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<html><head><meta http-equiv="content-type" content="text/html; charset=utf-8"/><title>4.13 Hash Tables</title><link rel="stylesheet" type="text/css" href="../scribble.css" title="default"/><link rel="stylesheet" type="text/css" href="extras.css" title="default"/><link rel="stylesheet" type="text/css" href="icons.css" title="default"/><link rel="stylesheet" type="text/css" href="../racket.css" title="default"/><link rel="stylesheet" type="text/css" href="../manual-style.css" title="default"/><link rel="stylesheet" type="text/css" href="../manual-racket.css" title="default"/><link rel="stylesheet" type="text/css" href="../manual-racket.css" title="default"/><link rel="stylesheet" type="text/css" href="../doc-site.css" title="default"/><script type="text/javascript" src="../scribble-common.js"></script><script type="text/javascript" src="../manual-racket.js"></script><script type="text/javascript" src="../manual-racket.js"></script><script type="text/javascript" src="../doc-site.js"></script><script type="text/javascript" src="../local-redirect/local-redirect.js"></script><script type="text/javascript" src="../local-redirect/local-user-redirect.js"></script><!--[if IE 6]><style type="text/css">.SIEHidden { overflow: hidden; }</style><![endif]--></head><body id="doc-racket-lang-org"><div class="tocset"><div class="tocview"><div class="tocviewlist tocviewlisttopspace"><div class="tocviewtitle"><table cellspacing="0" cellpadding="0"><tr><td style="width: 1em;"><a href="javascript:void(0);" title="Expand/Collapse" class="tocviewtoggle" onclick="TocviewToggle(this,"tocview_0");">►</a></td><td></td><td><a href="index.html" class="tocviewlink" data-pltdoc="x"><span style="font-weight: bold">The Racket Reference</span></a></td></tr></table></div><div class="tocviewsublisttop" style="display: none;" id="tocview_0"><table cellspacing="0" cellpadding="0"><tr><td align="right">1 </td><td><a href="model.html" class="tocviewlink" data-pltdoc="x">Language Model</a></td></tr><tr><td align="right">2 </td><td><a href="notation.html" class="tocviewlink" data-pltdoc="x">Notation for Documentation</a></td></tr><tr><td align="right">3 </td><td><a href="syntax.html" class="tocviewlink" data-pltdoc="x">Syntactic Forms</a></td></tr><tr><td align="right">4 </td><td><a href="data.html" class="tocviewselflink" data-pltdoc="x">Datatypes</a></td></tr><tr><td align="right">5 </td><td><a href="structures.html" class="tocviewlink" data-pltdoc="x">Structures</a></td></tr><tr><td align="right">6 </td><td><a href="mzlib_class.html" class="tocviewlink" data-pltdoc="x">Classes and Objects</a></td></tr><tr><td align="right">7 </td><td><a href="mzlib_unit.html" class="tocviewlink" data-pltdoc="x">Units</a></td></tr><tr><td align="right">8 </td><td><a href="contracts.html" class="tocviewlink" data-pltdoc="x">Contracts</a></td></tr><tr><td align="right">9 </td><td><a href="match.html" class="tocviewlink" data-pltdoc="x">Pattern Matching</a></td></tr><tr><td align="right">10 </td><td><a href="control.html" class="tocviewlink" data-pltdoc="x">Control Flow</a></td></tr><tr><td align="right">11 </td><td><a href="concurrency.html" class="tocviewlink" data-pltdoc="x">Concurrency and Parallelism</a></td></tr><tr><td align="right">12 </td><td><a href="Macros.html" class="tocviewlink" data-pltdoc="x">Macros</a></td></tr><tr><td align="right">13 </td><td><a href="input-and-output.html" class="tocviewlink" data-pltdoc="x">Input and Output</a></td></tr><tr><td align="right">14 </td><td><a href="security.html" class="tocviewlink" data-pltdoc="x">Reflection and Security</a></td></tr><tr><td align="right">15 </td><td><a href="os.html" class="tocviewlink" data-pltdoc="x">Operating System</a></td></tr><tr><td align="right">16 </td><td><a href="memory.html" class="tocviewlink" data-pltdoc="x">Memory Management</a></td></tr><tr><td align="right">17 </td><td><a href="unsafe.html" class="tocviewlink" data-pltdoc="x">Unsafe Operations</a></td></tr><tr><td align="right">18 </td><td><a href="running.html" class="tocviewlink" data-pltdoc="x">Running Racket</a></td></tr><tr><td align="right"></td><td><a href="doc-bibliography.html" class="tocviewlink" data-pltdoc="x">Bibliography</a></td></tr><tr><td align="right"></td><td><a href="doc-index.html" class="tocviewlink" data-pltdoc="x">Index</a></td></tr></table></div></div><div class="tocviewlist"><table cellspacing="0" cellpadding="0"><tr><td style="width: 1em;"><a href="javascript:void(0);" title="Expand/Collapse" class="tocviewtoggle" onclick="TocviewToggle(this,"tocview_1");">▼</a></td><td>4 </td><td><a href="data.html" class="tocviewlink" data-pltdoc="x">Datatypes</a></td></tr></table><div class="tocviewsublistbottom" style="display: block;" id="tocview_1"><table cellspacing="0" cellpadding="0"><tr><td align="right">4.1 </td><td><a href="booleans.html" class="tocviewlink" data-pltdoc="x">Booleans and Equality</a></td></tr><tr><td align="right">4.2 </td><td><a href="numbers.html" class="tocviewlink" data-pltdoc="x">Numbers</a></td></tr><tr><td align="right">4.3 </td><td><a href="strings.html" class="tocviewlink" data-pltdoc="x">Strings</a></td></tr><tr><td align="right">4.4 </td><td><a href="bytestrings.html" class="tocviewlink" data-pltdoc="x">Byte Strings</a></td></tr><tr><td align="right">4.5 </td><td><a href="characters.html" class="tocviewlink" data-pltdoc="x">Characters</a></td></tr><tr><td align="right">4.6 </td><td><a href="symbols.html" class="tocviewlink" data-pltdoc="x">Symbols</a></td></tr><tr><td align="right">4.7 </td><td><a href="regexp.html" class="tocviewlink" data-pltdoc="x">Regular Expressions</a></td></tr><tr><td align="right">4.8 </td><td><a href="keywords.html" class="tocviewlink" data-pltdoc="x">Keywords</a></td></tr><tr><td align="right">4.9 </td><td><a href="pairs.html" class="tocviewlink" data-pltdoc="x">Pairs and Lists</a></td></tr><tr><td align="right">4.10 </td><td><a href="mpairs.html" class="tocviewlink" data-pltdoc="x">Mutable Pairs and Lists</a></td></tr><tr><td align="right">4.11 </td><td><a href="vectors.html" class="tocviewlink" data-pltdoc="x">Vectors</a></td></tr><tr><td align="right">4.12 </td><td><a href="boxes.html" class="tocviewlink" data-pltdoc="x">Boxes</a></td></tr><tr><td align="right">4.13 </td><td><a href="" class="tocviewselflink" data-pltdoc="x">Hash Tables</a></td></tr><tr><td align="right">4.14 </td><td><a href="sequences_streams.html" class="tocviewlink" data-pltdoc="x">Sequences and Streams</a></td></tr><tr><td align="right">4.15 </td><td><a href="dicts.html" class="tocviewlink" data-pltdoc="x">Dictionaries</a></td></tr><tr><td align="right">4.16 </td><td><a href="sets.html" class="tocviewlink" data-pltdoc="x">Sets</a></td></tr><tr><td align="right">4.17 </td><td><a href="procedures.html" class="tocviewlink" data-pltdoc="x">Procedures</a></td></tr><tr><td align="right">4.18 </td><td><a href="void.html" class="tocviewlink" data-pltdoc="x">Void</a></td></tr><tr><td align="right">4.19 </td><td><a href="undefined.html" class="tocviewlink" data-pltdoc="x">Undefined</a></td></tr></table></div></div></div><div class="tocsub"><div class="tocsubtitle">On this page:</div><table class="tocsublist" cellspacing="0"><tr><td><a href="#%28def._%28%28quote._~23~25kernel%29._hash~3f%29%29" class="tocsublink" data-pltdoc="x"><span class="RktSym"><span class="RktValLink">hash?</span></span></a></td></tr><tr><td><a href="#%28def._%28%28quote._~23~25kernel%29._hash-equal~3f%29%29" class="tocsublink" data-pltdoc="x"><span class="RktSym"><span class="RktValLink">hash-<wbr></wbr>equal?</span></span></a></td></tr><tr><td><a href="#%28def._%28%28quote._~23~25kernel%29._hash-eqv~3f%29%29" class="tocsublink" data-pltdoc="x"><span class="RktSym"><span class="RktValLink">hash-<wbr></wbr>eqv?</span></span></a></td></tr><tr><td><a href="#%28def._%28%28quote._~23~25kernel%29._hash-eq~3f%29%29" class="tocsublink" data-pltdoc="x"><span class="RktSym"><span class="RktValLink">hash-<wbr></wbr>eq?</span></span></a></td></tr><tr><td><a href="#%28def._%28%28quote._~23~25kernel%29._hash-weak~3f%29%29" class="tocsublink" data-pltdoc="x"><span class="RktSym"><span class="RktValLink">hash-<wbr></wbr>weak?</span></span></a></td></tr><tr><td><a href="#%28def._%28%28quote._~23~25kernel%29._hash%29%29" class="tocsublink" data-pltdoc="x"><span class="RktSym"><span class="RktValLink">hash</span></span></a></td></tr><tr><td><a href="#%28def._%28%28quote._~23~25kernel%29._hasheq%29%29" class="tocsublink" data-pltdoc="x"><span class="RktSym"><span class="RktValLink">hasheq</span></span></a></td></tr><tr><td><a href="#%28def._%28%28quote._~23~25kernel%29._hasheqv%29%29" class="tocsublink" data-pltdoc="x"><span class="RktSym"><span class="RktValLink">hasheqv</span></span></a></td></tr><tr><td><a href="#%28def._%28%28quote._~23~25kernel%29._make-hash%29%29" class="tocsublink" data-pltdoc="x"><span class="RktSym"><span class="RktValLink">make-<wbr></wbr>hash</span></span></a></td></tr><tr><td><a href="#%28def._%28%28quote._~23~25kernel%29._make-hasheqv%29%29" class="tocsublink" data-pltdoc="x"><span class="RktSym"><span class="RktValLink">make-<wbr></wbr>hasheqv</span></span></a></td></tr><tr><td><a href="#%28def._%28%28quote._~23~25kernel%29._make-hasheq%29%29" class="tocsublink" data-pltdoc="x"><span class="RktSym"><span class="RktValLink">make-<wbr></wbr>hasheq</span></span></a></td></tr><tr><td><a href="#%28def._%28%28quote._~23~25kernel%29._make-weak-hash%29%29" class="tocsublink" data-pltdoc="x"><span class="RktSym"><span class="RktValLink">make-<wbr></wbr>weak-<wbr></wbr>hash</span></span></a></td></tr><tr><td><a href="#%28def._%28%28quote._~23~25kernel%29._make-weak-hasheqv%29%29" class="tocsublink" data-pltdoc="x"><span class="RktSym"><span class="RktValLink">make-<wbr></wbr>weak-<wbr></wbr>hasheqv</span></span></a></td></tr><tr><td><a href="#%28def._%28%28quote._~23~25kernel%29._make-weak-hasheq%29%29" class="tocsublink" data-pltdoc="x"><span class="RktSym"><span class="RktValLink">make-<wbr></wbr>weak-<wbr></wbr>hasheq</span></span></a></td></tr><tr><td><a href="#%28def._%28%28quote._~23~25kernel%29._make-immutable-hash%29%29" class="tocsublink" data-pltdoc="x"><span class="RktSym"><span class="RktValLink">make-<wbr></wbr>immutable-<wbr></wbr>hash</span></span></a></td></tr><tr><td><a href="#%28def._%28%28quote._~23~25kernel%29._make-immutable-hasheqv%29%29" class="tocsublink" data-pltdoc="x"><span class="RktSym"><span class="RktValLink">make-<wbr></wbr>immutable-<wbr></wbr>hasheqv</span></span></a></td></tr><tr><td><a href="#%28def._%28%28quote._~23~25kernel%29._make-immutable-hasheq%29%29" class="tocsublink" data-pltdoc="x"><span class="RktSym"><span class="RktValLink">make-<wbr></wbr>immutable-<wbr></wbr>hasheq</span></span></a></td></tr><tr><td><a href="#%28def._%28%28quote._~23~25kernel%29._hash-set%21%29%29" class="tocsublink" data-pltdoc="x"><span class="RktSym"><span class="RktValLink">hash-<wbr></wbr>set!</span></span></a></td></tr><tr><td><a href="#%28def._%28%28lib._racket%2Fprivate%2Fbase..rkt%29._hash-set%2A%21%29%29" class="tocsublink" data-pltdoc="x"><span class="RktSym"><span class="RktValLink">hash-<wbr></wbr>set*!</span></span></a></td></tr><tr><td><a href="#%28def._%28%28quote._~23~25kernel%29._hash-set%29%29" class="tocsublink" data-pltdoc="x"><span class="RktSym"><span class="RktValLink">hash-<wbr></wbr>set</span></span></a></td></tr><tr><td><a href="#%28def._%28%28lib._racket%2Fprivate%2Fbase..rkt%29._hash-set%2A%29%29" class="tocsublink" data-pltdoc="x"><span class="RktSym"><span class="RktValLink">hash-<wbr></wbr>set*</span></span></a></td></tr><tr><td><a href="#%28def._%28%28quote._~23~25kernel%29._hash-ref%29%29" class="tocsublink" data-pltdoc="x"><span class="RktSym"><span class="RktValLink">hash-<wbr></wbr>ref</span></span></a></td></tr><tr><td><a href="#%28def._%28%28lib._racket%2Fprivate%2Fmore-scheme..rkt%29._hash-ref%21%29%29" class="tocsublink" data-pltdoc="x"><span class="RktSym"><span class="RktValLink">hash-<wbr></wbr>ref!</span></span></a></td></tr><tr><td><a href="#%28def._%28%28lib._racket%2Fprivate%2Fmore-scheme..rkt%29._hash-has-key~3f%29%29" class="tocsublink" data-pltdoc="x"><span class="RktSym"><span class="RktValLink">hash-<wbr></wbr>has-<wbr></wbr>key?</span></span></a></td></tr><tr><td><a href="#%28def._%28%28lib._racket%2Fprivate%2Fmore-scheme..rkt%29._hash-update%21%29%29" class="tocsublink" data-pltdoc="x"><span class="RktSym"><span class="RktValLink">hash-<wbr></wbr>update!</span></span></a></td></tr><tr><td><a href="#%28def._%28%28lib._racket%2Fprivate%2Fmore-scheme..rkt%29._hash-update%29%29" class="tocsublink" data-pltdoc="x"><span class="RktSym"><span class="RktValLink">hash-<wbr></wbr>update</span></span></a></td></tr><tr><td><a href="#%28def._%28%28quote._~23~25kernel%29._hash-remove%21%29%29" class="tocsublink" data-pltdoc="x"><span class="RktSym"><span class="RktValLink">hash-<wbr></wbr>remove!</span></span></a></td></tr><tr><td><a href="#%28def._%28%28quote._~23~25kernel%29._hash-remove%29%29" class="tocsublink" data-pltdoc="x"><span class="RktSym"><span class="RktValLink">hash-<wbr></wbr>remove</span></span></a></td></tr><tr><td><a href="#%28def._%28%28quote._~23~25kernel%29._hash-clear%21%29%29" class="tocsublink" data-pltdoc="x"><span class="RktSym"><span class="RktValLink">hash-<wbr></wbr>clear!</span></span></a></td></tr><tr><td><a href="#%28def._%28%28quote._~23~25kernel%29._hash-clear%29%29" class="tocsublink" data-pltdoc="x"><span class="RktSym"><span class="RktValLink">hash-<wbr></wbr>clear</span></span></a></td></tr><tr><td><a href="#%28def._%28%28lib._racket%2Fprivate%2Fbase..rkt%29._hash-copy-clear%29%29" class="tocsublink" data-pltdoc="x"><span class="RktSym"><span class="RktValLink">hash-<wbr></wbr>copy-<wbr></wbr>clear</span></span></a></td></tr><tr><td><a href="#%28def._%28%28quote._~23~25kernel%29._hash-map%29%29" class="tocsublink" data-pltdoc="x"><span class="RktSym"><span class="RktValLink">hash-<wbr></wbr>map</span></span></a></td></tr><tr><td><a href="#%28def._%28%28lib._racket%2Fprivate%2Fbase..rkt%29._hash-keys%29%29" class="tocsublink" data-pltdoc="x"><span class="RktSym"><span class="RktValLink">hash-<wbr></wbr>keys</span></span></a></td></tr><tr><td><a href="#%28def._%28%28lib._racket%2Fprivate%2Fbase..rkt%29._hash-values%29%29" class="tocsublink" data-pltdoc="x"><span class="RktSym"><span class="RktValLink">hash-<wbr></wbr>values</span></span></a></td></tr><tr><td><a href="#%28def._%28%28lib._racket%2Fprivate%2Fbase..rkt%29._hash-~3elist%29%29" class="tocsublink" data-pltdoc="x"><span class="RktSym"><span class="RktValLink">hash-<wbr></wbr>>list</span></span></a></td></tr><tr><td><a href="#%28def._%28%28quote._~23~25kernel%29._hash-for-each%29%29" class="tocsublink" data-pltdoc="x"><span class="RktSym"><span class="RktValLink">hash-<wbr></wbr>for-<wbr></wbr>each</span></span></a></td></tr><tr><td><a href="#%28def._%28%28quote._~23~25kernel%29._hash-count%29%29" class="tocsublink" data-pltdoc="x"><span class="RktSym"><span class="RktValLink">hash-<wbr></wbr>count</span></span></a></td></tr><tr><td><a href="#%28def._%28%28lib._racket%2Fprivate%2Fbase..rkt%29._hash-empty~3f%29%29" class="tocsublink" data-pltdoc="x"><span class="RktSym"><span class="RktValLink">hash-<wbr></wbr>empty?</span></span></a></td></tr><tr><td><a href="#%28def._%28%28quote._~23~25kernel%29._hash-iterate-first%29%29" class="tocsublink" data-pltdoc="x"><span class="RktSym"><span class="RktValLink">hash-<wbr></wbr>iterate-<wbr></wbr>first</span></span></a></td></tr><tr><td><a href="#%28def._%28%28quote._~23~25kernel%29._hash-iterate-next%29%29" class="tocsublink" data-pltdoc="x"><span class="RktSym"><span class="RktValLink">hash-<wbr></wbr>iterate-<wbr></wbr>next</span></span></a></td></tr><tr><td><a href="#%28def._%28%28quote._~23~25kernel%29._hash-iterate-key%29%29" class="tocsublink" data-pltdoc="x"><span class="RktSym"><span class="RktValLink">hash-<wbr></wbr>iterate-<wbr></wbr>key</span></span></a></td></tr><tr><td><a href="#%28def._%28%28quote._~23~25kernel%29._hash-iterate-value%29%29" class="tocsublink" data-pltdoc="x"><span class="RktSym"><span class="RktValLink">hash-<wbr></wbr>iterate-<wbr></wbr>value</span></span></a></td></tr><tr><td><a href="#%28def._%28%28quote._~23~25kernel%29._hash-copy%29%29" class="tocsublink" data-pltdoc="x"><span class="RktSym"><span class="RktValLink">hash-<wbr></wbr>copy</span></span></a></td></tr><tr><td><a href="#%28def._%28%28quote._~23~25kernel%29._eq-hash-code%29%29" class="tocsublink" data-pltdoc="x"><span class="RktSym"><span class="RktValLink">eq-<wbr></wbr>hash-<wbr></wbr>code</span></span></a></td></tr><tr><td><a href="#%28def._%28%28quote._~23~25kernel%29._eqv-hash-code%29%29" class="tocsublink" data-pltdoc="x"><span class="RktSym"><span class="RktValLink">eqv-<wbr></wbr>hash-<wbr></wbr>code</span></span></a></td></tr><tr><td><a href="#%28def._%28%28quote._~23~25kernel%29._equal-hash-code%29%29" class="tocsublink" data-pltdoc="x"><span class="RktSym"><span class="RktValLink">equal-<wbr></wbr>hash-<wbr></wbr>code</span></span></a></td></tr><tr><td><a href="#%28def._%28%28quote._~23~25kernel%29._equal-secondary-hash-code%29%29" class="tocsublink" data-pltdoc="x"><span class="RktSym"><span class="RktValLink">equal-<wbr></wbr>secondary-<wbr></wbr>hash-<wbr></wbr>code</span></span></a></td></tr></table></div></div><div class="maincolumn"><div class="main"><div class="navsettop"><span class="navleft"><form class="searchform"><input class="searchbox" style="color: #888;" type="text" value="...search manuals..." title="Enter a search string to search the manuals" onkeypress="return DoSearchKey(event, this, "6.1", "../");" onfocus="this.style.color="black"; this.style.textAlign="left"; if (this.value == "...search manuals...") this.value="";" onblur="if (this.value.match(/^ *$/)) { this.style.color="#888"; this.style.textAlign="center"; this.value="...search manuals..."; }"/></form> <a href="../index.html" title="up to the documentation top" data-pltdoc="x" onclick="return GotoPLTRoot("6.1");">top</a></span><span class="navright"> <a href="boxes.html" title="backward to "4.12 Boxes"" data-pltdoc="x">← prev</a> <a href="data.html" title="up to "4 Datatypes"" data-pltdoc="x">up</a> <a href="sequences_streams.html" title="forward to "4.14 Sequences and Streams"" data-pltdoc="x">next →</a></span> </div><h4 x-source-module="(lib "scribblings/reference/reference.scrbl")" x-part-tag=""hashtables"">4.13<tt> </tt><a name="(part._hashtables)"></a>Hash Tables</h4><blockquote class="refpara"><blockquote class="refcolumn"><blockquote class="refcontent"><p><span class="imageleft"><img src="finger.png" alt="+" width="24" height="24"/></span><a href="http://download.racket-lang.org/docs/6.1/html/local-redirect/index.html?doc=guide&rel=hash-tables.html&version=6.1" class="Sq" data-pltdoc="x">Hash Tables</a> in <a href="http://download.racket-lang.org/docs/6.1/html/local-redirect/index.html?doc=guide&rel=index.html&version=6.1" class="Sq" data-pltdoc="x"><span style="font-weight: bold">The Racket Guide</span></a> introduces hash tables.</p></blockquote></blockquote></blockquote><p>A <a name="(tech._hash._table)"></a><span style="font-style: italic">hash table</span> (or simply <a name="(tech._hash)"></a><span style="font-style: italic">hash</span>) maps each of its
keys to a single value. For a given hash table, keys are equivalent
via <span class="RktSym"><a href="booleans.html#%28def._%28%28quote._~23~25kernel%29._equal~3f%29%29" class="RktValLink" data-pltdoc="x">equal?</a></span>, <span class="RktSym"><a href="booleans.html#%28def._%28%28quote._~23~25kernel%29._eqv~3f%29%29" class="RktValLink" data-pltdoc="x">eqv?</a></span>, or <span class="RktSym"><a href="booleans.html#%28def._%28%28quote._~23~25kernel%29._eq~3f%29%29" class="RktValLink" data-pltdoc="x">eq?</a></span>, and keys are
retained either strongly or weakly (see <a href="weakbox.html" data-pltdoc="x">Weak Boxes</a>). A hash
table is also either mutable or immutable. Immutable hash tables
support effectively constant-time access and update, just like mutable
hash tables; the constant on immutable operations is usually larger,
but the functional nature of immutable hash tables can pay off in
certain algorithms.</p><blockquote class="refpara"><blockquote class="refcolumn"><blockquote class="refcontent"><p>Immutable hash tables actually provide <span style="font-style: italic">O</span>(<span style="font-style: italic">log N</span>)<span style="font-style: italic"></span>
access and update. Since <span style="font-style: italic">N</span> is limited by the address space so
that <span style="font-style: italic">log N</span> is limited to less than 30 or 62 (depending on the
platform), <span style="font-style: italic">log N</span> can be treated reasonably as a constant.</p></blockquote></blockquote></blockquote><p>For <span class="RktSym"><a href="booleans.html#%28def._%28%28quote._~23~25kernel%29._equal~3f%29%29" class="RktValLink" data-pltdoc="x">equal?</a></span>-based hashing, the built-in hash functions on
<a href="strings.html#%28tech._string%29" class="techoutside" data-pltdoc="x"><span class="techinside">strings</span></a>, <a href="pairs.html#%28tech._pair%29" class="techoutside" data-pltdoc="x"><span class="techinside">pairs</span></a>, <a href="pairs.html#%28tech._list%29" class="techoutside" data-pltdoc="x"><span class="techinside">lists</span></a>, <a href="vectors.html#%28tech._vector%29" class="techoutside" data-pltdoc="x"><span class="techinside">vectors</span></a>,
<a href="structures.html#%28tech._prefab%29" class="techoutside" data-pltdoc="x"><span class="techinside">prefab</span></a> or transparent <a href="structures.html#%28tech._structure%29" class="techoutside" data-pltdoc="x"><span class="techinside">structures</span></a>, etc<span class="Sendabbrev">.</span>, take time
proportional to the size of the value. The hash code for a compound
data structure, such as a list or vector, depends on hashing each item
of the container, but the depth of such recursive hashing is
limited (to avoid potential problems with cyclic data). For a
non-<a href="pairs.html#%28tech._list%29" class="techoutside" data-pltdoc="x"><span class="techinside">list</span></a> <a href="pairs.html#%28tech._pair%29" class="techoutside" data-pltdoc="x"><span class="techinside">pair</span></a>, both <span class="RktSym"><a href="pairs.html#%28def._%28%28quote._~23~25kernel%29._car%29%29" class="RktValLink" data-pltdoc="x">car</a></span> and <span class="RktSym"><a href="pairs.html#%28def._%28%28quote._~23~25kernel%29._cdr%29%29" class="RktValLink" data-pltdoc="x">cdr</a></span>
hashing is treated as a deeper hash, but the <span class="RktSym"><a href="pairs.html#%28def._%28%28quote._~23~25kernel%29._cdr%29%29" class="RktValLink" data-pltdoc="x">cdr</a></span> of a
<a href="pairs.html#%28tech._list%29" class="techoutside" data-pltdoc="x"><span class="techinside">list</span></a> is treated as having the same hashing depth as the list.</p><p>A hash table can be used as a two-valued <a href="sequences.html#%28tech._sequence%29" class="techoutside" data-pltdoc="x"><span class="techinside">sequence</span></a> (see
<a href="sequences.html" data-pltdoc="x">Sequences</a>). The keys and values of the hash table serve as
elements of the sequence (i.e., each element is a key and its
associated value). If a mapping is added to or removed from the hash
table during iteration, then an iteration step may fail with
<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>, or the iteration may skip or duplicate
keys and values. See also <span class="RktSym"><a href="sequences.html#%28def._%28%28lib._racket%2Fprivate%2Fbase..rkt%29._in-hash%29%29" class="RktValLink" data-pltdoc="x">in-hash</a></span>, <span class="RktSym"><a href="sequences.html#%28def._%28%28lib._racket%2Fprivate%2Fbase..rkt%29._in-hash-keys%29%29" class="RktValLink" data-pltdoc="x">in-hash-keys</a></span>,
<span class="RktSym"><a href="sequences.html#%28def._%28%28lib._racket%2Fprivate%2Fbase..rkt%29._in-hash-values%29%29" class="RktValLink" data-pltdoc="x">in-hash-values</a></span>, and <span class="RktSym"><a href="sequences.html#%28def._%28%28lib._racket%2Fprivate%2Fbase..rkt%29._in-hash-pairs%29%29" class="RktValLink" data-pltdoc="x">in-hash-pairs</a></span>.</p><p>Two hash tables cannot be <span class="RktSym"><a href="booleans.html#%28def._%28%28quote._~23~25kernel%29._equal~3f%29%29" class="RktValLink" data-pltdoc="x">equal?</a></span> unless they use the same
key-comparison procedure (<span class="RktSym"><a href="booleans.html#%28def._%28%28quote._~23~25kernel%29._equal~3f%29%29" class="RktValLink" data-pltdoc="x">equal?</a></span>, <span class="RktSym"><a href="booleans.html#%28def._%28%28quote._~23~25kernel%29._eqv~3f%29%29" class="RktValLink" data-pltdoc="x">eqv?</a></span>, or
<span class="RktSym"><a href="booleans.html#%28def._%28%28quote._~23~25kernel%29._eq~3f%29%29" class="RktValLink" data-pltdoc="x">eq?</a></span>), both hold keys strongly or weakly, and have the same
mutability.</p><p><a name="(elem._(caveat._concurrency))"></a><span style="font-weight: bold">Caveats concerning concurrent
modification:</span> A mutable hash table can be manipulated with
<span class="RktSym"><a href="#%28def._%28%28quote._~23~25kernel%29._hash-ref%29%29" class="RktValLink" data-pltdoc="x">hash-ref</a></span>, <span class="RktSym"><a href="#%28def._%28%28quote._~23~25kernel%29._hash-set%21%29%29" class="RktValLink" data-pltdoc="x">hash-set!</a></span>, and <span class="RktSym"><a href="#%28def._%28%28quote._~23~25kernel%29._hash-remove%21%29%29" class="RktValLink" data-pltdoc="x">hash-remove!</a></span>
concurrently by multiple threads, and the operations are protected by
a table-specific semaphore as needed. Three caveats apply, however:</p><ul><li><p>If a thread is terminated while applying <span class="RktSym"><a href="#%28def._%28%28quote._~23~25kernel%29._hash-ref%29%29" class="RktValLink" data-pltdoc="x">hash-ref</a></span>,
<span class="RktSym"><a href="#%28def._%28%28quote._~23~25kernel%29._hash-set%21%29%29" class="RktValLink" data-pltdoc="x">hash-set!</a></span>, <span class="RktSym"><a href="#%28def._%28%28quote._~23~25kernel%29._hash-remove%21%29%29" class="RktValLink" data-pltdoc="x">hash-remove!</a></span>, <span class="RktSym"><a href="#%28def._%28%28lib._racket%2Fprivate%2Fmore-scheme..rkt%29._hash-ref%21%29%29" class="RktValLink" data-pltdoc="x">hash-ref!</a></span>,
or <span class="RktSym"><a href="#%28def._%28%28lib._racket%2Fprivate%2Fmore-scheme..rkt%29._hash-update%21%29%29" class="RktValLink" data-pltdoc="x">hash-update!</a></span> to a hash table that
uses <span class="RktSym"><a href="booleans.html#%28def._%28%28quote._~23~25kernel%29._equal~3f%29%29" class="RktValLink" data-pltdoc="x">equal?</a></span> or <span class="RktSym"><a href="booleans.html#%28def._%28%28quote._~23~25kernel%29._eqv~3f%29%29" class="RktValLink" data-pltdoc="x">eqv?</a></span> key comparisons, all current
and future operations on the hash table may block indefinitely.</p></li><li><p>The <span class="RktSym"><a href="#%28def._%28%28quote._~23~25kernel%29._hash-map%29%29" class="RktValLink" data-pltdoc="x">hash-map</a></span>, <span class="RktSym"><a href="#%28def._%28%28quote._~23~25kernel%29._hash-for-each%29%29" class="RktValLink" data-pltdoc="x">hash-for-each</a></span>, and <span class="RktSym"><a href="#%28def._%28%28quote._~23~25kernel%29._hash-clear%21%29%29" class="RktValLink" data-pltdoc="x">hash-clear!</a></span> procedures do
not use the table’s semaphore to guard the traversal as a whole.
Changes by one thread to a hash table can affect the keys and values
seen by another thread part-way through its traversal of the same
hash table.</p></li><li><p>The <span class="RktSym"><a href="#%28def._%28%28lib._racket%2Fprivate%2Fmore-scheme..rkt%29._hash-update%21%29%29" class="RktValLink" data-pltdoc="x">hash-update!</a></span> and <span class="RktSym"><a href="#%28def._%28%28lib._racket%2Fprivate%2Fmore-scheme..rkt%29._hash-ref%21%29%29" class="RktValLink" data-pltdoc="x">hash-ref!</a></span> functions
use a table’s semaphore
independently for the <span class="RktSym"><a href="#%28def._%28%28quote._~23~25kernel%29._hash-ref%29%29" class="RktValLink" data-pltdoc="x">hash-ref</a></span> and <span class="RktSym"><a href="#%28def._%28%28quote._~23~25kernel%29._hash-set%21%29%29" class="RktValLink" data-pltdoc="x">hash-set!</a></span> parts
of their functionality, which means that the update as a whole is not
“atomic.”</p></li></ul><p><a name="(elem._(caveat._mutable-keys))"></a><span style="font-weight: bold">Caveat concerning mutable
keys:</span> If a key in an <span class="RktSym"><a href="booleans.html#%28def._%28%28quote._~23~25kernel%29._equal~3f%29%29" class="RktValLink" data-pltdoc="x">equal?</a></span>-based hash table is mutated
(e.g., a key string is modified with <span class="RktSym"><a href="strings.html#%28def._%28%28quote._~23~25kernel%29._string-set%21%29%29" class="RktValLink" data-pltdoc="x">string-set!</a></span>), then the
hash table’s behavior for insertion and lookup operations becomes
unpredictable.</p><p>A literal or printed hash table starts with <span class="RktInBG"><span class="hspace"></span><span class="RktIn">#hash</span><span class="hspace"></span></span>,
<span class="RktInBG"><span class="hspace"></span><span class="RktIn">#hasheqv</span><span class="hspace"></span></span>, or
<span class="RktInBG"><span class="hspace"></span><span class="RktIn">#hasheq</span><span class="hspace"></span></span>. See <a href="reader.html#%28part._parse-hashtable%29" data-pltdoc="x">Reading Hash Tables</a>
for information on <span class="RktSym"><a href="Reading.html#%28def._%28%28quote._~23~25kernel%29._read%29%29" class="RktValLink" data-pltdoc="x">read</a></span>ing
hash tables and <a href="printing.html#%28part._print-hashtable%29" data-pltdoc="x">Printing Hash Tables</a>
for information on <span class="RktSym"><a href="Writing.html#%28def._%28%28quote._~23~25kernel%29._print%29%29" class="RktValLink" data-pltdoc="x">print</a></span>ing hash tables.</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)._hash~3f))"></a><span title="Provided from: racket/base, racket | Package: base"><span class="RktSym"><a href="#%28def._%28%28quote._~23~25kernel%29._hash~3f%29%29" class="RktValDef RktValLink" data-pltdoc="x">hash?</a></span></span><span class="hspace"> </span><span class="RktVar">v</span><span class="RktPn">)</span><span class="hspace"> </span>→<span class="hspace"> </span><span class="RktSym"><a href="booleans.html#%28def._%28%28quote._~23~25kernel%29._boolean~3f%29%29" class="RktValLink" data-pltdoc="x">boolean?</a></span></p></blockquote></td></tr><tr><td><span class="hspace"> </span><span class="RktVar">v</span><span class="hspace"> </span>:<span class="hspace"> </span><span class="RktSym"><a href="data-structure-contracts.html#%28def._%28%28lib._racket%2Fcontract%2Fprivate%2Fmisc..rkt%29._any%2Fc%29%29" class="RktValLink" data-pltdoc="x">any/c</a></span></td></tr></table></blockquote></div><div class="SIntrapara">Returns <span class="RktVal">#t</span> if <span class="RktVar">v</span> is a <a href="#%28tech._hash._table%29" class="techoutside" data-pltdoc="x"><span class="techinside">hash table</span></a>, <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)._hash-equal~3f))"></a><span title="Provided from: racket/base, racket | Package: base"><span class="RktSym"><a href="#%28def._%28%28quote._~23~25kernel%29._hash-equal~3f%29%29" class="RktValDef RktValLink" data-pltdoc="x">hash-equal?</a></span></span><span class="hspace"> </span><span class="RktVar">hash</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">hash</span><span class="hspace"> </span>:<span class="hspace"> </span><span class="RktSym"><a href="#%28def._%28%28quote._~23~25kernel%29._hash~3f%29%29" class="RktValLink" data-pltdoc="x">hash?</a></span></td></tr></table></blockquote></div><div class="SIntrapara">Returns <span class="RktVal">#t</span> if <span class="RktVar">hash</span> compares keys with <span class="RktSym"><a href="booleans.html#%28def._%28%28quote._~23~25kernel%29._equal~3f%29%29" class="RktValLink" data-pltdoc="x">equal?</a></span>,
<span class="RktVal">#f</span> if it compares with <span class="RktSym"><a href="booleans.html#%28def._%28%28quote._~23~25kernel%29._eq~3f%29%29" class="RktValLink" data-pltdoc="x">eq?</a></span> or <span class="RktSym"><a href="booleans.html#%28def._%28%28quote._~23~25kernel%29._eqv~3f%29%29" class="RktValLink" data-pltdoc="x">eqv?</a></span>.</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)._hash-eqv~3f))"></a><span title="Provided from: racket/base, racket | Package: base"><span class="RktSym"><a href="#%28def._%28%28quote._~23~25kernel%29._hash-eqv~3f%29%29" class="RktValDef RktValLink" data-pltdoc="x">hash-eqv?</a></span></span><span class="hspace"> </span><span class="RktVar">hash</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">hash</span><span class="hspace"> </span>:<span class="hspace"> </span><span class="RktSym"><a href="#%28def._%28%28quote._~23~25kernel%29._hash~3f%29%29" class="RktValLink" data-pltdoc="x">hash?</a></span></td></tr></table></blockquote></div><div class="SIntrapara">Returns <span class="RktVal">#t</span> if <span class="RktVar">hash</span> compares keys with <span class="RktSym"><a href="booleans.html#%28def._%28%28quote._~23~25kernel%29._eqv~3f%29%29" class="RktValLink" data-pltdoc="x">eqv?</a></span>,
<span class="RktVal">#f</span> if it compares with <span class="RktSym"><a href="booleans.html#%28def._%28%28quote._~23~25kernel%29._equal~3f%29%29" class="RktValLink" data-pltdoc="x">equal?</a></span> or <span class="RktSym"><a href="booleans.html#%28def._%28%28quote._~23~25kernel%29._eq~3f%29%29" class="RktValLink" data-pltdoc="x">eq?</a></span>.</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)._hash-eq~3f))"></a><span title="Provided from: racket/base, racket | Package: base"><span class="RktSym"><a href="#%28def._%28%28quote._~23~25kernel%29._hash-eq~3f%29%29" class="RktValDef RktValLink" data-pltdoc="x">hash-eq?</a></span></span><span class="hspace"> </span><span class="RktVar">hash</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">hash</span><span class="hspace"> </span>:<span class="hspace"> </span><span class="RktSym"><a href="#%28def._%28%28quote._~23~25kernel%29._hash~3f%29%29" class="RktValLink" data-pltdoc="x">hash?</a></span></td></tr></table></blockquote></div><div class="SIntrapara">Returns <span class="RktVal">#t</span> if <span class="RktVar">hash</span> compares keys with <span class="RktSym"><a href="booleans.html#%28def._%28%28quote._~23~25kernel%29._eq~3f%29%29" class="RktValLink" data-pltdoc="x">eq?</a></span>,
<span class="RktVal">#f</span> if it compares with <span class="RktSym"><a href="booleans.html#%28def._%28%28quote._~23~25kernel%29._equal~3f%29%29" class="RktValLink" data-pltdoc="x">equal?</a></span> or <span class="RktSym"><a href="booleans.html#%28def._%28%28quote._~23~25kernel%29._eqv~3f%29%29" class="RktValLink" data-pltdoc="x">eqv?</a></span>.</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)._hash-weak~3f))"></a><span title="Provided from: racket/base, racket | Package: base"><span class="RktSym"><a href="#%28def._%28%28quote._~23~25kernel%29._hash-weak~3f%29%29" class="RktValDef RktValLink" data-pltdoc="x">hash-weak?</a></span></span><span class="hspace"> </span><span class="RktVar">hash</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">hash</span><span class="hspace"> </span>:<span class="hspace"> </span><span class="RktSym"><a href="#%28def._%28%28quote._~23~25kernel%29._hash~3f%29%29" class="RktValLink" data-pltdoc="x">hash?</a></span></td></tr></table></blockquote></div><div class="SIntrapara">Returns <span class="RktVal">#t</span> if <span class="RktVar">hash</span> retains its keys weakly,
<span class="RktVal">#f</span> if it retains keys strongly.</div></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)._hash))"></a><span title="Provided from: racket/base, racket | Package: base"><span class="RktSym"><a href="#%28def._%28%28quote._~23~25kernel%29._hash%29%29" class="RktValDef RktValLink" data-pltdoc="x">hash</a></span></span><span class="hspace"> </span><span class="RktVar">key</span><span class="hspace"> </span><span class="RktVar">val</span><span class="hspace"> </span><span class="RktMeta">...</span><span class="hspace"> </span><span class="RktMeta">...</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._and%2Fc%29%29" class="RktValLink" data-pltdoc="x">and/c</a></span><span class="hspace"> </span><span class="RktSym"><a href="#%28def._%28%28quote._~23~25kernel%29._hash~3f%29%29" class="RktValLink" data-pltdoc="x">hash?</a></span><span class="hspace"> </span><span class="RktSym"><a href="#%28def._%28%28quote._~23~25kernel%29._hash-equal~3f%29%29" class="RktValLink" data-pltdoc="x">hash-equal?</a></span><span class="hspace"> </span><span class="RktSym"><a href="booleans.html#%28def._%28%28quote._~23~25kernel%29._immutable~3f%29%29" class="RktValLink" data-pltdoc="x">immutable?</a></span><span class="RktPn">)</span></p></blockquote></td></tr><tr><td><span class="hspace"> </span><span class="RktVar">key</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">val</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="RBackgroundLabel SIEHidden"><div class="RBackgroundLabelInner"><p>procedure</p></div></div><p class="RForeground"><span class="RktPn">(</span><a name="(def._((quote._~23~25kernel)._hasheq))"></a><span title="Provided from: racket/base, racket | Package: base"><span class="RktSym"><a href="#%28def._%28%28quote._~23~25kernel%29._hasheq%29%29" class="RktValDef RktValLink" data-pltdoc="x">hasheq</a></span></span><span class="hspace"> </span><span class="RktVar">key</span><span class="hspace"> </span><span class="RktVar">val</span><span class="hspace"> </span><span class="RktMeta">...</span><span class="hspace"> </span><span class="RktMeta">...</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._and%2Fc%29%29" class="RktValLink" data-pltdoc="x">and/c</a></span><span class="hspace"> </span><span class="RktSym"><a href="#%28def._%28%28quote._~23~25kernel%29._hash~3f%29%29" class="RktValLink" data-pltdoc="x">hash?</a></span><span class="hspace"> </span><span class="RktSym"><a href="#%28def._%28%28quote._~23~25kernel%29._hash-eq~3f%29%29" class="RktValLink" data-pltdoc="x">hash-eq?</a></span><span class="hspace"> </span><span class="RktSym"><a href="booleans.html#%28def._%28%28quote._~23~25kernel%29._immutable~3f%29%29" class="RktValLink" data-pltdoc="x">immutable?</a></span><span class="RktPn">)</span></p></blockquote></td></tr><tr><td><span class="hspace"> </span><span class="RktVar">key</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">val</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="RBackgroundLabel SIEHidden"><div class="RBackgroundLabelInner"><p>procedure</p></div></div><p class="RForeground"><span class="RktPn">(</span><a name="(def._((quote._~23~25kernel)._hasheqv))"></a><span title="Provided from: racket/base, racket | Package: base"><span class="RktSym"><a href="#%28def._%28%28quote._~23~25kernel%29._hasheqv%29%29" class="RktValDef RktValLink" data-pltdoc="x">hasheqv</a></span></span><span class="hspace"> </span><span class="RktVar">key</span><span class="hspace"> </span><span class="RktVar">val</span><span class="hspace"> </span><span class="RktMeta">...</span><span class="hspace"> </span><span class="RktMeta">...</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._and%2Fc%29%29" class="RktValLink" data-pltdoc="x">and/c</a></span><span class="hspace"> </span><span class="RktSym"><a href="#%28def._%28%28quote._~23~25kernel%29._hash~3f%29%29" class="RktValLink" data-pltdoc="x">hash?</a></span><span class="hspace"> </span><span class="RktSym"><a href="#%28def._%28%28quote._~23~25kernel%29._hash-eqv~3f%29%29" class="RktValLink" data-pltdoc="x">hash-eqv?</a></span><span class="hspace"> </span><span class="RktSym"><a href="booleans.html#%28def._%28%28quote._~23~25kernel%29._immutable~3f%29%29" class="RktValLink" data-pltdoc="x">immutable?</a></span><span class="RktPn">)</span></p></blockquote></td></tr><tr><td><span class="hspace"> </span><span class="RktVar">key</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">val</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></table></blockquote></div><div class="SIntrapara">Creates an immutable hash table with each given <span class="RktVar">key</span> mapped to
the following <span class="RktVar">val</span>; each <span class="RktVar">key</span> must have a <span class="RktVar">val</span>,
so the total number of arguments to <span class="RktSym"><a href="#%28def._%28%28quote._~23~25kernel%29._hash%29%29" class="RktValLink" data-pltdoc="x">hash</a></span> must be even.</div></p><p>The <span class="RktSym"><a href="#%28def._%28%28quote._~23~25kernel%29._hash%29%29" class="RktValLink" data-pltdoc="x">hash</a></span> procedure creates a table where keys are compared
with <span class="RktSym"><a href="booleans.html#%28def._%28%28quote._~23~25kernel%29._equal~3f%29%29" class="RktValLink" data-pltdoc="x">equal?</a></span>, <span class="RktSym"><a href="#%28def._%28%28quote._~23~25kernel%29._hasheq%29%29" class="RktValLink" data-pltdoc="x">hasheq</a></span> procedure creates a table where
keys are compared with <span class="RktSym"><a href="booleans.html#%28def._%28%28quote._~23~25kernel%29._eq~3f%29%29" class="RktValLink" data-pltdoc="x">eq?</a></span>, and <span class="RktSym"><a href="#%28def._%28%28quote._~23~25kernel%29._hasheqv%29%29" class="RktValLink" data-pltdoc="x">hasheqv</a></span> procedure
creates a table where keys are compared with <span class="RktSym"><a href="booleans.html#%28def._%28%28quote._~23~25kernel%29._eqv~3f%29%29" class="RktValLink" data-pltdoc="x">eqv?</a></span>.</p><p>The <span class="RktVar">key</span> to <span class="RktVar">val</span> mappings are added to the table in
the order that they appear in the argument list, so later mappings can
hide earlier mappings if the <span class="RktVar">key</span>s are equal.</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)._make-hash))"></a><span title="Provided from: racket/base, racket | Package: base"><span class="RktSym"><a href="#%28def._%28%28quote._~23~25kernel%29._make-hash%29%29" class="RktValDef RktValLink" data-pltdoc="x">make-hash</a></span></span><span class="hspace"> </span>[<span class="RktVar">assocs</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._and%2Fc%29%29" class="RktValLink" data-pltdoc="x">and/c</a></span><span class="hspace"> </span><span class="RktSym"><a href="#%28def._%28%28quote._~23~25kernel%29._hash~3f%29%29" class="RktValLink" data-pltdoc="x">hash?</a></span><span class="hspace"> </span><span class="RktSym"><a href="#%28def._%28%28quote._~23~25kernel%29._hash-equal~3f%29%29" class="RktValLink" data-pltdoc="x">hash-equal?</a></span><span class="RktPn">)</span></p></blockquote></td></tr><tr><td><span class="hspace"> </span><span class="RktVar">assocs</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._listof%29%29" class="RktValLink" data-pltdoc="x">listof</a></span><span class="hspace"> </span><span class="RktSym"><a href="pairs.html#%28def._%28%28quote._~23~25kernel%29._pair~3f%29%29" class="RktValLink" data-pltdoc="x">pair?</a></span><span class="RktPn">)</span><span class="hspace"> </span>=<span class="hspace"> </span><span class="RktSym"><a href="pairs.html#%28def._%28%28quote._~23~25kernel%29._null%29%29" class="RktValLink" data-pltdoc="x">null</a></span></td></tr></table></td></tr><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)._make-hasheqv))"></a><span title="Provided from: racket/base, racket | Package: base"><span class="RktSym"><a href="#%28def._%28%28quote._~23~25kernel%29._make-hasheqv%29%29" class="RktValDef RktValLink" data-pltdoc="x">make-hasheqv</a></span></span><span class="hspace"> </span>[<span class="RktVar">assocs</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._and%2Fc%29%29" class="RktValLink" data-pltdoc="x">and/c</a></span><span class="hspace"> </span><span class="RktSym"><a href="#%28def._%28%28quote._~23~25kernel%29._hash~3f%29%29" class="RktValLink" data-pltdoc="x">hash?</a></span><span class="hspace"> </span><span class="RktSym"><a href="#%28def._%28%28quote._~23~25kernel%29._hash-eqv~3f%29%29" class="RktValLink" data-pltdoc="x">hash-eqv?</a></span><span class="RktPn">)</span></p></blockquote></td></tr><tr><td><span class="hspace"> </span><span class="RktVar">assocs</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._listof%29%29" class="RktValLink" data-pltdoc="x">listof</a></span><span class="hspace"> </span><span class="RktSym"><a href="pairs.html#%28def._%28%28quote._~23~25kernel%29._pair~3f%29%29" class="RktValLink" data-pltdoc="x">pair?</a></span><span class="RktPn">)</span><span class="hspace"> </span>=<span class="hspace"> </span><span class="RktSym"><a href="pairs.html#%28def._%28%28quote._~23~25kernel%29._null%29%29" class="RktValLink" data-pltdoc="x">null</a></span></td></tr></table></td></tr><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)._make-hasheq))"></a><span title="Provided from: racket/base, racket | Package: base"><span class="RktSym"><a href="#%28def._%28%28quote._~23~25kernel%29._make-hasheq%29%29" class="RktValDef RktValLink" data-pltdoc="x">make-hasheq</a></span></span><span class="hspace"> </span>[<span class="RktVar">assocs</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._and%2Fc%29%29" class="RktValLink" data-pltdoc="x">and/c</a></span><span class="hspace"> </span><span class="RktSym"><a href="#%28def._%28%28quote._~23~25kernel%29._hash~3f%29%29" class="RktValLink" data-pltdoc="x">hash?</a></span><span class="hspace"> </span><span class="RktSym"><a href="#%28def._%28%28quote._~23~25kernel%29._hash-eq~3f%29%29" class="RktValLink" data-pltdoc="x">hash-eq?</a></span><span class="RktPn">)</span></p></blockquote></td></tr><tr><td><span class="hspace"> </span><span class="RktVar">assocs</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._listof%29%29" class="RktValLink" data-pltdoc="x">listof</a></span><span class="hspace"> </span><span class="RktSym"><a href="pairs.html#%28def._%28%28quote._~23~25kernel%29._pair~3f%29%29" class="RktValLink" data-pltdoc="x">pair?</a></span><span class="RktPn">)</span><span class="hspace"> </span>=<span class="hspace"> </span><span class="RktSym"><a href="pairs.html#%28def._%28%28quote._~23~25kernel%29._null%29%29" class="RktValLink" data-pltdoc="x">null</a></span></td></tr></table></td></tr></table></blockquote></div><div class="SIntrapara">Creates a mutable hash table that holds keys strongly.</div></p><p>The <span class="RktSym"><a href="#%28def._%28%28quote._~23~25kernel%29._make-hash%29%29" class="RktValLink" data-pltdoc="x">make-hash</a></span> procedure creates a table where keys are
compared with <span class="RktSym"><a href="booleans.html#%28def._%28%28quote._~23~25kernel%29._equal~3f%29%29" class="RktValLink" data-pltdoc="x">equal?</a></span>, <span class="RktSym"><a href="#%28def._%28%28quote._~23~25kernel%29._make-hasheq%29%29" class="RktValLink" data-pltdoc="x">make-hasheq</a></span> procedure creates
a table where keys are compared with <span class="RktSym"><a href="booleans.html#%28def._%28%28quote._~23~25kernel%29._eq~3f%29%29" class="RktValLink" data-pltdoc="x">eq?</a></span>, and
<span class="RktSym"><a href="#%28def._%28%28quote._~23~25kernel%29._make-hasheqv%29%29" class="RktValLink" data-pltdoc="x">make-hasheqv</a></span> procedure creates a table where keys are
compared with <span class="RktSym"><a href="booleans.html#%28def._%28%28quote._~23~25kernel%29._eqv~3f%29%29" class="RktValLink" data-pltdoc="x">eqv?</a></span>.</p><p>The table is initialized with the content of <span class="RktVar">assocs</span>. In each
element of <span class="RktVar">assocs</span>, the <span class="RktSym"><a href="pairs.html#%28def._%28%28quote._~23~25kernel%29._car%29%29" class="RktValLink" data-pltdoc="x">car</a></span> is a key, and the
<span class="RktSym"><a href="pairs.html#%28def._%28%28quote._~23~25kernel%29._cdr%29%29" class="RktValLink" data-pltdoc="x">cdr</a></span> is the corresponding value. The mappings are added to the
table in the order that they appear in <span class="RktVar">assocs</span>, so later
mappings can hide earlier mappings.</p><p>See also <span class="RktSym"><a href="dicts.html#%28def._%28%28lib._racket%2Fdict..rkt%29._make-custom-hash%29%29" class="RktValLink" data-pltdoc="x">make-custom-hash</a></span>.</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)._make-weak-hash))"></a><span title="Provided from: racket/base, racket | Package: base"><span class="RktSym"><a href="#%28def._%28%28quote._~23~25kernel%29._make-weak-hash%29%29" class="RktValDef RktValLink" data-pltdoc="x">make-weak-hash</a></span></span><span class="hspace"> </span>[<span class="RktVar">assocs</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._and%2Fc%29%29" class="RktValLink" data-pltdoc="x">and/c</a></span><span class="hspace"> </span><span class="RktSym"><a href="#%28def._%28%28quote._~23~25kernel%29._hash~3f%29%29" class="RktValLink" data-pltdoc="x">hash?</a></span><span class="hspace"> </span><span class="RktSym"><a href="#%28def._%28%28quote._~23~25kernel%29._hash-equal~3f%29%29" class="RktValLink" data-pltdoc="x">hash-equal?</a></span><span class="hspace"> </span><span class="RktSym"><a href="#%28def._%28%28quote._~23~25kernel%29._hash-weak~3f%29%29" class="RktValLink" data-pltdoc="x">hash-weak?</a></span><span class="RktPn">)</span></p></blockquote></td></tr><tr><td><span class="hspace"> </span><span class="RktVar">assocs</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._listof%29%29" class="RktValLink" data-pltdoc="x">listof</a></span><span class="hspace"> </span><span class="RktSym"><a href="pairs.html#%28def._%28%28quote._~23~25kernel%29._pair~3f%29%29" class="RktValLink" data-pltdoc="x">pair?</a></span><span class="RktPn">)</span><span class="hspace"> </span>=<span class="hspace"> </span><span class="RktSym"><a href="pairs.html#%28def._%28%28quote._~23~25kernel%29._null%29%29" class="RktValLink" data-pltdoc="x">null</a></span></td></tr></table></td></tr><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)._make-weak-hasheqv))"></a><span title="Provided from: racket/base, racket | Package: base"><span class="RktSym"><a href="#%28def._%28%28quote._~23~25kernel%29._make-weak-hasheqv%29%29" class="RktValDef RktValLink" data-pltdoc="x">make-weak-hasheqv</a></span></span><span class="hspace"> </span>[<span class="RktVar">assocs</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._and%2Fc%29%29" class="RktValLink" data-pltdoc="x">and/c</a></span><span class="hspace"> </span><span class="RktSym"><a href="#%28def._%28%28quote._~23~25kernel%29._hash~3f%29%29" class="RktValLink" data-pltdoc="x">hash?</a></span><span class="hspace"> </span><span class="RktSym"><a href="#%28def._%28%28quote._~23~25kernel%29._hash-eqv~3f%29%29" class="RktValLink" data-pltdoc="x">hash-eqv?</a></span><span class="hspace"> </span><span class="RktSym"><a href="#%28def._%28%28quote._~23~25kernel%29._hash-weak~3f%29%29" class="RktValLink" data-pltdoc="x">hash-weak?</a></span><span class="RktPn">)</span></p></blockquote></td></tr><tr><td><span class="hspace"> </span><span class="RktVar">assocs</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._listof%29%29" class="RktValLink" data-pltdoc="x">listof</a></span><span class="hspace"> </span><span class="RktSym"><a href="pairs.html#%28def._%28%28quote._~23~25kernel%29._pair~3f%29%29" class="RktValLink" data-pltdoc="x">pair?</a></span><span class="RktPn">)</span><span class="hspace"> </span>=<span class="hspace"> </span><span class="RktSym"><a href="pairs.html#%28def._%28%28quote._~23~25kernel%29._null%29%29" class="RktValLink" data-pltdoc="x">null</a></span></td></tr></table></td></tr><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)._make-weak-hasheq))"></a><span title="Provided from: racket/base, racket | Package: base"><span class="RktSym"><a href="#%28def._%28%28quote._~23~25kernel%29._make-weak-hasheq%29%29" class="RktValDef RktValLink" data-pltdoc="x">make-weak-hasheq</a></span></span><span class="hspace"> </span>[<span class="RktVar">assocs</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._and%2Fc%29%29" class="RktValLink" data-pltdoc="x">and/c</a></span><span class="hspace"> </span><span class="RktSym"><a href="#%28def._%28%28quote._~23~25kernel%29._hash~3f%29%29" class="RktValLink" data-pltdoc="x">hash?</a></span><span class="hspace"> </span><span class="RktSym"><a href="#%28def._%28%28quote._~23~25kernel%29._hash-eq~3f%29%29" class="RktValLink" data-pltdoc="x">hash-eq?</a></span><span class="hspace"> </span><span class="RktSym"><a href="#%28def._%28%28quote._~23~25kernel%29._hash-weak~3f%29%29" class="RktValLink" data-pltdoc="x">hash-weak?</a></span><span class="RktPn">)</span></p></blockquote></td></tr><tr><td><span class="hspace"> </span><span class="RktVar">assocs</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._listof%29%29" class="RktValLink" data-pltdoc="x">listof</a></span><span class="hspace"> </span><span class="RktSym"><a href="pairs.html#%28def._%28%28quote._~23~25kernel%29._pair~3f%29%29" class="RktValLink" data-pltdoc="x">pair?</a></span><span class="RktPn">)</span><span class="hspace"> </span>=<span class="hspace"> </span><span class="RktSym"><a href="pairs.html#%28def._%28%28quote._~23~25kernel%29._null%29%29" class="RktValLink" data-pltdoc="x">null</a></span></td></tr></table></td></tr></table></blockquote></div><div class="SIntrapara">Like <span class="RktSym"><a href="#%28def._%28%28quote._~23~25kernel%29._make-hash%29%29" class="RktValLink" data-pltdoc="x">make-hash</a></span>, <span class="RktSym"><a href="#%28def._%28%28quote._~23~25kernel%29._make-hasheq%29%29" class="RktValLink" data-pltdoc="x">make-hasheq</a></span>, and
<span class="RktSym"><a href="#%28def._%28%28quote._~23~25kernel%29._make-hasheqv%29%29" class="RktValLink" data-pltdoc="x">make-hasheqv</a></span>, but creates a mutable hash table that holds
keys weakly.</div></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)._make-immutable-hash))"></a><span title="Provided from: racket/base, racket | Package: base"><span class="RktSym"><a href="#%28def._%28%28quote._~23~25kernel%29._make-immutable-hash%29%29" class="RktValDef RktValLink" data-pltdoc="x">make-immutable-hash</a></span></span><span class="hspace"> </span>[<span class="RktVar">assocs</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="data-structure-contracts.html#%28def._%28%28lib._racket%2Fcontract%2Fprivate%2Fmisc..rkt%29._and%2Fc%29%29" class="RktValLink" data-pltdoc="x">and/c</a></span><span class="hspace"> </span><span class="RktSym"><a href="#%28def._%28%28quote._~23~25kernel%29._hash~3f%29%29" class="RktValLink" data-pltdoc="x">hash?</a></span><span class="hspace"> </span><span class="RktSym"><a href="#%28def._%28%28quote._~23~25kernel%29._hash-equal~3f%29%29" class="RktValLink" data-pltdoc="x">hash-equal?</a></span><span class="hspace"> </span><span class="RktSym"><a href="booleans.html#%28def._%28%28quote._~23~25kernel%29._immutable~3f%29%29" class="RktValLink" data-pltdoc="x">immutable?</a></span><span class="RktPn">)</span></td></tr><tr><td><span class="hspace"> </span><span class="RktVar">assocs</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._listof%29%29" class="RktValLink" data-pltdoc="x">listof</a></span><span class="hspace"> </span><span class="RktSym"><a href="pairs.html#%28def._%28%28quote._~23~25kernel%29._pair~3f%29%29" class="RktValLink" data-pltdoc="x">pair?</a></span><span class="RktPn">)</span><span class="hspace"> </span>=<span class="hspace"> </span><span class="RktSym"><a href="pairs.html#%28def._%28%28quote._~23~25kernel%29._null%29%29" class="RktValLink" data-pltdoc="x">null</a></span></td></tr></table></td></tr><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)._make-immutable-hasheqv))"></a><span title="Provided from: racket/base, racket | Package: base"><span class="RktSym"><a href="#%28def._%28%28quote._~23~25kernel%29._make-immutable-hasheqv%29%29" class="RktValDef RktValLink" data-pltdoc="x">make-immutable-hasheqv</a></span></span><span class="hspace"> </span>[<span class="RktVar">assocs</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="data-structure-contracts.html#%28def._%28%28lib._racket%2Fcontract%2Fprivate%2Fmisc..rkt%29._and%2Fc%29%29" class="RktValLink" data-pltdoc="x">and/c</a></span><span class="hspace"> </span><span class="RktSym"><a href="#%28def._%28%28quote._~23~25kernel%29._hash~3f%29%29" class="RktValLink" data-pltdoc="x">hash?</a></span><span class="hspace"> </span><span class="RktSym"><a href="#%28def._%28%28quote._~23~25kernel%29._hash-eqv~3f%29%29" class="RktValLink" data-pltdoc="x">hash-eqv?</a></span><span class="hspace"> </span><span class="RktSym"><a href="booleans.html#%28def._%28%28quote._~23~25kernel%29._immutable~3f%29%29" class="RktValLink" data-pltdoc="x">immutable?</a></span><span class="RktPn">)</span></td></tr><tr><td><span class="hspace"> </span><span class="RktVar">assocs</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._listof%29%29" class="RktValLink" data-pltdoc="x">listof</a></span><span class="hspace"> </span><span class="RktSym"><a href="pairs.html#%28def._%28%28quote._~23~25kernel%29._pair~3f%29%29" class="RktValLink" data-pltdoc="x">pair?</a></span><span class="RktPn">)</span><span class="hspace"> </span>=<span class="hspace"> </span><span class="RktSym"><a href="pairs.html#%28def._%28%28quote._~23~25kernel%29._null%29%29" class="RktValLink" data-pltdoc="x">null</a></span></td></tr></table></td></tr><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)._make-immutable-hasheq))"></a><span title="Provided from: racket/base, racket | Package: base"><span class="RktSym"><a href="#%28def._%28%28quote._~23~25kernel%29._make-immutable-hasheq%29%29" class="RktValDef RktValLink" data-pltdoc="x">make-immutable-hasheq</a></span></span><span class="hspace"> </span>[<span class="RktVar">assocs</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="data-structure-contracts.html#%28def._%28%28lib._racket%2Fcontract%2Fprivate%2Fmisc..rkt%29._and%2Fc%29%29" class="RktValLink" data-pltdoc="x">and/c</a></span><span class="hspace"> </span><span class="RktSym"><a href="#%28def._%28%28quote._~23~25kernel%29._hash~3f%29%29" class="RktValLink" data-pltdoc="x">hash?</a></span><span class="hspace"> </span><span class="RktSym"><a href="#%28def._%28%28quote._~23~25kernel%29._hash-eq~3f%29%29" class="RktValLink" data-pltdoc="x">hash-eq?</a></span><span class="hspace"> </span><span class="RktSym"><a href="booleans.html#%28def._%28%28quote._~23~25kernel%29._immutable~3f%29%29" class="RktValLink" data-pltdoc="x">immutable?</a></span><span class="RktPn">)</span></td></tr><tr><td><span class="hspace"> </span><span class="RktVar">assocs</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._listof%29%29" class="RktValLink" data-pltdoc="x">listof</a></span><span class="hspace"> </span><span class="RktSym"><a href="pairs.html#%28def._%28%28quote._~23~25kernel%29._pair~3f%29%29" class="RktValLink" data-pltdoc="x">pair?</a></span><span class="RktPn">)</span><span class="hspace"> </span>=<span class="hspace"> </span><span class="RktSym"><a href="pairs.html#%28def._%28%28quote._~23~25kernel%29._null%29%29" class="RktValLink" data-pltdoc="x">null</a></span></td></tr></table></td></tr></table></blockquote></div><div class="SIntrapara">Like <span class="RktSym"><a href="#%28def._%28%28quote._~23~25kernel%29._hash%29%29" class="RktValLink" data-pltdoc="x">hash</a></span>, <span class="RktSym"><a href="#%28def._%28%28quote._~23~25kernel%29._hasheq%29%29" class="RktValLink" data-pltdoc="x">hasheq</a></span>, and <span class="RktSym"><a href="#%28def._%28%28quote._~23~25kernel%29._hasheqv%29%29" class="RktValLink" data-pltdoc="x">hasheqv</a></span>, but accepts
the key–value mapping in association-list form like
<span class="RktSym"><a href="#%28def._%28%28quote._~23~25kernel%29._make-hash%29%29" class="RktValLink" data-pltdoc="x">make-hash</a></span>, <span class="RktSym"><a href="#%28def._%28%28quote._~23~25kernel%29._make-hasheq%29%29" class="RktValLink" data-pltdoc="x">make-hasheq</a></span>, and <span class="RktSym"><a href="#%28def._%28%28quote._~23~25kernel%29._make-hasheqv%29%29" class="RktValLink" data-pltdoc="x">make-hasheqv</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>procedure</p></div></div><p class="RForeground"><span class="RktPn">(</span><a name="(def._((quote._~23~25kernel)._hash-set!))"></a><span title="Provided from: racket/base, racket | Package: base"><span class="RktSym"><a href="#%28def._%28%28quote._~23~25kernel%29._hash-set%21%29%29" class="RktValDef RktValLink" data-pltdoc="x">hash-set!</a></span></span><span class="hspace"> </span><span class="RktVar">hash</span><span class="hspace"> </span><span class="RktVar">key</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="void.html#%28def._%28%28quote._~23~25kernel%29._void~3f%29%29" class="RktValLink" data-pltdoc="x">void?</a></span></p></blockquote></td></tr><tr><td><span class="hspace"> </span><span class="RktVar">hash</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._and%2Fc%29%29" class="RktValLink" data-pltdoc="x">and/c</a></span><span class="hspace"> </span><span class="RktSym"><a href="#%28def._%28%28quote._~23~25kernel%29._hash~3f%29%29" class="RktValLink" data-pltdoc="x">hash?</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._not%2Fc%29%29" class="RktValLink" data-pltdoc="x">not/c</a></span><span class="hspace"> </span><span class="RktSym"><a href="booleans.html#%28def._%28%28quote._~23~25kernel%29._immutable~3f%29%29" class="RktValLink" data-pltdoc="x">immutable?</a></span><span class="RktPn">)</span><span class="RktPn">)</span></td></tr><tr><td><span class="hspace"> </span><span class="RktVar">key</span><span class="hspace"> </span>:<span class="hspace"> </span><span class="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">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">Maps <span class="RktVar">key</span> to <span class="RktVar">v</span> in <span class="RktVar">hash</span>, overwriting
any existing mapping for <span class="RktVar">key</span>.</div></p><p>See also the <a href="#%28elem._%28caveat._concurrency%29%29" data-pltdoc="x">caveats concerning concurrent modification</a> and the <a href="#%28elem._%28caveat._mutable-keys%29%29" data-pltdoc="x">caveat concerning mutable keys</a> above.</p><p><div class="SIntrapara"><blockquote class="SVInsetFlow"><table cellspacing="0" cellpadding="0" class="boxed RBoxed"><tr><td><blockquote class="SubFlow"><div class="RBackgroundLabel SIEHidden"><div class="RBackgroundLabelInner"><p>procedure</p></div></div><p class="RForeground"><span class="RktPn">(</span><a name="(def._((lib._racket/private/base..rkt)._hash-set*!))"></a><span title="Provided from: racket/base, racket | Package: base"><span class="RktSym"><a href="#%28def._%28%28lib._racket%2Fprivate%2Fbase..rkt%29._hash-set%2A%21%29%29" class="RktValDef RktValLink" data-pltdoc="x">hash-set*!</a></span></span><span class="hspace"> </span><span class="RktVar">hash</span><span class="hspace"> </span><span class="RktVar">key</span><span class="hspace"> </span><span class="RktVar">v</span><span class="hspace"> </span><span class="RktMeta">...</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="void.html#%28def._%28%28quote._~23~25kernel%29._void~3f%29%29" class="RktValLink" data-pltdoc="x">void?</a></span></p></blockquote></td></tr><tr><td><span class="hspace"> </span><span class="RktVar">hash</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._and%2Fc%29%29" class="RktValLink" data-pltdoc="x">and/c</a></span><span class="hspace"> </span><span class="RktSym"><a href="#%28def._%28%28quote._~23~25kernel%29._hash~3f%29%29" class="RktValLink" data-pltdoc="x">hash?</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._not%2Fc%29%29" class="RktValLink" data-pltdoc="x">not/c</a></span><span class="hspace"> </span><span class="RktSym"><a href="booleans.html#%28def._%28%28quote._~23~25kernel%29._immutable~3f%29%29" class="RktValLink" data-pltdoc="x">immutable?</a></span><span class="RktPn">)</span><span class="RktPn">)</span></td></tr><tr><td><span class="hspace"> </span><span class="RktVar">key</span><span class="hspace"> </span>:<span class="hspace"> </span><span class="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">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">Maps each <span class="RktVar">key</span> to each <span class="RktVar">v</span> in <span class="RktVar">hash</span>, overwriting
any existing mapping for each <span class="RktVar">key</span>. Mappings are added from the left, so
later mappings overwrite earlier mappings.</div></p><p>See also the <a href="#%28elem._%28caveat._concurrency%29%29" data-pltdoc="x">caveats concerning concurrent modification</a> and the <a href="#%28elem._%28caveat._mutable-keys%29%29" data-pltdoc="x">caveat concerning mutable keys</a> above.</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)._hash-set))"></a><span title="Provided from: racket/base, racket | Package: base"><span class="RktSym"><a href="#%28def._%28%28quote._~23~25kernel%29._hash-set%29%29" class="RktValDef RktValLink" data-pltdoc="x">hash-set</a></span></span><span class="hspace"> </span><span class="RktVar">hash</span><span class="hspace"> </span><span class="RktVar">key</span><span class="hspace"> </span><span class="RktVar">v</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._and%2Fc%29%29" class="RktValLink" data-pltdoc="x">and/c</a></span><span class="hspace"> </span><span class="RktSym"><a href="#%28def._%28%28quote._~23~25kernel%29._hash~3f%29%29" class="RktValLink" data-pltdoc="x">hash?</a></span><span class="hspace"> </span><span class="RktSym"><a href="booleans.html#%28def._%28%28quote._~23~25kernel%29._immutable~3f%29%29" class="RktValLink" data-pltdoc="x">immutable?</a></span><span class="RktPn">)</span></p></blockquote></td></tr><tr><td><span class="hspace"> </span><span class="RktVar">hash</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._and%2Fc%29%29" class="RktValLink" data-pltdoc="x">and/c</a></span><span class="hspace"> </span><span class="RktSym"><a href="#%28def._%28%28quote._~23~25kernel%29._hash~3f%29%29" class="RktValLink" data-pltdoc="x">hash?</a></span><span class="hspace"> </span><span class="RktSym"><a href="booleans.html#%28def._%28%28quote._~23~25kernel%29._immutable~3f%29%29" class="RktValLink" data-pltdoc="x">immutable?</a></span><span class="RktPn">)</span></td></tr><tr><td><span class="hspace"> </span><span class="RktVar">key</span><span class="hspace"> </span>:<span class="hspace"> </span><span class="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">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">Functionally extends <span class="RktVar">hash</span> by mapping <span class="RktVar">key</span> to
<span class="RktVar">v</span>, overwriting any existing mapping for <span class="RktVar">key</span>, and
returning the extended hash table.</div></p><p>See also the <a href="#%28elem._%28caveat._mutable-keys%29%29" data-pltdoc="x">caveat concerning mutable keys</a> above.</p><p><div class="SIntrapara"><blockquote class="SVInsetFlow"><table cellspacing="0" cellpadding="0" class="boxed RBoxed"><tr><td><blockquote class="SubFlow"><div class="RBackgroundLabel SIEHidden"><div class="RBackgroundLabelInner"><p>procedure</p></div></div><p class="RForeground"><span class="RktPn">(</span><a name="(def._((lib._racket/private/base..rkt)._hash-set*))"></a><span title="Provided from: racket/base, racket | Package: base"><span class="RktSym"><a href="#%28def._%28%28lib._racket%2Fprivate%2Fbase..rkt%29._hash-set%2A%29%29" class="RktValDef RktValLink" data-pltdoc="x">hash-set*</a></span></span><span class="hspace"> </span><span class="RktVar">hash</span><span class="hspace"> </span><span class="RktVar">key</span><span class="hspace"> </span><span class="RktVar">v</span><span class="hspace"> </span><span class="RktMeta">...</span><span class="hspace"> </span><span class="RktMeta">...</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._and%2Fc%29%29" class="RktValLink" data-pltdoc="x">and/c</a></span><span class="hspace"> </span><span class="RktSym"><a href="#%28def._%28%28quote._~23~25kernel%29._hash~3f%29%29" class="RktValLink" data-pltdoc="x">hash?</a></span><span class="hspace"> </span><span class="RktSym"><a href="booleans.html#%28def._%28%28quote._~23~25kernel%29._immutable~3f%29%29" class="RktValLink" data-pltdoc="x">immutable?</a></span><span class="RktPn">)</span></p></blockquote></td></tr><tr><td><span class="hspace"> </span><span class="RktVar">hash</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._and%2Fc%29%29" class="RktValLink" data-pltdoc="x">and/c</a></span><span class="hspace"> </span><span class="RktSym"><a href="#%28def._%28%28quote._~23~25kernel%29._hash~3f%29%29" class="RktValLink" data-pltdoc="x">hash?</a></span><span class="hspace"> </span><span class="RktSym"><a href="booleans.html#%28def._%28%28quote._~23~25kernel%29._immutable~3f%29%29" class="RktValLink" data-pltdoc="x">immutable?</a></span><span class="RktPn">)</span></td></tr><tr><td><span class="hspace"> </span><span class="RktVar">key</span><span class="hspace"> </span>:<span class="hspace"> </span><span class="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">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">Functionally extends <span class="RktVar">hash</span> by mapping each <span class="RktVar">key</span> to
<span class="RktVar">v</span>, overwriting any existing mapping for each <span class="RktVar">key</span>, and
returning the extended hash table. Mappings are added from the left, so
later mappings overwrite earlier mappings.</div></p><p>See also the <a href="#%28elem._%28caveat._mutable-keys%29%29" data-pltdoc="x">caveat concerning mutable keys</a> above.</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)._hash-ref))"></a><span title="Provided from: racket/base, racket | Package: base"><span class="RktSym"><a href="#%28def._%28%28quote._~23~25kernel%29._hash-ref%29%29" class="RktValDef RktValLink" data-pltdoc="x">hash-ref</a></span></span><span class="hspace"> </span><span class="RktVar">hash</span><span class="hspace"> </span><span class="RktVar">key</span><span class="hspace"> </span>[<span class="RktVar">failure-result</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">hash</span><span class="hspace"> </span>:<span class="hspace"> </span><span class="RktSym"><a href="#%28def._%28%28quote._~23~25kernel%29._hash~3f%29%29" class="RktValLink" data-pltdoc="x">hash?</a></span></td></tr><tr><td><span class="hspace"> </span><span class="RktVar">key</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="argcontract"><tr><td><span class="hspace"> </span></td><td><span class="RktVar">failure-result</span></td><td><span class="hspace"> </span></td><td>:</td><td><span class="hspace"> </span></td><td><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></td><td><span class="hspace"> </span></td><td><span class="hspace"> </span></td><td>=</td><td><span class="hspace"> </span></td><td><table cellspacing="0" cellpadding="0" class="RktBlk"><tr><td><span class="RktPn">(</span><span class="RktSym"><a href="lambda.html#%28form._%28%28lib._racket%2Fprivate%2Fbase..rkt%29._lambda%29%29" class="RktStxLink" data-pltdoc="x">lambda</a></span><span class="hspace"> </span><span class="RktPn">(</span><span class="RktPn">)</span></td></tr><tr><td><span class="hspace"> </span><span class="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="RktPn">(</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><span class="hspace"> </span><span class="RktSym">....</span><span class="RktPn">)</span><span class="RktPn">)</span><span class="RktPn">)</span></td></tr></table></td></tr></table></td></tr></table></blockquote></div><div class="SIntrapara">Returns the value for <span class="RktVar">key</span> in <span class="RktVar">hash</span>. If no value
is found for <span class="RktVar">key</span>, then <span class="RktVar">failure-result</span> determines the
result:</div></p><ul><li><p>If <span class="RktVar">failure-result</span> is a procedure, it is called
(through a tail call) with no arguments to produce the result.</p></li><li><p>Otherwise, <span class="RktVar">failure-result</span> is returned as the result.</p></li></ul><p>See also the <a href="#%28elem._%28caveat._concurrency%29%29" data-pltdoc="x">caveats concerning concurrent modification</a> and the <a href="#%28elem._%28caveat._mutable-keys%29%29" data-pltdoc="x">caveat concerning mutable keys</a> above.</p><p><div class="SIntrapara"><blockquote class="SVInsetFlow"><table cellspacing="0" cellpadding="0" class="boxed RBoxed"><tr><td><blockquote class="SubFlow"><div class="RBackgroundLabel SIEHidden"><div class="RBackgroundLabelInner"><p>procedure</p></div></div><p class="RForeground"><span class="RktPn">(</span><a name="(def._((lib._racket/private/more-scheme..rkt)._hash-ref!))"></a><span title="Provided from: racket/base, racket | Package: base"><span class="RktSym"><a href="#%28def._%28%28lib._racket%2Fprivate%2Fmore-scheme..rkt%29._hash-ref%21%29%29" class="RktValDef RktValLink" data-pltdoc="x">hash-ref!</a></span></span><span class="hspace"> </span><span class="RktVar">hash</span><span class="hspace"> </span><span class="RktVar">key</span><span class="hspace"> </span><span class="RktVar">to-set</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">hash</span><span class="hspace"> </span>:<span class="hspace"> </span><span class="RktSym"><a href="#%28def._%28%28quote._~23~25kernel%29._hash~3f%29%29" class="RktValLink" data-pltdoc="x">hash?</a></span></td></tr><tr><td><span class="hspace"> </span><span class="RktVar">key</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">to-set</span><span class="hspace"> </span>:<span class="hspace"> </span><span class="RktSym"><a href="data-structure-contracts.html#%28def._%28%28lib._racket%2Fcontract%2Fprivate%2Fmisc..rkt%29._any%2Fc%29%29" class="RktValLink" data-pltdoc="x">any/c</a></span></td></tr></table></blockquote></div><div class="SIntrapara">Returns the value for <span class="RktVar">key</span> in <span class="RktVar">hash</span>. If no value is
found for <span class="RktVar">key</span>, then <span class="RktVar">to-set</span> determines the result as
in <span class="RktSym"><a href="#%28def._%28%28quote._~23~25kernel%29._hash-ref%29%29" class="RktValLink" data-pltdoc="x">hash-ref</a></span> (i.e., it is either a thunk that computes a value
or a plain value), and this result is stored in <span class="RktVar">hash</span> for the
<span class="RktVar">key</span>. (Note that if <span class="RktVar">to-set</span> is a thunk, it is not
invoked in tail position.)</div></p><p>See also the <a href="#%28elem._%28caveat._concurrency%29%29" data-pltdoc="x">caveats concerning concurrent modification</a> and the <a href="#%28elem._%28caveat._mutable-keys%29%29" data-pltdoc="x">caveat concerning mutable keys</a> above.</p><p><div class="SIntrapara"><blockquote class="SVInsetFlow"><table cellspacing="0" cellpadding="0" class="boxed RBoxed"><tr><td><blockquote class="SubFlow"><div class="RBackgroundLabel SIEHidden"><div class="RBackgroundLabelInner"><p>procedure</p></div></div><p class="RForeground"><span class="RktPn">(</span><a name="(def._((lib._racket/private/more-scheme..rkt)._hash-has-key~3f))"></a><span title="Provided from: racket/base, racket | Package: base"><span class="RktSym"><a href="#%28def._%28%28lib._racket%2Fprivate%2Fmore-scheme..rkt%29._hash-has-key~3f%29%29" class="RktValDef RktValLink" data-pltdoc="x">hash-has-key?</a></span></span><span class="hspace"> </span><span class="RktVar">hash</span><span class="hspace"> </span><span class="RktVar">key</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">hash</span><span class="hspace"> </span>:<span class="hspace"> </span><span class="RktSym"><a href="#%28def._%28%28quote._~23~25kernel%29._hash~3f%29%29" class="RktValLink" data-pltdoc="x">hash?</a></span></td></tr><tr><td><span class="hspace"> </span><span class="RktVar">key</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">hash</span> contains a value for the given
<span class="RktVar">key</span>, <span class="RktVal">#f</span> otherwise.</div></p><p><div class="SIntrapara"><blockquote class="SVInsetFlow"><table cellspacing="0" cellpadding="0" class="boxed RBoxed"><tr><td><blockquote class="SubFlow"><div class="RBackgroundLabel SIEHidden"><div class="RBackgroundLabelInner"><p>procedure</p></div></div><table cellspacing="0" cellpadding="0" class="prototype RForeground"><tr><td><span class="RktPn">(</span><a name="(def._((lib._racket/private/more-scheme..rkt)._hash-update!))"></a><span title="Provided from: racket/base, racket | Package: base"><span class="RktSym"><a href="#%28def._%28%28lib._racket%2Fprivate%2Fmore-scheme..rkt%29._hash-update%21%29%29" class="RktValDef RktValLink" data-pltdoc="x">hash-update!</a></span></span></td><td><span class="hspace"> </span></td><td><span class="RktVar">hash</span></td><td><span class="hspace"> </span></td><td><span class="hspace"> </span></td><td><span class="hspace"> </span></td><td><span class="hspace"> </span></td></tr><tr><td><span class="hspace"> </span></td><td><span class="hspace"> </span></td><td><span class="RktVar">key</span></td><td><span class="hspace"> </span></td><td><span class="hspace"> </span></td><td><span class="hspace"> </span></td><td><span class="hspace"> </span></td></tr><tr><td><span class="hspace"> </span></td><td><span class="hspace"> </span></td><td><span class="RktVar">updater</span></td><td><span class="hspace"> </span></td><td><span class="hspace"> </span></td><td><span class="hspace"> </span></td><td><span class="hspace"> </span></td></tr><tr><td><span class="hspace"> </span></td><td><span class="hspace"> </span>[</td><td><span class="RktVar">failure-result</span>]<span class="RktPn">)</span></td><td><span class="hspace"> </span></td><td>→</td><td><span class="hspace"> </span></td><td><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></table></blockquote></td></tr><tr><td><span class="hspace"> </span><span class="RktVar">hash</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._and%2Fc%29%29" class="RktValLink" data-pltdoc="x">and/c</a></span><span class="hspace"> </span><span class="RktSym"><a href="#%28def._%28%28quote._~23~25kernel%29._hash~3f%29%29" class="RktValLink" data-pltdoc="x">hash?</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._not%2Fc%29%29" class="RktValLink" data-pltdoc="x">not/c</a></span><span class="hspace"> </span><span class="RktSym"><a href="booleans.html#%28def._%28%28quote._~23~25kernel%29._immutable~3f%29%29" class="RktValLink" data-pltdoc="x">immutable?</a></span><span class="RktPn">)</span><span class="RktPn">)</span></td></tr><tr><td><span class="hspace"> </span><span class="RktVar">key</span><span class="hspace"> </span>:<span class="hspace"> </span><span class="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">updater</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#%28def._%28%28lib._racket%2Fcontract%2Fprivate%2Fmisc..rkt%29._any%2Fc%29%29" class="RktValLink" data-pltdoc="x">any/c</a></span><span class="RktPn">)</span></td></tr><tr><td><table cellspacing="0" cellpadding="0" class="argcontract"><tr><td><span class="hspace"> </span></td><td><span class="RktVar">failure-result</span></td><td><span class="hspace"> </span></td><td>:</td><td><span class="hspace"> </span></td><td><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></td><td><span class="hspace"> </span></td><td><span class="hspace"> </span></td><td>=</td><td><span class="hspace"> </span></td><td><table cellspacing="0" cellpadding="0" class="RktBlk"><tr><td><span class="RktPn">(</span><span class="RktSym"><a href="lambda.html#%28form._%28%28lib._racket%2Fprivate%2Fbase..rkt%29._lambda%29%29" class="RktStxLink" data-pltdoc="x">lambda</a></span><span class="hspace"> </span><span class="RktPn">(</span><span class="RktPn">)</span></td></tr><tr><td><span class="hspace"> </span><span class="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="RktPn">(</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><span class="hspace"> </span><span class="RktSym">....</span><span class="RktPn">)</span><span class="RktPn">)</span><span class="RktPn">)</span></td></tr></table></td></tr></table></td></tr></table></blockquote></div><div class="SIntrapara">Composes <span class="RktSym"><a href="#%28def._%28%28quote._~23~25kernel%29._hash-ref%29%29" class="RktValLink" data-pltdoc="x">hash-ref</a></span> and <span class="RktSym"><a href="#%28def._%28%28quote._~23~25kernel%29._hash-set%21%29%29" class="RktValLink" data-pltdoc="x">hash-set!</a></span> to update an
existing mapping in <span class="RktVar">hash</span>, where the optional
<span class="RktVar">failure-result</span> argument is used as in <span class="RktSym"><a href="#%28def._%28%28quote._~23~25kernel%29._hash-ref%29%29" class="RktValLink" data-pltdoc="x">hash-ref</a></span> when
no mapping exists for <span class="RktVar">key</span> already. See the caveat above about
concurrent updates.</div></p><p>See also the <a href="#%28elem._%28caveat._concurrency%29%29" data-pltdoc="x">caveats concerning concurrent modification</a> and the <a href="#%28elem._%28caveat._mutable-keys%29%29" data-pltdoc="x">caveat concerning mutable keys</a> above.</p><p><div class="SIntrapara"><blockquote class="SVInsetFlow"><table cellspacing="0" cellpadding="0" class="boxed RBoxed"><tr><td><blockquote class="SubFlow"><div class="RBackgroundLabel SIEHidden"><div class="RBackgroundLabelInner"><p>procedure</p></div></div><p class="RForeground"><span class="RktPn">(</span><a name="(def._((lib._racket/private/more-scheme..rkt)._hash-update))"></a><span title="Provided from: racket/base, racket | Package: base"><span class="RktSym"><a href="#%28def._%28%28lib._racket%2Fprivate%2Fmore-scheme..rkt%29._hash-update%29%29" class="RktValDef RktValLink" data-pltdoc="x">hash-update</a></span></span><span class="hspace"> </span><span class="RktVar">hash</span><span class="hspace"> </span><span class="RktVar">key</span><span class="hspace"> </span><span class="RktVar">updater</span><span class="hspace"> </span>[<span class="RktVar">failure-result</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="data-structure-contracts.html#%28def._%28%28lib._racket%2Fcontract%2Fprivate%2Fmisc..rkt%29._and%2Fc%29%29" class="RktValLink" data-pltdoc="x">and/c</a></span><span class="hspace"> </span><span class="RktSym"><a href="#%28def._%28%28quote._~23~25kernel%29._hash~3f%29%29" class="RktValLink" data-pltdoc="x">hash?</a></span><span class="hspace"> </span><span class="RktSym"><a href="booleans.html#%28def._%28%28quote._~23~25kernel%29._immutable~3f%29%29" class="RktValLink" data-pltdoc="x">immutable?</a></span><span class="RktPn">)</span></td></tr><tr><td><span class="hspace"> </span><span class="RktVar">hash</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._and%2Fc%29%29" class="RktValLink" data-pltdoc="x">and/c</a></span><span class="hspace"> </span><span class="RktSym"><a href="#%28def._%28%28quote._~23~25kernel%29._hash~3f%29%29" class="RktValLink" data-pltdoc="x">hash?</a></span><span class="hspace"> </span><span class="RktSym"><a href="booleans.html#%28def._%28%28quote._~23~25kernel%29._immutable~3f%29%29" class="RktValLink" data-pltdoc="x">immutable?</a></span><span class="RktPn">)</span></td></tr><tr><td><span class="hspace"> </span><span class="RktVar">key</span><span class="hspace"> </span>:<span class="hspace"> </span><span class="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">updater</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#%28def._%28%28lib._racket%2Fcontract%2Fprivate%2Fmisc..rkt%29._any%2Fc%29%29" class="RktValLink" data-pltdoc="x">any/c</a></span><span class="RktPn">)</span></td></tr><tr><td><table cellspacing="0" cellpadding="0" class="argcontract"><tr><td><span class="hspace"> </span></td><td><span class="RktVar">failure-result</span></td><td><span class="hspace"> </span></td><td>:</td><td><span class="hspace"> </span></td><td><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></td><td><span class="hspace"> </span></td><td><span class="hspace"> </span></td><td>=</td><td><span class="hspace"> </span></td><td><table cellspacing="0" cellpadding="0" class="RktBlk"><tr><td><span class="RktPn">(</span><span class="RktSym"><a href="lambda.html#%28form._%28%28lib._racket%2Fprivate%2Fbase..rkt%29._lambda%29%29" class="RktStxLink" data-pltdoc="x">lambda</a></span><span class="hspace"> </span><span class="RktPn">(</span><span class="RktPn">)</span></td></tr><tr><td><span class="hspace"> </span><span class="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="RktPn">(</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><span class="hspace"> </span><span class="RktSym">....</span><span class="RktPn">)</span><span class="RktPn">)</span><span class="RktPn">)</span></td></tr></table></td></tr></table></td></tr></table></blockquote></div><div class="SIntrapara">Composes <span class="RktSym"><a href="#%28def._%28%28quote._~23~25kernel%29._hash-ref%29%29" class="RktValLink" data-pltdoc="x">hash-ref</a></span> and <span class="RktSym"><a href="#%28def._%28%28quote._~23~25kernel%29._hash-set%29%29" class="RktValLink" data-pltdoc="x">hash-set</a></span> to functionally
update an existing mapping in <span class="RktVar">hash</span>, where the optional
<span class="RktVar">failure-result</span> argument is used as in <span class="RktSym"><a href="#%28def._%28%28quote._~23~25kernel%29._hash-ref%29%29" class="RktValLink" data-pltdoc="x">hash-ref</a></span> when
no mapping exists for <span class="RktVar">key</span> already.</div></p><p>See also the <a href="#%28elem._%28caveat._mutable-keys%29%29" data-pltdoc="x">caveat concerning mutable keys</a> above.</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)._hash-remove!))"></a><span title="Provided from: racket/base, racket | Package: base"><span class="RktSym"><a href="#%28def._%28%28quote._~23~25kernel%29._hash-remove%21%29%29" class="RktValDef RktValLink" data-pltdoc="x">hash-remove!</a></span></span><span class="hspace"> </span><span class="RktVar">hash</span><span class="hspace"> </span><span class="RktVar">key</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></p></blockquote></td></tr><tr><td><span class="hspace"> </span><span class="RktVar">hash</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._and%2Fc%29%29" class="RktValLink" data-pltdoc="x">and/c</a></span><span class="hspace"> </span><span class="RktSym"><a href="#%28def._%28%28quote._~23~25kernel%29._hash~3f%29%29" class="RktValLink" data-pltdoc="x">hash?</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._not%2Fc%29%29" class="RktValLink" data-pltdoc="x">not/c</a></span><span class="hspace"> </span><span class="RktSym"><a href="booleans.html#%28def._%28%28quote._~23~25kernel%29._immutable~3f%29%29" class="RktValLink" data-pltdoc="x">immutable?</a></span><span class="RktPn">)</span><span class="RktPn">)</span></td></tr><tr><td><span class="hspace"> </span><span class="RktVar">key</span><span class="hspace"> </span>:<span class="hspace"> </span><span class="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">Removes any existing mapping for <span class="RktVar">key</span> in <span class="RktVar">hash</span>.</div></p><p>See also the <a href="#%28elem._%28caveat._concurrency%29%29" data-pltdoc="x">caveats concerning concurrent modification</a> and the <a href="#%28elem._%28caveat._mutable-keys%29%29" data-pltdoc="x">caveat concerning mutable keys</a> above.</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)._hash-remove))"></a><span title="Provided from: racket/base, racket | Package: base"><span class="RktSym"><a href="#%28def._%28%28quote._~23~25kernel%29._hash-remove%29%29" class="RktValDef RktValLink" data-pltdoc="x">hash-remove</a></span></span><span class="hspace"> </span><span class="RktVar">hash</span><span class="hspace"> </span><span class="RktVar">key</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._and%2Fc%29%29" class="RktValLink" data-pltdoc="x">and/c</a></span><span class="hspace"> </span><span class="RktSym"><a href="#%28def._%28%28quote._~23~25kernel%29._hash~3f%29%29" class="RktValLink" data-pltdoc="x">hash?</a></span><span class="hspace"> </span><span class="RktSym"><a href="booleans.html#%28def._%28%28quote._~23~25kernel%29._immutable~3f%29%29" class="RktValLink" data-pltdoc="x">immutable?</a></span><span class="RktPn">)</span></p></blockquote></td></tr><tr><td><span class="hspace"> </span><span class="RktVar">hash</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._and%2Fc%29%29" class="RktValLink" data-pltdoc="x">and/c</a></span><span class="hspace"> </span><span class="RktSym"><a href="#%28def._%28%28quote._~23~25kernel%29._hash~3f%29%29" class="RktValLink" data-pltdoc="x">hash?</a></span><span class="hspace"> </span><span class="RktSym"><a href="booleans.html#%28def._%28%28quote._~23~25kernel%29._immutable~3f%29%29" class="RktValLink" data-pltdoc="x">immutable?</a></span><span class="RktPn">)</span></td></tr><tr><td><span class="hspace"> </span><span class="RktVar">key</span><span class="hspace"> </span>:<span class="hspace"> </span><span class="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">Functionally removes any existing mapping for <span class="RktVar">key</span> in
<span class="RktVar">hash</span>, returning the fresh hash table.</div></p><p>See also the <a href="#%28elem._%28caveat._mutable-keys%29%29" data-pltdoc="x">caveat concerning mutable keys</a> above.</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)._hash-clear!))"></a><span title="Provided from: racket/base, racket | Package: base"><span class="RktSym"><a href="#%28def._%28%28quote._~23~25kernel%29._hash-clear%21%29%29" class="RktValDef RktValLink" data-pltdoc="x">hash-clear!</a></span></span><span class="hspace"> </span><span class="RktVar">hash</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></p></blockquote></td></tr><tr><td><span class="hspace"> </span><span class="RktVar">hash</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._and%2Fc%29%29" class="RktValLink" data-pltdoc="x">and/c</a></span><span class="hspace"> </span><span class="RktSym"><a href="#%28def._%28%28quote._~23~25kernel%29._hash~3f%29%29" class="RktValLink" data-pltdoc="x">hash?</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._not%2Fc%29%29" class="RktValLink" data-pltdoc="x">not/c</a></span><span class="hspace"> </span><span class="RktSym"><a href="booleans.html#%28def._%28%28quote._~23~25kernel%29._immutable~3f%29%29" class="RktValLink" data-pltdoc="x">immutable?</a></span><span class="RktPn">)</span><span class="RktPn">)</span></td></tr></table></blockquote></div><div class="SIntrapara">Removes all mappings from <span class="RktVar">hash</span>.</div></p><p>If <span class="RktVar">hash</span> is not an <a href="chaperones.html#%28tech._impersonator%29" class="techoutside" data-pltdoc="x"><span class="techinside">impersonator</span></a>, then all mappings are
removed in constant time. If <span class="RktVar">hash</span> is an <a href="chaperones.html#%28tech._impersonator%29" class="techoutside" data-pltdoc="x"><span class="techinside">impersonator</span></a>,
then each key is removed one-by-one using <span class="RktSym"><a href="#%28def._%28%28quote._~23~25kernel%29._hash-remove%21%29%29" class="RktValLink" data-pltdoc="x">hash-remove!</a></span>.</p><p>See also the <a href="#%28elem._%28caveat._concurrency%29%29" data-pltdoc="x">caveats concerning concurrent modification</a> and the <a href="#%28elem._%28caveat._mutable-keys%29%29" data-pltdoc="x">caveat concerning mutable keys</a> above.</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)._hash-clear))"></a><span title="Provided from: racket/base, racket | Package: base"><span class="RktSym"><a href="#%28def._%28%28quote._~23~25kernel%29._hash-clear%29%29" class="RktValDef RktValLink" data-pltdoc="x">hash-clear</a></span></span><span class="hspace"> </span><span class="RktVar">hash</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._and%2Fc%29%29" class="RktValLink" data-pltdoc="x">and/c</a></span><span class="hspace"> </span><span class="RktSym"><a href="#%28def._%28%28quote._~23~25kernel%29._hash~3f%29%29" class="RktValLink" data-pltdoc="x">hash?</a></span><span class="hspace"> </span><span class="RktSym"><a href="booleans.html#%28def._%28%28quote._~23~25kernel%29._immutable~3f%29%29" class="RktValLink" data-pltdoc="x">immutable?</a></span><span class="RktPn">)</span></p></blockquote></td></tr><tr><td><span class="hspace"> </span><span class="RktVar">hash</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._and%2Fc%29%29" class="RktValLink" data-pltdoc="x">and/c</a></span><span class="hspace"> </span><span class="RktSym"><a href="#%28def._%28%28quote._~23~25kernel%29._hash~3f%29%29" class="RktValLink" data-pltdoc="x">hash?</a></span><span class="hspace"> </span><span class="RktSym"><a href="booleans.html#%28def._%28%28quote._~23~25kernel%29._immutable~3f%29%29" class="RktValLink" data-pltdoc="x">immutable?</a></span><span class="RktPn">)</span></td></tr></table></blockquote></div><div class="SIntrapara">Functionally removes all mappings from <span class="RktVar">hash</span>.</div></p><p>If <span class="RktVar">hash</span> is not a <a href="chaperones.html#%28tech._chaperone%29" class="techoutside" data-pltdoc="x"><span class="techinside">chaperone</span></a>, then clearing is
equivalent to creating a new <a href="#%28tech._hash._table%29" class="techoutside" data-pltdoc="x"><span class="techinside">hash table</span></a>, and the operation is
performed in constant time. If <span class="RktVar">hash</span> is a <a href="chaperones.html#%28tech._chaperone%29" class="techoutside" data-pltdoc="x"><span class="techinside">chaperone</span></a>,
then each key is removed one-by-one using <span class="RktSym"><a href="#%28def._%28%28quote._~23~25kernel%29._hash-remove%29%29" class="RktValLink" data-pltdoc="x">hash-remove</a></span>.</p><p><div class="SIntrapara"><blockquote class="SVInsetFlow"><table cellspacing="0" cellpadding="0" class="boxed RBoxed"><tr><td><blockquote class="SubFlow"><div class="RBackgroundLabel SIEHidden"><div class="RBackgroundLabelInner"><p>procedure</p></div></div><p class="RForeground"><span class="RktPn">(</span><a name="(def._((lib._racket/private/base..rkt)._hash-copy-clear))"></a><span title="Provided from: racket/base, racket | Package: base"><span class="RktSym"><a href="#%28def._%28%28lib._racket%2Fprivate%2Fbase..rkt%29._hash-copy-clear%29%29" class="RktValDef RktValLink" data-pltdoc="x">hash-copy-clear</a></span></span><span class="hspace"> </span><span class="RktVar">hash</span><span class="RktPn">)</span><span class="hspace"> </span>→<span class="hspace"> </span><span class="RktSym"><a href="#%28def._%28%28quote._~23~25kernel%29._hash~3f%29%29" class="RktValLink" data-pltdoc="x">hash?</a></span></p></blockquote></td></tr><tr><td><span class="hspace"> </span><span class="RktVar">hash</span><span class="hspace"> </span>:<span class="hspace"> </span><span class="RktSym"><a href="#%28def._%28%28quote._~23~25kernel%29._hash~3f%29%29" class="RktValLink" data-pltdoc="x">hash?</a></span></td></tr></table></blockquote></div><div class="SIntrapara">Produces an empty <a href="#%28tech._hash._table%29" class="techoutside" data-pltdoc="x"><span class="techinside">hash table</span></a> with the same key-comparison
procedure and mutability of <span class="RktVar">hash</span>.</div></p><p><div class="SIntrapara"><blockquote class="SVInsetFlow"><table cellspacing="0" cellpadding="0" class="boxed RBoxed"><tr><td><blockquote class="SubFlow"><div class="RBackgroundLabel SIEHidden"><div class="RBackgroundLabelInner"><p>procedure</p></div></div><p class="RForeground"><span class="RktPn">(</span><a name="(def._((quote._~23~25kernel)._hash-map))"></a><span title="Provided from: racket/base, racket | Package: base"><span class="RktSym"><a href="#%28def._%28%28quote._~23~25kernel%29._hash-map%29%29" class="RktValDef RktValLink" data-pltdoc="x">hash-map</a></span></span><span class="hspace"> </span><span class="RktVar">hash</span><span class="hspace"> </span><span class="RktVar">proc</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._listof%29%29" class="RktValLink" data-pltdoc="x">listof</a></span><span class="hspace"> </span><span class="RktSym"><a href="data-structure-contracts.html#%28def._%28%28lib._racket%2Fcontract%2Fprivate%2Fmisc..rkt%29._any%2Fc%29%29" class="RktValLink" data-pltdoc="x">any/c</a></span><span class="RktPn">)</span></p></blockquote></td></tr><tr><td><span class="hspace"> </span><span class="RktVar">hash</span><span class="hspace"> </span>:<span class="hspace"> </span><span class="RktSym"><a href="#%28def._%28%28quote._~23~25kernel%29._hash~3f%29%29" class="RktValLink" data-pltdoc="x">hash?</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="data-structure-contracts.html#%28def._%28%28lib._racket%2Fcontract%2Fprivate%2Fmisc..rkt%29._any%2Fc%29%29" class="RktValLink" data-pltdoc="x">any/c</a></span><span class="hspace"> </span><span class="RktSym"><a href="data-structure-contracts.html#%28def._%28%28lib._racket%2Fcontract%2Fprivate%2Fmisc..rkt%29._any%2Fc%29%29" class="RktValLink" data-pltdoc="x">any/c</a></span><span class="hspace"> </span><span class="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#%28def._%28%28lib._racket%2Fcontract%2Fprivate%2Fmisc..rkt%29._any%2Fc%29%29" class="RktValLink" data-pltdoc="x">any/c</a></span><span class="RktPn">)</span></td></tr></table></blockquote></div><div class="SIntrapara">Applies the procedure <span class="RktVar">proc</span> to each element in
<span class="RktVar">hash</span> in an unspecified order, accumulating the results
into a list. The procedure <span class="RktVar">proc</span> is called each time with a
key and its value.</div></p><p>If a hash table is extended with new keys (either through
<span class="RktVar">proc</span> or by another thread) while a <span class="RktSym"><a href="#%28def._%28%28quote._~23~25kernel%29._hash-map%29%29" class="RktValLink" data-pltdoc="x">hash-map</a></span> or
<span class="RktSym"><a href="#%28def._%28%28quote._~23~25kernel%29._hash-for-each%29%29" class="RktValLink" data-pltdoc="x">hash-for-each</a></span> traversal is in process, arbitrary key–value
pairs can be dropped or duplicated in the traversal. Key mappings can
be deleted or remapped (by any thread) with no adverse affects; the
change does not affect a traversal if the key has been seen already,
otherwise the traversal skips a deleted key or uses the remapped key’s
new value.</p><p>See also the <a href="#%28elem._%28caveat._concurrency%29%29" data-pltdoc="x">caveats concerning concurrent modification</a> above.</p><p><div class="SIntrapara"><blockquote class="SVInsetFlow"><table cellspacing="0" cellpadding="0" class="boxed RBoxed"><tr><td><blockquote class="SubFlow"><div class="RBackgroundLabel SIEHidden"><div class="RBackgroundLabelInner"><p>procedure</p></div></div><p class="RForeground"><span class="RktPn">(</span><a name="(def._((lib._racket/private/base..rkt)._hash-keys))"></a><span title="Provided from: racket/base, racket | Package: base"><span class="RktSym"><a href="#%28def._%28%28lib._racket%2Fprivate%2Fbase..rkt%29._hash-keys%29%29" class="RktValDef RktValLink" data-pltdoc="x">hash-keys</a></span></span><span class="hspace"> </span><span class="RktVar">hash</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._listof%29%29" class="RktValLink" data-pltdoc="x">listof</a></span><span class="hspace"> </span><span class="RktSym"><a href="data-structure-contracts.html#%28def._%28%28lib._racket%2Fcontract%2Fprivate%2Fmisc..rkt%29._any%2Fc%29%29" class="RktValLink" data-pltdoc="x">any/c</a></span><span class="RktPn">)</span></p></blockquote></td></tr><tr><td><span class="hspace"> </span><span class="RktVar">hash</span><span class="hspace"> </span>:<span class="hspace"> </span><span class="RktSym"><a href="#%28def._%28%28quote._~23~25kernel%29._hash~3f%29%29" class="RktValLink" data-pltdoc="x">hash?</a></span></td></tr></table></blockquote></div><div class="SIntrapara">Returns a list of the keys of <span class="RktVar">hash</span> in an unspecified order.</div></p><p><div class="SIntrapara">See <span class="RktSym"><a href="#%28def._%28%28quote._~23~25kernel%29._hash-map%29%29" class="RktValLink" data-pltdoc="x">hash-map</a></span> for information about modifying <span class="RktVar">hash</span>
during <span class="RktSym"><a href="#%28def._%28%28lib._racket%2Fprivate%2Fbase..rkt%29._hash-keys%29%29" class="RktValLink" data-pltdoc="x">hash-keys</a></span>. </div><div class="SIntrapara">See also the <a href="#%28elem._%28caveat._concurrency%29%29" data-pltdoc="x">caveats concerning concurrent modification</a> above.</div></p><p><div class="SIntrapara"><blockquote class="SVInsetFlow"><table cellspacing="0" cellpadding="0" class="boxed RBoxed"><tr><td><blockquote class="SubFlow"><div class="RBackgroundLabel SIEHidden"><div class="RBackgroundLabelInner"><p>procedure</p></div></div><p class="RForeground"><span class="RktPn">(</span><a name="(def._((lib._racket/private/base..rkt)._hash-values))"></a><span title="Provided from: racket/base, racket | Package: base"><span class="RktSym"><a href="#%28def._%28%28lib._racket%2Fprivate%2Fbase..rkt%29._hash-values%29%29" class="RktValDef RktValLink" data-pltdoc="x">hash-values</a></span></span><span class="hspace"> </span><span class="RktVar">hash</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._listof%29%29" class="RktValLink" data-pltdoc="x">listof</a></span><span class="hspace"> </span><span class="RktSym"><a href="data-structure-contracts.html#%28def._%28%28lib._racket%2Fcontract%2Fprivate%2Fmisc..rkt%29._any%2Fc%29%29" class="RktValLink" data-pltdoc="x">any/c</a></span><span class="RktPn">)</span></p></blockquote></td></tr><tr><td><span class="hspace"> </span><span class="RktVar">hash</span><span class="hspace"> </span>:<span class="hspace"> </span><span class="RktSym"><a href="#%28def._%28%28quote._~23~25kernel%29._hash~3f%29%29" class="RktValLink" data-pltdoc="x">hash?</a></span></td></tr></table></blockquote></div><div class="SIntrapara">Returns a list of the values of <span class="RktVar">hash</span> in an unspecified order.</div></p><p><div class="SIntrapara">See <span class="RktSym"><a href="#%28def._%28%28quote._~23~25kernel%29._hash-map%29%29" class="RktValLink" data-pltdoc="x">hash-map</a></span> for information about modifying <span class="RktVar">hash</span>
during <span class="RktSym"><a href="#%28def._%28%28lib._racket%2Fprivate%2Fbase..rkt%29._hash-values%29%29" class="RktValLink" data-pltdoc="x">hash-values</a></span>. </div><div class="SIntrapara">See also the <a href="#%28elem._%28caveat._concurrency%29%29" data-pltdoc="x">caveats concerning concurrent modification</a> above.</div></p><p><div class="SIntrapara"><blockquote class="SVInsetFlow"><table cellspacing="0" cellpadding="0" class="boxed RBoxed"><tr><td><blockquote class="SubFlow"><div class="RBackgroundLabel SIEHidden"><div class="RBackgroundLabelInner"><p>procedure</p></div></div><p class="RForeground"><span class="RktPn">(</span><a name="(def._((lib._racket/private/base..rkt)._hash-~3elist))"></a><span title="Provided from: racket/base, racket | Package: base"><span class="RktSym"><a href="#%28def._%28%28lib._racket%2Fprivate%2Fbase..rkt%29._hash-~3elist%29%29" class="RktValDef RktValLink" data-pltdoc="x">hash->list</a></span></span><span class="hspace"> </span><span class="RktVar">hash</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._listof%29%29" class="RktValLink" data-pltdoc="x">listof</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._cons%2Fc%29%29" class="RktValLink" data-pltdoc="x">cons/c</a></span><span class="hspace"> </span><span class="RktSym"><a href="data-structure-contracts.html#%28def._%28%28lib._racket%2Fcontract%2Fprivate%2Fmisc..rkt%29._any%2Fc%29%29" class="RktValLink" data-pltdoc="x">any/c</a></span><span class="hspace"> </span><span class="RktSym"><a href="data-structure-contracts.html#%28def._%28%28lib._racket%2Fcontract%2Fprivate%2Fmisc..rkt%29._any%2Fc%29%29" class="RktValLink" data-pltdoc="x">any/c</a></span><span class="RktPn">)</span><span class="RktPn">)</span></p></blockquote></td></tr><tr><td><span class="hspace"> </span><span class="RktVar">hash</span><span class="hspace"> </span>:<span class="hspace"> </span><span class="RktSym"><a href="#%28def._%28%28quote._~23~25kernel%29._hash~3f%29%29" class="RktValLink" data-pltdoc="x">hash?</a></span></td></tr></table></blockquote></div><div class="SIntrapara">Returns a list of the key–value pairs of <span class="RktVar">hash</span> in an unspecified order.</div></p><p><div class="SIntrapara">See <span class="RktSym"><a href="#%28def._%28%28quote._~23~25kernel%29._hash-map%29%29" class="RktValLink" data-pltdoc="x">hash-map</a></span> for information about modifying <span class="RktVar">hash</span>
during <span class="RktSym"><a href="#%28def._%28%28lib._racket%2Fprivate%2Fbase..rkt%29._hash-~3elist%29%29" class="RktValLink" data-pltdoc="x">hash->list</a></span>. </div><div class="SIntrapara">See also the <a href="#%28elem._%28caveat._concurrency%29%29" data-pltdoc="x">caveats concerning concurrent modification</a> above.</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)._hash-for-each))"></a><span title="Provided from: racket/base, racket | Package: base"><span class="RktSym"><a href="#%28def._%28%28quote._~23~25kernel%29._hash-for-each%29%29" class="RktValDef RktValLink" data-pltdoc="x">hash-for-each</a></span></span><span class="hspace"> </span><span class="RktVar">hash</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></p></blockquote></td></tr><tr><td><span class="hspace"> </span><span class="RktVar">hash</span><span class="hspace"> </span>:<span class="hspace"> </span><span class="RktSym"><a href="#%28def._%28%28quote._~23~25kernel%29._hash~3f%29%29" class="RktValLink" data-pltdoc="x">hash?</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="data-structure-contracts.html#%28def._%28%28lib._racket%2Fcontract%2Fprivate%2Fmisc..rkt%29._any%2Fc%29%29" class="RktValLink" data-pltdoc="x">any/c</a></span><span class="hspace"> </span><span class="RktSym"><a href="data-structure-contracts.html#%28def._%28%28lib._racket%2Fcontract%2Fprivate%2Fmisc..rkt%29._any%2Fc%29%29" class="RktValLink" data-pltdoc="x">any/c</a></span><span class="hspace"> </span><span class="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">Applies <span class="RktVar">proc</span> to each element in <span class="RktVar">hash</span> (for the
side-effects of <span class="RktVar">proc</span>) in an unspecified order. The procedure
<span class="RktVar">proc</span> is called each time with a key and its value.</div></p><p><div class="SIntrapara">See <span class="RktSym"><a href="#%28def._%28%28quote._~23~25kernel%29._hash-map%29%29" class="RktValLink" data-pltdoc="x">hash-map</a></span> for information about modifying <span class="RktVar">hash</span>
within <span class="RktVar">proc</span>. </div><div class="SIntrapara">See also the <a href="#%28elem._%28caveat._concurrency%29%29" data-pltdoc="x">caveats concerning concurrent modification</a> above.</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)._hash-count))"></a><span title="Provided from: racket/base, racket | Package: base"><span class="RktSym"><a href="#%28def._%28%28quote._~23~25kernel%29._hash-count%29%29" class="RktValDef RktValLink" data-pltdoc="x">hash-count</a></span></span><span class="hspace"> </span><span class="RktVar">hash</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="hspace"> </span><span class="RktVar">hash</span><span class="hspace"> </span>:<span class="hspace"> </span><span class="RktSym"><a href="#%28def._%28%28quote._~23~25kernel%29._hash~3f%29%29" class="RktValLink" data-pltdoc="x">hash?</a></span></td></tr></table></blockquote></div><div class="SIntrapara">Returns the number of keys mapped by <span class="RktVar">hash</span>. Unless <span class="RktVar">hash</span>
retains keys weakly, the result is computed in
constant time and atomically. If <span class="RktVar">hash</span> retains it keys weakly, a
traversal is required to count the keys.</div></p><p><div class="SIntrapara"><blockquote class="SVInsetFlow"><table cellspacing="0" cellpadding="0" class="boxed RBoxed"><tr><td><blockquote class="SubFlow"><div class="RBackgroundLabel SIEHidden"><div class="RBackgroundLabelInner"><p>procedure</p></div></div><p class="RForeground"><span class="RktPn">(</span><a name="(def._((lib._racket/private/base..rkt)._hash-empty~3f))"></a><span title="Provided from: racket/base, racket | Package: base"><span class="RktSym"><a href="#%28def._%28%28lib._racket%2Fprivate%2Fbase..rkt%29._hash-empty~3f%29%29" class="RktValDef RktValLink" data-pltdoc="x">hash-empty?</a></span></span><span class="hspace"> </span><span class="RktVar">hash</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">hash</span><span class="hspace"> </span>:<span class="hspace"> </span><span class="RktSym"><a href="#%28def._%28%28quote._~23~25kernel%29._hash~3f%29%29" class="RktValLink" data-pltdoc="x">hash?</a></span></td></tr></table></blockquote></div><div class="SIntrapara">Equivalent to <span class="RktPn">(</span><span class="RktSym"><a href="number-types.html#%28def._%28%28quote._~23~25kernel%29._zero~3f%29%29" class="RktValLink" data-pltdoc="x">zero?</a></span><span class="stt"> </span><span class="RktPn">(</span><span class="RktSym"><a href="#%28def._%28%28quote._~23~25kernel%29._hash-count%29%29" class="RktValLink" data-pltdoc="x">hash-count</a></span><span class="stt"> </span><span class="RktVar">hash</span><span class="RktPn">)</span><span class="RktPn">)</span>.</div></p><p><div class="SIntrapara"><blockquote class="SVInsetFlow"><table cellspacing="0" cellpadding="0" class="boxed RBoxed"><tr><td><blockquote class="SubFlow"><div class="RBackgroundLabel SIEHidden"><div class="RBackgroundLabelInner"><p>procedure</p></div></div><p class="RForeground"><span class="RktPn">(</span><a name="(def._((quote._~23~25kernel)._hash-iterate-first))"></a><span title="Provided from: racket/base, racket | Package: base"><span class="RktSym"><a href="#%28def._%28%28quote._~23~25kernel%29._hash-iterate-first%29%29" class="RktValDef RktValLink" data-pltdoc="x">hash-iterate-first</a></span></span><span class="hspace"> </span><span class="RktVar">hash</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="data-structure-contracts.html#%28def._%28%28lib._racket%2Fcontract%2Fbase..rkt%29._or%2Fc%29%29" class="RktValLink" data-pltdoc="x">or/c</a></span><span class="hspace"> </span><span class="RktVal">#f</span><span class="hspace"> </span><span class="RktSym"><a href="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="RktPn">)</span></td></tr><tr><td><span class="hspace"> </span><span class="RktVar">hash</span><span class="hspace"> </span>:<span class="hspace"> </span><span class="RktSym"><a href="#%28def._%28%28quote._~23~25kernel%29._hash~3f%29%29" class="RktValLink" data-pltdoc="x">hash?</a></span></td></tr></table></blockquote></div><div class="SIntrapara">Returns <span class="RktVal">#f</span> if <span class="RktVar">hash</span> contains no elements, otherwise
it returns an integer that is an index to the first element in the hash
table; “first” refers to an unspecified ordering of the table
elements, and the index values are not necessarily consecutive
integers. For a mutable <span class="RktVar">hash</span>, this index is guaranteed to
refer to the first item only as long as no items are added to or
removed from <span class="RktVar">hash</span>.</div></p><p><div class="SIntrapara"><blockquote class="SVInsetFlow"><table cellspacing="0" cellpadding="0" class="boxed RBoxed"><tr><td><blockquote class="SubFlow"><div class="RBackgroundLabel SIEHidden"><div class="RBackgroundLabelInner"><p>procedure</p></div></div><p class="RForeground"><span class="RktPn">(</span><a name="(def._((quote._~23~25kernel)._hash-iterate-next))"></a><span title="Provided from: racket/base, racket | Package: base"><span class="RktSym"><a href="#%28def._%28%28quote._~23~25kernel%29._hash-iterate-next%29%29" class="RktValDef RktValLink" data-pltdoc="x">hash-iterate-next</a></span></span><span class="hspace"> </span><span class="RktVar">hash</span><span class="hspace"> </span><span class="RktVar">pos</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="data-structure-contracts.html#%28def._%28%28lib._racket%2Fcontract%2Fbase..rkt%29._or%2Fc%29%29" class="RktValLink" data-pltdoc="x">or/c</a></span><span class="hspace"> </span><span class="RktVal">#f</span><span class="hspace"> </span><span class="RktSym"><a href="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="RktPn">)</span></td></tr><tr><td><span class="hspace"> </span><span class="RktVar">hash</span><span class="hspace"> </span>:<span class="hspace"> </span><span class="RktSym"><a href="#%28def._%28%28quote._~23~25kernel%29._hash~3f%29%29" class="RktValLink" data-pltdoc="x">hash?</a></span></td></tr><tr><td><span class="hspace"> </span><span class="RktVar">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-integer?</a></span></td></tr></table></blockquote></div><div class="SIntrapara">Returns either an integer that is an index to the element in
<span class="RktVar">hash</span> after the element indexed by <span class="RktVar">pos</span> (which is not
necessarily one more than <span class="RktVar">pos</span>) or <span class="RktVal">#f</span> if <span class="RktVar">pos</span>
refers to the last element in <span class="RktVar">hash</span>. If <span class="RktVar">pos</span> is not a
valid index, then 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. For a mutable
<span class="RktVar">hash</span>, the result index is guaranteed to refer to its item
only as long as no items are added to or removed from <span class="RktVar">hash</span>.</div></p><p><div class="SIntrapara"><blockquote class="SVInsetFlow"><table cellspacing="0" cellpadding="0" class="boxed RBoxed"><tr><td><blockquote class="SubFlow"><div class="RBackgroundLabel SIEHidden"><div class="RBackgroundLabelInner"><p>procedure</p></div></div><p class="RForeground"><span class="RktPn">(</span><a name="(def._((quote._~23~25kernel)._hash-iterate-key))"></a><span title="Provided from: racket/base, racket | Package: base"><span class="RktSym"><a href="#%28def._%28%28quote._~23~25kernel%29._hash-iterate-key%29%29" class="RktValDef RktValLink" data-pltdoc="x">hash-iterate-key</a></span></span><span class="hspace"> </span><span class="RktVar">hash</span><span class="hspace"> </span><span class="RktVar">pos</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">hash</span><span class="hspace"> </span>:<span class="hspace"> </span><span class="RktSym"><a href="#%28def._%28%28quote._~23~25kernel%29._hash~3f%29%29" class="RktValLink" data-pltdoc="x">hash?</a></span></td></tr><tr><td><span class="hspace"> </span><span class="RktVar">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-integer?</a></span></td></tr></table></blockquote></div><div class="SIntrapara">Returns the key for the element in <span class="RktVar">hash</span> at index
<span class="RktVar">pos</span>. If <span class="RktVar">pos</span> is not a valid index for
<span class="RktVar">hash</span>, 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.</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)._hash-iterate-value))"></a><span title="Provided from: racket/base, racket | Package: base"><span class="RktSym"><a href="#%28def._%28%28quote._~23~25kernel%29._hash-iterate-value%29%29" class="RktValDef RktValLink" data-pltdoc="x">hash-iterate-value</a></span></span><span class="hspace"> </span><span class="RktVar">hash</span><span class="hspace"> </span><span class="RktVar">pos</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">hash</span><span class="hspace"> </span>:<span class="hspace"> </span><span class="RktSym"><a href="#%28def._%28%28quote._~23~25kernel%29._hash~3f%29%29" class="RktValLink" data-pltdoc="x">hash?</a></span></td></tr><tr><td><span class="hspace"> </span><span class="RktVar">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-integer?</a></span></td></tr></table></blockquote></div><div class="SIntrapara">Returns the value for the element in <span class="RktVar">hash</span> at index
<span class="RktVar">pos</span>. If <span class="RktVar">pos</span> is not a valid index for
<span class="RktVar">hash</span>, 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.</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)._hash-copy))"></a><span title="Provided from: racket/base, racket | Package: base"><span class="RktSym"><a href="#%28def._%28%28quote._~23~25kernel%29._hash-copy%29%29" class="RktValDef RktValLink" data-pltdoc="x">hash-copy</a></span></span><span class="hspace"> </span><span class="RktVar">hash</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._and%2Fc%29%29" class="RktValLink" data-pltdoc="x">and/c</a></span><span class="hspace"> </span><span class="RktSym"><a href="#%28def._%28%28quote._~23~25kernel%29._hash~3f%29%29" class="RktValLink" data-pltdoc="x">hash?</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._not%2Fc%29%29" class="RktValLink" data-pltdoc="x">not/c</a></span><span class="hspace"> </span><span class="RktSym"><a href="booleans.html#%28def._%28%28quote._~23~25kernel%29._immutable~3f%29%29" class="RktValLink" data-pltdoc="x">immutable?</a></span><span class="RktPn">)</span><span class="RktPn">)</span></p></blockquote></td></tr><tr><td><span class="hspace"> </span><span class="RktVar">hash</span><span class="hspace"> </span>:<span class="hspace"> </span><span class="RktSym"><a href="#%28def._%28%28quote._~23~25kernel%29._hash~3f%29%29" class="RktValLink" data-pltdoc="x">hash?</a></span></td></tr></table></blockquote></div><div class="SIntrapara">Returns a mutable hash table with the same mappings, same
key-comparison mode, and same key-holding strength as <span class="RktVar">hash</span>.</div></p><p><div class="SIntrapara"><blockquote class="SVInsetFlow"><table cellspacing="0" cellpadding="0" class="boxed RBoxed"><tr><td><blockquote class="SubFlow"><div class="RBackgroundLabel SIEHidden"><div class="RBackgroundLabelInner"><p>procedure</p></div></div><p class="RForeground"><span class="RktPn">(</span><a name="(def._((quote._~23~25kernel)._eq-hash-code))"></a><span title="Provided from: racket/base, racket | Package: base"><span class="RktSym"><a href="#%28def._%28%28quote._~23~25kernel%29._eq-hash-code%29%29" class="RktValDef RktValLink" data-pltdoc="x">eq-hash-code</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="number-types.html#%28def._%28%28quote._~23~25kernel%29._fixnum~3f%29%29" class="RktValLink" data-pltdoc="x">fixnum?</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 a <a href="numbers.html#%28tech._fixnum%29" class="techoutside" data-pltdoc="x"><span class="techinside">fixnum</span></a>; for any two calls with <span class="RktSym"><a href="booleans.html#%28def._%28%28quote._~23~25kernel%29._eq~3f%29%29" class="RktValLink" data-pltdoc="x">eq?</a></span> values,
the returned number is the same.</div></p><blockquote class="refpara"><blockquote class="refcolumn"><blockquote class="refcontent"><p>Equal <a href="numbers.html#%28tech._fixnum%29" class="techoutside" data-pltdoc="x"><span class="techinside">fixnums</span></a> are always <span class="RktSym"><a href="booleans.html#%28def._%28%28quote._~23~25kernel%29._eq~3f%29%29" class="RktValLink" data-pltdoc="x">eq?</a></span>.</p></blockquote></blockquote></blockquote><p><div class="SIntrapara"><blockquote class="SVInsetFlow"><table cellspacing="0" cellpadding="0" class="boxed RBoxed"><tr><td><blockquote class="SubFlow"><div class="RBackgroundLabel SIEHidden"><div class="RBackgroundLabelInner"><p>procedure</p></div></div><p class="RForeground"><span class="RktPn">(</span><a name="(def._((quote._~23~25kernel)._eqv-hash-code))"></a><span title="Provided from: racket/base, racket | Package: base"><span class="RktSym"><a href="#%28def._%28%28quote._~23~25kernel%29._eqv-hash-code%29%29" class="RktValDef RktValLink" data-pltdoc="x">eqv-hash-code</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="number-types.html#%28def._%28%28quote._~23~25kernel%29._fixnum~3f%29%29" class="RktValLink" data-pltdoc="x">fixnum?</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 a <a href="numbers.html#%28tech._fixnum%29" class="techoutside" data-pltdoc="x"><span class="techinside">fixnum</span></a>; for any two calls with <span class="RktSym"><a href="booleans.html#%28def._%28%28quote._~23~25kernel%29._eqv~3f%29%29" class="RktValLink" data-pltdoc="x">eqv?</a></span> values,
the returned number is the same.</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)._equal-hash-code))"></a><span title="Provided from: racket/base, racket | Package: base"><span class="RktSym"><a href="#%28def._%28%28quote._~23~25kernel%29._equal-hash-code%29%29" class="RktValDef RktValLink" data-pltdoc="x">equal-hash-code</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="number-types.html#%28def._%28%28quote._~23~25kernel%29._fixnum~3f%29%29" class="RktValLink" data-pltdoc="x">fixnum?</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 a <a href="numbers.html#%28tech._fixnum%29" class="techoutside" data-pltdoc="x"><span class="techinside">fixnum</span></a>; for any two calls with <span class="RktSym"><a href="booleans.html#%28def._%28%28quote._~23~25kernel%29._equal~3f%29%29" class="RktValLink" data-pltdoc="x">equal?</a></span> values,
the returned number is the same. A hash code is computed even when
<span class="RktVar">v</span> contains a cycle through pairs, vectors, boxes, and/or
inspectable structure fields. See also <span class="RktSym"><a href="booleans.html#%28def._%28%28lib._racket%2Fprivate%2Fbase..rkt%29._gen~3aequal%2Bhash%29%29" class="RktValLink" data-pltdoc="x">gen:equal+hash</a></span>.</div></p><p><div class="SIntrapara"><blockquote class="SVInsetFlow"><table cellspacing="0" cellpadding="0" class="boxed RBoxed"><tr><td><blockquote class="SubFlow"><div class="RBackgroundLabel SIEHidden"><div class="RBackgroundLabelInner"><p>procedure</p></div></div><p class="RForeground"><span class="RktPn">(</span><a name="(def._((quote._~23~25kernel)._equal-secondary-hash-code))"></a><span title="Provided from: racket/base, racket | Package: base"><span class="RktSym"><a href="#%28def._%28%28quote._~23~25kernel%29._equal-secondary-hash-code%29%29" class="RktValDef RktValLink" data-pltdoc="x">equal-secondary-hash-code</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="number-types.html#%28def._%28%28quote._~23~25kernel%29._fixnum~3f%29%29" class="RktValLink" data-pltdoc="x">fixnum?</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">Like <span class="RktSym"><a href="#%28def._%28%28quote._~23~25kernel%29._equal-hash-code%29%29" class="RktValLink" data-pltdoc="x">equal-hash-code</a></span>, but computes a secondary value suitable
for use in double hashing.</div></p><div class="navsetbottom"><span class="navleft"><form class="searchform"><input class="searchbox" style="color: #888;" type="text" value="...search manuals..." title="Enter a search string to search the manuals" onkeypress="return DoSearchKey(event, this, "6.1", "../");" onfocus="this.style.color="black"; this.style.textAlign="left"; if (this.value == "...search manuals...") this.value="";" onblur="if (this.value.match(/^ *$/)) { this.style.color="#888"; this.style.textAlign="center"; this.value="...search manuals..."; }"/></form> <a href="../index.html" title="up to the documentation top" data-pltdoc="x" onclick="return GotoPLTRoot("6.1");">top</a></span><span class="navright"> <a href="boxes.html" title="backward to "4.12 Boxes"" data-pltdoc="x">← prev</a> <a href="data.html" title="up to "4 Datatypes"" data-pltdoc="x">up</a> <a href="sequences_streams.html" title="forward to "4.14 Sequences and Streams"" data-pltdoc="x">next →</a></span> </div></div></div><div id="contextindicator"> </div></body></html>
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