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<html><head><meta http-equiv="content-type" content="text/html; charset=utf-8"/><meta name="viewport" content="width=device-width, initial-scale=0.8"/><title>4.15 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">The Racket Reference</a></td></tr></table></div><div class="tocviewsublisttop" style="display: none;" id="tocview_0"><table cellspacing="0" cellpadding="0"><tr><td align="right">1 </td><td><a href="model.html" class="tocviewlink" data-pltdoc="x">Language Model</a></td></tr><tr><td align="right">2 </td><td><a href="notation.html" class="tocviewlink" data-pltdoc="x">Notation for Documentation</a></td></tr><tr><td align="right">3 </td><td><a href="syntax.html" class="tocviewlink" data-pltdoc="x">Syntactic Forms</a></td></tr><tr><td align="right">4 </td><td><a href="data.html" class="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><
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keys to a single value. For a given hash table, keys are equivalent
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via <span class="RktSym"><a href="Equality.html#%28def._%28%28quote._~23~25kernel%29._equal~3f%29%29" class="RktValLink" data-pltdoc="x">equal?</a></span>, <span class="RktSym"><a href="Equality.html#%28def._%28%28quote._~23~25kernel%29._equal-always~3f%29%29" class="RktValLink" data-pltdoc="x">equal-always?</a></span>, <span class="RktSym"><a href="Equality.html#%28def._%28%28quote._~23~25kernel%29._eqv~3f%29%29" class="RktValLink" data-pltdoc="x">eqv?</a></span>, or
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<span class="RktSym"><a href="Equality.html#%28def._%28%28quote._~23~25kernel%29._eq~3f%29%29" class="RktValLink" data-pltdoc="x">eq?</a></span>, and keys are retained either strongly, weakly
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(see <a href="weakbox.html" data-pltdoc="x">Weak Boxes</a>), or like <a href="ephemerons.html#%28tech._ephemeron%29" class="techoutside" data-pltdoc="x"><span class="techinside">ephemerons</span></a>.
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A hash table is also either mutable or immutable.
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Immutable hash tables support effectively constant-time access and
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update, just like mutable hash tables; the constant on immutable
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operations is usually larger, but the functional nature of immutable
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hash tables can pay off in certain algorithms. Use <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>
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to check whether a hash table is immutable.</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>
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access and update. Since <span style="font-style: italic">N</span> is limited by the address space so
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that <span style="font-style: italic">log N</span> is limited to less than 30 or 62 (depending on the
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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="Equality.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
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<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>,
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<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
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proportional to the size of the value. The hash code for a compound
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data structure, such as a list or vector, depends on hashing each item
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of the container, but the depth of such recursive hashing is
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limited (to avoid potential problems with cyclic data). For a
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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>
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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
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<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
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<a href="sequences.html" data-pltdoc="x">Sequences</a>). The keys and values of the hash table serve as
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elements of the sequence (i.e., each element is a key and its
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associated value). If a mapping is added to or removed from the hash
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table during iteration, then an iteration step may fail with
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<span class="RktSym"><a href="exns.html#%28def._%28%28lib._racket%2Fprivate%2Fbase..rkt%29._exn~3afail~3acontract%29%29" class="RktValLink" data-pltdoc="x">exn:fail:contract</a></span>, or the iteration may skip or duplicate
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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>,
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<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="Equality.html#%28def._%28%28quote._~23~25kernel%29._equal~3f%29%29" class="RktValLink" data-pltdoc="x">equal?</a></span> unless they have the same
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mutability, use the same key-comparison procedure (<span class="RktSym"><a href="Equality.html#%28def._%28%28quote._~23~25kernel%29._equal~3f%29%29" class="RktValLink" data-pltdoc="x">equal?</a></span>,
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<span class="RktSym"><a href="Equality.html#%28def._%28%28quote._~23~25kernel%29._equal-always~3f%29%29" class="RktValLink" data-pltdoc="x">equal-always?</a></span>, <span class="RktSym"><a href="Equality.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="Equality.html#%28def._%28%28quote._~23~25kernel%29._eq~3f%29%29" class="RktValLink" data-pltdoc="x">eq?</a></span>), both hold
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keys strongly, weakly, or like <a href="ephemerons.html#%28tech._ephemeron%29" class="techoutside" data-pltdoc="x"><span class="techinside">ephemerons</span></a>.
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Empty immutable hash tables are <span class="RktSym"><a href="Equality.html#%28def._%28%28quote._~23~25kernel%29._eq~3f%29%29" class="RktValLink" data-pltdoc="x">eq?</a></span>
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when they are <span class="RktSym"><a href="Equality.html#%28def._%28%28quote._~23~25kernel%29._equal~3f%29%29" class="RktValLink" data-pltdoc="x">equal?</a></span>.</p><p class="SHistory">Changed in version 7.2.0.9 of package <span class="stt">base</span>: Made empty immutable hash tables
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<span class="RktSym"><a href="Equality.html#%28def._%28%28quote._~23~25kernel%29._eq~3f%29%29" class="RktValLink" data-pltdoc="x">eq?</a></span> when they are
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<span class="RktSym"><a href="Equality.html#%28def._%28%28quote._~23~25kernel%29._equal~3f%29%29" class="RktValLink" data-pltdoc="x">equal?</a></span>.</p><p><a name="(elem._(caveat._concurrency))"></a><span style="font-weight: bold">Caveats concerning concurrent
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modification:</span> A mutable hash table can be manipulated with
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<span class="RktSym"><a href="hashtables.html#%28def._%28%28quote._~23~25kernel%29._hash-ref%29%29" class="RktValLink" data-pltdoc="x">hash-ref</a></span>, <span class="RktSym"><a href="hashtables.html#%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="hashtables.html#%28def._%28%28quote._~23~25kernel%29._hash-remove%21%29%29" class="RktValLink" data-pltdoc="x">hash-remove!</a></span>
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concurrently by multiple threads, and the operations are protected by
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a table-specific semaphore as needed. Several caveats apply, however:</p><ul><li><p>If a thread is terminated while applying <span class="RktSym"><a href="hashtables.html#%28def._%28%28quote._~23~25kernel%29._hash-ref%29%29" class="RktValLink" data-pltdoc="x">hash-ref</a></span>,
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<span class="RktSym"><a href="hashtables.html#%28def._%28%28quote._~23~25kernel%29._hash-ref-key%29%29" class="RktValLink" data-pltdoc="x">hash-ref-key</a></span>, <span class="RktSym"><a href="hashtables.html#%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="hashtables.html#%28def._%28%28quote._~23~25kernel%29._hash-remove%21%29%29" class="RktValLink" data-pltdoc="x">hash-remove!</a></span>,
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<span class="RktSym"><a href="hashtables.html#%28def._%28%28lib._racket%2Fprivate%2Fmore-scheme..rkt%29._hash-ref%21%29%29" class="RktValLink" data-pltdoc="x">hash-ref!</a></span>, <span class="RktSym"><a href="hashtables.html#%28def._%28%28lib._racket%2Fprivate%2Fmore-scheme..rkt%29._hash-update%21%29%29" class="RktValLink" data-pltdoc="x">hash-update!</a></span>, or <span class="RktSym"><a href="hashtables.html#%28def._%28%28quote._~23~25kernel%29._hash-clear%21%29%29" class="RktValLink" data-pltdoc="x">hash-clear!</a></span>
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to a hash table that
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uses <span class="RktSym"><a href="Equality.html#%28def._%28%28quote._~23~25kernel%29._equal~3f%29%29" class="RktValLink" data-pltdoc="x">equal?</a></span>, <span class="RktSym"><a href="Equality.html#%28def._%28%28quote._~23~25kernel%29._equal-always~3f%29%29" class="RktValLink" data-pltdoc="x">equal-always?</a></span>, or <span class="RktSym"><a href="Equality.html#%28def._%28%28quote._~23~25kernel%29._eqv~3f%29%29" class="RktValLink" data-pltdoc="x">eqv?</a></span> key
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comparisons, all current and future operations on the hash table may
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block indefinitely.</p></li><li><p>The <span class="RktSym"><a href="hashtables.html#%28def._%28%28quote._~23~25kernel%29._hash-map%29%29" class="RktValLink" data-pltdoc="x">hash-map</a></span>, <span class="RktSym"><a href="hashtables.html#%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="hashtables.html#%28def._%28%28quote._~23~25kernel%29._hash-clear%21%29%29" class="RktValLink" data-pltdoc="x">hash-clear!</a></span> procedures do
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not use the table’s semaphore to guard the traversal as a whole
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(if a traversal is needed, in the case of <span class="RktSym"><a href="hashtables.html#%28def._%28%28quote._~23~25kernel%29._hash-clear%21%29%29" class="RktValLink" data-pltdoc="x">hash-clear!</a></span>).
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Changes by one thread to a hash table can affect the keys and values
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seen by another thread part-way through its traversal of the same
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hash table.</p></li><li><p>The <span class="RktSym"><a href="hashtables.html#%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="hashtables.html#%28def._%28%28lib._racket%2Fprivate%2Fmore-scheme..rkt%29._hash-ref%21%29%29" class="RktValLink" data-pltdoc="x">hash-ref!</a></span> functions
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use a table’s semaphore
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independently for the <span class="RktSym"><a href="hashtables.html#%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="hashtables.html#%28def._%28%28quote._~23~25kernel%29._hash-set%21%29%29" class="RktValLink" data-pltdoc="x">hash-set!</a></span> parts
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of their functionality, which means that the update as a whole is not
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“atomic.”</p></li><li><p>Adding a mutable hash table as a key in itself is trouble on
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the grounds that the key is being mutated (see the caveat below),
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but it is also a kind of concurrent use of the hash table: computing
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a hash table’s hash code may require waiting on the table’s
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semaphore, but the semaphore is already held for modifying the hash
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table, so the hash-table addition can block indefinitely.</p></li></ul><p><a name="(elem._(caveat._mutable-keys))"></a><span style="font-weight: bold">Caveat concerning mutable
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keys:</span> If a key in an <span class="RktSym"><a href="Equality.html#%28def._%28%28quote._~23~25kernel%29._equal~3f%29%29" class="RktValLink" data-pltdoc="x">equal?</a></span>-based hash table is mutated
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(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
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hash table’s behavior for insertion and lookup operations becomes
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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>,
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<span class="RktInBG"><span class="hspace"></span><span class="RktIn">#hashalw</span><span class="hspace"></span></span>, <span class="RktInBG"><span class="hspace"></span><span class="RktIn">#hasheqv</span><span class="hspace"></span></span>, or
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<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>
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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
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hash tables and <a href="printing.html#%28part._print-hashtable%29" data-pltdoc="x">Printing Hash Tables</a>
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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="hashtables.html#%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="hashtables.html#%28tech._hash._table%29" class="techoutside" data-pltdoc="x"><span class="techinside">hash table</span></a>, <span class="RktVal">#f</span>
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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="hashtables.html#%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="hashtables.html#%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="Equality.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="Equality.html#%28def._%28%28quote._~23~25kernel%29._eq~3f%29%29" class="RktValLink" data-pltdoc="x">eq?</a></span>, <span class="RktSym"><a href="Equality.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="Equality.html#%28def._%28%28quote._~23~25kernel%29._equal-always~3f%29%29" class="RktValLink" data-pltdoc="x">equal-always?</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-equal-always~3f))"></a><span title="Provided from: racket/base, racket | Package: base"><span class="RktSym"><a href="hashtables.html#%28def._%28%28quote._~23~25kernel%29._hash-equal-always~3f%29%29" class="RktValDef RktValLink" data-pltdoc="x">hash-equal-always?</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="hashtables.html#%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="Equality.html#%28def._%28%28quote._~23~25kernel%29._equal-always~3f%29%29" class="RktValLink" data-pltdoc="x">equal-always?</a></span>, <span class="RktVal">#f</span> if it compares with <span class="RktSym"><a href="Equality.html#%28def._%28%28quote._~23~25kernel%29._eq~3f%29%29" class="RktValLink" data-pltdoc="x">eq?</a></span>,
|
||
|
|
<span class="RktSym"><a href="Equality.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="Equality.html#%28def._%28%28quote._~23~25kernel%29._equal~3f%29%29" class="RktValLink" data-pltdoc="x">equal?</a></span>.</div></p><p class="SHistory">Added in version 8.5.0.3 of package <span class="stt">base</span>.</p><p><div class="SIntrapara"><blockquote class="SVInsetFlow"><table cellspacing="0" cellpadding="0" class="boxed RBoxed"><tr><td><blockquote class="SubFlow"><div class="RBackgroundLabel SIEHidden"><div class="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="hashtables.html#%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="hashtables.html#%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="Equality.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="Equality.html#%28def._%28%28quote._~23~25kernel%29._equal~3f%29%29" class="RktValLink" data-pltdoc="x">equal?</a></span>,
|
||
|
|
<span class="RktSym"><a href="Equality.html#%28def._%28%28quote._~23~25kernel%29._equal-always~3f%29%29" class="RktValLink" data-pltdoc="x">equal-always?</a></span>, or <span class="RktSym"><a href="Equality.html#%28def._%28%28quote._~23~25kernel%29._eq~3f%29%29" class="RktValLink" data-pltdoc="x">eq?</a></span>.</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="hashtables.html#%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="hashtables.html#%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="Equality.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="Equality.html#%28def._%28%28quote._~23~25kernel%29._equal~3f%29%29" class="RktValLink" data-pltdoc="x">equal?</a></span>,
|
||
|
|
<span class="RktSym"><a href="Equality.html#%28def._%28%28quote._~23~25kernel%29._equal-always~3f%29%29" class="RktValLink" data-pltdoc="x">equal-always?</a></span>, or <span class="RktSym"><a href="Equality.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-strong~3f))"></a><span title="Provided from: racket/base, racket | Package: base"><span class="RktSym"><a href="hashtables.html#%28def._%28%28quote._~23~25kernel%29._hash-strong~3f%29%29" class="RktValDef RktValLink" data-pltdoc="x">hash-strong?</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="hashtables.html#%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 strongly,
|
||
|
|
<span class="RktVal">#f</span> if it retains keys weakly or like <a href="ephemerons.html#%28tech._ephemeron%29" class="techoutside" data-pltdoc="x"><span class="techinside">ephemerons</span></a>.</div></p><p class="SHistory">Added in version 8.0.0.10 of package <span class="stt">base</span>.</p><p><div class="SIntrapara"><blockquote class="SVInsetFlow"><table cellspacing="0" cellpadding="0" class="boxed RBoxed"><tr><td><blockquote class="SubFlow"><div class="RBackgroundLabel SIEHidden"><div class="RBackgroundLabelInner"><p>procedure</p></div></div><p class="RForeground"><span class="RktPn">(</span><a name="(def._((quote._~23~25kernel)._hash-weak~3f))"></a><span title="Provided from: racket/base, racket | Package: base"><span class="RktSym"><a href="hashtables.html#%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="hashtables.html#%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 or like <a href="ephemerons.html#%28tech._ephemeron%29" class="techoutside" data-pltdoc="x"><span class="techinside">ephemerons</span></a>.</div></p><p><div class="SIntrapara"><blockquote class="SVInsetFlow"><table cellspacing="0" cellpadding="0" class="boxed RBoxed"><tr><td><blockquote class="SubFlow"><div class="RBackgroundLabel SIEHidden"><div class="RBackgroundLabelInner"><p>procedure</p></div></div><p class="RForeground"><span class="RktPn">(</span><a name="(def._((quote._~23~25kernel)._hash-ephemeron~3f))"></a><span title="Provided from: racket/base, racket | Package: base"><span class="RktSym"><a href="hashtables.html#%28def._%28%28quote._~23~25kernel%29._hash-ephemeron~3f%29%29" class="RktValDef RktValLink" data-pltdoc="x">hash-ephemeron?</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="hashtables.html#%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 like
|
||
|
|
<a href="ephemerons.html#%28tech._ephemeron%29" class="techoutside" data-pltdoc="x"><span class="techinside">ephemerons</span></a>, <span class="RktVal">#f</span> if it retains keys strongly or merely
|
||
|
|
weakly.</div></p><p class="SHistory">Added in version 8.0.0.10 of package <span class="stt">base</span>.</p><p><div class="SIntrapara"><blockquote class="SVInsetFlow"><table cellspacing="0" cellpadding="0" class="boxed RBoxed"><tr><td><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="hashtables.html#%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></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._and%2Fc%29%29" class="RktValLink" data-pltdoc="x">and/c</a></span><span class="hspace"> </span><span class="RktSym"><a href="hashtables.html#%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="hashtables.html#%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="hspace"> </span><span class="RktSym"><a href="hashtables.html#%28def._%28%28quote._~23~25kernel%29._hash-strong~3f%29%29" class="RktValLink" data-pltdoc="x">hash-strong?</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">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)._hashalw))"></a><span title="Provided from: racket/base, racket | Package: base"><span class="RktSym"><a href="hashtables.html#%28def._%28%28quote._~23~25kernel%29._hashalw%29%29" class="RktValDef RktValLink" data-pltdoc="x">hashalw</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></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._and%2Fc%29%29" class="RktValLink" data-pltdoc="x">and/c</a></span><span class="hspace"> </span><span class="RktSym"><a hre
|
||
|
|
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="hashtables.html#%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="hashtables.html#%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="Equality.html#%28def._%28%28quote._~23~25kernel%29._equal~3f%29%29" class="RktValLink" data-pltdoc="x">equal?</a></span>, <span class="RktSym"><a href="hashtables.html#%28def._%28%28quote._~23~25kernel%29._hashalw%29%29" class="RktValLink" data-pltdoc="x">hashalw</a></span> creates a table where keys are compared with
|
||
|
|
<span class="RktSym"><a href="Equality.html#%28def._%28%28quote._~23~25kernel%29._equal-always~3f%29%29" class="RktValLink" data-pltdoc="x">equal-always?</a></span>, <span class="RktSym"><a href="hashtables.html#%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="Equality.html#%28def._%28%28quote._~23~25kernel%29._eq~3f%29%29" class="RktValLink" data-pltdoc="x">eq?</a></span>, <span class="RktSym"><a href="hashtables.html#%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="Equality.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 class="SHistory">Changed in version 8.5.0.3 of package <span class="stt">base</span>: Added <span class="RktSym"><a href="hashtables.html#%28def._%28%28quote._~23~25kernel%29._hashalw%29%29" class="RktValLink" data-pltdoc="x">hashalw</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-hash))"></a><span title="Provided from: racket/base, racket | Package: base"><span class="RktSym"><a href="hashtables.html#%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="RktOpt">[</span><span class="RktVar">assocs</span><span class="RktOpt">]</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._and%2Fc%29%29" class="RktValLink" data-pltdoc="x">and/c</a></span><span class="hspace"> </span><span class="RktSym"><a href="hashtables.html#%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="hashtables.html#%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="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="hspace"> </span><span class="RktSym"><a href="hashtables.html#%28def._%28%28quote._~23~25kernel%29._hash-strong~3f%29%29" class="RktValLink" data-pltdoc="x">hash-strong?</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%2Fbase..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-hashalw))"></a><span title="Provided from: racket/base, racket | Package: base"><span class="RktSym"><a href="hashtables.html#%28def._%28%28quote._~23~25kernel%29._make-hashalw%29%29" class="RktValDef RktValLink" data-pltdoc="x">make-hashalw</a></span></span><span class="hspace"> </span><span class="RktOpt">[</span><span class="RktVar">assocs</span><span class="RktOpt">]</span><span class="RktPn">)</span></p></blockquote></td></tr><t
|
||
|
|
compared with <span class="RktSym"><a href="Equality.html#%28def._%28%28quote._~23~25kernel%29._equal~3f%29%29" class="RktValLink" data-pltdoc="x">equal?</a></span>, <span class="RktSym"><a href="hashtables.html#%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="Equality.html#%28def._%28%28quote._~23~25kernel%29._eq~3f%29%29" class="RktValLink" data-pltdoc="x">eq?</a></span>,
|
||
|
|
<span class="RktSym"><a href="hashtables.html#%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="Equality.html#%28def._%28%28quote._~23~25kernel%29._eqv~3f%29%29" class="RktValLink" data-pltdoc="x">eqv?</a></span>, and <span class="RktSym"><a href="hashtables.html#%28def._%28%28quote._~23~25kernel%29._make-hashalw%29%29" class="RktValLink" data-pltdoc="x">make-hashalw</a></span> creates a table
|
||
|
|
where keys are compared with <span class="RktSym"><a href="Equality.html#%28def._%28%28quote._~23~25kernel%29._equal-always~3f%29%29" class="RktValLink" data-pltdoc="x">equal-always?</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 class="SHistory">Changed in version 8.5.0.3 of package <span class="stt">base</span>: Added <span class="RktSym"><a href="hashtables.html#%28def._%28%28quote._~23~25kernel%29._make-hashalw%29%29" class="RktValLink" data-pltdoc="x">make-hashalw</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="hashtables.html#%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="RktOpt">[</span><span class="RktVar">assocs</span><span class="RktOpt">]</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._and%2Fc%29%29" class="RktValLink" data-pltdoc="x">and/c</a></span><span class="hspace"> </span><span class="RktSym"><a href="hashtables.html#%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="hashtables.html#%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="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="hspace"> </span><span class="RktSym"><a href="hashtables.html#%28def._%28%28quote._~23~25kernel%29._hash-weak~3f%29%29" class="RktValLink" data-pltdoc="x">hash-weak?</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%2Fbase..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-hashalw))"></a><span title="Provided from: racket/base, racket | Package: base"><span class="RktSym"><a href="hashtables.html#%28def._%28%28quote._~23~25kernel%29._make-weak-hashalw%29%29" class="RktValDef RktValLink" data-pltdoc="x">make-weak-hashalw</a></span></spa
|
||
|
|
<span class="RktSym"><a href="hashtables.html#%28def._%28%28quote._~23~25kernel%29._make-hasheqv%29%29" class="RktValLink" data-pltdoc="x">make-hasheqv</a></span>, and <span class="RktSym"><a href="hashtables.html#%28def._%28%28quote._~23~25kernel%29._make-hashalw%29%29" class="RktValLink" data-pltdoc="x">make-hashalw</a></span>, but creates a
|
||
|
|
mutable hash table that holds keys weakly.</div></p><p>Beware that values in a weak hash table are retained normally. If a value in
|
||
|
|
the table refers back to its key, then the table will retain the value
|
||
|
|
and therefore the key; the mapping will never be removed from the
|
||
|
|
table even if the key becomes otherwise inaccessible. To avoid that
|
||
|
|
problem, use an ephemeron hash table as created by
|
||
|
|
<span class="RktSym"><a href="hashtables.html#%28def._%28%28quote._~23~25kernel%29._make-ephemeron-hash%29%29" class="RktValLink" data-pltdoc="x">make-ephemeron-hash</a></span>, <span class="RktSym"><a href="hashtables.html#%28def._%28%28quote._~23~25kernel%29._make-ephemeron-hashalw%29%29" class="RktValLink" data-pltdoc="x">make-ephemeron-hashalw</a></span>,
|
||
|
|
<span class="RktSym"><a href="hashtables.html#%28def._%28%28quote._~23~25kernel%29._make-ephemeron-hasheqv%29%29" class="RktValLink" data-pltdoc="x">make-ephemeron-hasheqv</a></span>, or <span class="RktSym"><a href="hashtables.html#%28def._%28%28quote._~23~25kernel%29._make-ephemeron-hasheq%29%29" class="RktValLink" data-pltdoc="x">make-ephemeron-hasheq</a></span>.
|
||
|
|
For values that do not refer to keys,
|
||
|
|
there is a modest extra cost to using an ephemeron hash table instead
|
||
|
|
of a weak hash table, but prefer an ephemeron hash table when in
|
||
|
|
doubt.</p><p class="SHistory">Changed in version 8.5.0.3 of package <span class="stt">base</span>: Added <span class="RktSym"><a href="hashtables.html#%28def._%28%28quote._~23~25kernel%29._make-weak-hashalw%29%29" class="RktValLink" data-pltdoc="x">make-weak-hashalw</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-ephemeron-hash))"></a><span title="Provided from: racket/base, racket | Package: base"><span class="RktSym"><a href="hashtables.html#%28def._%28%28quote._~23~25kernel%29._make-ephemeron-hash%29%29" class="RktValDef RktValLink" data-pltdoc="x">make-ephemeron-hash</a></span></span><span class="hspace"> </span><span class="RktOpt">[</span><span class="RktVar">assocs</span><span class="RktOpt">]</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._and%2Fc%29%29" class="RktValLink" data-pltdoc="x">and/c</a></span><span class="hspace"> </span><span class="RktSym"><a href="hashtables.html#%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="hashtables.html#%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="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="hspace"> </span><span class="RktSym"><a href="hashtables.html#%28def._%28%28quote._~23~25kernel%29._hash-ephemeron~3f%29%29" class="RktValLink" data-pltdoc="x">hash-ephemeron?</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%2Fbase..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-ephemeron-hashalw))"></a><span title="Provided from: racket/base, racket | Package: base"><span class="RktSym"><a href="hashtables.html#%28def._%28%28quote._~23~25kernel%29._make-ephemeron-hashalw%29%29" class="RktValDef RktValLink" data-pltdoc="x">make-ephemeron-hashalw</a></span></span><span class="hspace"> </span><span class="RktOpt">[</span><span class="RktVar">assocs</span><span class="RktOpt">]</span><span class="RktPn">)</span></p></blo
|
||
|
|
<span class="RktSym"><a href="hashtables.html#%28def._%28%28quote._~23~25kernel%29._make-hasheqv%29%29" class="RktValLink" data-pltdoc="x">make-hasheqv</a></span>, and <span class="RktSym"><a href="hashtables.html#%28def._%28%28quote._~23~25kernel%29._make-hashalw%29%29" class="RktValLink" data-pltdoc="x">make-hashalw</a></span>,
|
||
|
|
but creates a mutable hash table that holds
|
||
|
|
key-value combinations in the same way as an <a href="ephemerons.html#%28tech._ephemeron%29" class="techoutside" data-pltdoc="x"><span class="techinside">ephemeron</span></a>.</div></p><p>Using an ephemeron hash table is like using a weak hash table and
|
||
|
|
mapping each key to a <a href="ephemerons.html#%28tech._ephemeron%29" class="techoutside" data-pltdoc="x"><span class="techinside">ephemeron</span></a> that pairs the key and value.
|
||
|
|
An advantage of an ephemeron hash table is that the value need not be
|
||
|
|
extracted with <span class="RktSym"><a href="ephemerons.html#%28def._%28%28quote._~23~25kernel%29._ephemeron-value%29%29" class="RktValLink" data-pltdoc="x">ephemeron-value</a></span> from the result of functions
|
||
|
|
like <span class="RktSym"><a href="hashtables.html#%28def._%28%28quote._~23~25kernel%29._hash-ref%29%29" class="RktValLink" data-pltdoc="x">hash-ref</a></span>. An ephemeron hash table might also be
|
||
|
|
represented more compactly than a weak hash table with explicit
|
||
|
|
<a href="ephemerons.html#%28tech._ephemeron%29" class="techoutside" data-pltdoc="x"><span class="techinside">ephemeron</span></a> values.</p><p class="SHistory">Added in version 8.0.0.10 of package <span class="stt">base</span>.<br/>Changed in version 8.5.0.3: Added <span class="RktSym"><a href="hashtables.html#%28def._%28%28quote._~23~25kernel%29._make-ephemeron-hashalw%29%29" class="RktValLink" data-pltdoc="x">make-ephemeron-hashalw</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-immutable-hash))"></a><span title="Provided from: racket/base, racket | Package: base"><span class="RktSym"><a href="hashtables.html#%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="RktOpt">[</span><span class="RktVar">assocs</span><span class="RktOpt">]</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._and%2Fc%29%29" class="RktValLink" data-pltdoc="x">and/c</a></span><span class="hspace"> </span><span class="RktSym"><a href="hashtables.html#%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="hashtables.html#%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="hspace"> </span><span class="RktSym"><a href="hashtables.html#%28def._%28%28quote._~23~25kernel%29._hash-strong~3f%29%29" class="RktValLink" data-pltdoc="x">hash-strong?</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%2Fbase..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-hashalw))"></a><span title="Provided from: racket/base, racket | Package: base"><span class="RktSym"><a href="hashtables.html#%28def._%28%28quote._~23~25kernel%29._make-immutable-hashalw%29%29" class="RktValDef RktValLink" data-pltdoc="x">make-immutable-hashalw</a></span></span><span class="hspace"> </span><span class="RktOpt">[</span><span class="RktVar">assocs</span><span class="RktOpt">]</span><span class="RktPn">)</span></p></blockquote></td></tr><tr><td><span class="hspace"> </span>→<span class="hspace"> </span><span class="
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||
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<span class="RktSym"><a href="hashtables.html#%28def._%28%28quote._~23~25kernel%29._hasheqv%29%29" class="RktValLink" data-pltdoc="x">hasheqv</a></span>, but accepts
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the key–value mapping in association-list form like
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<span class="RktSym"><a href="hashtables.html#%28def._%28%28quote._~23~25kernel%29._make-hash%29%29" class="RktValLink" data-pltdoc="x">make-hash</a></span>, <span class="RktSym"><a href="hashtables.html#%28def._%28%28quote._~23~25kernel%29._make-hashalw%29%29" class="RktValLink" data-pltdoc="x">make-hashalw</a></span>, <span class="RktSym"><a href="hashtables.html#%28def._%28%28quote._~23~25kernel%29._make-hasheq%29%29" class="RktValLink" data-pltdoc="x">make-hasheq</a></span>, and
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<span class="RktSym"><a href="hashtables.html#%28def._%28%28quote._~23~25kernel%29._make-hasheqv%29%29" class="RktValLink" data-pltdoc="x">make-hasheqv</a></span>.</div></p><p class="SHistory">Changed in version 8.5.0.3 of package <span class="stt">base</span>: Added <span class="RktSym"><a href="hashtables.html#%28def._%28%28quote._~23~25kernel%29._make-immutable-hashalw%29%29" class="RktValLink" data-pltdoc="x">make-immutable-hashalw</a></span>.</p><p><div class="SIntrapara"><blockquote class="SVInsetFlow"><table cellspacing="0" cellpadding="0" class="boxed RBoxed"><tr><td><blockquote class="SubFlow"><div class="RBackgroundLabel SIEHidden"><div class="RBackgroundLabelInner"><p>procedure</p></div></div><p class="RForeground"><span class="RktPn">(</span><a name="(def._((quote._~23~25kernel)._hash-set!))"></a><span title="Provided from: racket/base, racket | Package: base"><span class="RktSym"><a href="hashtables.html#%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%2Fbase..rkt%29._and%2Fc%29%29" class="RktValLink" data-pltdoc="x">and/c</a></span><span class="hspace"> </span><span class="RktSym"><a href="hashtables.html#%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
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any existing mapping for <span class="RktVar">key</span>.</div></p><p>See also the <a href="hashtables.html#%28elem._%28caveat._concurrency%29%29" data-pltdoc="x">caveats concerning concurrent modification</a> and the <a href="hashtables.html#%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="hashtables.html#%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%2Fbase..rkt%29._and%2Fc%29%29" class="RktValLink" data-pltdoc="x">and/c</a></span><span class="hspace"> </span><span class="RktSym"><a href="hashtables.html#%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
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||
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any existing mapping for each <span class="RktVar">key</span>. Mappings are added from the left, so
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later mappings overwrite earlier mappings.</div></p><p>See also the <a href="hashtables.html#%28elem._%28caveat._concurrency%29%29" data-pltdoc="x">caveats concerning concurrent modification</a> and the <a href="hashtables.html#%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="hashtables.html#%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%2Fbase..rkt%29._and%2Fc%29%29" class="RktValLink" data-pltdoc="x">and/c</a></span><span class="hspace"> </span><span class="RktSym"><a href="hashtables.html#%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%2Fbase..rkt%29._and%2Fc%29%29" class="RktValLink" data-pltdoc="x">and/c</a></span><span class="hspace"> </span><span class="RktSym"><a href="hashtables.html#%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
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<span class="RktVar">v</span>, overwriting any existing mapping for <span class="RktVar">key</span>, and
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returning the extended hash table.</div></p><p>See also the <a href="hashtables.html#%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="hashtables.html#%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%2Fbase..rkt%29._and%2Fc%29%29" class="RktValLink" data-pltdoc="x">and/c</a></span><span class="hspace"> </span><span class="RktSym"><a href="hashtables.html#%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%2Fbase..rkt%29._and%2Fc%29%29" class="RktValLink" data-pltdoc="x">and/c</a></span><span class="hspace"> </span><span class="RktSym"><a href="hashtables.html#%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
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||
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<span class="RktVar">v</span>, overwriting any existing mapping for each <span class="RktVar">key</span>, and
|
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returning the extended hash table. Mappings are added from the left, so
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|
|
later mappings overwrite earlier mappings.</div></p><p>See also the <a href="hashtables.html#%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="hashtables.html#%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="RktOpt">[</span><span class="RktVar">failure-result</span><span class="RktOpt">]</span><span class="RktPn">)</span><span class="hspace"> </span>→<span class="hspace"> </span><span class="RktSym"><a href="data-structure-contracts.html#%28form._%28%28lib._racket%2Fcontract%2Fprivate%2Fmisc..rkt%29._any%29%29" class="RktStxLink" data-pltdoc="x">any</a></span></p></blockquote></td></tr><tr><td><span class="hspace"> </span><span class="RktVar">hash</span><span class="hspace"> </span>:<span class="hspace"> </span><span class="RktSym"><a href="hashtables.html#%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 valign="top"><span class="hspace"> </span></td><td valign="top"><span class="RktVar">failure-result</span></td><td valign="top"><span class="hspace"> </span></td><td valign="top">:</td><td valign="top"><span class="hspace"> </span></td><td valign="top"><span class="RktSym"><a href="contract-utilities.html#%28def._%28%28lib._racket%2Fcontract%2Fbase..rkt%29._failure-result%2Fc%29%29" class="RktValLink" data-pltdoc="x">failure-result/c</a></span></td></tr><tr><td valign="top"><span class="hspace"> </span></td><td valign="top"><span class="hspace"> </span></td><td valign="top"><span class="hspace"> </span></td><td valign="top">=</td><td valign="top"><span class="hspace"> </span></td><td valign="top"><table cellspacing="0" cellpadding="0" class="RktBlk"><tr><td><span class="RktPn">(</span><span class="RktSym"><a href="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="hashtables.html#%28elem._%28caveat._concurrency%29%29" data-pltdoc="x">caveats concerning concurrent modification</a> and the <a href="hashtables.html#%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-key))"></a><span title="Provided from: racket/base, racket | Package: base"><span class="RktSym"><a href="hashtables.html#%28def._%28%28quote._~23~25kernel%29._hash-ref-key%29%29" class="RktValDef RktValLink" data-pltdoc="x">hash-ref-key</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="RktOpt">[</span><span class="RktVar">failure-result</span><span class="RktOpt">]</span><span class="RktPn">)</span><span class="hspace"> </span>→<span class="hspace"> </span><span class="RktSym"><a href="data-structure-contracts.html#%28form._%28%28lib._racket%2Fcontract%2Fprivate%2Fmisc..rkt%29._any%29%29" class="RktStxLink" data-pltdoc="x">any</a></span></p></blockquote></td></tr><tr><td><span class="hspace"> </span><span class="RktVar">hash</span><span class="hspace"> </span>:<span class="hspace"> </span><span class="RktSym"><a href="hashtables.html#%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 valign="top"><span class="hspace"> </span></td><td valign="top"><span class="RktVar">failure-result</span></td><td valign="top"><span class="hspace"> </span></td><td valign="top">:</td><td valign="top"><span class="hspace"> </span></td><td valign="top"><span class="RktSym"><a href="contract-utilities.html#%28def._%28%28lib._racket%2Fcontract%2Fbase..rkt%29._failure-result%2Fc%29%29" class="RktValLink" data-pltdoc="x">failure-result/c</a></span></td></tr><tr><td valign="top"><span class="hspace"> </span></td><td valign="top"><span class="hspace"> </span></td><td valign="top"><span class="hspace"> </span></td><td valign="top">=</td><td valign="top"><span class="hspace"> </span></td><td valign="top"><table cellspacing="0" cellpadding="0" class="RktBlk"><tr><td><span class="RktPn">(</span><span class="RktSym"><a href="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></t
|
||
|
|
according to <span class="RktVar">hash</span>’s key-comparison function. If no key is found,
|
||
|
|
then <span class="RktVar">failure-result</span> is used as in <span class="RktSym"><a href="hashtables.html#%28def._%28%28quote._~23~25kernel%29._hash-ref%29%29" class="RktValLink" data-pltdoc="x">hash-ref</a></span> to determine
|
||
|
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the result.</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 the returned key,
|
||
|
|
assuming it is found, will be <span class="RktSym"><a href="Equality.html#%28def._%28%28quote._~23~25kernel%29._eq~3f%29%29" class="RktValLink" data-pltdoc="x">eq?</a></span>-equivalent to the one
|
||
|
|
actually retained by <span class="RktVar">hash</span>:</p><p><div class="SIntrapara">Examples:</div><div class="SIntrapara"><blockquote class="SCodeFlow"><table cellspacing="0" cellpadding="0" class="RktBlk"><tr><td><span class="stt">> </span><span class="RktPn">(</span><span class="RktSym"><a href="define.html#%28form._%28%28lib._racket%2Fprivate%2Fbase..rkt%29._define%29%29" class="RktStxLink" data-pltdoc="x">define</a></span><span class="hspace"> </span><span class="RktSym">original-key</span><span class="hspace"> </span><span class="RktVal">"hello"</span><span class="RktPn">)</span></td></tr><tr><td><span class="stt">> </span><span class="RktPn">(</span><span class="RktSym"><a href="define.html#%28form._%28%28lib._racket%2Fprivate%2Fbase..rkt%29._define%29%29" class="RktStxLink" data-pltdoc="x">define</a></span><span class="hspace"> </span><span class="RktSym">key-copy</span><span class="hspace"> </span><span class="RktPn">(</span><span class="RktSym"><a href="strings.html#%28def._%28%28quote._~23~25kernel%29._string-copy%29%29" class="RktValLink" data-pltdoc="x">string-copy</a></span><span class="hspace"> </span><span class="RktSym">original-key</span><span class="RktPn">)</span><span class="RktPn">)</span></td></tr><tr><td><span class="stt">> </span><span class="RktPn">(</span><span class="RktSym"><a href="Equality.html#%28def._%28%28quote._~23~25kernel%29._equal~3f%29%29" class="RktValLink" data-pltdoc="x">equal?</a></span><span class="hspace"> </span><span class="RktSym">original-key</span><span class="hspace"> </span><span class="RktSym">key-copy</span><span class="RktPn">)</span></td></tr><tr><td><p><span class="RktRes">#t</span></p></td></tr><tr><td><span class="stt">> </span><span class="RktPn">(</span><span class="RktSym"><a href="Equality.html#%28def._%28%28quote._~23~25kernel%29._eq~3f%29%29" class="RktValLink" data-pltdoc="x">eq?</a></span><span class="hspace"> </span><span class="RktSym">original-key</span><span class="hspace"> </span><span class="RktSym">key-copy</span><span class="RktPn">)</span></td></tr><tr><td><p><span class="RktRes">#f</span></p></td></tr><tr><td><span class="stt">> </span><span class="RktPn">(</span><span class="RktSym"><a href="define.html#%28form._%28%28lib._racket%2Fprivate%2Fbase..rkt%29._define%29%29" class="RktStxLink" data-pltdoc="x">define</a></span><span class="hspace"> </span><span class="RktSym">table</span><span class="hspace"> </span><span class="RktPn">(</span><span class="RktSym"><a href="hashtables.html#%28def._%28%28quote._~23~25kernel%29._make-hash%29%29" class="RktValLink" data-pltdoc="x">make-hash</a></span><span class="RktPn">)</span><span class="RktPn">)</span></td></tr><tr><td><span class="stt">> </span><span class="RktPn">(</span><span class="RktSym"><a href="hashtables.html#%28def._%28%28quote._~23~25kernel%29._hash-set%21%29%29" class="RktValLink" data-pltdoc="x">hash-set!</a></span><span class="hspace"> </span><span class="RktSym">table</span><span class="hspace"> </span><span class="RktSym">original-key</span><span class="hspace"> </span><span class="RktVal">'</span><span class="RktVal">value</span><span class="RktPn">)</span></td></tr><tr><td><span class="stt">> </span><span class="RktPn">(</span><span class="RktSym"><a href="Equality.html#%28def._%28%28quote._~23~25kernel%29._eq~3f%29%29" class="RktValLink" data-pltdoc="x">eq?</a></span><span class="hspace"> </span><span class="RktPn">(</span><span class="RktSym"><a href="hashtables.html#%28def._%28%28quote._~23~25kernel%29._hash-ref-key%29%29" class="RktValLink" data-pltdoc="x">hash-ref-key</a></span><span class="hspace"> </span><span class="RktSym">table</span><span class="hspace"> </span><span class="RktVal">"hello"</span><span class="RktPn">)</span><span class="hspace"> </span><span class="RktSym">original-key</span><span class="RktPn">)</span></td></tr><tr><td><p><span class="RktRes">#t</span></p></td></tr><tr><td><span class="stt">> </span><span class="RktPn">(</span><span class="Rk
|
||
|
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not <span class="RktSym"><a href="Equality.html#%28def._%28%28quote._~23~25kernel%29._eq~3f%29%29" class="RktValLink" data-pltdoc="x">eq?</a></span>-equivalent but are equivalent according to the
|
||
|
|
hash’s key-comparison procedure, the hash retains the first one:</p><p><div class="SIntrapara">Examples:</div><div class="SIntrapara"><blockquote class="SCodeFlow"><table cellspacing="0" cellpadding="0" class="RktBlk"><tr><td><span class="stt">> </span><span class="RktPn">(</span><span class="RktSym"><a href="define.html#%28form._%28%28lib._racket%2Fprivate%2Fbase..rkt%29._define%29%29" class="RktStxLink" data-pltdoc="x">define</a></span><span class="hspace"> </span><span class="RktSym">original-key</span><span class="hspace"> </span><span class="RktVal">"hello"</span><span class="RktPn">)</span></td></tr><tr><td><span class="stt">> </span><span class="RktPn">(</span><span class="RktSym"><a href="define.html#%28form._%28%28lib._racket%2Fprivate%2Fbase..rkt%29._define%29%29" class="RktStxLink" data-pltdoc="x">define</a></span><span class="hspace"> </span><span class="RktSym">key-copy</span><span class="hspace"> </span><span class="RktPn">(</span><span class="RktSym"><a href="strings.html#%28def._%28%28quote._~23~25kernel%29._string-copy%29%29" class="RktValLink" data-pltdoc="x">string-copy</a></span><span class="hspace"> </span><span class="RktSym">original-key</span><span class="RktPn">)</span><span class="RktPn">)</span></td></tr><tr><td><span class="stt">> </span><span class="RktPn">(</span><span class="RktSym"><a href="define.html#%28form._%28%28lib._racket%2Fprivate%2Fbase..rkt%29._define%29%29" class="RktStxLink" data-pltdoc="x">define</a></span><span class="hspace"> </span><span class="RktSym">table</span><span class="hspace"> </span><span class="RktPn">(</span><span class="RktSym"><a href="hashtables.html#%28def._%28%28quote._~23~25kernel%29._make-hash%29%29" class="RktValLink" data-pltdoc="x">make-hash</a></span><span class="RktPn">)</span><span class="RktPn">)</span></td></tr><tr><td><span class="stt">> </span><span class="RktPn">(</span><span class="RktSym"><a href="hashtables.html#%28def._%28%28quote._~23~25kernel%29._hash-set%21%29%29" class="RktValLink" data-pltdoc="x">hash-set!</a></span><span class="hspace"> </span><span class="RktSym">table</span><span class="hspace"> </span><span class="RktSym">original-key</span><span class="hspace"> </span><span class="RktVal">'</span><span class="RktVal">one</span><span class="RktPn">)</span></td></tr><tr><td><span class="stt">> </span><span class="RktPn">(</span><span class="RktSym"><a href="hashtables.html#%28def._%28%28quote._~23~25kernel%29._hash-set%21%29%29" class="RktValLink" data-pltdoc="x">hash-set!</a></span><span class="hspace"> </span><span class="RktSym">table</span><span class="hspace"> </span><span class="RktSym">key-copy</span><span class="hspace"> </span><span class="RktVal">'</span><span class="RktVal">two</span><span class="RktPn">)</span></td></tr><tr><td><span class="stt">> </span><span class="RktPn">(</span><span class="RktSym"><a href="Equality.html#%28def._%28%28quote._~23~25kernel%29._eq~3f%29%29" class="RktValLink" data-pltdoc="x">eq?</a></span><span class="hspace"> </span><span class="RktPn">(</span><span class="RktSym"><a href="hashtables.html#%28def._%28%28quote._~23~25kernel%29._hash-ref-key%29%29" class="RktValLink" data-pltdoc="x">hash-ref-key</a></span><span class="hspace"> </span><span class="RktSym">table</span><span class="hspace"> </span><span class="RktVal">"hello"</span><span class="RktPn">)</span><span class="hspace"> </span><span class="RktSym">original-key</span><span class="RktPn">)</span></td></tr><tr><td><p><span class="RktRes">#t</span></p></td></tr><tr><td><span class="stt">> </span><span class="RktPn">(</span><span class="RktSym"><a href="Equality.html#%28def._%28%28quote._~23~25kernel%29._eq~3f%29%29" class="RktValLink" data-pltdoc="x">eq?</a></span><span class="hspace"> </span><span class="RktPn">(</span><span class="RktSym"><a href="hashtables.html#%28def._%28%28quote._~23~25kernel%29._hash-ref-key%29%29" class="RktValLink" data-pltdoc="x">hash-ref-key</a></span><span class="hspace"> </span><span
|
||
|
|
used to update it:
|
||
|
|
</div><div class="SIntrapara"><p><div class="SIntrapara">Examples:</div><div class="SIntrapara"><blockquote class="SCodeFlow"><table cellspacing="0" cellpadding="0" class="RktBlk"><tr><td><span class="stt">> </span><span class="RktPn">(</span><span class="RktSym"><a href="define.html#%28form._%28%28lib._racket%2Fprivate%2Fbase..rkt%29._define%29%29" class="RktStxLink" data-pltdoc="x">define</a></span><span class="hspace"> </span><span class="RktSym">original-key</span><span class="hspace"> </span><span class="RktVal">"hello"</span><span class="RktPn">)</span></td></tr><tr><td><span class="stt">> </span><span class="RktPn">(</span><span class="RktSym"><a href="define.html#%28form._%28%28lib._racket%2Fprivate%2Fbase..rkt%29._define%29%29" class="RktStxLink" data-pltdoc="x">define</a></span><span class="hspace"> </span><span class="RktSym">key-copy</span><span class="hspace"> </span><span class="RktPn">(</span><span class="RktSym"><a href="strings.html#%28def._%28%28quote._~23~25kernel%29._string-copy%29%29" class="RktValLink" data-pltdoc="x">string-copy</a></span><span class="hspace"> </span><span class="RktSym">original-key</span><span class="RktPn">)</span><span class="RktPn">)</span></td></tr><tr><td><span class="stt">> </span><span class="RktPn">(</span><span class="RktSym"><a href="define.html#%28form._%28%28lib._racket%2Fprivate%2Fbase..rkt%29._define%29%29" class="RktStxLink" data-pltdoc="x">define</a></span><span class="hspace"> </span><span class="RktSym">table0</span><span class="hspace"> </span><span class="RktPn">(</span><span class="RktVar">hash</span><span class="RktPn">)</span><span class="RktPn">)</span></td></tr><tr><td><span class="stt">> </span><span class="RktPn">(</span><span class="RktSym"><a href="define.html#%28form._%28%28lib._racket%2Fprivate%2Fbase..rkt%29._define%29%29" class="RktStxLink" data-pltdoc="x">define</a></span><span class="hspace"> </span><span class="RktSym">table1</span><span class="hspace"> </span><span class="RktPn">(</span><span class="RktSym"><a href="hashtables.html#%28def._%28%28quote._~23~25kernel%29._hash-set%29%29" class="RktValLink" data-pltdoc="x">hash-set</a></span><span class="hspace"> </span><span class="RktSym">table0</span><span class="hspace"> </span><span class="RktSym">original-key</span><span class="hspace"> </span><span class="RktVal">'</span><span class="RktVal">one</span><span class="RktPn">)</span><span class="RktPn">)</span></td></tr><tr><td><span class="stt">> </span><span class="RktPn">(</span><span class="RktSym"><a href="define.html#%28form._%28%28lib._racket%2Fprivate%2Fbase..rkt%29._define%29%29" class="RktStxLink" data-pltdoc="x">define</a></span><span class="hspace"> </span><span class="RktSym">table2</span><span class="hspace"> </span><span class="RktPn">(</span><span class="RktSym"><a href="hashtables.html#%28def._%28%28quote._~23~25kernel%29._hash-set%29%29" class="RktValLink" data-pltdoc="x">hash-set</a></span><span class="hspace"> </span><span class="RktSym">table1</span><span class="hspace"> </span><span class="RktSym">key-copy</span><span class="hspace"> </span><span class="RktVal">'</span><span class="RktVal">two</span><span class="RktPn">)</span><span class="RktPn">)</span></td></tr><tr><td><span class="stt">> </span><span class="RktPn">(</span><span class="RktSym"><a href="Equality.html#%28def._%28%28quote._~23~25kernel%29._eq~3f%29%29" class="RktValLink" data-pltdoc="x">eq?</a></span><span class="hspace"> </span><span class="RktPn">(</span><span class="RktSym"><a href="hashtables.html#%28def._%28%28quote._~23~25kernel%29._hash-ref-key%29%29" class="RktValLink" data-pltdoc="x">hash-ref-key</a></span><span class="hspace"> </span><span class="RktSym">table2</span><span class="hspace"> </span><span class="RktVal">"hello"</span><span class="RktPn">)</span><span class="hspace"> </span><span class="RktSym">original-key</span><span class="RktPn">)</span></td></tr><tr><td><p><span class="RktRes">#f</span></p></td></tr><tr><td>
|
||
|
|
will be determined as described in the documentation to
|
||
|
|
<span class="RktSym"><a href="chaperones.html#%28def._%28%28quote._~23~25kernel%29._impersonate-hash%29%29" class="RktValLink" data-pltdoc="x">impersonate-hash</a></span>.</p><p>See also the <a href="hashtables.html#%28elem._%28caveat._concurrency%29%29" data-pltdoc="x">caveats concerning concurrent modification</a> and the <a href="hashtables.html#%28elem._%28caveat._mutable-keys%29%29" data-pltdoc="x">caveat concerning mutable keys</a> above.</p><p class="SHistory">Added in version 7.4.0.3 of package <span class="stt">base</span>.</p><p><div class="SIntrapara"><blockquote class="SVInsetFlow"><table cellspacing="0" cellpadding="0" class="boxed RBoxed"><tr><td><blockquote class="SubFlow"><div class="RBackgroundLabel SIEHidden"><div class="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="hashtables.html#%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="hashtables.html#%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="contract-utilities.html#%28def._%28%28lib._racket%2Fcontract%2Fbase..rkt%29._failure-result%2Fc%29%29" class="RktValLink" data-pltdoc="x">failure-result/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
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found for <span class="RktVar">key</span>, then <span class="RktVar">to-set</span> determines the result as
|
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in <span class="RktSym"><a href="hashtables.html#%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
|
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or a plain value), and this result is stored in <span class="RktVar">hash</span> for the
|
||
|
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<span class="RktVar">key</span>. (Note that if <span class="RktVar">to-set</span> is a thunk, it is not
|
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|
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invoked in tail position.)</div></p><p>See also the <a href="hashtables.html#%28elem._%28caveat._concurrency%29%29" data-pltdoc="x">caveats concerning concurrent modification</a> and the <a href="hashtables.html#%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="hashtables.html#%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="hashtables.html#%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
|
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<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 valign="top"><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="hashtables.html#%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 valign="top"><span class="hspace"> </span></td><td valign="top"><span class="RktVar">hash</span></td><td valign="top"><span class="hspace"> </span></td><td valign="top"><span class="hspace"> </span></td><td valign="top"><span class="hspace"> </span></td><td valign="top"><span class="hspace"> </span></td></tr><tr><td valign="top"><span class="hspace"> </span></td><td valign="top"><span class="hspace"> </span></td><td valign="top"><span class="RktVar">key</span></td><td valign="top"><span class="hspace"> </span></td><td valign="top"><span class="hspace"> </span></td><td valign="top"><span class="hspace"> </span></td><td valign="top"><span class="hspace"> </span></td></tr><tr><td valign="top"><span class="hspace"> </span></td><td valign="top"><span class="hspace"> </span></td><td valign="top"><span class="RktVar">updater</span></td><td valign="top"><span class="hspace"> </span></td><td valign="top"><span class="hspace"> </span></td><td valign="top"><span class="hspace"> </span></td><td valign="top"><span class="hspace"> </span></td></tr><tr><td valign="top"><span class="hspace"> </span></td><td valign="top"><span class="hspace"> </span><span class="RktOpt">[</span></td><td valign="top"><span class="RktVar">failure-result</span><span class="RktOpt">]</span><span class="RktPn">)</span></td><td valign="top"><span class="hspace"> </span></td><td valign="top">→</td><td valign="top"><span class="hspace"> </span></td><td valign="top"><span class="RktSym"><a href="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%2Fbase..rkt%29._and%2Fc%29%29" class="RktValLink" data-pltdoc="x">and/c</a></span><span class="hspace"> </span><span class="RktSym"><a href="hashtables.html#%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"> 
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The value returned by <span class="RktVar">updater</span> becomes the new mapping for <span class="RktVar">key</span>, overwriting the
|
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original value in <span class="RktVar">hash</span>.</div></p><p><div class="SIntrapara">Examples:</div><div class="SIntrapara"><blockquote class="SCodeFlow"><table cellspacing="0" cellpadding="0" class="RktBlk"><tr><td><table cellspacing="0" cellpadding="0" class="RktBlk"><tr><td><span class="RktPn">(</span><span class="RktSym"><a href="define.html#%28form._%28%28lib._racket%2Fprivate%2Fbase..rkt%29._define%29%29" class="RktStxLink" data-pltdoc="x">define</a></span><span class="hspace"> </span><span class="RktSym">h</span><span class="hspace"> </span><span class="RktPn">(</span><span class="RktSym"><a href="hashtables.html#%28def._%28%28quote._~23~25kernel%29._make-hash%29%29" class="RktValLink" data-pltdoc="x">make-hash</a></span><span class="RktPn">)</span><span class="RktPn">)</span></td></tr><tr><td><span class="RktPn">(</span><span class="RktSym"><a href="hashtables.html#%28def._%28%28quote._~23~25kernel%29._hash-set%21%29%29" class="RktValLink" data-pltdoc="x">hash-set!</a></span><span class="hspace"> </span><span class="RktSym">h</span><span class="hspace"> </span><span class="RktVal">'</span><span class="RktVal">a</span><span class="hspace"> </span><span class="RktVal">5</span><span class="RktPn">)</span></td></tr></table></td></tr><tr><td><p> </p></td></tr><tr><td><span class="stt">> </span><span class="RktPn">(</span><span class="RktSym"><a href="hashtables.html#%28def._%28%28lib._racket%2Fprivate%2Fmore-scheme..rkt%29._hash-update%21%29%29" class="RktValLink" data-pltdoc="x">hash-update!</a></span><span class="hspace"> </span><span class="RktSym">h</span><span class="hspace"> </span><span class="RktVal">'</span><span class="RktVal">a</span><span class="hspace"> </span><span class="RktSym"><a href="generic-numbers.html#%28def._%28%28quote._~23~25kernel%29._add1%29%29" class="RktValLink" data-pltdoc="x">add1</a></span><span class="RktPn">)</span></td></tr><tr><td><span class="stt">> </span><span class="RktSym">h</span></td></tr><tr><td><p><span class="RktRes">'#hash((a . 6))</span></p></td></tr></table></blockquote></div></p><p>The optional <span class="RktVar">failure-result</span> argument is used when no mapping exists for <span class="RktVar">key</span>
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already, in the same manner as in <span class="RktSym"><a href="hashtables.html#%28def._%28%28quote._~23~25kernel%29._hash-ref%29%29" class="RktValLink" data-pltdoc="x">hash-ref</a></span>.</p><p><div class="SIntrapara">Examples:</div><div class="SIntrapara"><blockquote class="SCodeFlow"><table cellspacing="0" cellpadding="0" class="RktBlk"><tr><td><span class="RktPn">(</span><span class="RktSym"><a href="define.html#%28form._%28%28lib._racket%2Fprivate%2Fbase..rkt%29._define%29%29" class="RktStxLink" data-pltdoc="x">define</a></span><span class="hspace"> </span><span class="RktSym">h</span><span class="hspace"> </span><span class="RktPn">(</span><span class="RktSym"><a href="hashtables.html#%28def._%28%28quote._~23~25kernel%29._make-hash%29%29" class="RktValLink" data-pltdoc="x">make-hash</a></span><span class="RktPn">)</span><span class="RktPn">)</span></td></tr><tr><td><p> </p></td></tr><tr><td><span class="stt">> </span><span class="RktPn">(</span><span class="RktSym"><a href="hashtables.html#%28def._%28%28lib._racket%2Fprivate%2Fmore-scheme..rkt%29._hash-update%21%29%29" class="RktValLink" data-pltdoc="x">hash-update!</a></span><span class="hspace"> </span><span class="RktSym">h</span><span class="hspace"> </span><span class="RktVal">'</span><span class="RktVal">b</span><span class="hspace"> </span><span class="RktSym"><a href="generic-numbers.html#%28def._%28%28quote._~23~25kernel%29._add1%29%29" class="RktValLink" data-pltdoc="x">add1</a></span><span class="RktPn">)</span></td></tr><tr><td><p><span class="RktErr">hash-update!: no value found for key: 'b</span></p></td></tr><tr><td><span class="stt">> </span><span class="RktPn">(</span><span class="RktSym"><a href="hashtables.html#%28def._%28%28lib._racket%2Fprivate%2Fmore-scheme..rkt%29._hash-update%21%29%29" class="RktValLink" data-pltdoc="x">hash-update!</a></span><span class="hspace"> </span><span class="RktSym">h</span><span class="hspace"> </span><span class="RktVal">'</span><span class="RktVal">b</span><span class="hspace"> </span><span class="RktSym"><a href="generic-numbers.html#%28def._%28%28quote._~23~25kernel%29._add1%29%29" class="RktValLink" data-pltdoc="x">add1</a></span><span class="hspace"> </span><span class="RktVal">0</span><span class="RktPn">)</span></td></tr><tr><td><span class="stt">> </span><span class="RktSym">h</span></td></tr><tr><td><p><span class="RktRes">'#hash((b . 1))</span></p></td></tr></table></blockquote></div></p><p>See also the <a href="hashtables.html#%28elem._%28caveat._concurrency%29%29" data-pltdoc="x">caveats concerning concurrent modification</a> and the <a href="hashtables.html#%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="hashtables.html#%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="RktOpt">[</span><span class="RktVar">failure-result</span><span class="RktOpt">]</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._and%2Fc%29%29" class="RktValLink" data-pltdoc="x">a
|
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to the value and returning a new hash table. The value returned by <span class="RktVar">updater</span> becomes the new
|
||
|
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mapping for <span class="RktVar">key</span> in the returned hash table.</div></p><p><div class="SIntrapara">Examples:</div><div class="SIntrapara"><blockquote class="SCodeFlow"><table cellspacing="0" cellpadding="0" class="RktBlk"><tr><td><span class="RktPn">(</span><span class="RktSym"><a href="define.html#%28form._%28%28lib._racket%2Fprivate%2Fbase..rkt%29._define%29%29" class="RktStxLink" data-pltdoc="x">define</a></span><span class="hspace"> </span><span class="RktSym">h</span><span class="hspace"> </span><span class="RktPn">(</span><span class="RktVar">hash</span><span class="hspace"> </span><span class="RktVal">'</span><span class="RktVal">a</span><span class="hspace"> </span><span class="RktVal">5</span><span class="RktPn">)</span><span class="RktPn">)</span></td></tr><tr><td><p> </p></td></tr><tr><td><span class="stt">> </span><span class="RktPn">(</span><span class="RktSym"><a href="hashtables.html#%28def._%28%28lib._racket%2Fprivate%2Fmore-scheme..rkt%29._hash-update%29%29" class="RktValLink" data-pltdoc="x">hash-update</a></span><span class="hspace"> </span><span class="RktSym">h</span><span class="hspace"> </span><span class="RktVal">'</span><span class="RktVal">a</span><span class="hspace"> </span><span class="RktSym"><a href="generic-numbers.html#%28def._%28%28quote._~23~25kernel%29._add1%29%29" class="RktValLink" data-pltdoc="x">add1</a></span><span class="RktPn">)</span></td></tr><tr><td><p><span class="RktRes">'#hash((a . 6))</span></p></td></tr></table></blockquote></div></p><p>The optional <span class="RktVar">failure-result</span> argument is used when no mapping exists for <span class="RktVar">key</span>
|
||
|
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already, in the same manner as in <span class="RktSym"><a href="hashtables.html#%28def._%28%28quote._~23~25kernel%29._hash-ref%29%29" class="RktValLink" data-pltdoc="x">hash-ref</a></span>.</p><p><div class="SIntrapara">Examples:</div><div class="SIntrapara"><blockquote class="SCodeFlow"><table cellspacing="0" cellpadding="0" class="RktBlk"><tr><td><span class="RktPn">(</span><span class="RktSym"><a href="define.html#%28form._%28%28lib._racket%2Fprivate%2Fbase..rkt%29._define%29%29" class="RktStxLink" data-pltdoc="x">define</a></span><span class="hspace"> </span><span class="RktSym">h</span><span class="hspace"> </span><span class="RktPn">(</span><span class="RktVar">hash</span><span class="RktPn">)</span><span class="RktPn">)</span></td></tr><tr><td><p> </p></td></tr><tr><td><span class="stt">> </span><span class="RktPn">(</span><span class="RktSym"><a href="hashtables.html#%28def._%28%28lib._racket%2Fprivate%2Fmore-scheme..rkt%29._hash-update%29%29" class="RktValLink" data-pltdoc="x">hash-update</a></span><span class="hspace"> </span><span class="RktSym">h</span><span class="hspace"> </span><span class="RktVal">'</span><span class="RktVal">b</span><span class="hspace"> </span><span class="RktSym"><a href="generic-numbers.html#%28def._%28%28quote._~23~25kernel%29._add1%29%29" class="RktValLink" data-pltdoc="x">add1</a></span><span class="RktPn">)</span></td></tr><tr><td><p><span class="RktErr">hash-update: no value found for key: 'b</span></p></td></tr><tr><td><span class="stt">> </span><span class="RktPn">(</span><span class="RktSym"><a href="hashtables.html#%28def._%28%28lib._racket%2Fprivate%2Fmore-scheme..rkt%29._hash-update%29%29" class="RktValLink" data-pltdoc="x">hash-update</a></span><span class="hspace"> </span><span class="RktSym">h</span><span class="hspace"> </span><span class="RktVal">'</span><span class="RktVal">b</span><span class="hspace"> </span><span class="RktSym"><a href="generic-numbers.html#%28def._%28%28quote._~23~25kernel%29._add1%29%29" class="RktValLink" data-pltdoc="x">add1</a></span><span class="hspace"> </span><span class="RktVal">0</span><span class="RktPn">)</span></td></tr><tr><td><p><span class="RktRes">'#hash((b . 1))</span></p></td></tr></table></blockquote></div></p><p>See also the <a href="hashtables.html#%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="hashtables.html#%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%2Fbase..rkt%29._and%2Fc%29%29" class="RktValLink" data-pltdoc="x">and/c</a></span><span class="hspace"> </span><span class="RktSym"><a href="hashtables.html#%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-
|
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|
|
<span class="RktVar">hash</span>, returning the fresh hash table.</div></p><p>See also the <a href="hashtables.html#%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="hashtables.html#%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%2Fbase..rkt%29._and%2Fc%29%29" class="RktValLink" data-pltdoc="x">and/c</a></span><span class="hspace"> </span><span class="RktSym"><a href="hashtables.html#%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="hashtables.html#%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="hashtables.html#%28elem._%28caveat._concurrency%29%29" data-pltdoc="x">caveats concerning concurrent modification</a> and the <a href="hashtables.html#%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="hashtables.html#%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%2Fbase..rkt%29._and%2Fc%29%29" class="RktValLink" data-pltdoc="x">and/c</a></span><span class="hspace"> </span><span class="RktSym"><a href="hashtables.html#%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%2Fbase..rkt%29._and%2Fc%29%29" class="RktValLink" data-pltdoc="x">and/c</a></span><span class="hspace"> </span><span class="RktSym"><a href="hashtables.html#%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="hashtables.html#%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="hashtables.html#%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="hashtables.html#%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="hspace"> </span><span class="RktOpt">[</span><span class="RktPn">#:kind</span><span class="hspace"> </span><span class="RktVar">kind</span><span class="RktOpt">]</span><span class="RktPn">)</span><span class="hspace"> </span>→<span class="hspace"> </span><span class="RktSym"><a href="hashtables.html#%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="hashtables.html#%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">kind</span><span class="hspace"> </span>:<span class="hspace"> </span><span class="RktPn">(</span><span class="RktSym"><a href="data-structure-contracts.html#%28def._%28%28lib._racket%2Fcontract%2Fbase..rkt%29._or%2Fc%29%29" class="RktValLink" data-pltdoc="x">or/c</a></span><span class="hspace"> </span><span class="RktVal">#f</span><span class="hspace"> </span><span class="RktVal">'</span><span class="RktVal">immutable</span><span class="hspace"> </span><span class="RktVal">'</span><span class="RktVal">mutable</span><span class="hspace"> </span><span class="RktVal">'</span><span class="RktVal">weak</span><span class="hspace"> </span><span class="RktVal">'</span><span class="RktVal">ephemeron</span><span class="RktPn">)</span><span class="hspace"> </span>=<span class="hspace"> </span><span class="RktVal">#f</span></td></tr></table></blockquote></div><div class="SIntrapara">Produces an empty <a href="hashtables.html#%28tech._hash._table%29" class="techoutside" data-pltdoc="x"><span class="techinside">hash table</span></a> with the same key-comparison
|
||
|
|
procedure as <span class="RktVar">hash</span>, with either the given <span class="RktVar">kind</span>
|
||
|
|
or the same kind as the given <span class="RktVar">hash</span>.</div></p><p>If <span class="RktVar">kind</span> is not supplied or <span class="RktVal">#f</span>, produces a hash
|
||
|
|
table of the same kind and mutability as the given <span class="RktVar">hash</span>.
|
||
|
|
If <span class="RktVar">kind</span> is <span class="RktVal">'</span><span class="RktVal">immutable</span>, <span class="RktVal">'</span><span class="RktVal">mutable</span>,
|
||
|
|
<span class="RktVal">'</span><span class="RktVal">weak</span>, or <span class="RktVal">'</span><span class="RktVal">ephemeron</span>, produces a table that’s
|
||
|
|
immutable, mutable with strongly-held keys, mutable with
|
||
|
|
weakly-held keys, or mutable with ephemeron-held keys
|
||
|
|
respectively.</p><p class="SHistory">Changed in version 8.5.0.2 of package <span class="stt">base</span>: Added the <span class="RktVar">kind</span> argument.</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="hashtables.html#%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="hspace"> </span><span class="RktOpt">[</span><span class="RktVar">try-order?</span><span class="RktOpt">]</span><span class="RktPn">)</span><span class="hspace"> </span>→<span class="hspace"> </span><span class="RktPn">(</span><span class="RktSym"><a href="data-structure-contracts.html#%28def._%28%28lib._racket%2Fcontract%2Fbase..rkt%29._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="hashtables.html#%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><tr><td><span class="hspace"> </span><span class="RktVar">try-order?</span><span class="hspace"> </span>:<span class="hspace"> </span><span class="RktSym"><a href="data-structure-contracts.html#%28def._%28%28lib._racket%2Fcontract%2Fprivate%2Fmisc..rkt%29._any%2Fc%29%29" class="RktValLink" data-pltdoc="x">any/c</a></span><span class="hspace"> </span>=<span class="hspace"> </span><span class="RktVal">#f</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, and the procedure’s individual results appear in
|
||
|
|
order in the result list.</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="hashtables.html#%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="hashtables.html#%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="hashtables.html#%28elem._%28caveat._concurrency%29%29" data-pltdoc="x">caveats concerning concurrent modification</a> above.</p><p>If <span class="RktVar">try-order?</span> is true, then the order of keys and values
|
||
|
|
passed to <span class="RktVar">proc</span> is normalized under certain
|
||
|
|
circumstances—<wbr></wbr>including when every key is one of the following and
|
||
|
|
with the following order (earlier bullets before later):</p><ul><li><p><a href="booleans.html#%28tech._boolean%29" class="techoutside" data-pltdoc="x"><span class="techinside">booleans</span></a> sorted <span class="RktVal">#f</span> before <span class="RktVal">#t</span>;</p></li><li><p><a href="characters.html#%28tech._character%29" class="techoutside" data-pltdoc="x"><span class="techinside">characters</span></a> sorted by <span class="RktSym"><a href="characters.html#%28def._%28%28quote._~23~25kernel%29._char~3c~3f%29%29" class="RktValLink" data-pltdoc="x">char<?</a></span>;</p></li><li><p><a href="numbers.html#%28tech._real._number%29" class="techoutside" data-pltdoc="x"><span class="techinside">real numbers</span></a> sorted by <span class="RktSym"><a href="generic-numbers.html#%28def._%28%28quote._~23~25kernel%29._~3c%29%29" class="RktValLink" data-pltdoc="x"><</a></span>;</p></li><li><p><a href="symbols.html#%28tech._symbol%29" class="techoutside" data-pltdoc="x"><span class="techinside">symbols</span></a> sorted with <a href="symbols.html#%28tech._uninterned%29" class="techoutside" data-pltdoc="x"><span class="techinside">uninterned</span></a> symbols before
|
||
|
|
<a href="symbols.html#%28tech._unreadable._symbol%29" class="techoutside" data-pltdoc="x"><span class="techinside">unreadable symbols</span></a> before <a href="reader.html#%28tech._interned%29" class="techoutside" data-pltdoc="x"><span class="techinside">interned</span></a> symbols,
|
||
|
|
then sorted by <span class="RktSym"><a href="symbols.html#%28def._%28%28quote._~23~25kernel%29._symbol~3c~3f%29%29" class="RktValLink" data-pltdoc="x">symbol<?</a></span>;</p></li><li><p><a href="keywords.html#%28tech._keyword%29" class="techoutside" data-pltdoc="x"><span class="techinside">keywords</span></a> sorted by <span class="RktSym"><a href="keywords.html#%28def._%28%28quote._~23~25kernel%29._keyword~3c~3f%29%29" class="RktValLink" data-pltdoc="x">keyword<?</a></span>;</p></li><li><p><a href="strings.html#%28tech._string%29" class="techoutside" data-pltdoc="x"><span class="techinside">strings</span></a> sorted by <span class="RktSym"><a href="strings.html#%28def._%28%28quote._~23~25kernel%29._string~3c~3f%29%29" class="RktValLink" data-pltdoc="x">string<?</a></span>;</p></li><li><p><a href="bytestrings.html#%28tech._byte._string%29" class="techoutside" data-pltdoc="x"><span class="techinside">byte strings</span></a> sorted by <span class="RktSym"><a href="bytestrings.html#%28def._%28%28quote._~23~25kernel%29._bytes~3c~3f%29%29" class="RktValLink" data-pltdoc="x">bytes<?</a></span>;</p></li><li><p><span class="RktSym"><a href="pairs.html#%28def._%28%28quote._~23~25kernel%29._null%29%29" class="RktValLink" data-pltdoc="x">null</a></span>;</p></li><li><p><a href="https://download.racket-lang.org/releases/8.6/doc/local-redirect/index.html?doc=guide&rel=void_undefined.html&version=8.6" class="RktModLink Sq" data-pltdoc="x"><span class="nobreak"><span class="RktRes">#<void></span></span></a>; and</p></li><li><p><span class="RktSym"><a href="port-ops.html#%28def._%28%28quote._~23~25kernel%29._eof%29%29" class="RktValLink" data-pltdoc="x">eof</a></span>.</p></li></ul><p class="SHistory">Changed in version 6.3 of package <span class="stt">base</span>: Added the <span class="RktVar">try-order?</span> argument.<br/>Changed in version 7.1.0.7: Added guarantees for <span class="RktVar">try-order?</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-map/copy))"></a><span title="Provided from: racket/base, racket | Package: base"><span class="RktSym"><a href="hashtables.html#%28def._%28%28lib._racket%2Fprivate%2Fbase..rkt%29._hash-map%2Fcopy%29%29" class="RktValDef RktValLink" data-pltdoc="x">hash-map/copy</a></span></span><span class="hspace"> </span><span class="RktVar">hash</span><span class="hspace"> </span><span class="RktVar">proc</span><span class="hspace"> </span><span class="RktOpt">[</span><span class="RktPn">#:kind</span><span class="hspace"> </span><span class="RktVar">kind</span><span class="RktOpt">]</span><span class="RktPn">)</span><span class="hspace"> </span>→<span class="hspace"> </span><span class="RktSym"><a href="hashtables.html#%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="hashtables.html#%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 class="RktVar">hash</span> in an unspecified order, accumulating the results
|
||
|
|
into a new hash with the same key-comparison procedure as
|
||
|
|
<span class="RktVar">hash</span>, with either the given <span class="RktVar">kind</span> or the same
|
||
|
|
kind as the given <span class="RktVar">hash</span>.</div></p><p>If <span class="RktVar">kind</span> is not supplied or <span class="RktVal">#f</span>, produces a hash
|
||
|
|
table of the same kind and mutability as the given <span class="RktVar">hash</span>.
|
||
|
|
If <span class="RktVar">kind</span> is <span class="RktVal">'</span><span class="RktVal">immutable</span>, <span class="RktVal">'</span><span class="RktVal">mutable</span>,
|
||
|
|
<span class="RktVal">'</span><span class="RktVal">weak</span>, or <span class="RktVal">'</span><span class="RktVal">ephemeron</span>, produces a table that’s
|
||
|
|
immutable, mutable with strongly-held keys, mutable with
|
||
|
|
weakly-held keys, or mutable with ephemeron-held keys
|
||
|
|
respectively.</p><p><div class="SIntrapara">Examples:</div><div class="SIntrapara"><blockquote class="SCodeFlow"><table cellspacing="0" cellpadding="0" class="RktBlk"><tr><td><table cellspacing="0" cellpadding="0" class="RktBlk"><tr><td><span class="stt">> </span><span class="RktPn">(</span><span class="RktSym"><a href="hashtables.html#%28def._%28%28lib._racket%2Fprivate%2Fbase..rkt%29._hash-map%2Fcopy%29%29" class="RktValLink" data-pltdoc="x">hash-map/copy</a></span><span class="hspace"> </span><span class="RktVal">#hash</span><span class="RktPn">(</span><span class="RktPn">(</span><span class="RktVal">a</span><span class="hspace"> </span><span class="RktPn">. </span><span class="RktVal">"apple"</span><span class="RktPn">)</span><span class="hspace"> </span><span class="RktPn">(</span><span class="RktVal">b</span><span class="hspace"> </span><span class="RktPn">. </span><span class="RktVal">"banana"</span><span class="RktPn">)</span><span class="RktPn">)</span></td></tr><tr><td><span class="hspace"> </span><span class="hspace"> </span><span class="RktPn">(</span><span class="RktSym"><a href="lambda.html#%28form._%28%28lib._racket%2Fprivate%2Fbase..rkt%29._lambda%29%29" class="RktStxLink" data-pltdoc="x">lambda</a></span><span class="hspace"> </span><span class="RktPn">(</span><span class="RktSym">k</span><span class="hspace"> </span><span class="RktSym">v</span><span class="RktPn">)</span><span class="hspace"> </span><span class="RktPn">(</span><span class="RktSym"><a href="values.html#%28def._%28%28quote._~23~25kernel%29._values%29%29" class="RktValLink" data-pltdoc="x">values</a></span><span class="hspace"> </span><span class="RktSym">k</span><span class="hspace"> </span><span class="RktPn">(</span><span class="RktSym"><a href="strings.html#%28def._%28%28quote._~23~25kernel%29._string-upcase%29%29" class="RktValLink" data-pltdoc="x">string-upcase</a></span><span class="hspace"> </span><span class="RktSym">v</span><span class="RktPn">)</span><span class="RktPn">)</span><span class="RktPn">)</span><span class="RktPn">)</span></td></tr></table></td></tr><tr><td><p><span class="RktRes">'#hash((a . "APPLE") (b . "BANANA"))</span></p></td></tr><tr><td><table cellspacing="0" cellpadding="0" class="RktBlk"><tr><td><span class="stt">> </span><span class="RktPn">(</span><span class="RktSym"><a href="define.html#%28form._%28%28lib._racket%2Fprivate%2Fbase..rkt%29._define%29%29" class="RktStxLink" data-pltdoc="x">define</a></span><span class="hspace"> </span><span class="RktSym">frozen-capital</span></td></tr><tr><td><span class="hspace"> </span><span class="hspace"> </span><span class="RktPn">(</span><span class="RktSym"><a href="hashtables.html#%28def._%28%28lib._racket%2Fprivate%2Fbase..rkt%29._hash-map%2Fcopy%29%29" class="RktValLink" data-pltdoc="x">hash-map/copy</a></span><span class="hspace"> </span><span class="RktPn">(</span><span class="RktSym"><a href="hashtables.html#%28def._%28%28quote._~23~25kernel%29._make-hash%29%29" class="RktValLink" data-pltdoc="x">make-hash</a></span><span class="hspace"> </span><span class="RktVal">'</span><span class="RktVal">(</span><span class="RktVal">(</span><span class="RktVal">a</span><span class="hspace"> </span><span class="RktVal">. </span><span class="RktVal">"apple"</span><span class="RktVal">)</span><span class="hspace"> </span><span class="RktVal">(</span><span class="RktVal">b</span><span class="hspace"> </span><span class="RktVal">. </span><span class="RktVal">"banana"</span><span class="RktVal">)</span><span class="RktVal">)</span><span class="RktPn">)</span></td></tr><tr><td><span class="hspace"> </span><span class="hspace"> </span><span class="RktPn">(</span><span class="RktSym"><a href="lambda.html#%28form._%28%28lib._racket%2Fprivate%2Fbase..rkt%29._lambda%
|
||
|
|
certain circumstances. See <span class="RktSym"><a href="hashtables.html#%28def._%28%28quote._~23~25kernel%29._hash-map%29%29" class="RktValLink" data-pltdoc="x">hash-map</a></span> for further explanations on
|
||
|
|
<span class="RktVar">try-order?</span> and on information about modifying <span class="RktVar">hash</span> during
|
||
|
|
<span class="RktSym"><a href="hashtables.html#%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="hashtables.html#%28elem._%28caveat._concurrency%29%29" data-pltdoc="x">caveats concerning concurrent modification</a> above.</div></p><p class="SHistory">Changed in version 8.3.0.11 of package <span class="stt">base</span>: Added the <span class="RktVar">try-order?</span> argument.</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="hashtables.html#%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="hspace"> </span><span class="RktOpt">[</span><span class="RktVar">try-order?</span><span class="RktOpt">]</span><span class="RktPn">)</span><span class="hspace"> </span>→<span class="hspace"> </span><span class="RktPn">(</span><span class="RktSym"><a href="data-structure-contracts.html#%28def._%28%28lib._racket%2Fcontract%2Fbase..rkt%29._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="hashtables.html#%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">try-order?</span><span class="hspace"> </span>:<span class="hspace"> </span><span class="RktSym"><a href="data-structure-contracts.html#%28def._%28%28lib._racket%2Fcontract%2Fprivate%2Fmisc..rkt%29._any%2Fc%29%29" class="RktValLink" data-pltdoc="x">any/c</a></span><span class="hspace"> </span>=<span class="hspace"> </span><span class="RktVal">#f</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">If <span class="RktVar">try-order?</span> is true, then the order of values is normalized under
|
||
|
|
certain circumstances, based on the ordering of the associated keys.
|
||
|
|
See <span class="RktSym"><a href="hashtables.html#%28def._%28%28quote._~23~25kernel%29._hash-map%29%29" class="RktValLink" data-pltdoc="x">hash-map</a></span> for further explanations on <span class="RktVar">try-order?</span> and on
|
||
|
|
information about modifying <span class="RktVar">hash</span> during
|
||
|
|
<span class="RktSym"><a href="hashtables.html#%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="hashtables.html#%28elem._%28caveat._concurrency%29%29" data-pltdoc="x">caveats concerning concurrent modification</a> above.</div></p><p class="SHistory">Changed in version 8.3.0.11 of package <span class="stt">base</span>: Added the <span class="RktVar">try-order?</span> argument.</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="hashtables.html#%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="hspace"> </span><span class="RktOpt">[</span><span class="RktVar">try-order?</span><span class="RktOpt">]</span><span class="RktPn">)</span><span class="hspace"> </span>→<span class="hspace"> </span><span class="RktPn">(</span><span class="RktSym"><a href="data-structure-contracts.html#%28def._%28%28lib._racket%2Fcontract%2Fbase..rkt%29._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%2Fbase..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="hashtables.html#%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">try-order?</span><span class="hspace"> </span>:<span class="hspace"> </span><span class="RktSym"><a href="data-structure-contracts.html#%28def._%28%28lib._racket%2Fcontract%2Fprivate%2Fmisc..rkt%29._any%2Fc%29%29" class="RktValLink" data-pltdoc="x">any/c</a></span><span class="hspace"> </span>=<span class="hspace"> </span><span class="RktVal">#f</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">If <span class="RktVar">try-order?</span> is true, then the order of keys and values is normalized
|
||
|
|
under certain circumstances. See <span class="RktSym"><a href="hashtables.html#%28def._%28%28quote._~23~25kernel%29._hash-map%29%29" class="RktValLink" data-pltdoc="x">hash-map</a></span> for further explanations on
|
||
|
|
<span class="RktVar">try-order?</span> and on information about modifying <span class="RktVar">hash</span> during
|
||
|
|
<span class="RktSym"><a href="hashtables.html#%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="hashtables.html#%28elem._%28caveat._concurrency%29%29" data-pltdoc="x">caveats concerning concurrent modification</a> above.</div></p><p class="SHistory">Changed in version 8.3.0.11 of package <span class="stt">base</span>: Added the <span class="RktVar">try-order?</span> argument.</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-keys-subset~3f))"></a><span title="Provided from: racket/base, racket | Package: base"><span class="RktSym"><a href="hashtables.html#%28def._%28%28quote._~23~25kernel%29._hash-keys-subset~3f%29%29" class="RktValDef RktValLink" data-pltdoc="x">hash-keys-subset?</a></span></span><span class="hspace"> </span><span class="RktVar">hash1</span><span class="hspace"> </span><span class="RktVar">hash2</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">hash1</span><span class="hspace"> </span>:<span class="hspace"> </span><span class="RktSym"><a href="hashtables.html#%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">hash2</span><span class="hspace"> </span>:<span class="hspace"> </span><span class="RktSym"><a href="hashtables.html#%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 the keys of <span class="RktVar">hash1</span> are a subset of or
|
||
|
|
the same as the keys of <span class="RktVar">hash2</span>. The hash tables must both use
|
||
|
|
the same key-comparison function (<span class="RktSym"><a href="Equality.html#%28def._%28%28quote._~23~25kernel%29._equal~3f%29%29" class="RktValLink" data-pltdoc="x">equal?</a></span>,
|
||
|
|
<span class="RktSym"><a href="Equality.html#%28def._%28%28quote._~23~25kernel%29._equal-always~3f%29%29" class="RktValLink" data-pltdoc="x">equal-always?</a></span>, <span class="RktSym"><a href="Equality.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="Equality.html#%28def._%28%28quote._~23~25kernel%29._eq~3f%29%29" class="RktValLink" data-pltdoc="x">eq?</a></span>), otherwise the
|
||
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<span class="RktSym"><a href="exns.html#%28def._%28%28lib._racket%2Fprivate%2Fbase..rkt%29._exn~3afail~3acontract%29%29" class="RktValLink" data-pltdoc="x">exn:fail:contract</a></span> exception is raised.</div></p><p>Using <span class="RktSym"><a href="hashtables.html#%28def._%28%28quote._~23~25kernel%29._hash-keys-subset~3f%29%29" class="RktValLink" data-pltdoc="x">hash-keys-subset?</a></span> on immutable hash tables can be much
|
||
|
|
faster than iterating through the keys of <span class="RktVar">hash1</span> to make sure
|
||
|
|
that each is in <span class="RktVar">hash2</span>.</p><p class="SHistory">Added in version 6.5.0.8 of package <span class="stt">base</span>.</p><p><div class="SIntrapara"><blockquote class="SVInsetFlow"><table cellspacing="0" cellpadding="0" class="boxed RBoxed"><tr><td><blockquote class="SubFlow"><div class="RBackgroundLabel SIEHidden"><div class="RBackgroundLabelInner"><p>procedure</p></div></div><p class="RForeground"><span class="RktPn">(</span><a name="(def._((quote._~23~25kernel)._hash-for-each))"></a><span title="Provided from: racket/base, racket | Package: base"><span class="RktSym"><a href="hashtables.html#%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="hspace"> </span><span class="RktOpt">[</span><span class="RktVar">try-order?</span><span class="RktOpt">]</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="hashtables.html#%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><tr><td><span class="hspace"> </span><span class="RktVar">try-order?</span><span class="hspace"> </span>:<span class="hspace"> </span><span class="RktSym"><a href="data-structure-contracts.html#%28def._%28%28lib._racket%2Fcontract%2Fprivate%2Fmisc..rkt%29._any%2Fc%29%29" class="RktValLink" data-pltdoc="x">any/c</a></span><span class="hspace"> </span>=<span class="hspace"> </span><span class="RktVal">#f</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="hashtables.html#%28def._%28%28quote._~23~25kernel%29._hash-map%29%29" class="RktValLink" data-pltdoc="x">hash-map</a></span> for information about <span class="RktVar">try-order?</span> and
|
||
|
|
about modifying <span class="RktVar">hash</span> within <span class="RktVar">proc</span>.
|
||
|
|
</div><div class="SIntrapara">See also the <a href="hashtables.html#%28elem._%28caveat._concurrency%29%29" data-pltdoc="x">caveats concerning concurrent modification</a> above.</div></p><p class="SHistory">Changed in version 6.3 of package <span class="stt">base</span>: Added the <span class="RktVar">try-order?</span> argument.<br/>Changed in version 7.1.0.7: Added guarantees for <span class="RktVar">try-order?</span>.</p><p><div class="SIntrapara"><blockquote class="SVInsetFlow"><table cellspacing="0" cellpadding="0" class="boxed RBoxed"><tr><td><blockquote class="SubFlow"><div class="RBackgroundLabel SIEHidden"><div class="RBackgroundLabelInner"><p>procedure</p></div></div><p class="RForeground"><span class="RktPn">(</span><a name="(def._((quote._~23~25kernel)._hash-count))"></a><span title="Provided from: racket/base, racket | Package: base"><span class="RktSym"><a href="hashtables.html#%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="hashtables.html#%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>.</div></p><p>For the <a href="implementations.html#%28tech._c%29" class="techoutside" data-pltdoc="x"><span class="techinside">CS</span></a> implementation of Racket, the result is always
|
||
|
|
computed in constant time and atomically. For the <a href="implementations.html#%28tech._bc%29" class="techoutside" data-pltdoc="x"><span class="techinside">BC</span></a> implementation
|
||
|
|
of Racket, the result is computed in constant time and atomically only if
|
||
|
|
<span class="RktVar">hash</span> does not retain keys weakly or like an <a href="ephemerons.html#%28tech._ephemeron%29" class="techoutside" data-pltdoc="x"><span class="techinside">ephemeron</span></a>,
|
||
|
|
otherwise, a traversal is required to count the keys.</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="hashtables.html#%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="hashtables.html#%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="hashtables.html#%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="hashtables.html#%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="hashtables.html#%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.</div></p><p>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>. More generally, an index is guaranteed to be a
|
||
|
|
<a name="(tech._valid._hash._index)"></a><span style="font-style: italic">valid hash index</span> for a given hash table only as long it
|
||
|
|
comes from <span class="RktSym"><a href="hashtables.html#%28def._%28%28quote._~23~25kernel%29._hash-iterate-first%29%29" class="RktValLink" data-pltdoc="x">hash-iterate-first</a></span> or <span class="RktSym"><a href="hashtables.html#%28def._%28%28quote._~23~25kernel%29._hash-iterate-next%29%29" class="RktValLink" data-pltdoc="x">hash-iterate-next</a></span>,
|
||
|
|
and only as long as the hash table is not modified. In the case of a
|
||
|
|
hash table with weakly held keys or keys held like <a href="ephemerons.html#%28tech._ephemeron%29" class="techoutside" data-pltdoc="x"><span class="techinside">ephemerons</span></a>,
|
||
|
|
the hash table can be implicitly modified by the garbage collector
|
||
|
|
(see <a href="eval-model.html#%28part._gc-model%29" data-pltdoc="x">Garbage Collection</a>) when it discovers that the key is not
|
||
|
|
reachable.</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="hashtables.html#%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="hashtables.html#%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>.</div></p><p>If <span class="RktVar">pos</span> is not a <a href="hashtables.html#%28tech._valid._hash._index%29" class="techoutside" data-pltdoc="x"><span class="techinside">valid hash index</span></a> of <span class="RktVar">hash</span>,
|
||
|
|
then the result may be <span class="RktVal">#f</span> or it may be the next later index
|
||
|
|
that remains valid. The latter result is guaranteed if a hash table
|
||
|
|
has been modified only by the removal of keys.</p><p class="SHistory">Changed in version 7.0.0.10 of package <span class="stt">base</span>: Handle an invalid index by returning <span class="RktVal">#f</span>
|
||
|
|
instead of raising <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>.</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-iterate-key))"></a><span title="Provided from: racket/base, racket | Package: base"><span class="RktSym"><a href="hashtables.html#%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#%28def._%28%28lib._racket%2Fcontract%2Fprivate%2Fmisc..rkt%29._any%2Fc%29%29" class="RktValLink" data-pltdoc="x">any/c</a></span></p></blockquote></td></tr><tr><td><span class="hspace"> </span><span class="RktVar">hash</span><span class="hspace"> </span>:<span class="hspace"> </span><span class="RktSym"><a href="hashtables.html#%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></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><span class="RktSym"><a href="hashtables.html#%28def._%28%28quote._~23~25kernel%29._hash-iterate-key%29%29" class="RktValDef RktValLink" data-pltdoc="x">hash-iterate-key</a></span><span class="hspace"> </span><span class="RktVar">hash</span><span class="hspace"> </span><span class="RktVar">pos</span><span class="hspace"> </span><span class="RktVar">bad-index-v</span><span class="RktPn">)</span><span class="hspace"> </span>→<span class="hspace"> </span><span class="RktSym"><a href="data-structure-contracts.html#%28def._%28%28lib._racket%2Fcontract%2Fprivate%2Fmisc..rkt%29._any%2Fc%29%29" class="RktValLink" data-pltdoc="x">any/c</a></span></p></blockquote></td></tr><tr><td><span class="hspace"> </span><span class="RktVar">hash</span><span class="hspace"> </span>:<span class="hspace"> </span><span class="RktSym"><a href="hashtables.html#%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><tr><td><span class="hspace"> </span><span class="RktVar">bad-index-v</span><span class="hspace"> </span>:<span class="hspace"> </span><span class="RktSym"><a href="data-structure-contracts.html#%28def._%28%28lib._racket%2Fcontract%2Fprivate%2Fmisc..rkt%29._any%2Fc%29%29" class="RktValLink" data-pltdoc="x">any/c</a></span></td></tr></table></td></tr></table></blockquote></div><div class="SIntrapara">Returns the key for the elemen
|
||
|
|
<span class="RktVar">pos</span>.</div></p><p>If <span class="RktVar">pos</span> is not a <a href="hashtables.html#%28tech._valid._hash._index%29" class="techoutside" data-pltdoc="x"><span class="techinside">valid hash index</span></a> for <span class="RktVar">hash</span>,
|
||
|
|
the result is <span class="RktVar">bad-index-v</span> if provided, otherwise the
|
||
|
|
<span class="RktSym"><a href="exns.html#%28def._%28%28lib._racket%2Fprivate%2Fbase..rkt%29._exn~3afail~3acontract%29%29" class="RktValLink" data-pltdoc="x">exn:fail:contract</a></span> exception is raised.</p><p class="SHistory">Changed in version 7.0.0.10 of package <span class="stt">base</span>: Added the optional <span class="RktVar">bad-index-v</span> argument.</p><p><div class="SIntrapara"><blockquote class="SVInsetFlow"><table cellspacing="0" cellpadding="0" class="boxed RBoxed"><tr><td><table cellspacing="0" cellpadding="0" class="together"><tr><td><blockquote class="SubFlow"><div class="RBackgroundLabel SIEHidden"><div class="RBackgroundLabelInner"><p>procedure</p></div></div><p class="RForeground"><span class="RktPn">(</span><a name="(def._((quote._~23~25kernel)._hash-iterate-value))"></a><span title="Provided from: racket/base, racket | Package: base"><span class="RktSym"><a href="hashtables.html#%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="hashtables.html#%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></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><span class="RktSym"><a href="hashtables.html#%28def._%28%28quote._~23~25kernel%29._hash-iterate-value%29%29" class="RktValDef RktValLink" data-pltdoc="x">hash-iterate-value</a></span><span class="hspace"> </span><span class="RktVar">hash</span><span class="hspace"> </span><span class="RktVar">pos</span><span class="hspace"> </span><span class="RktVar">bad-index-v</span><span class="RktPn">)</span><span class="hspace"> </span>→<span class="hspace"> </span><span class="RktSym"><a href="data-structure-contracts.html#%28form._%28%28lib._racket%2Fcontract%2Fprivate%2Fmisc..rkt%29._any%29%29" class="RktStxLink" data-pltdoc="x">any</a></span></p></blockquote></td></tr><tr><td><span class="hspace"> </span><span class="RktVar">hash</span><span class="hspace"> </span>:<span class="hspace"> </span><span class="RktSym"><a href="hashtables.html#%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><tr><td><span class="hspace"> </span><span class="RktVar">bad-index-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%2
|
||
|
|
<span class="RktVar">pos</span>.</div></p><p>If <span class="RktVar">pos</span> is not a <a href="hashtables.html#%28tech._valid._hash._index%29" class="techoutside" data-pltdoc="x"><span class="techinside">valid hash index</span></a> for <span class="RktVar">hash</span>,
|
||
|
|
the result is <span class="RktVar">bad-index-v</span> if provided, otherwise the
|
||
|
|
<span class="RktSym"><a href="exns.html#%28def._%28%28lib._racket%2Fprivate%2Fbase..rkt%29._exn~3afail~3acontract%29%29" class="RktValLink" data-pltdoc="x">exn:fail:contract</a></span> exception is raised.</p><p class="SHistory">Changed in version 7.0.0.10 of package <span class="stt">base</span>: Added the optional <span class="RktVar">bad-index-v</span> argument.</p><p><div class="SIntrapara"><blockquote class="SVInsetFlow"><table cellspacing="0" cellpadding="0" class="boxed RBoxed"><tr><td><table cellspacing="0" cellpadding="0" class="together"><tr><td><blockquote class="SubFlow"><div class="RBackgroundLabel SIEHidden"><div class="RBackgroundLabelInner"><p>procedure</p></div></div><p class="RForeground"><span class="RktPn">(</span><a name="(def._((quote._~23~25kernel)._hash-iterate-pair))"></a><span title="Provided from: racket/base, racket | Package: base"><span class="RktSym"><a href="hashtables.html#%28def._%28%28quote._~23~25kernel%29._hash-iterate-pair%29%29" class="RktValDef RktValLink" data-pltdoc="x">hash-iterate-pair</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="RktPn">(</span><span class="RktSym"><a href="pairs.html#%28def._%28%28quote._~23~25kernel%29._cons%29%29" class="RktValLink" data-pltdoc="x">cons</a></span><span class="hspace"> </span><span class="RktSym"><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></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="hashtables.html#%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></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><span class="RktSym"><a href="hashtables.html#%28def._%28%28quote._~23~25kernel%29._hash-iterate-pair%29%29" class="RktValDef RktValLink" data-pltdoc="x">hash-iterate-pair</a></span><span class="hspace"> </span><span class="RktVar">hash</span><span class="hspace"> </span><span class="RktVar">pos</span><span class="hspace"> </span><span class="RktVar">bad-index-v</span><span class="RktPn">)</span><span class="hspace"> </span>→<span class="hspace"> </span><span class="RktPn">(</span><span class="RktSym"><a href="pairs.html#%28def._%28%28quote._~23~25kernel%29._cons%29%29" class="RktValLink" data-pltdoc="x">cons</a></span><span class="hspace"> </span><span class="RktSym"><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></p></blockquote></td></tr><tr><td><span class="hspace"> &nbs
|
||
|
|
in <span class="RktVar">hash</span> at index <span class="RktVar">pos</span>.</div></p><p>If <span class="RktVar">pos</span> is not a <a href="hashtables.html#%28tech._valid._hash._index%29" class="techoutside" data-pltdoc="x"><span class="techinside">valid hash index</span></a> for <span class="RktVar">hash</span>,
|
||
|
|
the result is <span class="RktPn">(</span><span class="RktSym"><a href="pairs.html#%28def._%28%28quote._~23~25kernel%29._cons%29%29" class="RktValLink" data-pltdoc="x">cons</a></span><span class="stt"> </span><span class="RktVar">bad-index-v</span><span class="stt"> </span><span class="RktVar">bad-index-v</span><span class="RktPn">)</span> if
|
||
|
|
<span class="RktVar">bad-index-v</span> is provided, otherwise the
|
||
|
|
<span class="RktSym"><a href="exns.html#%28def._%28%28lib._racket%2Fprivate%2Fbase..rkt%29._exn~3afail~3acontract%29%29" class="RktValLink" data-pltdoc="x">exn:fail:contract</a></span> exception is raised.</p><p class="SHistory">Added in version 6.4.0.5 of package <span class="stt">base</span>.<br/>Changed in version 7.0.0.10: Added the optional <span class="RktVar">bad-index-v</span> argument.</p><p><div class="SIntrapara"><blockquote class="SVInsetFlow"><table cellspacing="0" cellpadding="0" class="boxed RBoxed"><tr><td><table cellspacing="0" cellpadding="0" class="together"><tr><td><blockquote class="SubFlow"><div class="RBackgroundLabel SIEHidden"><div class="RBackgroundLabelInner"><p>procedure</p></div></div><table cellspacing="0" cellpadding="0" class="prototype RForeground"><tr><td valign="top"><span class="RktPn">(</span><a name="(def._((quote._~23~25kernel)._hash-iterate-key+value))"></a><span title="Provided from: racket/base, racket | Package: base"><span class="RktSym"><a href="hashtables.html#%28def._%28%28quote._~23~25kernel%29._hash-iterate-key%2Bvalue%29%29" class="RktValDef RktValLink" data-pltdoc="x">hash-iterate-key+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></td><td valign="top"><span class="hspace"> </span></td><td valign="top">→</td><td valign="top"><span class="hspace"> </span></td><td valign="top"><table cellspacing="0" cellpadding="0"><tr><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><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></table></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="RktSym"><a href="hashtables.html#%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></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><table cellspacing="0" cellpadding="0" class="prototype RForeground"><tr><td valign="top"><span class="RktPn">(</span><span class="RktSym"><a href="hashtables.html#%28def._%28%28quote._~23~25kernel%29._hash-iterate-key%2Bvalue%29%29" class="RktValDef RktValLink" data-pltdoc="x">hash-iterate-key+value</a></span></td><td valign="top"><span class="hspace"> </span></td><td valign="top"><span class="RktVar">hash</span></td><td valign="top"><span class="hspace"> </span></td><td valign="top"><span class="hspace"> </span></td><td valign="top"><span class="hspace"> </span></td><td valign="top"><span class="hspace"> </span></td></tr><tr><td valign="top"><span class="hspace"> </span></td><td valign="top"><span class="hspace"> </span></td><td valign="top"><span class="RktVar">pos</span></td><td valign="top"><span class="hspace"> </span></td><td valign="top"><span class="hspace"> </span></td><td valign="top"><span class="hspace"> </span></td><td valign="top"><span class="hspace"> </span></td></tr><tr><td valign="top"><span class="hspace"> </span></td><td valign="top"><span class="hspace"> </span></td><td valign
|
||
|
|
<span class="RktVar">pos</span>.</div></p><p>If <span class="RktVar">pos</span> is not a <a href="hashtables.html#%28tech._valid._hash._index%29" class="techoutside" data-pltdoc="x"><span class="techinside">valid hash index</span></a> for <span class="RktVar">hash</span>,
|
||
|
|
the result is <span class="RktPn">(</span><span class="RktSym"><a href="values.html#%28def._%28%28quote._~23~25kernel%29._values%29%29" class="RktValLink" data-pltdoc="x">values</a></span><span class="stt"> </span><span class="RktVar">bad-index-v</span><span class="stt"> </span><span class="RktVar">bad-index-v</span><span class="RktPn">)</span> if
|
||
|
|
<span class="RktVar">bad-index-v</span> is provided, otherwise the
|
||
|
|
<span class="RktSym"><a href="exns.html#%28def._%28%28lib._racket%2Fprivate%2Fbase..rkt%29._exn~3afail~3acontract%29%29" class="RktValLink" data-pltdoc="x">exn:fail:contract</a></span> exception is raised.</p><p class="SHistory">Added in version 6.4.0.5 of package <span class="stt">base</span>.<br/>Changed in version 7.0.0.10: Added the optional <span class="RktVar">bad-index-v</span> argument.</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="hashtables.html#%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%2Fbase..rkt%29._and%2Fc%29%29" class="RktValLink" data-pltdoc="x">and/c</a></span><span class="hspace"> </span><span class="RktSym"><a href="hashtables.html#%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="hashtables.html#%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><h5 x-source-module="(lib "scribblings/reference/reference.scrbl")" x-source-pkg="racket-doc" x-part-tag=""Additional_Hash_Table_Functions"">4.15.1<tt> </tt><a name="(part._.Additional_.Hash_.Table_.Functions)"></a><a name="(mod-path._racket/hash)"></a>Additional Hash Table Functions</h5><p><div class="SIntrapara"><table cellspacing="0" cellpadding="0" class="defmodule"><tr><td align="left"><span class="hspace"> </span><span class="RktPn">(</span><span class="RktSym"><a href="require.html#%28form._%28%28lib._racket%2Fprivate%2Fbase..rkt%29._require%29%29" class="RktStxLink" data-pltdoc="x">require</a></span><span class="stt"> </span><a href="hashtables.html#%28mod-path._racket%2Fhash%29" class="RktModLink" data-pltdoc="x"><span class="RktSym">racket/hash</span></a><span class="RktPn">)</span></td><td align="right"><span class="RpackageSpec"><span class="Smaller"> package:</span> <a href="https://pkgs.racket-lang.org/package/base" title="Install this package using `raco pkg install base`"><span class="stt">base</span></a></span></td></tr></table></div><div class="SIntrapara">The bindings documented in this section are provided by the <a href="hashtables.html#%28mod-path._racket%2Fhash%29" class="RktModLink" data-pltdoc="x"><span class="RktSym">racket/hash</span></a> library, not <a href="index.html" class="RktModLink" data-pltdoc="x"><span class="RktSym">racket/base</span></a> or <a href="index.html" class="RktModLink" data-pltdoc="x"><span class="RktSym">racket</span></a>.</div></p><p><div class="SIntrapara"><blockquote class="SVInsetFlow"><table cellspacing="0" cellpadding="0" class="boxed RBoxed"><tr><td><blockquote class="SubFlow"><div class="RBackgroundLabel SIEHidden"><div class="RBackgroundLabelInner"><p>procedure</p></div></div><table cellspacing="0" cellpadding="0" class="prototype RForeground"><tr><td valign="top"><span class="RktPn">(</span><a name="(def._((lib._racket/hash..rkt)._hash-union))"></a><span title="Provided from: racket/hash | Package: base"><span class="RktSym"><a href="hashtables.html#%28def._%28%28lib._racket%2Fhash..rkt%29._hash-union%29%29" class="RktValDef RktValLink" data-pltdoc="x">hash-union</a></span></span></td><td valign="top"><span class="hspace"> </span></td><td valign="top"><span class="RktVar">h0</span></td><td valign="top"><span class="hspace"> </span></td></tr><tr><td valign="top"><span class="hspace"> </span></td><td valign="top"><span class="hspace"> </span></td><td valign="top"><span class="RktVar">h</span><span class="hspace"> </span><span class="RktMeta">...</span></td><td valign="top"><span class="hspace"> </span></td></tr><tr><td valign="top"><span class="hspace"> </span></td><td valign="top"><span class="hspace"> </span><span class="RktOpt">[</span></td><td valign="top"><span class="RktPn">#:combine</span><span class="hspace"> </span><span class="RktVar">combine</span></td><td valign="top"><span class="hspace"> </span></td></tr><tr><td valign="top"><span class="hspace"> </span></td><td valign="top"><span class="hspace"> </span></td><td valign="top"><span class="RktPn">#:combine/key</span><span class="hspace"> </span><span class="RktVar">combine/key</span><span class="RktOpt">]</span><span class="RktPn">)</span></td><td valign="top"><span class="hspace"> </span></td></tr></table></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._and%2Fc%29%29" class="RktValLink" data-pltdoc="x">and/c</a></span><span class="hspace"> </span><span class="RktSym"><a href="hashtables.html#%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
|
||
|
|
update, adding each element of each <span class="RktVar">h</span> to <span class="RktVar">h0</span> in turn. For each
|
||
|
|
key <span class="RktSym">k</span> and value <span class="RktSym">v</span>, if a mapping from <span class="RktSym">k</span> to some value
|
||
|
|
<span class="RktSym">v0</span> already exists, it is replaced with a mapping from <span class="RktSym">k</span> to
|
||
|
|
<span class="RktPn">(</span><span class="RktVar">combine/key</span><span class="stt"> </span><span class="RktSym">k</span><span class="stt"> </span><span class="RktSym">v0</span><span class="stt"> </span><span class="RktSym">v</span><span class="RktPn">)</span>.</div></p><p><div class="SIntrapara">Examples:</div><div class="SIntrapara"><blockquote class="SCodeFlow"><table cellspacing="0" cellpadding="0" class="RktBlk"><tr><td><table cellspacing="0" cellpadding="0" class="RktBlk"><tr><td><span class="stt">> </span><span class="RktPn">(</span><span class="RktSym"><a href="hashtables.html#%28def._%28%28lib._racket%2Fhash..rkt%29._hash-union%29%29" class="RktValLink" data-pltdoc="x">hash-union</a></span><span class="hspace"> </span><span class="RktPn">(</span><span class="RktSym"><a href="hashtables.html#%28def._%28%28quote._~23~25kernel%29._make-immutable-hash%29%29" class="RktValLink" data-pltdoc="x">make-immutable-hash</a></span><span class="hspace"> </span><span class="RktVal">'</span><span class="RktVal">(</span><span class="RktVal">[</span><span class="RktVal">1</span><span class="hspace"> </span><span class="RktVal">. </span><span class="RktVal">one</span><span class="RktVal">]</span><span class="RktVal">)</span><span class="RktPn">)</span></td></tr><tr><td><span class="hspace"> </span><span class="hspace"> </span><span class="RktPn">(</span><span class="RktSym"><a href="hashtables.html#%28def._%28%28quote._~23~25kernel%29._make-immutable-hash%29%29" class="RktValLink" data-pltdoc="x">make-immutable-hash</a></span><span class="hspace"> </span><span class="RktVal">'</span><span class="RktVal">(</span><span class="RktVal">[</span><span class="RktVal">2</span><span class="hspace"> </span><span class="RktVal">. </span><span class="RktVal">two</span><span class="RktVal">]</span><span class="RktVal">)</span><span class="RktPn">)</span></td></tr><tr><td><span class="hspace"> </span><span class="hspace"> </span><span class="RktPn">(</span><span class="RktSym"><a href="hashtables.html#%28def._%28%28quote._~23~25kernel%29._make-immutable-hash%29%29" class="RktValLink" data-pltdoc="x">make-immutable-hash</a></span><span class="hspace"> </span><span class="RktVal">'</span><span class="RktVal">(</span><span class="RktVal">[</span><span class="RktVal">3</span><span class="hspace"> </span><span class="RktVal">. </span><span class="RktVal">three</span><span class="RktVal">]</span><span class="RktVal">)</span><span class="RktPn">)</span><span class="RktPn">)</span></td></tr></table></td></tr><tr><td><p><span class="RktRes">'#hash((1 . one) (2 . two) (3 . three))</span></p></td></tr><tr><td><table cellspacing="0" cellpadding="0" class="RktBlk"><tr><td><span class="stt">> </span><span class="RktPn">(</span><span class="RktSym"><a href="hashtables.html#%28def._%28%28lib._racket%2Fhash..rkt%29._hash-union%29%29" class="RktValLink" data-pltdoc="x">hash-union</a></span><span class="hspace"> </span><span class="RktPn">(</span><span class="RktSym"><a href="hashtables.html#%28def._%28%28quote._~23~25kernel%29._make-immutable-hash%29%29" class="RktValLink" data-pltdoc="x">make-immutable-hash</a></span><span class="hspace"> </span><span class="RktVal">'</span><span class="RktVal">(</span><span class="RktVal">[</span><span class="RktVal">1</span><span class="hspace"> </span><span class="RktVal">one</span><span class="hspace"> </span><span class="RktVal">uno</span><span class="RktVal">]</span><span class="hspace"> </span><span class="RktVal">[</span><span class="RktVal">2</span><span class="hspace"> </span><span class="RktVal">two</span><span class="hspace"> </span><span class="RktVal">dos</span><span class="RktVal">]</span><span class="RktVal">)</span><span class="RktPn">)</span></td></tr><tr><td><span class="hspace"> </span><span class="hspace">
|
||
|
|
update, adding each element of each <span class="RktVar">h</span> to <span class="RktVar">h0</span> in turn. For each
|
||
|
|
key <span class="RktSym">k</span> and value <span class="RktSym">v</span>, if a mapping from <span class="RktSym">k</span> to some value
|
||
|
|
<span class="RktSym">v0</span> already exists, it is replaced with a mapping from <span class="RktSym">k</span> to
|
||
|
|
<span class="RktPn">(</span><span class="RktVar">combine/key</span><span class="stt"> </span><span class="RktSym">k</span><span class="stt"> </span><span class="RktSym">v0</span><span class="stt"> </span><span class="RktSym">v</span><span class="RktPn">)</span>.</div></p><p><div class="SIntrapara">Examples:</div><div class="SIntrapara"><blockquote class="SCodeFlow"><table cellspacing="0" cellpadding="0" class="RktBlk"><tr><td><span class="stt">> </span><span class="RktPn">(</span><span class="RktSym"><a href="define.html#%28form._%28%28lib._racket%2Fprivate%2Fbase..rkt%29._define%29%29" class="RktStxLink" data-pltdoc="x">define</a></span><span class="hspace"> </span><span class="RktVar">h</span><span class="hspace"> </span><span class="RktPn">(</span><span class="RktSym"><a href="hashtables.html#%28def._%28%28quote._~23~25kernel%29._make-hash%29%29" class="RktValLink" data-pltdoc="x">make-hash</a></span><span class="RktPn">)</span><span class="RktPn">)</span></td></tr><tr><td><span class="stt">> </span><span class="RktVar">h</span></td></tr><tr><td><p><span class="RktRes">'#hash()</span></p></td></tr><tr><td><span class="stt">> </span><span class="RktPn">(</span><span class="RktSym"><a href="hashtables.html#%28def._%28%28lib._racket%2Fhash..rkt%29._hash-union%21%29%29" class="RktValLink" data-pltdoc="x">hash-union!</a></span><span class="hspace"> </span><span class="RktVar">h</span><span class="hspace"> </span><span class="RktPn">(</span><span class="RktSym"><a href="hashtables.html#%28def._%28%28quote._~23~25kernel%29._make-immutable-hash%29%29" class="RktValLink" data-pltdoc="x">make-immutable-hash</a></span><span class="hspace"> </span><span class="RktVal">'</span><span class="RktVal">(</span><span class="RktVal">[</span><span class="RktVal">1</span><span class="hspace"> </span><span class="RktVal">one</span><span class="hspace"> </span><span class="RktVal">uno</span><span class="RktVal">]</span><span class="hspace"> </span><span class="RktVal">[</span><span class="RktVal">2</span><span class="hspace"> </span><span class="RktVal">two</span><span class="hspace"> </span><span class="RktVal">dos</span><span class="RktVal">]</span><span class="RktVal">)</span><span class="RktPn">)</span><span class="RktPn">)</span></td></tr><tr><td><span class="stt">> </span><span class="RktVar">h</span></td></tr><tr><td><p><span class="RktRes">'#hash((1 . (one uno)) (2 . (two dos)))</span></p></td></tr><tr><td><table cellspacing="0" cellpadding="0" class="RktBlk"><tr><td><span class="stt">> </span><span class="RktPn">(</span><span class="RktSym"><a href="hashtables.html#%28def._%28%28lib._racket%2Fhash..rkt%29._hash-union%21%29%29" class="RktValLink" data-pltdoc="x">hash-union!</a></span><span class="hspace"> </span><span class="RktVar">h</span></td></tr><tr><td><span class="hspace"> </span><span class="hspace"> </span><span class="RktPn">(</span><span class="RktSym"><a href="hashtables.html#%28def._%28%28quote._~23~25kernel%29._make-immutable-hash%29%29" class="RktValLink" data-pltdoc="x">make-immutable-hash</a></span><span class="hspace"> </span><span class="RktVal">'</span><span class="RktVal">(</span><span class="RktVal">[</span><span class="RktVal">1</span><span class="hspace"> </span><span class="RktVal">eins</span><span class="hspace"> </span><span class="RktVal">un</span><span class="RktVal">]</span><span class="hspace"> </span><span class="RktVal">[</span><span class="RktVal">2</span><span class="hspace"> </span><span class="RktVal">zwei</span><span class="hspace"> </span><span class="RktVal">deux</span><span class="RktVal">]</span><span class="RktVal">)</span><span class="RktPn">)</span></td></tr><tr><td><span class="hspace"> </span><span class="hspace"> </span><span class=
|
||
|
|
with every hash table <span class="RktVar">h</span>. In the resulting hash table, a key
|
||
|
|
<span class="RktSym">k</span> is mapped to a combination of the values to which
|
||
|
|
<span class="RktSym">k</span> is mapped in each of the hash tables. The final values are
|
||
|
|
computed by stepwise combination of the values appearing in each of
|
||
|
|
the hash tables by applying <span class="RktPn">(</span><span class="RktVar">combine/key</span><span class="stt"> </span><span class="RktSym">k</span><span class="stt"> </span><span class="RktSym">v</span><span class="stt"> </span><span class="RktSym">vi</span><span class="RktPn">)</span> or
|
||
|
|
<span class="RktPn">(</span><span class="RktVar">combine</span><span class="stt"> </span><span class="RktSym">v</span><span class="stt"> </span><span class="RktSym">vi</span><span class="RktPn">)</span>, where <span class="RktSym">vi</span> is the value to which
|
||
|
|
<span class="RktSym">k</span> is mapped in the i-th hash table <span class="RktVar">h</span>, and
|
||
|
|
<span class="RktSym">v</span> is the accumulation of the values from the previous steps.
|
||
|
|
The comparison predicate of the first argument (<span class="RktSym"><a href="Equality.html#%28def._%28%28quote._~23~25kernel%29._eq~3f%29%29" class="RktValLink" data-pltdoc="x">eq?</a></span>,
|
||
|
|
<span class="RktSym"><a href="Equality.html#%28def._%28%28quote._~23~25kernel%29._eqv~3f%29%29" class="RktValLink" data-pltdoc="x">eqv?</a></span>, <span class="RktSym"><a href="Equality.html#%28def._%28%28quote._~23~25kernel%29._equal-always~3f%29%29" class="RktValLink" data-pltdoc="x">equal-always?</a></span>, <span class="RktSym"><a href="Equality.html#%28def._%28%28quote._~23~25kernel%29._equal~3f%29%29" class="RktValLink" data-pltdoc="x">equal?</a></span>) determines the
|
||
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one for the result.</div></p><p><div class="SIntrapara">Examples:</div><div class="SIntrapara"><blockquote class="SCodeFlow"><table cellspacing="0" cellpadding="0" class="RktBlk"><tr><td><table cellspacing="0" cellpadding="0" class="RktBlk"><tr><td><span class="stt">> </span><span class="RktPn">(</span><span class="RktSym"><a href="hashtables.html#%28def._%28%28lib._racket%2Fhash..rkt%29._hash-intersect%29%29" class="RktValLink" data-pltdoc="x">hash-intersect</a></span><span class="hspace"> </span><span class="RktPn">(</span><span class="RktSym"><a href="hashtables.html#%28def._%28%28quote._~23~25kernel%29._make-immutable-hash%29%29" class="RktValLink" data-pltdoc="x">make-immutable-hash</a></span><span class="hspace"> </span><span class="RktVal">'</span><span class="RktVal">(</span><span class="RktVal">(</span><span class="RktVal">a</span><span class="hspace"> </span><span class="RktVal">. </span><span class="RktVal">1</span><span class="RktVal">)</span><span class="hspace"> </span><span class="RktVal">(</span><span class="RktVal">b</span><span class="hspace"> </span><span class="RktVal">. </span><span class="RktVal">2</span><span class="RktVal">)</span><span class="hspace"> </span><span class="RktVal">(</span><span class="RktVal">c</span><span class="hspace"> </span><span class="RktVal">. </span><span class="RktVal">3</span><span class="RktVal">)</span><span class="RktVal">)</span><span class="RktPn">)</span></td></tr><tr><td><span class="hspace"> </span><span class="hspace"> </span><span class="RktPn">(</span><span class="RktSym"><a href="hashtables.html#%28def._%28%28quote._~23~25kernel%29._make-immutable-hash%29%29" class="RktValLink" data-pltdoc="x">make-immutable-hash</a></span><span class="hspace"> </span><span class="RktVal">'</span><span class="RktVal">(</span><span class="RktVal">(</span><span class="RktVal">a</span><span class="hspace"> </span><span class="RktVal">. </span><span class="RktVal">4</span><span class="RktVal">)</span><span class="hspace"> </span><span class="RktVal">(</span><span class="RktVal">b</span><span class="hspace"> </span><span class="RktVal">. </span><span class="RktVal">5</span><span class="RktVal">)</span><span class="RktVal">)</span><span class="RktPn">)</span></td></tr><tr><td><span class="hspace"> </span><span class="hspace"> </span><span class="RktPn">#:combine</span><span class="hspace"> </span><span class="RktSym"><a href="generic-numbers.html#%28def._%28%28quote._~23~25kernel%29._%2B%29%29" class="RktValLink" data-pltdoc="x">+</a></span><span class="RktPn">)</span></td></tr></table></td></tr><tr><td><p><span class="RktRes">'#hash((a . 5) (b . 7))</span></p></td></tr><tr><td><table cellspacing="0" cellpadding="0" class="RktBlk"><tr><td><span class="stt">> </span><span class="RktPn">(</span><span class="RktSym"><a href="hashtables.html#%28def._%28%28lib._racket%2Fhash..rkt%29._hash-intersect%29%29" class="RktValLink" data-pltdoc="x">hash-intersect</a></span><span class="hspace"> </span><span class="RktPn">(</span><span class="RktSym"><a href="hashtables.html#%28def._%28%28quote._~23~25kernel%29._make-immutable-hash%29%29" class="RktValLink" data-pltdoc="x">make-immutable-hash</a></span><span class="hspace"> </span><span class="RktVal">'</span><span class="RktVal">(</span><span class="RktVal">(</span><span class="RktVal">a</span><span class="hspace"> </span><span class="RktVal">. </span><span class="RktVal">1</span><span class="RktVal">)</span><span class="hspace"> </span><span class="RktVal">(</span><span class="RktVal">b</span><span class="hspace"> </span><span class="RktVal">. </span><span class="RktVal">2</span><span class="RktVal">)</span><span class="hspace"> </span><span class="RktVal">(</span><span class="RktVal">c</span><span class="hspace"> </span><span class="Rk
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