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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>8.12 Random generation</title><link rel="stylesheet" type="text/css" href="../scribble.css" title="default"/><link rel="stylesheet" type="text/css" href="extras.css" title="default"/><link rel="stylesheet" type="text/css" href="../racket.css" title="default"/><link rel="stylesheet" type="text/css" href="../manual-style.css" title="default"/><link rel="stylesheet" type="text/css" href="../manual-racket.css" title="default"/><link rel="stylesheet" type="text/css" href="../manual-racket.css" title="default"/><link rel="stylesheet" type="text/css" href="../doc-site.css" title="default"/><script type="text/javascript" src="../scribble-common.js"></script><script type="text/javascript" src="../manual-racket.js"></script><script type="text/javascript" src="../manual-racket.js"></script><script type="text/javascript" src="../doc-site.js"></script><script type="text/javascript" src="../local-redirect/local-redirect.js"></script><script type="text/javascript" src="../local-redirect/local-user-redirect.js"></script><!--[if IE 6]><style type="text/css">.SIEHidden { overflow: hidden; }</style><![endif]--></head><body id="doc-racket-lang-org"><div class="tocset"><div class="tocview"><div class="tocviewlist tocviewlisttopspace"><div class="tocviewtitle"><table cellspacing="0" cellpadding="0"><tr><td style="width: 1em;"><a href="javascript:void(0);" title="Expand/Collapse" class="tocviewtoggle" onclick="TocviewToggle(this,"tocview_0");">►</a></td><td></td><td><a href="index.html" class="tocviewlink" data-pltdoc="x">The Racket Reference</a></td></tr></table></div><div class="tocviewsublisttop" style="display: none;" id="tocview_0"><table cellspacing="0" cellpadding="0"><tr><td align="right">1 </td><td><a href="model.html" class="tocviewlink" data-pltdoc="x">Language Model</a></td></tr><tr><td align="right">2 </td><td><a href="notation.html" class="tocviewlink" data-pltdoc="x">Notation for Documentation</a></td></tr><tr><td align="right">3 </td><td><a href="syntax.html" class="tocviewlink" data-pltdoc="x">Syntactic Forms</a></td></tr><tr><td align="right">4 </td><td><a href="data.html" class="tocviewlink" data-pltdoc="x">Datatypes</a></td></tr><tr><td align="right">5 </td><td><a href="structures.html" class="tocviewlink" data-pltdoc="x">Structures</a></td></tr><tr><td align="right">6 </td><td><a href="mzlib_class.html" class="tocviewlink" data-pltdoc="x">Classes and Objects</a></td></tr><tr><td align="right">7 </td><td><a href="mzlib_unit.html" class="tocviewlink" data-pltdoc="x">Units</a></td></tr><tr><td align="right">8 </td><td><a href="contracts.html" class="tocviewselflink" data-pltdoc="x">Contracts</a></td></tr><tr><td align="right">9 </td><td><a href="match.html" class="tocviewlink" data-pltdoc="x">Pattern Matching</a></td></tr><tr><td align="right">10 </td><td><a href="control.html" class="tocviewlink" data-pltdoc="x">Control Flow</a></td></tr><tr><td align="right">11 </td><td><a href="concurrency.html" class="tocviewlink" data-pltdoc="x">Concurrency and Parallelism</a></td></tr><tr><td align="right">12 </td><td><a href="Macros.html" class="tocviewlink" data-pltdoc="x">Macros</a></td></tr><tr><td align="right">13 </td><td><a href="input-and-output.html" class="tocviewlink" data-pltdoc="x">Input and Output</a></td></tr><tr><td align="right">14 </td><td><a href="security.html" class="tocviewlink" data-pltdoc="x">Reflection and Security</a></td></tr><tr><td align="right">15 </td><td><a href="os.html" class="tocviewlink" data-pltdoc="x">Operating System</a></td></tr><tr><td align="right">16 </td><td><a href="memory.html" class="tocviewlink" data-pltdoc="x">Memory Management</a></td></tr><tr><td align="right">17 </td><td><a href="unsafe.html" class="tocviewlink" data-pltdoc="x">Unsafe Operations</a></td></tr><tr><td align="right">18 </td><td><a href="running.html" class=
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argument limits how hard the generator tries to generate a value matching the
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contract and is a rough limit of the size of the resulting value.</div></p><p>The generator may fail to generate a value, either because some contracts
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do not have corresponding generators (for example, not all predicates have
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generators) or because there is not enough fuel. In either case, the
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function <span class="RktVar">fail</span> is invoked. If <span class="RktVar">fail</span> accepts an argument,
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it is called with <span class="RktVal">#t</span> when there is no generator for <span class="RktVar">ctc</span>
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and called with <span class="RktVal">#f</span> when there is a generator, but the generator
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ended up returning <span class="RktSym"><a href="Random_generation.html#%28def._%28%28lib._racket%2Fcontract..rkt%29._contract-random-generate-fail%29%29" class="RktValLink" data-pltdoc="x">contract-random-generate-fail</a></span>.</p><p><div class="SIntrapara">Example:</div><div class="SIntrapara"><blockquote class="SCodeFlow"><table cellspacing="0" cellpadding="0" class="RktBlk"><tr><td><table cellspacing="0" cellpadding="0" class="RktBlk"><tr><td><span class="stt">> </span><span class="RktPn">(</span><span class="RktSym"><a href="for.html#%28form._%28%28lib._racket%2Fprivate%2Fbase..rkt%29._for%2Flist%29%29" class="RktStxLink" data-pltdoc="x">for/list</a></span><span class="hspace"> </span><span class="RktPn">(</span><span class="RktPn">[</span><span class="RktSym">i</span><span class="hspace"> </span><span class="RktPn">(</span><span class="RktSym"><a href="sequences.html#%28def._%28%28lib._racket%2Fprivate%2Fbase..rkt%29._in-range%29%29" class="RktValLink" data-pltdoc="x">in-range</a></span><span class="hspace"> </span><span class="RktVal">10</span><span class="RktPn">)</span><span class="RktPn">]</span><span class="RktPn">)</span></td></tr><tr><td><span class="hspace"> </span><span class="hspace"> </span><span class="RktPn">(</span><span class="RktSym"><a href="Random_generation.html#%28def._%28%28lib._racket%2Fcontract..rkt%29._contract-random-generate%29%29" class="RktValLink" data-pltdoc="x">contract-random-generate</a></span><span class="hspace"> </span><span class="RktPn">(</span><span class="RktSym"><a href="data-structure-contracts.html#%28def._%28%28lib._racket%2Fcontract%2Fbase..rkt%29._or%2Fc%29%29" class="RktValLink" data-pltdoc="x">or/c</a></span><span class="hspace"> </span><span class="RktSym"><a href="number-types.html#%28def._%28%28quote._~23~25kernel%29._integer~3f%29%29" class="RktValLink" data-pltdoc="x">integer?</a></span><span class="hspace"> </span><span class="RktVal">#f</span><span class="RktPn">)</span><span class="RktPn">)</span><span class="RktPn">)</span></td></tr></table></td></tr><tr><td><p><span class="RktRes">'(#f -476814620 -2147483647.0 110.0 540119564.0 -1 #f #f -1886291931.0 168.0)</span></p></td></tr></table></blockquote></div></p><p class="SHistory">Changed in version 6.1.1.5 of package <span class="stt">base</span>: Allow <span class="RktVar">fail</span> to accept a boolean.</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/contract..rkt)._contract-exercise))"></a><span title="Provided from: racket/contract, racket | Package: base"><span class="RktSym"><a href="Random_generation.html#%28def._%28%28lib._racket%2Fcontract..rkt%29._contract-exercise%29%29" class="RktValDef RktValLink" data-pltdoc="x">contract-exercise</a></span></span></td><td valign="top"><span class="hspace"> </span><span class="RktOpt">[</span></td><td valign="top"><span class="RktPn">#:fuel</span><span class="hspace"> </span><span class="RktVar">fuel</span></td><td valign="top"><span class="hspace"> </span></td><td valign="top"><span class="hspace"> </span></td><td valign="top"><span class="hspace"> </span></td><td valign="top"><span class="hspace"> </span></td></tr><tr><td valign="top"><span class="hspace"> </span></td><td valign="top"><span class="hspace"> </span></td><td valign="top"><span class="RktPn">#:shuffle?</span><span class="hspace"> </span><span class="RktVar">shuffle?</span><span class="RktOpt">]</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
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contract and, for those that do, uses information about the contract’s shape
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to poke and prod at the value. For example, if the value is function, it will
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use the contract to tell it what arguments to supply to the value.</p><p>The argument <span class="RktVar">fuel</span> determines how hard <span class="RktSym"><a href="Random_generation.html#%28def._%28%28lib._racket%2Fcontract..rkt%29._contract-exercise%29%29" class="RktValLink" data-pltdoc="x">contract-exercise</a></span>
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tries to break the values. It controls both the number of exercise iterations
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and the size of the intermediate values generated during the exercises.</p><p>The argument <span class="RktVar">shuffle?</span> controls whether <span class="RktSym"><a href="Random_generation.html#%28def._%28%28lib._racket%2Fcontract..rkt%29._contract-exercise%29%29" class="RktValLink" data-pltdoc="x">contract-exercise</a></span>
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randomizes the exercise order or not. If <span class="RktVar">shuffle?</span> is not <span class="RktVal">#f</span>,
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<span class="RktSym"><a href="Random_generation.html#%28def._%28%28lib._racket%2Fcontract..rkt%29._contract-exercise%29%29" class="RktValLink" data-pltdoc="x">contract-exercise</a></span> would shuffle the order of the contracts in each
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exercise iteration.</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="attaching-contracts-to-values.html#%28form._%28%28lib._racket%2Fcontract%2Fregion..rkt%29._define%2Fcontract%29%29" class="RktStxLink" data-pltdoc="x">define/contract</a></span><span class="hspace"> </span><span class="RktPn">(</span><span class="RktSym">returns-false</span><span class="hspace"> </span><span class="RktSym">x</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="function-contracts.html#%28form._%28%28lib._racket%2Fcontract%2Fbase..rkt%29._-~3e%29%29" class="RktStxLink" data-pltdoc="x"><span class="nobreak">-></span></a></span><span class="hspace"> </span><span class="RktSym"><a href="number-types.html#%28def._%28%28quote._~23~25kernel%29._integer~3f%29%29" class="RktValLink" data-pltdoc="x">integer?</a></span><span class="hspace"> </span><span class="RktSym"><a href="number-types.html#%28def._%28%28quote._~23~25kernel%29._integer~3f%29%29" class="RktValLink" data-pltdoc="x">integer?</a></span><span class="RktPn">)</span></td></tr><tr><td><span class="hspace"> </span><span class="hspace"> </span><span class="RktCmt">;</span><span class="RktCmt"> </span><span class="RktCmt">does not obey its contract</span></td></tr><tr><td><span class="hspace"> </span><span class="hspace"> </span><span class="RktVal">#f</span><span class="RktPn">)</span></td></tr></table></td></tr><tr><td><span class="stt">> </span><span class="RktPn">(</span><span class="RktSym"><a href="Random_generation.html#%28def._%28%28lib._racket%2Fcontract..rkt%29._contract-exercise%29%29" class="RktValLink" data-pltdoc="x">contract-exercise</a></span><span class="hspace"> </span><span class="RktSym">returns-false</span><span class="RktPn">)</span></td></tr><tr><td><p><span class="RktErr">returns-false: broke its own contract</span></p></td></tr><tr><td><p><span class="RktErr"></span><span class="hspace"> </span><span class="RktErr">promised: integer?</span></p></td></tr><tr><td><p><span class="RktErr"></span><span class="hspace"> </span><span class="RktErr">produced: #f</span></p></td></tr><tr><td><p><span class="RktErr"></span><span class="hspace"> </span><span class="RktErr">in: the range of</span></p></td></tr><tr><td><p><span class="RktErr"></span><span class="hspace"> </span><span class="RktErr"></span><span class="hspace"> </span><span class="RktErr"></span><span class="hspace"> </span><span class="RktErr">(-> integer? integer?)</span></p></td></tr><tr><td><p><span class="RktErr"></span><span class="hspace"> </span><span class="RktErr">contract from: (function returns-false)</span></p></td></tr><tr><td><p><span class="RktErr"></span><span class="hspace"> </span><span class="RktErr">blaming: (function returns-false)</span></p></td></tr><tr><td><p><span class="RktErr"></span><span class="hspace"> </span><span class="RktErr"></span><span class="hspace"> </span><span class="RktErr">(assuming the contract is correct)</span></p></td></tr><tr><td><p><span class="RktErr"></span><span class="hspace"> </span><span class="RktErr">at: eval:2:0</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="attaching-contracts-to-values.html#%28form._%28%28lib._racket%2Fcontract%2Fregion..rkt%29._define%2Fcontract%29%29" class="RktStxLink" data-pltdoc="x">define/contract</a></span><span class="hspace"> </span><span class="RktPn">(</span><span class="RktSym">calls-its-argument-with-el
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be used with combinators that generate values based on sub-contracts
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they have. It must be called when <span class="RktSym"><a href="Random_generation.html#%28def._%28%28lib._racket%2Fcontract..rkt%29._contract-random-generate%29%29" class="RktValLink" data-pltdoc="x">contract-random-generate</a></span>
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(and <span class="RktSym"><a href="Random_generation.html#%28def._%28%28lib._racket%2Fcontract..rkt%29._contract-exercise%29%29" class="RktValLink" data-pltdoc="x">contract-exercise</a></span>) creates the generators.
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To be more precise, <span class="RktSym"><a href="Random_generation.html#%28def._%28%28lib._racket%2Fcontract..rkt%29._contract-random-generate%2Fchoose%29%29" class="RktValLink" data-pltdoc="x">contract-random-generate/choose</a></span> is available
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only for the <span class="RktVar">generate</span> and <span class="RktVar">exercise</span> arguments in
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<span class="RktSym"><a href="Building_New_Contract_Combinators.html#%28def._%28%28lib._racket%2Fcontract%2Fprivate%2Fprop..rkt%29._build-contract-property%29%29" class="RktValLink" data-pltdoc="x">build-contract-property</a></span>, <span class="RktSym"><a href="Building_New_Contract_Combinators.html#%28def._%28%28lib._racket%2Fcontract%2Fcombinator..rkt%29._build-chaperone-contract-property%29%29" class="RktValLink" data-pltdoc="x">build-chaperone-contract-property</a></span>
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or <span class="RktSym"><a href="Building_New_Contract_Combinators.html#%28def._%28%28lib._racket%2Fcontract%2Fcombinator..rkt%29._build-flat-contract-property%29%29" class="RktValLink" data-pltdoc="x">build-flat-contract-property</a></span> and only during the dynamic
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extent of the call to <span class="RktVar">generate</span> (and <span class="RktVar">exercise</span>).
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That is, after it receives the <span class="RktVar">c</span> and <span class="RktVar">fuel</span> arguments
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and before it returns the thunk (or the exerciser).</div></p><p><span class="RktSym"><a href="Random_generation.html#%28def._%28%28lib._racket%2Fcontract..rkt%29._contract-random-generate%2Fchoose%29%29" class="RktValLink" data-pltdoc="x">contract-random-generate/choose</a></span> will never fail,
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but it might escape back to an enclosing
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call or to the original call to <span class="RktSym"><a href="Random_generation.html#%28def._%28%28lib._racket%2Fcontract..rkt%29._contract-random-generate%29%29" class="RktValLink" data-pltdoc="x">contract-random-generate</a></span>.</p><p>It chooses one of several possible generation strategies, and thus it may not
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actually use the generator associated with <span class="RktVar">c</span>, but might instead
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use a stashed value that matches <span class="RktVar">c</span> that it knows about via
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<span class="RktSym"><a href="Random_generation.html#%28def._%28%28lib._racket%2Fcontract..rkt%29._contract-random-generate-stash%29%29" class="RktValLink" data-pltdoc="x">contract-random-generate-stash</a></span>.</p><p class="SHistory">Added in version 6.1.1.5 of package <span class="stt">base</span>.</p><p><div class="SIntrapara"><blockquote class="SVInsetFlow"><table cellspacing="0" cellpadding="0" class="boxed RBoxed"><tr><td><blockquote class="SubFlow"><div class="RBackgroundLabel SIEHidden"><div class="RBackgroundLabelInner"><p>value</p></div></div><p class="RForeground"><a name="(def._((lib._racket/contract..rkt)._contract-random-generate-fail))"></a><span title="Provided from: racket/contract, racket | Package: base"><span class="RktSym"><a href="Random_generation.html#%28def._%28%28lib._racket%2Fcontract..rkt%29._contract-random-generate-fail%29%29" class="RktValDef RktValLink" data-pltdoc="x">contract-random-generate-fail</a></span></span><span class="hspace"> </span>:<span class="hspace"> </span><span class="RktSym"><a href="Random_generation.html#%28def._%28%28lib._racket%2Fcontract..rkt%29._contract-random-generate-fail~3f%29%29" class="RktValLink" data-pltdoc="x">contract-random-generate-fail?</a></span></p></blockquote></td></tr></table></blockquote></div><div class="SIntrapara">An atomic value that is used to indicate that a generator
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failed to generate a value.</div></p><p class="SHistory">Added in version 6.1.1.5 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/contract..rkt)._contract-random-generate-fail~3f))"></a><span title="Provided from: racket/contract, racket | Package: base"><span class="RktSym"><a href="Random_generation.html#%28def._%28%28lib._racket%2Fcontract..rkt%29._contract-random-generate-fail~3f%29%29" class="RktValDef RktValLink" data-pltdoc="x">contract-random-generate-fail?</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">A predicate to recognize <span class="RktSym"><a href="Random_generation.html#%28def._%28%28lib._racket%2Fcontract..rkt%29._contract-random-generate-fail%29%29" class="RktValLink" data-pltdoc="x">contract-random-generate-fail</a></span>.</div></p><p class="SHistory">Added in version 6.1.1.5 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/contract..rkt)._contract-random-generate-env~3f))"></a><span title="Provided from: racket/contract, racket | Package: base"><span class="RktSym"><a href="Random_generation.html#%28def._%28%28lib._racket%2Fcontract..rkt%29._contract-random-generate-env~3f%29%29" class="RktValDef RktValLink" data-pltdoc="x">contract-random-generate-env?</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">Recognizes contract generation environments.</div></p><p class="SHistory">Added in version 6.1.1.5 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/contract..rkt)._contract-random-generate-stash))"></a><span title="Provided from: racket/contract, racket | Package: base"><span class="RktSym"><a href="Random_generation.html#%28def._%28%28lib._racket%2Fcontract..rkt%29._contract-random-generate-stash%29%29" class="RktValDef
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test supplies during contract generation. For example, when
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<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="stt"> </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="stt"> </span><span class="RktSym"><a href="number-types.html#%28def._%28%28quote._~23~25kernel%29._integer~3f%29%29" class="RktValLink" data-pltdoc="x">integer?</a></span><span class="stt"> </span><span class="RktSym"><a href="number-types.html#%28def._%28%28quote._~23~25kernel%29._integer~3f%29%29" class="RktValLink" data-pltdoc="x">integer?</a></span><span class="RktPn">)</span><span class="stt"> </span><span class="RktSym"><a href="number-types.html#%28def._%28%28quote._~23~25kernel%29._integer~3f%29%29" class="RktValLink" data-pltdoc="x">integer?</a></span><span class="RktPn">)</span> is generated,
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it may call its argument function. That argument function may
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return an integer and, if so, that integer should be saved by
|
||
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calling <span class="RktSym"><a href="Random_generation.html#%28def._%28%28lib._racket%2Fcontract..rkt%29._contract-random-generate-stash%29%29" class="RktValLink" data-pltdoc="x">contract-random-generate-stash</a></span>, so it can
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be used by other integer generators.</div></p><p class="SHistory">Added in version 6.1.1.5 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/contract..rkt)._contract-random-generate-get-current-environment))"></a><span title="Provided from: racket/contract, racket | Package: base"><span class="RktSym"><a href="Random_generation.html#%28def._%28%28lib._racket%2Fcontract..rkt%29._contract-random-generate-get-current-environment%29%29" class="RktValDef RktValLink" data-pltdoc="x">contract-random-generate-get-current-environment</a></span></span><span class="RktPn"></span><span class="RktPn">)</span></p></blockquote></td></tr><tr><td><span class="hspace"> </span>→<span class="hspace"> </span><span class="RktSym"><a href="Random_generation.html#%28def._%28%28lib._racket%2Fcontract..rkt%29._contract-random-generate-env~3f%29%29" class="RktValLink" data-pltdoc="x">contract-random-generate-env?</a></span></td></tr></table></blockquote></div><div class="SIntrapara">Returns the environment currently being for generation. This function
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can be called only during the dynamic extent of contract generation.
|
||
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It is intended to be grabbed during the construction of a contract
|
||
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generator and then used with <span class="RktSym"><a href="Random_generation.html#%28def._%28%28lib._racket%2Fcontract..rkt%29._contract-random-generate-stash%29%29" class="RktValLink" data-pltdoc="x">contract-random-generate-stash</a></span>
|
||
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while generation is happening.</div></p><p class="SHistory">Added in version 6.1.1.5 of package <span class="stt">base</span>.</p><div class="navsetbottom"><span class="navleft"><form class="searchform"><input class="searchbox" id="searchbox" type="text" tabindex="1" placeholder="...search manuals..." title="Enter a search string to search the manuals" onkeypress="return DoSearchKey(event, this, "8.6", "../");"/></form> <a href="https://docs.racket-lang.org/index.html" title="up to the documentation top" data-pltdoc="x" onclick="return GotoPLTRoot("8.6");">top</a><span class="tocsettoggle"> <a href="javascript:void(0);" title="show/hide table of contents" onclick="TocsetToggle();">contents</a></span></span><span class="navright"> <a href="Legacy_Contracts.html" title="backward to "8.11 Legacy Contracts"" data-pltdoc="x">← prev</a> <a href="contracts.html" title="up to "8 Contracts"" data-pltdoc="x">up</a> <a href="match.html" title="forward to "9 Pattern Matching"" data-pltdoc="x">next →</a></span> </div></div></div><div id="contextindicator"> </div></body></html>
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