a><a name="(def._((quote._~23~25kernel)._struct~3aexn~3afail~3aread~3anon-char))"></a><a name="(def._((lib._racket/private/base..rkt)._exn~3afail~3aread~3anon-char))"></a><span title="Provided from: racket/base, racket | Package: base"><span class="RktSym"><a href="exns.html#%28def._%28%28lib._racket%2Fprivate%2Fbase..rkt%29._exn~3afail~3aread~3anon-char%29%29" class="RktValDef RktValLink" data-pltdoc="x">exn:fail:read:non-char</a></span></span><span class="hspace"> </span><span class="RktSym"><a href="exns.html#%28def._%28%28lib._racket%2Fprivate%2Fbase..rkt%29._exn~3afail~3aread%29%29" class="RktValLink" data-pltdoc="x">exn:fail:read</a></span><span class="hspace"> </span><span class="RktPn">(</span><span class="RktPn">)</span></td></tr></table></blockquote></td></tr><tr><td><span class="hspace"> </span><span class="RktPn">#:extra-constructor-name</span><span class="hspace"> </span><span class="RktSym"><a href="exns.html#%28def._%28%28lib._racket%2Fprivate%2Fbase..rkt%29._make-exn~3afail~3aread~3anon-char%29%29" class="RktValLink" data-pltdoc="x">make-exn:fail:read:non-char</a></span></td></tr><tr><td><span class="hspace"> </span><span class="RktPn">#:transparent</span><span class="RktPn">)</span></td></tr></table></blockquote></div><div class="SIntrapara">Raised for a <span class="RktSym"><a href="Reading.html#%28def._%28%28quote._~23~25kernel%29._read%29%29" class="RktValLink" data-pltdoc="x">read</a></span> error, specifically when the error is due
|
||
|
|
to an unexpected non-character (i.e., “special”) element in the
|
||
|
|
input stream.</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>struct</p></div></div><table cellspacing="0" cellpadding="0" class="RForeground"><tr><td><span class="RktPn">(</span><span class="RktSym"><a href="define-struct.html#%28form._%28%28lib._racket%2Fprivate%2Fbase..rkt%29._struct%29%29" class="RktStxLink" data-pltdoc="x">struct</a></span></td><td><span class="hspace"> </span></td><td><a name="(def._((lib._racket/private/base..rkt)._make-exn~3afail~3afilesystem))"></a><a name="(def._((quote._~23~25kernel)._exn~3afail~3afilesystem~3f))"></a><a name="(def._((quote._~23~25kernel)._struct~3aexn~3afail~3afilesystem))"></a><a name="(def._((lib._racket/private/base..rkt)._exn~3afail~3afilesystem))"></a><span title="Provided from: racket/base, racket | Package: base"><span class="RktSym"><a href="exns.html#%28def._%28%28lib._racket%2Fprivate%2Fbase..rkt%29._exn~3afail~3afilesystem%29%29" class="RktValDef RktValLink" data-pltdoc="x">exn:fail:filesystem</a></span></span><span class="hspace"> </span><span class="RktSym"><a href="exns.html#%28def._%28%28lib._racket%2Fprivate%2Fbase..rkt%29._exn~3afail%29%29" class="RktValLink" data-pltdoc="x">exn:fail</a></span><span class="hspace"> </span><span class="RktPn">(</span><span class="RktPn">)</span></td></tr></table></blockquote></td></tr><tr><td><span class="hspace"> </span><span class="RktPn">#:extra-constructor-name</span><span class="hspace"> </span><span class="RktSym"><a href="exns.html#%28def._%28%28lib._racket%2Fprivate%2Fbase..rkt%29._make-exn~3afail~3afilesystem%29%29" class="RktValLink" data-pltdoc="x">make-exn:fail:filesystem</a></span></td></tr><tr><td><span class="hspace"> </span><span class="RktPn">#:transparent</span><span class="RktPn">)</span></td></tr></table></blockquote></div><div class="SIntrapara">Raised for an error related to the filesystem (such as a file not
|
||
|
|
found).</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>struct</p></div></div><table cellspacing="0" cellpadding="0" class="RForeground"><tr><td><span class="RktPn">(</span><span class="RktSym"><a href="define-struct.html#%28form._%28%28lib._racket%2Fprivate%2Fbase..rkt%29._struct%29%29" class="RktStxLink" data-pltdoc="x">struct</a></span></td><td><span class="hspace"> </span></td><td><a name="(def._((lib._racket/private/base..rkt)._make-exn~3afail~3afilesystem~3aexists))"></a><a name="(def._((quote._~23~25kernel)._exn~3afail~3afilesystem~3aexists~3f))"></a><a name="(def._((quote._~23~25kernel)._struct~3aexn~3afail~3afilesystem~3aexists))"></a><a name="(def._((lib._racket/private/base..rkt)._exn~3afail~3afilesystem~3aexists))"></a><span title="Provided from: racket/base, racket | Package: base"><span class="RktSym"><a href="exns.html#%28def._%28%28lib._racket%2Fprivate%2Fbase..rkt%29._exn~3afail~3afilesystem~3aexists%29%29" class="RktValDef RktValLink" data-pltdoc="x">exn:fail:filesystem:exists</a></span></span><span class="hspace"> </span><span class="RktSym"><a href="exns.html#%28def._%28%28lib._racket%2Fprivate%2Fbase..rkt%29._exn~3afail~3afilesystem%29%29" class="RktValLink" data-pltdoc="x">exn:fail:filesystem</a></span><span class="hspace"> </span><span class="RktPn">(</span><span class="RktPn">)</span></td></tr></table></blockquote></td></tr><tr><td><span class="hspace"> </span><span class="RktPn">#:extra-constructor-name</span><span class="hspace"> </span><span class="RktSym"><a href="exns.html#%28def._%28%28lib._racket%2Fprivate%2Fbase..rkt%29._make-exn~3afail~3afilesystem~3aexists%29%29" class="RktValLink" data-pltdoc="x">make-exn:fail:filesystem:exists</a></span></td></tr><tr><td><span class="hspace"> </span><span class="RktPn">#:transparent</span><span class="RktPn">)</span></td></tr></table></blockquote></div><div class="SIntrapara">Raised for an error when attempting to create a file that exists
|
||
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|
already.</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>struct</p></div></div><table cellspacing="0" cellpadding="0" class="RForeground"><tr><td><span class="RktPn">(</span><span class="RktSym"><a href="define-struct.html#%28form._%28%28lib._racket%2Fprivate%2Fbase..rkt%29._struct%29%29" class="RktStxLink" data-pltdoc="x">struct</a></span></td><td><span class="hspace"> </span></td><td><a name="(def._((lib._racket/private/base..rkt)._make-exn~3afail~3afilesystem~3aversion))"></a><a name="(def._((quote._~23~25kernel)._exn~3afail~3afilesystem~3aversion~3f))"></a><a name="(def._((quote._~23~25kernel)._struct~3aexn~3afail~3afilesystem~3aversion))"></a><a name="(def._((lib._racket/private/base..rkt)._exn~3afail~3afilesystem~3aversion))"></a><span title="Provided from: racket/base, racket | Package: base"><span class="RktSym"><a href="exns.html#%28def._%28%28lib._racket%2Fprivate%2Fbase..rkt%29._exn~3afail~3afilesystem~3aversion%29%29" class="RktValDef RktValLink" data-pltdoc="x">exn:fail:filesystem:version</a></span></span><span class="hspace"> </span><span class="RktSym"><a href="exns.html#%28def._%28%28lib._racket%2Fprivate%2Fbase..rkt%29._exn~3afail~3afilesystem%29%29" class="RktValLink" data-pltdoc="x">exn:fail:filesystem</a></span><span class="hspace"> </span><span class="RktPn">(</span><span class="RktPn">)</span></td></tr></table></blockquote></td></tr><tr><td><span class="hspace"> </span><span class="RktPn">#:extra-constructor-name</span><span class="hspace"> </span><span class="RktSym"><a href="exns.html#%28def._%28%28lib._racket%2Fprivate%2Fbase..rkt%29._make-exn~3afail~3afilesystem~3aversion%29%29" class="RktValLink" data-pltdoc="x">make-exn:fail:filesystem:version</a></span></td></tr><tr><td><span class="hspace"> </span><span class="RktPn">#:transparent</span><span class="RktPn">)</span></td></tr></table></blockquote></div><div class="SIntrapara">Raised for a version-mismatch error when loading an extension.</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>struct</p></div></div><table cellspacing="0" cellpadding="0" class="RForeground"><tr><td><span class="RktPn">(</span><span class="RktSym"><a href="define-struct.html#%28form._%28%28lib._racket%2Fprivate%2Fbase..rkt%29._struct%29%29" class="RktStxLink" data-pltdoc="x">struct</a></span></td><td><span class="hspace"> </span></td><td><a name="(def._((quote._~23~25kernel)._exn~3afail~3afilesystem~3aerrno-errno))"></a><a name="(def._((lib._racket/private/base..rkt)._make-exn~3afail~3afilesystem~3aerrno))"></a><a name="(def._((quote._~23~25kernel)._exn~3afail~3afilesystem~3aerrno~3f))"></a><a name="(def._((quote._~23~25kernel)._struct~3aexn~3afail~3afilesystem~3aerrno))"></a><a name="(def._((lib._racket/private/base..rkt)._exn~3afail~3afilesystem~3aerrno))"></a><span title="Provided from: racket/base, racket | Package: base"><span class="RktSym"><a href="exns.html#%28def._%28%28lib._racket%2Fprivate%2Fbase..rkt%29._exn~3afail~3afilesystem~3aerrno%29%29" class="RktValDef RktValLink" data-pltdoc="x">exn:fail:filesystem:errno</a></span></span><span class="hspace"> </span><span class="RktSym"><a href="exns.html#%28def._%28%28lib._racket%2Fprivate%2Fbase..rkt%29._exn~3afail~3afilesystem%29%29" class="RktValLink" data-pltdoc="x">exn:fail:filesystem</a></span><span class="hspace"> </span><span class="RktPn">(</span><span class="RktSym">errno</span><span class="RktPn">)</span></td></tr></table></blockquote></td></tr><tr><td><span class="hspace"> </span><span class="RktPn">#:extra-constructor-name</span><span class="hspace"> </span><span class="RktSym"><a href="exns.html#%28def._%28%28lib._
|
||
|
|
available. The symbol part of an <span class="RktSym">errno</span> field indicates the
|
||
|
|
category of the error code: <span class="RktVal">'</span><span class="RktVal">posix</span> indicates a C/Posix
|
||
|
|
<span class="stt">errno</span> value, <span class="RktVal">'</span><span class="RktVal">windows</span> indicates a Windows system error
|
||
|
|
code (under Windows, only), and <span class="RktVal">'</span><span class="RktVal">gai</span> indicates a
|
||
|
|
<span class="stt">getaddrinfo</span> error code (which shows up only in
|
||
|
|
<span class="RktSym"><a href="exns.html#%28def._%28%28lib._racket%2Fprivate%2Fbase..rkt%29._exn~3afail~3anetwork~3aerrno%29%29" class="RktValLink" data-pltdoc="x">exn:fail:network:errno</a></span> exceptions for operations that resolve
|
||
|
|
hostnames, but is allowed in <span class="RktSym"><a href="exns.html#%28def._%28%28lib._racket%2Fprivate%2Fbase..rkt%29._exn~3afail~3afilesystem~3aerrno%29%29" class="RktValLink" data-pltdoc="x">exn:fail:filesystem:errno</a></span>
|
||
|
|
instances for consistency).</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>struct</p></div></div><table cellspacing="0" cellpadding="0" class="RForeground"><tr><td><span class="RktPn">(</span><span class="RktSym"><a href="define-struct.html#%28form._%28%28lib._racket%2Fprivate%2Fbase..rkt%29._struct%29%29" class="RktStxLink" data-pltdoc="x">struct</a></span></td><td><span class="hspace"> </span></td><td><span class="nobreak"><a name="(def._((quote._~23~25kernel)._exn~3afail~3afilesystem~3amissing-module-path))"></a><a name="(def._((lib._racket/private/base..rkt)._make-exn~3afail~3afilesystem~3amissing-module))"></a><a name="(def._((quote._~23~25kernel)._exn~3afail~3afilesystem~3amissing-module~3f))"></a><a name="(def._((quote._~23~25kernel)._struct~3aexn~3afail~3afilesystem~3amissing-module))"></a><a name="(def._((lib._racket/private/base..rkt)._exn~3afail~3afilesystem~3amissing-module))"></a><span title="Provided from: racket/base, racket | Package: base"><span class="RktSym"><a href="exns.html#%28def._%28%28lib._racket%2Fprivate%2Fbase..rkt%29._exn~3afail~3afilesystem~3amissing-module%29%29" class="RktValDef RktValLink" data-pltdoc="x">exn:fail:filesystem:missing-module</a></span></span><span class="hspace"> </span><span class="RktSym"><a href="exns.html#%28def._%28%28lib._racket%2Fprivate%2Fbase..rkt%29._exn~3afail~3afilesystem%29%29" class="RktValLink" data-pltdoc="x">exn:fail:filesystem</a></span></span></td></tr><tr><td><span class="hspace"> </span></td><td><span class="hspace"> </span></td><td><span class="RktPn">(</span><span class="nobreak"><span class="RktSym">path</span><span class="RktPn">)</span></span></td></tr></table></blockquote></td></tr><tr><td><span class="hspace"> </span><span class="RktPn">#:extra-constructor-name</span></td></tr><tr><td><span class="hspace"> </span><span class="RktSym"><a href="exns.html#%28def._%28%28lib._racket%2Fprivate%2Fbase..rkt%29._make-exn~3afail~3afilesystem~3amissing-module%29%29" class="RktValLink" data-pltdoc="x">make-exn:fail:filesystem:missing-module</a></span></td></tr><tr><td><span class="hspace"> </span><span class="RktPn">#:transparent</span><span class="RktPn">)</span></td></tr><tr><td><span class="hspace"> </span><span class="RktSym">path</span><span class="hspace"> </span>:<span class="hspace"> </span><span class="RktSym"><a href="Module_Names_and_Loading.html#%28def._%28%28quote._~23~25kernel%29._module-path~3f%29%29" class="RktValLink" data-pltdoc="x">module-path?</a></span></td></tr></table></blockquote></div><div class="SIntrapara">Raised by the default <a href="Module_Names_and_Loading.html#%28tech._module._name._resolver%29" class="techoutside" data-pltdoc="x"><span class="techinside">module name resolver</span></a> or default
|
||
|
|
<a href="eval.html#%28tech._load._handler%29" class="techoutside" data-pltdoc="x"><span class="techinside">load handler</span></a> to report a module path—<wbr></wbr>a reported in the
|
||
|
|
<span class="RktSym">path</span> field—<wbr></wbr>whose implementation file cannot be
|
||
|
|
found.</div></p><p>The default <a href="Module_Names_and_Loading.html#%28tech._module._name._resolver%29" class="techoutside" data-pltdoc="x"><span class="techinside">module name resolver</span></a> raises this exception only
|
||
|
|
when it is <span class="emph">not</span> given a syntax object as its second argument, and the
|
||
|
|
default <a href="eval.html#%28tech._load._handler%29" class="techoutside" data-pltdoc="x"><span class="techinside">load handler</span></a> raises this exception only when the value
|
||
|
|
of <span class="RktSym"><a href="Module_Names_and_Loading.html#%28def._%28%28quote._~23~25kernel%29._current-module-path-for-load%29%29" class="RktValLink" data-pltdoc="x">current-module-path-for-load</a></span> is <span class="emph">not</span> a syntax object.</p><p>This structure type implements the <span class="RktSym"><a href="exns.html#%28def._%28%28quote._~23~25kernel%29._prop~3aexn~3amissing-module%29%29" class="RktValLink" data-pltdoc="x">prop:exn:missing-module</a></span> property.</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>struct</p></div></div><table cellspacing="0" cellpadding="0" class="RForeground"><tr><td><span class="RktPn">(</span><span class="RktSym"><a href="define-struct.html#%28form._%28%28lib._racket%2Fprivate%2Fbase..rkt%29._struct%29%29" class="RktStxLink" data-pltdoc="x">struct</a></span></td><td><span class="hspace"> </span></td><td><a name="(def._((lib._racket/private/base..rkt)._make-exn~3afail~3anetwork))"></a><a name="(def._((quote._~23~25kernel)._exn~3afail~3anetwork~3f))"></a><a name="(def._((quote._~23~25kernel)._struct~3aexn~3afail~3anetwork))"></a><a name="(def._((lib._racket/private/base..rkt)._exn~3afail~3anetwork))"></a><span title="Provided from: racket/base, racket | Package: base"><span class="RktSym"><a href="exns.html#%28def._%28%28lib._racket%2Fprivate%2Fbase..rkt%29._exn~3afail~3anetwork%29%29" class="RktValDef RktValLink" data-pltdoc="x">exn:fail:network</a></span></span><span class="hspace"> </span><span class="RktSym"><a href="exns.html#%28def._%28%28lib._racket%2Fprivate%2Fbase..rkt%29._exn~3afail%29%29" class="RktValLink" data-pltdoc="x">exn:fail</a></span><span class="hspace"> </span><span class="RktPn">(</span><span class="RktPn">)</span></td></tr></table></blockquote></td></tr><tr><td><span class="hspace"> </span><span class="RktPn">#:extra-constructor-name</span><span class="hspace"> </span><span class="RktSym"><a href="exns.html#%28def._%28%28lib._racket%2Fprivate%2Fbase..rkt%29._make-exn~3afail~3anetwork%29%29" class="RktValLink" data-pltdoc="x">make-exn:fail:network</a></span></td></tr><tr><td><span class="hspace"> </span><span class="RktPn">#:transparent</span><span class="RktPn">)</span></td></tr></table></blockquote></div><div class="SIntrapara">Raised for TCP and UDP errors.</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>struct</p></div></div><table cellspacing="0" cellpadding="0" class="RForeground"><tr><td><span class="RktPn">(</span><span class="RktSym"><a href="define-struct.html#%28form._%28%28lib._racket%2Fprivate%2Fbase..rkt%29._struct%29%29" class="RktStxLink" data-pltdoc="x">struct</a></span></td><td><span class="hspace"> </span></td><td><a name="(def._((quote._~23~25kernel)._exn~3afail~3anetwork~3aerrno-errno))"></a><a name="(def._((lib._racket/private/base..rkt)._make-exn~3afail~3anetwork~3aerrno))"></a><a name="(def._((quote._~23~25kernel)._exn~3afail~3anetwork~3aerrno~3f))"></a><a name="(def._((quote._~23~25kernel)._struct~3aexn~3afail~3anetwork~3aerrno))"></a><a name="(def._((lib._racket/private/base..rkt)._exn~3afail~3anetwork~3aerrno))"></a><span title="Provided from: racket/base, racket | Package: base"><span class="RktSym"><a href="exns.html#%28def._%28%28lib._racket%2Fprivate%2Fbase..rkt%29._exn~3afail~3anetwork~3aerrno%29%29" class="RktValDef RktValLink" data-pltdoc="x">exn:fail:network:errno</a></span></span><span class="hspace"> </span><span class="RktSym"><a href="exns.html#%28def._%28%28lib._racket%2Fprivate%2Fbase..rkt%29._exn~3afail~3anetwork%29%29" class="RktValLink" data-pltdoc="x">exn:fail:network</a></span><span class="hspace"> </span><span class="RktPn">(</span><span cl
|
||
|
|
available, where the <span class="RktSym">errno</span> field is as for
|
||
|
|
<span class="RktSym"><a href="exns.html#%28def._%28%28lib._racket%2Fprivate%2Fbase..rkt%29._exn~3afail~3afilesystem~3aerrno%29%29" class="RktValLink" data-pltdoc="x">exn:fail:filesystem:errno</a></span>.</div></p><p><div class="SIntrapara"><blockquote class="SVInsetFlow"><table cellspacing="0" cellpadding="0" class="boxed RBoxed"><tr><td><blockquote class="SubFlow"><div class="RBackgroundLabel SIEHidden"><div class="RBackgroundLabelInner"><p>struct</p></div></div><table cellspacing="0" cellpadding="0" class="RForeground"><tr><td><span class="RktPn">(</span><span class="RktSym"><a href="define-struct.html#%28form._%28%28lib._racket%2Fprivate%2Fbase..rkt%29._struct%29%29" class="RktStxLink" data-pltdoc="x">struct</a></span></td><td><span class="hspace"> </span></td><td><a name="(def._((lib._racket/private/base..rkt)._make-exn~3afail~3aout-of-memory))"></a><a name="(def._((quote._~23~25kernel)._exn~3afail~3aout-of-memory~3f))"></a><a name="(def._((quote._~23~25kernel)._struct~3aexn~3afail~3aout-of-memory))"></a><a name="(def._((lib._racket/private/base..rkt)._exn~3afail~3aout-of-memory))"></a><span title="Provided from: racket/base, racket | Package: base"><span class="RktSym"><a href="exns.html#%28def._%28%28lib._racket%2Fprivate%2Fbase..rkt%29._exn~3afail~3aout-of-memory%29%29" class="RktValDef RktValLink" data-pltdoc="x">exn:fail:out-of-memory</a></span></span><span class="hspace"> </span><span class="RktSym"><a href="exns.html#%28def._%28%28lib._racket%2Fprivate%2Fbase..rkt%29._exn~3afail%29%29" class="RktValLink" data-pltdoc="x">exn:fail</a></span><span class="hspace"> </span><span class="RktPn">(</span><span class="RktPn">)</span></td></tr></table></blockquote></td></tr><tr><td><span class="hspace"> </span><span class="RktPn">#:extra-constructor-name</span><span class="hspace"> </span><span class="RktSym"><a href="exns.html#%28def._%28%28lib._racket%2Fprivate%2Fbase..rkt%29._make-exn~3afail~3aout-of-memory%29%29" class="RktValLink" data-pltdoc="x">make-exn:fail:out-of-memory</a></span></td></tr><tr><td><span class="hspace"> </span><span class="RktPn">#:transparent</span><span class="RktPn">)</span></td></tr></table></blockquote></div><div class="SIntrapara">Raised for an error due to insufficient memory, in cases where sufficient
|
||
|
|
memory is at least available for raising the exception.</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>struct</p></div></div><table cellspacing="0" cellpadding="0" class="RForeground"><tr><td><span class="RktPn">(</span><span class="RktSym"><a href="define-struct.html#%28form._%28%28lib._racket%2Fprivate%2Fbase..rkt%29._struct%29%29" class="RktStxLink" data-pltdoc="x">struct</a></span></td><td><span class="hspace"> </span></td><td><a name="(def._((lib._racket/private/base..rkt)._make-exn~3afail~3aunsupported))"></a><a name="(def._((quote._~23~25kernel)._exn~3afail~3aunsupported~3f))"></a><a name="(def._((quote._~23~25kernel)._struct~3aexn~3afail~3aunsupported))"></a><a name="(def._((lib._racket/private/base..rkt)._exn~3afail~3aunsupported))"></a><span title="Provided from: racket/base, racket | Package: base"><span class="RktSym"><a href="exns.html#%28def._%28%28lib._racket%2Fprivate%2Fbase..rkt%29._exn~3afail~3aunsupported%29%29" class="RktValDef RktValLink" data-pltdoc="x">exn:fail:unsupported</a></span></span><span class="hspace"> </span><span class="RktSym"><a href="exns.html#%28def._%28%28lib._racket%2Fprivate%2Fbase..rkt%29._exn~3afail%29%29" class="RktValLink" data-pltdoc="x">exn:fail</a></span><span class="hspace"> </span><span class="RktPn">(</span><span class="RktPn">)</span></td></tr></table></blockquote></td></tr><tr><td><span class="hspace"> </span><span class="RktPn">#:extra-constructor-name</span><span class="hspace"> </span><span class="RktSym"><a href="exns.html#%28def._%28%28lib._racket%2Fprivate%2Fbase..rkt%29._make-exn~3afail~3aunsupported%29%29" class="RktValLink" data-pltdoc="x">make-exn:fail:unsupported</a></span></td></tr><tr><td><span class="hspace"> </span><span class="RktPn">#:transparent</span><span class="RktPn">)</span></td></tr></table></blockquote></div><div class="SIntrapara">Raised for an error due to an unsupported feature on the current
|
||
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platform or configuration.</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>struct</p></div></div><table cellspacing="0" cellpadding="0" class="RForeground"><tr><td><span class="RktPn">(</span><span class="RktSym"><a href="define-struct.html#%28form._%28%28lib._racket%2Fprivate%2Fbase..rkt%29._struct%29%29" class="RktStxLink" data-pltdoc="x">struct</a></span></td><td><span class="hspace"> </span></td><td><a name="(def._((lib._racket/private/base..rkt)._make-exn~3afail~3auser))"></a><a name="(def._((quote._~23~25kernel)._exn~3afail~3auser~3f))"></a><a name="(def._((quote._~23~25kernel)._struct~3aexn~3afail~3auser))"></a><a name="(def._((lib._racket/private/base..rkt)._exn~3afail~3auser))"></a><span title="Provided from: racket/base, racket | Package: base"><span class="RktSym"><a href="exns.html#%28def._%28%28lib._racket%2Fprivate%2Fbase..rkt%29._exn~3afail~3auser%29%29" class="RktValDef RktValLink" data-pltdoc="x">exn:fail:user</a></span></span><span class="hspace"> </span><span class="RktSym"><a href="exns.html#%28def._%28%28lib._racket%2Fprivate%2Fbase..rkt%29._exn~3afail%29%29" class="RktValLink" data-pltdoc="x">exn:fail</a></span><span class="hspace"> </span><span class="RktPn">(</span><span class="RktPn">)</span></td></tr></table></blockquote></td></tr><tr><td><span class="hspace"> </span><span class="RktPn">#:extra-constructor-name</span><span class="hspace"> </span><span class="RktSym"><a href="exns.html#%28def._%28%28lib._racket%2Fprivate%2Fbase..rkt%29._make-exn~3afail~3auser%29%29" class="RktValLink" data-pltdoc="x">make-exn:fail:user</a></span></td></tr><tr><td><span class="hspace"> </span><span class="RktPn">#:transparent</span><span class="RktPn">)</span></td></tr></table></blockquote></div><div class="SIntrapara">Raised for errors that are intended to be seen by end users. In
|
||
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particular, the default error printer does not show the program
|
||
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context when printing the error message.</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>struct</p></div></div><table cellspacing="0" cellpadding="0" class="RForeground"><tr><td><span class="RktPn">(</span><span class="RktSym"><a href="define-struct.html#%28form._%28%28lib._racket%2Fprivate%2Fbase..rkt%29._struct%29%29" class="RktStxLink" data-pltdoc="x">struct</a></span></td><td><span class="hspace"> </span></td><td><a name="(def._((quote._~23~25kernel)._exn~3abreak-continuation))"></a><a name="(def._((lib._racket/private/base..rkt)._make-exn~3abreak))"></a><a name="(def._((quote._~23~25kernel)._exn~3abreak~3f))"></a><a name="(def._((quote._~23~25kernel)._struct~3aexn~3abreak))"></a><a name="(def._((lib._racket/private/base..rkt)._exn~3abreak))"></a><span title="Provided from: racket/base, racket | Package: base"><span class="RktSym"><a href="exns.html#%28def._%28%28lib._racket%2Fprivate%2Fbase..rkt%29._exn~3abreak%29%29" class="RktValDef RktValLink" data-pltdoc="x">exn:break</a></span></span><span class="hspace"> </span><span class="RktSym"><a href="exns.html#%28def._%28%28lib._racket%2Fprivate%2Fbase..rkt%29._exn%29%29" class="RktValLink" data-pltdoc="x">exn</a></span><span class="hspace"> </span><span class="RktPn">(</span><span class="RktSym">continuation</span><span class="RktPn">)</span></td></tr></table></blockquote></td></tr><tr><td><span class="hspace"> </span><span class="RktPn">#:extra-constructor-name</span><span class="hspace"> </span><span class="RktSym"><a href="exns.html#%28def._%28%28lib._racket%2Fprivate%2Fbase..rkt%29._make-exn~3abreak%29%29" class="RktValLink" data-pltdoc="x">make-exn:break</a></span></td></tr><tr><td><span class="hspace"> </span><span class="RktPn">#:transparent</span><span class="RktPn">)</span></td></tr><tr><td><span class="hspace"> </span><span class="RktSym">continuation</span><span class="hspace"> </span>:<span class="hspace"> </span><span class="RktSym"><a href="cont.html#%28def._%28%28quote._~23~25kernel%29._continuation~3f%29%29" class="RktValLink" data-pltdoc="x">continuation?</a></span></td></tr></table></blockquote></div><div class="SIntrapara">Raised asynchronously (when enabled) in response to a break request.
|
||
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The <span class="RktSym">continuation</span> field can be used to resume the interrupted
|
||
|
|
computation in the <a href="exns.html#%28tech._uncaught._exception._handler%29" class="techoutside" data-pltdoc="x"><span class="techinside">uncaught-exception handler</span></a> or
|
||
|
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<span class="RktSym"><a href="exns.html#%28def._%28%28lib._racket%2Fprivate%2Fmore-scheme..rkt%29._call-with-exception-handler%29%29" class="RktValLink" data-pltdoc="x">call-with-exception-handler</a></span> (but <span class="emph">not</span>
|
||
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<span class="RktSym"><a href="exns.html#%28form._%28%28lib._racket%2Fprivate%2Fmore-scheme..rkt%29._with-handlers%29%29" class="RktStxLink" data-pltdoc="x">with-handlers</a></span> because it escapes from the exception context
|
||
|
|
before evaluating any predicates or handlers).</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>struct</p></div></div><table cellspacing="0" cellpadding="0" class="RForeground"><tr><td><span class="RktPn">(</span><span class="RktSym"><a href="define-struct.html#%28form._%28%28lib._racket%2Fprivate%2Fbase..rkt%29._struct%29%29" class="RktStxLink" data-pltdoc="x">struct</a></span></td><td><span class="hspace"> </span></td><td><a name="(def._((lib._racket/private/base..rkt)._make-exn~3abreak~3ahang-up))"></a><a name="(def._((quote._~23~25kernel)._exn~3abreak~3ahang-up~3f))"></a><a name="(def._((quote._~23~25kernel)._struct~3aexn~3abreak~3ahang-up))"></a><a name="(def._((lib._racket/private/base..rkt)._exn~3abreak~3ahang-up))"></a><span title="Provided from: racket/base, racket | Package: base"><span class="RktSym"><a href="exns.html#%28def._%28%28lib._racket%2Fprivate%2Fbase..rkt%29._exn~3abreak~3ahang-up%29%29" class="RktValDef RktValLink" data-pltdoc="x">exn:break:hang-up</a></span></span><span class="hspace"> </span><span class="RktSym"><a href="exns.html#%28def._%28%28lib._racket%2Fprivate%2Fbase..rkt%29._exn~3abreak%29%29" class="RktValLink" data-pltdoc="x">exn:break</a></span><span class="hspace"> </span><span class="RktPn">(</span><span class="RktPn">)</span></td></tr></table></blockquote></td></tr><tr><td><span class="hspace"> </span><span class="RktPn">#:extra-constructor-name</span><span class="hspace"> </span><span class="RktSym"><a href="exns.html#%28def._%28%28lib._racket%2Fprivate%2Fbase..rkt%29._make-exn~3abreak~3ahang-up%29%29" class="RktValLink" data-pltdoc="x">make-exn:break:hang-up</a></span></td></tr><tr><td><span class="hspace"> </span><span class="RktPn">#:transparent</span><span class="RktPn">)</span></td></tr></table></blockquote></div><div class="SIntrapara">Raised asynchronously for hang-up breaks. The default
|
||
|
|
<a href="exns.html#%28tech._uncaught._exception._handler%29" class="techoutside" data-pltdoc="x"><span class="techinside">uncaught-exception handler</span></a> reacts to this exception type by
|
||
|
|
calling the <a href="Exiting.html#%28tech._exit._handler%29" class="techoutside" data-pltdoc="x"><span class="techinside">exit handler</span></a>.</div></p><p><div class="SIntrapara"><blockquote class="SVInsetFlow"><table cellspacing="0" cellpadding="0" class="boxed RBoxed"><tr><td><blockquote class="SubFlow"><div class="RBackgroundLabel SIEHidden"><div class="RBackgroundLabelInner"><p>struct</p></div></div><table cellspacing="0" cellpadding="0" class="RForeground"><tr><td><span class="RktPn">(</span><span class="RktSym"><a href="define-struct.html#%28form._%28%28lib._racket%2Fprivate%2Fbase..rkt%29._struct%29%29" class="RktStxLink" data-pltdoc="x">struct</a></span></td><td><span class="hspace"> </span></td><td><a name="(def._((lib._racket/private/base..rkt)._make-exn~3abreak~3aterminate))"></a><a name="(def._((quote._~23~25kernel)._exn~3abreak~3aterminate~3f))"></a><a name="(def._((quote._~23~25kernel)._struct~3aexn~3abreak~3aterminate))"></a><a name="(def._((lib._racket/private/base..rkt)._exn~3abreak~3aterminate))"></a><span title="Provided from: racket/base, racket | Package: base"><span class="RktSym"><a href="exns.html#%28def._%28%28lib._racket%2Fprivate%2Fbase..rkt%29._exn~3abreak~3aterminate%29%29" class="RktValDef RktValLink" data-pltdoc="x">exn:break:terminate</a></span></span><span class="hspace"> </span><span class="RktSym"><a href="exns.html#%28def._%28%28lib._racket%2Fprivate%2Fbase..rkt%29._exn~3abreak%29%29" class="RktValLink" data-pltdoc="x">exn:break</a></span><span class="hspace"> </span><span class="RktPn">(</span><span class="RktPn">)</span></td></tr></table></blockquote></td></tr><tr><td><span class="hspace"> </span><span class="RktPn">#:extra-constructor-name</span><span class="hspace"> </span><span class="RktSym"><a href="exns.html#%28def._%28%28lib._racket%2Fprivate%2Fbase..rkt%29._make-exn~3abreak~3aterminate%29%29" class="RktValLink" data-pltdoc="x">make-exn:break:terminate</a></span></td></tr><tr><td><span class="hspace"> </span><span class="RktPn">#:transparent</span><span class="RktPn">)</span></td></tr></table></blockquote></div><div class="SIntrapara">Raised asynchronously for termination-request breaks. The default
|
||
|
|
<a href="exns.html#%28tech._uncaught._exception._handler%29" class="techoutside" data-pltdoc="x"><span class="techinside">uncaught-exception handler</span></a> reacts to this exception type by
|
||
|
|
calling the <a href="Exiting.html#%28tech._exit._handler%29" class="techoutside" data-pltdoc="x"><span class="techinside">exit handler</span></a>.</div></p><p><div class="SIntrapara"><blockquote class="SVInsetFlow"><table cellspacing="0" cellpadding="0" class="boxed RBoxed"><tr><td><blockquote class="SubFlow"><div class="RBackgroundLabel SIEHidden"><div class="RBackgroundLabelInner"><p>value</p></div></div><p class="RForeground"><a name="(def._((quote._~23~25kernel)._prop~3aexn~3asrclocs))"></a><span title="Provided from: racket/base, racket | Package: base"><span class="RktSym"><a href="exns.html#%28def._%28%28quote._~23~25kernel%29._prop~3aexn~3asrclocs%29%29" class="RktValDef RktValLink" data-pltdoc="x">prop:exn:srclocs</a></span></span><span class="hspace"> </span>:<span class="hspace"> </span><span class="RktSym"><a href="structprops.html#%28def._%28%28quote._~23~25kernel%29._struct-type-property~3f%29%29" class="RktValLink" data-pltdoc="x">struct-type-property?</a></span></p></blockquote></td></tr></table></blockquote></div><div class="SIntrapara">A property that identifies structure types that provide a list of
|
||
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|
<span class="RktSym"><a href="exns.html#%28def._%28%28lib._racket%2Fprivate%2Fbase..rkt%29._srcloc%29%29" class="RktValLink" data-pltdoc="x">srcloc</a></span> values. The property is normally attached to structure
|
||
|
|
types used to represent exception information.</div></p><p>The property value must be a procedure that accepts a single
|
||
|
|
value—<wbr></wbr>the structure type instance from which to extract source
|
||
|
|
locations—<wbr></wbr>and returns a list of <span class="RktSym"><a href="exns.html#%28def._%28%28lib._racket%2Fprivate%2Fbase..rkt%29._srcloc%29%29" class="RktValLink" data-pltdoc="x">srcloc</a></span>s. Some <a href="exns.html#%28tech._error._display._handler%29" class="techoutside" data-pltdoc="x"><span class="techinside">error
|
||
|
|
display handlers</span></a> use only the first returned location.</p><p><div class="SIntrapara">As an example,
|
||
|
|
</div><div class="SIntrapara"><blockquote class="SCodeFlow"><table cellspacing="0" cellpadding="0" class="RktBlk"><tr><td><a href="https://download.racket-lang.org/releases/8.6/doc/local-redirect/index.html?doc=guide&rel=Module_Syntax.html%23%2528part._hash-lang%2529&version=8.6" class="RktModLink Sq" data-pltdoc="x"><span class="RktMod">#lang</span></a><span class="RktMeta"></span><span class="hspace"> </span><span class="RktMeta"></span><a href="index.html" class="RktModLink" data-pltdoc="x"><span class="RktSym">racket</span></a><span class="RktMeta"></span></td></tr><tr><td><span class="RktMeta"> </span></td></tr><tr><td><span class="RktMeta"></span><span class="RktCmt">;;</span><span class="hspace"> </span><span class="RktCmt">We</span><span class="hspace"> </span><span class="RktCmt">create</span><span class="hspace"> </span><span class="RktCmt">a</span><span class="hspace"> </span><span class="RktCmt">structure</span><span class="hspace"> </span><span class="RktCmt">that</span><span class="hspace"> </span><span class="RktCmt">supports</span><span class="hspace"> </span><span class="RktCmt">the</span><span class="RktMeta"></span></td></tr><tr><td><span class="RktMeta"></span><span class="RktCmt">;;</span><span class="hspace"> </span><span class="RktCmt">prop:exn:srcloc</span><span class="hspace"> </span><span class="RktCmt">protocol.</span><span class="hspace"> </span><span class="RktCmt">It</span><span class="hspace"> </span><span class="RktCmt">carries</span><span class="RktMeta"></span></td></tr><tr><td><span class="RktMeta"></span><span class="RktCmt">;;</span><span class="hspace"> </span><span class="RktCmt">with</span><span class="hspace"> </span><span class="RktCmt">it</span><span class="hspace"> </span><span class="RktCmt">the</span><span class="hspace"> </span><span class="RktCmt">location</span><span class="hspace"> </span><span class="RktCmt">of</span><span class="hspace"> </span><span class="RktCmt">the</span><span class="hspace"> </span><span class="RktCmt">syntax</span><span class="hspace"> </span><span class="RktCmt">that</span><span class="RktMeta"></span></td></tr><tr><td><span class="RktMeta"></span><span class="RktCmt">;;</span><span class="hspace"> </span><span class="RktCmt">is</span><span class="hspace"> </span><span class="RktCmt">guilty.</span><span class="RktMeta"></span></td></tr><tr><td><span class="RktMeta"></span><span class="RktPn">(</span><span class="RktSym"><a href="define-struct.html#%28form._%28%28lib._racket%2Fprivate%2Fbase..rkt%29._struct%29%29" class="RktStxLink" data-pltdoc="x">struct</a></span><span class="RktMeta"></span><span class="hspace"> </span><span class="RktMeta"></span><span class="RktSym">exn:fail:he-who-shall-not-be-named</span><span class="RktMeta"></span><span class="hspace"> </span><span class="RktMeta"></span><span class="RktSym"><a href="exns.html#%28def._%28%28lib._racket%2Fprivate%2Fbase..rkt%29._exn~3afail%29%29" class="RktValLink" data-pltdoc="x">exn:fail</a></span><span class="RktMeta"></span></td></tr><tr><td><span class="RktMeta"></span><span class="hspace"> </span><span class="RktMeta"></span><span class="RktPn">(</span><span class="RktSym">a-srcloc</span><span class="RktPn">)</span><span class="RktMeta"></span></td></tr><tr><td><span class="RktMeta"></span><span class="hspace"> </span><span class="RktMeta"></span><span class="RktPn">#:property</span><span class="RktMeta"></span><span class="hspace"> </span><span class="RktMeta"></span><span class="RktSym"><a href="exns.html#%28def._%28%28quote._~23~25kernel%29._prop~3aexn~3asrclocs%29%29" class="RktValLink" data-pltdoc="x">prop:exn:srclocs</a></span><span class="RktMeta"></span></td></tr><tr><td><span class="RktMeta"></span><span class="hspace"> </span><span class="RktMeta"></span><span class="RktPn">(</span><span class="RktSym"><a href="lambda.html#%28form._%28%28lib._racket%2Fprivate%2Fbase..rkt%29._lambda%29%29" class="Rkt
|
||
|
|
property, <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><p class="RForeground"><span class="RktPn">(</span><a name="(def._((quote._~23~25kernel)._exn~3asrclocs-accessor))"></a><span title="Provided from: racket/base, racket | Package: base"><span class="RktSym"><a href="exns.html#%28def._%28%28quote._~23~25kernel%29._exn~3asrclocs-accessor%29%29" class="RktValDef RktValLink" data-pltdoc="x">exn:srclocs-accessor</a></span></span><span class="hspace"> </span><span class="RktVar">v</span><span class="RktPn">)</span></p></blockquote></td></tr><tr><td><span class="hspace"> </span>→<span class="hspace"> </span><span class="RktPn">(</span><span class="RktSym"><a href="exns.html#%28def._%28%28quote._~23~25kernel%29._exn~3asrclocs~3f%29%29" class="RktValLink" data-pltdoc="x">exn:srclocs?</a></span><span class="hspace"> </span><span class="RktPn">. </span><span class="RktSym"><a href="function-contracts.html#%28form._%28%28lib._racket%2Fcontract%2Fbase..rkt%29._-~3e%29%29" class="RktStxLink" data-pltdoc="x"><span class="nobreak">-></span></a></span><span class="RktPn"> .</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._listof%29%29" class="RktValLink" data-pltdoc="x">listof</a></span><span class="hspace"> </span><span class="RktSym"><a href="exns.html#%28def._%28%28lib._racket%2Fprivate%2Fbase..rkt%29._srcloc%29%29" class="RktValLink" data-pltdoc="x">srcloc</a></span><span class="RktPn">)</span><span class="RktPn">)</span></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="exns.html#%28def._%28%28quote._~23~25kernel%29._exn~3asrclocs~3f%29%29" class="RktValLink" data-pltdoc="x">exn:srclocs?</a></span></td></tr></table></blockquote></div><div class="SIntrapara">Returns the <span class="RktSym"><a href="exns.html#%28def._%28%28lib._racket%2Fprivate%2Fbase..rkt%29._srcloc%29%29" class="RktValLink" data-pltdoc="x">srcloc</a></span>-getting procedure associated with <span class="RktVar">v</span>.</div></p><p><div class="SIntrapara"><blockquote class="SVInsetFlow"><table cellspacing="0" cellpadding="0" class="boxed RBoxed"><tr><td><blockquote class="SubFlow"><div class="RBackgroundLabel SIEHidden"><div class="RBackgroundLabelInner"><p>struct</p></div></div><table cellspacing="0" cellpadding="0" class="RForeground"><tr><td><span class="RktPn">(</span><span class="RktSym"><a href="define-struct.html#%28form._%28%28lib._racket%2Fprivate%2Fbase..rkt%29._struct%29%29" class="RktStxLink" data-pltdoc="x">struct</a></span></td><td><span class="hspace"> </span></td><td><a name="(def._((quote._~23~25kernel)._srcloc-span))"></a><a name="(def._((quote._~23~25kernel)._srcloc-position))"></a><a name="(def._((quote._~23~25kernel)._srcloc-column))"></a><a name="(def._((quote._~23~25kernel)._srcloc-line))"></a><a name="(def._((quote._~23~25kernel)._srcloc-source))"></a><a name="(def._((lib._racket/private/base..rkt)._make-srcloc))"></a><a name="(def._((quote._~23~25kernel)._srcloc~3f))"></a><a name="(def._((quote._~23~25kernel)._struct~3asrcloc))"></a><a name="(def._((lib._racket/private/base..rkt)._srcloc))"></a><span title="Provided from: racket/base, racket | Package: base"><span class="RktSym"><a href="exns.html#%28def._%28%28lib._racket%2Fprivate%2Fbase..rkt%29._srcloc%29%29" class="RktValDef RktValLink" data-pltdoc="x">srcloc</a></span></span><span class="hspace"> </span><span class="RktPn">(</span><span class="RktSym">source</span><span class="stt"> </span><span class="RktSym">line</span><span class="stt"> </span><span class="RktSym">column</span><span class="stt"> </span><span class=
|
||
|
|
<span class="RktSym"><a href="exns.html#%28def._%28%28lib._racket%2Fprivate%2Fbase..rkt%29._srcloc%29%29" class="RktValLink" data-pltdoc="x">srcloc</a></span> structure. More generally, a source location has the
|
||
|
|
same information as a <span class="RktSym"><a href="exns.html#%28def._%28%28lib._racket%2Fprivate%2Fbase..rkt%29._srcloc%29%29" class="RktValLink" data-pltdoc="x">srcloc</a></span> structure, but potentially
|
||
|
|
represented or accessed differently. For example, source-location
|
||
|
|
information is accessed from a <a href="syntax-model.html#%28tech._syntax._object%29" class="techoutside" data-pltdoc="x"><span class="techinside">syntax object</span></a> with functions
|
||
|
|
like <span class="RktSym"><a href="stxops.html#%28def._%28%28quote._~23~25kernel%29._syntax-source%29%29" class="RktValLink" data-pltdoc="x">syntax-source</a></span> and <span class="RktSym"><a href="stxops.html#%28def._%28%28quote._~23~25kernel%29._syntax-line%29%29" class="RktValLink" data-pltdoc="x">syntax-line</a></span>, while
|
||
|
|
<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> accepts a source location as a list, vector, or
|
||
|
|
another syntax object. For ports, a combination of
|
||
|
|
<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> and <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> provides location
|
||
|
|
information, especially in a port for which counting has been enabled
|
||
|
|
through <span class="RktSym"><a href="linecol.html#%28def._%28%28quote._~23~25kernel%29._port-count-lines%21%29%29" class="RktValLink" data-pltdoc="x">port-count-lines!</a></span>.</div></p><p>The fields of a <span class="RktSym"><a href="exns.html#%28def._%28%28lib._racket%2Fprivate%2Fbase..rkt%29._srcloc%29%29" class="RktValLink" data-pltdoc="x">srcloc</a></span> instance are as follows:</p><ul><li><p><span class="RktSym">source</span> —<wbr></wbr> An arbitrary value identifying the source,
|
||
|
|
often a path (see <a href="pathutils.html" data-pltdoc="x">Paths</a>).</p></li><li><p><span class="RktSym">line</span> —<wbr></wbr> The line number (counts from 1) or
|
||
|
|
<span class="RktVal">#f</span> (unknown).</p></li><li><p><span class="RktSym">column</span> —<wbr></wbr> The column number (counts from 0) or
|
||
|
|
<span class="RktVal">#f</span> (unknown).</p></li><li><p><span class="RktSym">position</span> —<wbr></wbr> The starting position (counts from 1) or
|
||
|
|
<span class="RktVal">#f</span> (unknown).</p></li><li><p><span class="RktSym">span</span> —<wbr></wbr> The number of covered positions (counts from
|
||
|
|
0) or <span class="RktVal">#f</span> (unknown).</p></li></ul><p>See <a href="printing.html#%28part._print-compiled%29" data-pltdoc="x">Printing Compiled Code</a> for information about the treatment of
|
||
|
|
<span class="RktSym"><a href="exns.html#%28def._%28%28lib._racket%2Fprivate%2Fbase..rkt%29._srcloc%29%29" class="RktValLink" data-pltdoc="x">srcloc</a></span> values that are embedded in compiled code.</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)._srcloc-~3estring))"></a><span title="Provided from: racket/base, racket | Package: base"><span class="RktSym"><a href="exns.html#%28def._%28%28quote._~23~25kernel%29._srcloc-~3estring%29%29" class="RktValDef RktValLink" data-pltdoc="x">srcloc->string</a></span></span><span class="hspace"> </span><span class="RktVar">srcloc</span><span class="RktPn">)</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="RktVal">#f</span><span class="RktPn">)</span></p></blockquote></td></tr><tr><td><span class="hspace"> </span><span class="RktVar">srcloc</span><span class="hspace"> </span>:<span class="hspace"> </span><span class="RktSym"><a href="exns.html#%28def._%28%28quote._~23~25kernel%29._srcloc~3f%29%29" class="RktValLink" data-pltdoc="x">srcloc?</a></span></td></tr></table></blockquote></div><div class="SIntrapara">Formats <span class="RktVar">srcloc</span> as a string suitable for error reporting. A
|
||
|
|
path source in <span class="RktVar">srcloc</span> is shown relative to the value of
|
||
|
|
<span class="RktSym"><a href="Filesystem.html#%28def._%28%28quote._~23~25kernel%29._current-directory-for-user%29%29" class="RktValLink" data-pltdoc="x">current-directory-for-user</a></span>. The result is <span class="RktVal">#f</span> if
|
||
|
|
<span class="RktVar">srcloc</span> does not contain enough information to format a
|
||
|
|
string.</div></p><p><div class="SIntrapara"><blockquote class="SVInsetFlow"><table cellspacing="0" cellpadding="0" class="boxed RBoxed"><tr><td><blockquote class="SubFlow"><div class="RBackgroundLabel SIEHidden"><div class="RBackgroundLabelInner"><p>value</p></div></div><p class="RForeground"><a name="(def._((quote._~23~25kernel)._prop~3aexn~3amissing-module))"></a><span title="Provided from: racket/base, racket | Package: base"><span class="RktSym"><a href="exns.html#%28def._%28%28quote._~23~25kernel%29._prop~3aexn~3amissing-module%29%29" class="RktValDef RktValLink" data-pltdoc="x">prop:exn:missing-module</a></span></span><span class="hspace"> </span>:<span class="hspace"> </span><span class="RktSym"><a href="structprops.html#%28def._%28%28quote._~23~25kernel%29._struct-type-property~3f%29%29" class="RktValLink" data-pltdoc="x">struct-type-property?</a></span></p></blockquote></td></tr></table></blockquote></div><div class="SIntrapara">A property that identifies structure types that provide a module path
|
||
|
|
for a load that fails because a module is not found.</div></p><p>The property value must be a procedure that accepts a single
|
||
|
|
value—<wbr></wbr>the structure type instance from which to extract source
|
||
|
|
locations—<wbr></wbr>and returns a <a href="Module_Names_and_Loading.html#%28tech._module._path%29" class="techoutside" data-pltdoc="x"><span class="techinside">module path</span></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)._exn~3amissing-module~3f))"></a><span title="Provided from: racket/base, racket | Package: base"><span class="RktSym"><a href="exns.html#%28def._%28%28quote._~23~25kernel%29._exn~3amissing-module~3f%29%29" class="RktValDef RktValLink" data-pltdoc="x">exn:missing-module?</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> has the <span class="RktSym"><a href="exns.html#%28def._%28%28quote._~23~25kernel%29._prop~3aexn~3amissing-module%29%29" class="RktValLink" data-pltdoc="x">prop:exn:missing-module</a></span>
|
||
|
|
property, <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><p class="RForeground"><span class="RktPn">(</span><a name="(def._((quote._~23~25kernel)._exn~3amissing-module-accessor))"></a><span title="Provided from: racket/base, racket | Package: base"><span class="RktSym"><a href="exns.html#%28def._%28%28quote._~23~25kernel%29._exn~3amissing-module-accessor%29%29" class="RktValDef RktValLink" data-pltdoc="x">exn:missing-module-accessor</a></span></span><span class="hspace"> </span><span class="RktVar">v</span><span class="RktPn">)</span></p></blockquote></td></tr><tr><td><span class="hspace"> </span>→<span class="hspace"> </span><span class="RktPn">(</span><span class="RktSym"><a href="exns.html#%28def._%28%28quote._~23~25kernel%29._exn~3amissing-module~3f%29%29" class="RktValLink" data-pltdoc="x">exn:missing-module?</a></span><span class="hspace"> </span><span class="RktPn">. </span><span class="RktSym"><a href="function-contracts.html#%28form._%28%28lib._racket%2Fcontract%2Fbase..rkt%29._-~3e%29%29" class="RktStxLink" data-pltdoc="x"><span class="nobreak">-></span></a></span><span class="RktPn"> .</span><span class="hspace"> </span><span class="RktSym"><a href="Module_Names_and_Loading.html#%28def._%28%28quote._~23~25kernel%29._module-path~3f%29%29" class="RktValLink" data-pltdoc="x">module-path?</a></span><span class="RktPn">)</span></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="exns.html#%28def._%28%28quote._~23~25kernel%29._exn~3asrclocs~3f%29%29" class="RktValLink" data-pltdoc="x">exn:srclocs?</a></span></td></tr></table></blockquote></div><div class="SIntrapara">Returns the <a href="Module_Names_and_Loading.html#%28tech._module._path%29" class="techoutside" data-pltdoc="x"><span class="techinside">module path</span></a>-getting procedure associated with <span class="RktVar">v</span>.</div></p><h5 x-source-module="(lib "scribblings/reference/reference.scrbl")" x-source-pkg="racket-doc" x-part-tag=""Additional_Exception_Functions"">10.2.6<tt> </tt><a name="(part._.Additional_.Exception_.Functions)"></a><a name="(mod-path._racket/exn)"></a>Additional Exception Functions</h5><p><div class="SIntrapara"><table cellspacing="0" cellpadding="0" class="defmodule"><tr><td align="left"><span class="hspace"> </span><span class="RktPn">(</span><span class="RktSym"><a href="require.html#%28form._%28%28lib._racket%2Fprivate%2Fbase..rkt%29._require%29%29" class="RktStxLink" data-pltdoc="x">require</a></span><span class="stt"> </span><a href="exns.html#%28mod-path._racket%2Fexn%29" class="RktModLink" data-pltdoc="x"><span class="RktSym">racket/exn</span></a><span class="RktPn">)</span></td><td align="right"><span class="RpackageSpec"><span class="Smaller"> package:</span> <a href="https://pkgs.racket-lang.org/package/base" title="Install this package using `raco pkg install base`"><span class="stt">base</span></a></span></td></tr></table></div><div class="SIntrapara">The bindings documented in this section are provided by the <a href="exns.html#%28mod-path._racket%2Fexn%29" class="RktModLink" data-pltdoc="x"><span class="RktSym">racket/exn</span></a> library, not <a href="index.html" class="RktModLink" data-pltdoc="x"><span class="RktSym">racket/base</span></a> or <a href="index.html" class="RktModLink" data-pltdoc="x"><span class="RktSym">racket</span></a>.</div></p><p class="SHistory">Added in version 6.3 of package <span class="stt">base</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="RBackgroundLabelInn
|
||
|
|
collects and returns the output from the current
|
||
|
|
<span class="RktPn">(</span><span class="RktSym"><a href="exns.html#%28def._%28%28quote._~23~25kernel%29._error-display-handler%29%29" class="RktValLink" data-pltdoc="x">error-display-handler</a></span><span class="RktPn">)</span>; otherwise, simply converts
|
||
|
|
<span class="RktVar">exn</span> to a string using <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="stt"> </span><span class="RktVal">"~s\n"</span><span class="stt"> </span><span class="RktVar">exn</span><span class="RktPn">)</span>.</div></p><h5 x-source-module="(lib "scribblings/reference/reference.scrbl")" x-source-pkg="racket-doc" x-part-tag=""err-realm"">10.2.7<tt> </tt><a name="(part._err-realm)"></a>Realms and Error Message Adjusters</h5><p>A <a name="(tech._realm)"></a><span style="font-style: italic">realm</span> identifies a convention for naming functions and
|
||
|
|
specifying contracts for function arguments and results. Realms are
|
||
|
|
intended to help improve layering and interoperability among languages
|
||
|
|
that are implemented on top of Racket.</p><p>Realms primarily enable a language to recognize and rewrite error
|
||
|
|
messages that are generated by lower layers of an implementation. For
|
||
|
|
example, a language’s implementation of “arrays” might use Racket
|
||
|
|
vectors directly, but when an object-type or primitive bounds check
|
||
|
|
fails for a vector, the generated error message mentions “vector”
|
||
|
|
and possibly a contract like <span class="RktSym"><a href="vectors.html#%28def._%28%28quote._~23~25kernel%29._vector~3f%29%29" class="RktValLink" data-pltdoc="x">vector?</a></span> and a function name like
|
||
|
|
<span class="RktSym"><a href="vectors.html#%28def._%28%28quote._~23~25kernel%29._vector-ref%29%29" class="RktValLink" data-pltdoc="x">vector-ref</a></span>. Since these error messages are identified as
|
||
|
|
being from the <span class="RktVal">'</span><span class="RktVal">racket/primitive</span> realm, a language
|
||
|
|
implementation can look for <span class="RktVal">'</span><span class="RktVal">racket/primitive</span> to detect and
|
||
|
|
rewrite error messages with minimal danger of mangling error messages
|
||
|
|
from other parts of an application (possibly implemented in the new
|
||
|
|
language) that happen to use the word “vector.”</p><p>Each procedure and each module also has a realm. A procedure’s realm
|
||
|
|
is relevant, for example, when it is applied to the wrong number of
|
||
|
|
arguments; in that case, the arity-error message itself is from the
|
||
|
|
<span class="RktVal">'</span><span class="RktVal">racket/primitive</span> realm, but the error message also should
|
||
|
|
include the name of the procedure, which can be from some different
|
||
|
|
realm. Along similar lines, <span class="RktSym"><a href="contmarks.html#%28def._%28%28quote._~23~25kernel%29._continuation-mark-set-~3econtext%29%29" class="RktValLink" data-pltdoc="x">continuation-mark-set->context</a></span>
|
||
|
|
can report the realm associated with (the procedure for) each frame in
|
||
|
|
a continuation, which might be useful to identify boundary crossings.</p><p>The construction of an error message must cooperate explicitly with
|
||
|
|
error-message adjusting. The most basic may to cooperate is through
|
||
|
|
functions like <span class="RktSym"><a href="exns.html#%28def._%28%28quote._~23~25kernel%29._error-message-~3eadjusted-string%29%29" class="RktValLink" data-pltdoc="x">error-message->adjusted-string</a></span> and
|
||
|
|
<span class="RktSym"><a href="exns.html#%28def._%28%28quote._~23~25kernel%29._error-contract-~3eadjusted-string%29%29" class="RktValLink" data-pltdoc="x">error-contract->adjusted-string</a></span>, which run error-message
|
||
|
|
adjusters via the <span class="RktSym"><a href="exns.html#%28def._%28%28quote._~23~25kernel%29._current-error-message-adjuster%29%29" class="RktValLink" data-pltdoc="x">current-error-message-adjuster</a></span> parameter
|
||
|
|
and other adjusters associated with the current continuation using
|
||
|
|
<span class="RktSym"><a href="exns.html#%28def._%28%28quote._~23~25kernel%29._error-message-adjuster-key%29%29" class="RktValLink" data-pltdoc="x">error-message-adjuster-key</a></span> as a <a href="eval-model.html#%28tech._continuation._mark%29" class="techoutside" data-pltdoc="x"><span class="techinside">continuation-mark</span></a> key.
|
||
|
|
Functions like <span class="RktSym"><a href="exns.html#%28def._%28%28quote._~23~25kernel%29._raise-argument-error%29%29" class="RktValLink" data-pltdoc="x">raise-argument-error</a></span> and
|
||
|
|
<span class="RktSym"><a href="exns.html#%28def._%28%28quote._~23~25kernel%29._raise-arity-error%29%29" class="RktValLink" data-pltdoc="x">raise-arity-error</a></span> use <span class="RktSym"><a href="exns.html#%28def._%28%28quote._~23~25kernel%29._error-message-~3eadjusted-string%29%29" class="RktValLink" data-pltdoc="x">error-message->adjusted-string</a></span>
|
||
|
|
and <span class="RktSym"><a href="exns.html#%28def._%28%28quote._~23~25kernel%29._error-contract-~3eadjusted-string%29%29" class="RktValLink" data-pltdoc="x">error-contract->adjusted-string</a></span> with the default realm,
|
||
|
|
<span class="RktVal">'</span><span class="RktVal">racket</span>. Functions like <span class="RktSym"><a href="exns.html#%28def._%28%28quote._~23~25kernel%29._raise-argument-error%2A%29%29" class="RktValLink" data-pltdoc="x">raise-argument-error*</a></span> and
|
||
|
|
<span class="RktSym"><a href="exns.html#%28def._%28%28quote._~23~25kernel%29._raise-arity-error%2A%29%29" class="RktValLink" data-pltdoc="x">raise-arity-error*</a></span> accept an explicit realm argument.</p><p>Not all error functions automatically cooperate with error-message
|
||
|
|
adjusting. For example, the <span class="RktSym">raise-reader-error</span> and
|
||
|
|
<span class="RktSym"><a href="exns.html#%28def._%28%28lib._racket%2Fprivate%2Fbase..rkt%29._raise-syntax-error%29%29" class="RktValLink" data-pltdoc="x">raise-syntax-error</a></span> functions do not call adjusters, because
|
||
|
|
they report errors that are intimately tied to syntax (and, along
|
||
|
|
those lines, errors of a more static nature).</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)._error-message-~3eadjusted-string))"></a><span title="Provided from: racket/base, racket | Package: base"><span class="RktSym"><a href="exns.html#%28def._%28%28quote._~23~25kernel%29._error-message-~3eadjusted-string%29%29" class="RktValDef RktValLink" data-pltdoc="x">error-message->adjusted-string</a></span></span></td><td valign="top"><span class="hspace"> </span></td><td valign="top"><span class="RktVar">name</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">name-realm</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">message</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">message-realm</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="strings.html#%28def._%28%28quote._~23~25kernel%29._string~3f%29%29" class="RktValLink" data-pltdoc="x">string?</a></span></td></tr></table></blockquote></td></tr><tr><td><span class="hspace"> </span><span class="RktVar">name</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="symbols.html#%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">#f</span><span class="RktPn">)</span></td></tr><tr><td><span class="hspace"> </span><span class="RktVar">name-realm</span><span class="hspace"> </span>:<span class="hspace"> </span><span class="RktSym"><a href="symbols.html#%28def._%28%28quote._~23~25kernel%29._symbol~3f%29%29" class="RktValLink" data-pltdoc="x">symbol?</a></span></td></tr><tr><td><span class="hspace"> </span><span class="RktVar">message</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><tr><td><span class="hspace"> </span><span class="RktVar">message-realm</span><span class="hspace"> </span>:<span class="hspace"> </span><span class="RktSym"><a href="symbols.html#%28def._%28%28quote._~23~25kernel%29._symbol~3f%29%29" class="RktValLink" data-pltdoc="x">symbol?</a></span></td></tr></table></blockq
|
||
|
|
and then <span class="RktVar">message</span> to generate an error-message string, but
|
||
|
|
first giving error-message adjusters a chance to adjust <span class="RktVar">name</span>
|
||
|
|
and/or <span class="RktVar">message</span>.</div></p><p>Any adjuster functions associated with the current continuation as a
|
||
|
|
<a href="eval-model.html#%28tech._continuation._mark%29" class="techoutside" data-pltdoc="x"><span class="techinside">continuation mark</span></a> with <span class="RktSym"><a href="exns.html#%28def._%28%28quote._~23~25kernel%29._error-message-adjuster-key%29%29" class="RktValLink" data-pltdoc="x">error-message-adjuster-key</a></span> are
|
||
|
|
run first; the adjusters are run in order from shallowest to deepest.
|
||
|
|
Then, the adjuster value of <span class="RktSym"><a href="exns.html#%28def._%28%28quote._~23~25kernel%29._current-error-message-adjuster%29%29" class="RktValLink" data-pltdoc="x">current-error-message-adjuster</a></span> is
|
||
|
|
used.</p><p>Each adjuster is tried with the <span class="RktVal">'</span><span class="RktVal">message</span> protocol, first. If
|
||
|
|
the adjuster responds with <span class="RktVal">#f</span> for <span class="RktVal">'</span><span class="RktVal">message</span>, then the
|
||
|
|
<span class="RktVal">'</span><span class="RktVal">name</span> protocol is tried. See
|
||
|
|
<span class="RktSym"><a href="exns.html#%28def._%28%28quote._~23~25kernel%29._current-error-message-adjuster%29%29" class="RktValLink" data-pltdoc="x">current-error-message-adjuster</a></span> for information on the
|
||
|
|
protocols. An adjuster that responds with <span class="RktVal">#f</span> for both is
|
||
|
|
skipped, as is any value associated as continuation mark using
|
||
|
|
<span class="RktSym"><a href="exns.html#%28def._%28%28quote._~23~25kernel%29._error-message-adjuster-key%29%29" class="RktValLink" data-pltdoc="x">error-message-adjuster-key</a></span> where the value is not a procedure
|
||
|
|
that accepts one argument. In addition, the <span class="RktVal">'</span><span class="RktVal">name</span> protocol is
|
||
|
|
skipped if the (possibly adjusted) <span class="RktVar">name</span> is <span class="RktVal">#f</span>.</p><p class="SHistory">Added in version 8.4.0.2 of package <span class="stt">base</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><table cellspacing="0" cellpadding="0" class="prototype RForeground"><tr><td valign="top"><span class="RktPn">(</span><a name="(def._((quote._~23~25kernel)._error-contract-~3eadjusted-string))"></a><span title="Provided from: racket/base, racket | Package: base"><span class="RktSym"><a href="exns.html#%28def._%28%28quote._~23~25kernel%29._error-contract-~3eadjusted-string%29%29" class="RktValDef RktValLink" data-pltdoc="x">error-contract->adjusted-string</a></span></span></td><td valign="top"><span class="hspace"> </span></td><td valign="top"><span class="RktVar">contract-str</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">contract-realm</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="strings.html#%28def._%28%28quote._~23~25kernel%29._string~3f%29%29" class="RktValLink" data-pltdoc="x">string?</a></span></td></tr></table></blockquote></td></tr><tr><td><span class="hspace"> </span><span class="RktVar">contract-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><tr><td><span class="hspace"> </span><span class="RktVar">contract-realm</span><span class="hspace"> </span>:<span class="hspace"> </span><span class="RktSym"><a href="symbols.html#%28def._%28%28quote._~23~25kernel%29._symbol~3f%29%29" class="RktValLink" data-pltdoc="x">symbol?</a></span></td></tr></table></blockquote></div><div class="SIntrapara">Analogous to <span class="RktSym"><a href="exns.html#%28def._%28%28quote._~23~25kernel%29._error-message-~3eadjusted-string%29%29" class="RktValLink" data-pltdoc="x">error-message->adjusted-string</a></span>, but for just the
|
||
|
|
contract part of an error message. The result string is typically
|
||
|
|
incorporated into a larger error message that may then be adjusted
|
||
|
|
further.</div></p><p>Adjustment of contract string uses the <span class="RktVal">'</span><span class="RktVal">contract</span> protocol as
|
||
|
|
described for <span class="RktSym"><a href="exns.html#%28def._%28%28quote._~23~25kernel%29._current-error-message-adjuster%29%29" class="RktValLink" data-pltdoc="x">current-error-message-adjuster</a></span>.</p><p class="SHistory">Added in version 8.4.0.2 of package <span class="stt">base</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>parameter</p></div></div><p class="RForeground"><span class="RktPn">(</span><a name="(def._((quote._~23~25kernel)._current-error-message-adjuster))"></a><span title="Provided from: racket/base, racket | Package: base"><span class="RktSym"><a href="exns.html#%28def._%28%28quote._~23~25kernel%29._current-error-message-adjuster%29%29" class="RktValDef RktValLink" data-pltdoc="x">current-error-message-adjuster</a></span></span><span class="RktPn"></span><span class="RktPn">)</span></p></blockquote></td></tr><tr><td><span class="hspace"> </span>→<span class="hspace"> </span><span class="RktPn">(</span><span class="RktSym"><a href="symbols.html#%28def._%28%28quote._~23~25kernel%29._symbol~3f%29%29" class="RktValLink" data-pltdoc="x">symbol?</a></span><span class="hspace"> </span><span class="RktPn">. </span><span class="RktSym"><a href="function-contracts.html#%28form._%28%28lib._racket%2Fcontract%2Fbase..rkt%29._-~3e%29%29" class="RktStxLink" data-pltdoc="x"><span class="nobreak">-></span></a></span><span class="RktPn"> .</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="procedures.html#%28def._%28%28quote._~23~25kernel%29._procedure~3f%29%29" class="RktValLink" data-pltdoc="x">procedure?</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="RktPn">(</span><span title="Provided from: racket/base, racket | Package: base"><span class="RktSym"><a href="exns.html#%28def._%28%28quote._~23~25kernel%29._current-error-message-adjuster%29%29" class="RktValDef RktValLink" data-pltdoc="x">current-error-message-adjuster</a></span></span><span class="hspace"> </span><span class="RktVar">proc</span><span class="RktPn">)</span><span class="hspace"> </span>→<span class="hspace"> </span><span class="RktSym"><a href="void.html#%28def._%28%28quote._~23~25kernel%29._void~3f%29%29" class="RktValLink" data-pltdoc="x">void?</a></span></td></tr><tr><td><span class="hspace"> </span><span class="RktVar">proc</span><span class="hspace"> </span>:<span class="hspace"> </span><span class="RktPn">(</span><span class="RktSym"><a href="symbols.html#%28def._%28%28quote._~23~25kernel%29._symbol~3f%29%29" class="RktValLink" data-pltdoc="x">symbol?</a></span><span class="hspace"> </span><span class="RktPn">. </span><span class="RktSym"><a href="function-contracts.html#%28form._%28%28lib._racket%2Fcontract%2Fbase..rkt%29._-~3e%29%29" class="RktStxLink" data-pltdoc="x"><span class="nobreak">-></span></a></span><span class="RktPn"> .</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="procedures.html#%28def._%28%28quote._~23~25kernel%29._procedure~3f%29%29" class="RktValLink" data-pltdoc="x">procedure?</a></span><span class="hspace"> </span><span class="RktVal">#f</span><span class="RktPn">)</span><span class="RktPn">)</span></td></tr></table></blockquote></div><div class="SIntrapara">A <a href="eval-model.html#%28tech._parameter%29" class="techoutside"
|
||
|
|
applied after any adjusters associated to the current continuation via
|
||
|
|
<span class="RktSym"><a href="exns.html#%28def._%28%28quote._~23~25kernel%29._error-message-adjuster-key%29%29" class="RktValLink" data-pltdoc="x">error-message-adjuster-key</a></span>.</div></p><p>An adjuster procedure receives a symbol identifying a protocol, and it
|
||
|
|
must return either <span class="RktVal">#f</span> or a procedure for performing
|
||
|
|
adjustments through that protocol. The following protocols are
|
||
|
|
currently defined, but more may be added in the future:</p><ul><li><p><span class="RktVal">'</span><span class="RktVal">name</span>: the procedure receives two arguments, a name
|
||
|
|
symbol and a realm symbol; it returns an adjusted name symbol
|
||
|
|
and an adjusted realm symbol.</p></li><li><p><span class="RktVal">'</span><span class="RktVal">message</span>: the procedure receives four arguments: a
|
||
|
|
name symbol or <span class="RktVal">#f</span> (which means that no name will be
|
||
|
|
prefixed on the message), a name-realm symbol, an message
|
||
|
|
string, and a message-realm symbol; it returns four adjusted
|
||
|
|
values.</p></li><li><p><span class="RktVal">'</span><span class="RktVal">contract</span>: the procedure receives two arguments, a
|
||
|
|
contract string and a realm symbol; it returns an adjusted
|
||
|
|
contract string and an adjusted realm symbol.</p></li></ul><p>A new library or language can introduce additional mode symbols, too.
|
||
|
|
To avoid conflicts, prefix the mode symbol with a collection or
|
||
|
|
library name followed by <span class="RktInBG"><span class="hspace"></span><span class="RktIn">/</span><span class="hspace"></span></span>.</p><p>If an adjuster procedure returns <span class="RktVal">#f</span> for a protocol, it’s the
|
||
|
|
same as returning a function that performs no adjustment and returns
|
||
|
|
its arguments. The default value of this parameter returns <span class="RktVal">#f</span>
|
||
|
|
for any symbol argument except the protocols listed above, for which
|
||
|
|
it returns a procedure that checks its arguments and returns them with
|
||
|
|
no adjustment.</p><p class="SHistory">Added in version 8.4.0.2 of package <span class="stt">base</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>value</p></div></div><p class="RForeground"><a name="(def._((quote._~23~25kernel)._error-message-adjuster-key))"></a><span title="Provided from: racket/base, racket | Package: base"><span class="RktSym"><a href="exns.html#%28def._%28%28quote._~23~25kernel%29._error-message-adjuster-key%29%29" class="RktValDef RktValLink" data-pltdoc="x">error-message-adjuster-key</a></span></span><span class="hspace"> </span>:<span class="hspace"> </span><span class="RktSym"><a href="symbols.html#%28def._%28%28quote._~23~25kernel%29._symbol~3f%29%29" class="RktValLink" data-pltdoc="x">symbol?</a></span></p></blockquote></td></tr></table></blockquote></div><div class="SIntrapara">An <a href="symbols.html#%28tech._uninterned%29" class="techoutside" data-pltdoc="x"><span class="techinside">uninterned</span></a> symbol intended for use as a <a href="eval-model.html#%28tech._continuation._mark%29" class="techoutside" data-pltdoc="x"><span class="techinside">continuation
|
||
|
|
mark</span></a> key with an error-adjuster procedure value. An error adjuster
|
||
|
|
associated with the key should follow the same protocol as a value of
|
||
|
|
<span class="RktSym"><a href="exns.html#%28def._%28%28quote._~23~25kernel%29._current-error-message-adjuster%29%29" class="RktValLink" data-pltdoc="x">current-error-message-adjuster</a></span>.</div></p><p>See <span class="RktSym"><a href="exns.html#%28def._%28%28quote._~23~25kernel%29._error-message-~3eadjusted-string%29%29" class="RktValLink" data-pltdoc="x">error-message->adjusted-string</a></span> for a description of how
|
||
|
|
marks using this key are can adjust error messages.</p><p class="SHistory">Added in version 8.4.0.2 of package <span class="stt">base</span>.</p><div class="navsetbottom"><span class="navleft"><form class="searchform"><input class="searchbox" id="searchbox" type="text" tabindex="1" placeholder="...search manuals..." title="Enter a search string to search the manuals" onkeypress="return DoSearchKey(event, this, "8.6", "../");"/></form> <a href="https://docs.racket-lang.org/index.html" title="up to the documentation top" data-pltdoc="x" onclick="return GotoPLTRoot("8.6");">top</a><span class="tocsettoggle"> <a href="javascript:void(0);" title="show/hide table of contents" onclick="TocsetToggle();">contents</a></span></span><span class="navright"> <a href="values.html" title="backward to "10.1 Multiple Values"" data-pltdoc="x">← prev</a> <a href="control.html" title="up to "10 Control Flow"" data-pltdoc="x">up</a> <a href="Delayed_Evaluation.html" title="forward to "10.3 Delayed Evaluation"" data-pltdoc="x">next →</a></span> </div></div></div><div id="contextindicator"> </div></body></html>
|