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<html><head><meta http-equiv="content-type" content="text/html; charset=utf-8"/><title>4.14.1 Sequences</title><link rel="stylesheet" type="text/css" href="../scribble.css" title="default"/><link rel="stylesheet" type="text/css" href="extras.css" title="default"/><link rel="stylesheet" type="text/css" href="icons.css" title="default"/><link rel="stylesheet" type="text/css" href="../racket.css" title="default"/><link rel="stylesheet" type="text/css" href="../manual-style.css" title="default"/><link rel="stylesheet" type="text/css" href="../manual-racket.css" title="default"/><link rel="stylesheet" type="text/css" href="../manual-racket.css" title="default"/><link rel="stylesheet" type="text/css" href="../doc-site.css" title="default"/><script type="text/javascript" src="../scribble-common.js"></script><script type="text/javascript" src="../manual-racket.js"></script><script type="text/javascript" src="../manual-racket.js"></script><script type="text/javascript" src="../doc-site.js"></script><script type="text/javascript" src="../local-redirect/local-redirect.js"></script><script type="text/javascript" src="../local-redirect/local-user-redirect.js"></script><!--[if IE 6]><style type="text/css">.SIEHidden { overflow: hidden; }</style><![endif]--></head><body id="doc-racket-lang-org"><div class="tocset"><div class="tocview"><div class="tocviewlist tocviewlisttopspace"><div class="tocviewtitle"><table cellspacing="0" cellpadding="0"><tr><td style="width: 1em;"><a href="javascript:void(0);" title="Expand/Collapse" class="tocviewtoggle" onclick="TocviewToggle(this,"tocview_0");">►</a></td><td></td><td><a href="index.html" class="tocviewlink" data-pltdoc="x"><span style="font-weight: bold">The Racket Reference</span></a></td></tr></table></div><div class="tocviewsublisttop" style="display: none;" id="tocview_0"><table cellspacing="0" cellpadding="0"><tr><td align="right">1 </td><td><a href="model.html" class="tocviewlink" data-pltdoc="x">Language Model</a></td></tr><tr><td align="right">2 </td><td><a href="notation.html" class="tocviewlink" data-pltdoc="x">Notation for Documentation</a></td></tr><tr><td align="right">3 </td><td><a href="syntax.html" class="tocviewlink" data-pltdoc="x">Syntactic Forms</a></td></tr><tr><td align="right">4 </td><td><a href="data.html" class="tocviewselflink" data-pltdoc="x">Datatypes</a></td></tr><tr><td align="right">5 </td><td><a href="structures.html" class="tocviewlink" data-pltdoc="x">Structures</a></td></tr><tr><td align="right">6 </td><td><a href="mzlib_class.html" class="tocviewlink" data-pltdoc="x">Classes and Objects</a></td></tr><tr><td align="right">7 </td><td><a href="mzlib_unit.html" class="tocviewlink" data-pltdoc="x">Units</a></td></tr><tr><td align="right">8 </td><td><a href="contracts.html" class="tocviewlink" data-pltdoc="x">Contracts</a></td></tr><tr><td align="right">9 </td><td><a href="match.html" class="tocviewlink" data-pltdoc="x">Pattern Matching</a></td></tr><tr><td align="right">10 </td><td><a href="control.html" class="tocviewlink" data-pltdoc="x">Control Flow</a></td></tr><tr><td align="right">11 </td><td><a href="concurrency.html" class="tocviewlink" data-pltdoc="x">Concurrency and Parallelism</a></td></tr><tr><td align="right">12 </td><td><a href="Macros.html" class="tocviewlink" data-pltdoc="x">Macros</a></td></tr><tr><td align="right">13 </td><td><a href="input-and-output.html" class="tocviewlink" data-pltdoc="x">Input and Output</a></td></tr><tr><td align="right">14 </td><td><a href="security.html" class="tocviewlink" data-pltdoc="x">Reflection and Security</a></td></tr><tr><td align="right">15 </td><td><a href="os.html" class="tocviewlink" data-pltdoc="x">Operating System</a></td></tr><tr><td align="right">16 </td><td><a href="memory.html" class="tocviewlink" data-pltdoc="x">Memory Management</a></td></tr><tr><td align="right">17 </td><td><a href="unsafe.html" class="tocviewlink" data-pltdoc="x">Unsafe Operations</a></td></tr><tr><td align="right">18 </td><td><a href="running.html" class="tocviewlink" data-pltdoc="x">Running Racket</a></td></tr><tr><td align="right"></td><td><a href="doc-bibliography.html" class="tocviewlink" data-pltdoc="x">Bibliography</a></td></tr><tr><td align="right"></td><td><a href="doc-index.html" class="tocviewlink" data-pltdoc="x">Index</a></td></tr></table></div></div><div class="tocviewlist"><table cellspacing="0" cellpadding="0"><tr><td style="width: 1em;"><a href="javascript:void(0);" title="Expand/Collapse" class="tocviewtoggle" onclick="TocviewToggle(this,"tocview_1");">►</a></td><td>4 </td><td><a href="data.html" class="tocviewlink" data-pltdoc="x">Datatypes</a></td></tr></table><div class="tocviewsublist" style="display: none;" id="tocview_1"><table cellspacing="0" cellpadding="0"><tr><td align="right">4.1 </td><td><a href="booleans.html" class="tocviewlink" data-pltdoc="x">Booleans and Equality</a></td></tr><tr><td align="right">4.2 </td><td><a href="numbers.html" class="tocviewlink" data-pltdoc="x">Numbers</a></td></tr><tr><td align="right">4.3 </td><td><a href="strings.html" class="tocviewlink" data-pltdoc="x">Strings</a></td></tr><tr><td align="right">4.4 </td><td><a href="bytestrings.html" class="tocviewlink" data-pltdoc="x">Byte Strings</a></td></tr><tr><td align="right">4.5 </td><td><a href="characters.html" class="tocviewlink" data-pltdoc="x">Characters</a></td></tr><tr><td align="right">4.6 </td><td><a href="symbols.html" class="tocviewlink" data-pltdoc="x">Symbols</a></td></tr><tr><td align="right">4.7 </td><td><a href="regexp.html" class="tocviewlink" data-pltdoc="x">Regular Expressions</a></td></tr><tr><td align="right">4.8 </td><td><a href="keywords.html" class="tocviewlink" data-pltdoc="x">Keywords</a></td></tr><tr><td align="right">4.9 </td><td><a href="pairs.html" class="tocviewlink" data-pltdoc="x">Pairs and Lists</a></td></tr><tr><td align="right">4.10 </td><td><a href="mpairs.html" class="tocviewlink" data-pltdoc="x">Mutable Pairs and Lists</a></td></tr><tr><td align="right">4.11 </td><td><a href="vectors.html" class="tocviewlink" data-pltdoc="x">Vectors</a></td></tr><tr><td align="right">4.12 </td><td><a href="boxes.html" class="tocviewlink" data-pltdoc="x">Boxes</a></td></tr><tr><td align="right">4.13 </td><td><a href="hashtables.html" class="tocviewlink" data-pltdoc="x">Hash Tables</a></td></tr><tr><td align="right">4.14 </td><td><a href="sequences_streams.html" class="tocviewselflink" data-pltdoc="x">Sequences and Streams</a></td></tr><tr><td align="right">4.15 </td><td><a href="dicts.html" class="tocviewlink" data-pltdoc="x">Dictionaries</a></td></tr><tr><td align="right">4.16 </td><td><a href="sets.html" class="tocviewlink" data-pltdoc="x">Sets</a></td></tr><tr><td align="right">4.17 </td><td><a href="procedures.html" class="tocviewlink" data-pltdoc="x">Procedures</a></td></tr><tr><td align="right">4.18 </td><td><a href="void.html" class="tocviewlink" data-pltdoc="x">Void</a></td></tr><tr><td align="right">4.19 </td><td><a href="undefined.html" class="tocviewlink" data-pltdoc="x">Undefined</a></td></tr></table></div></div><div class="tocviewlist"><table cellspacing="0" cellpadding="0"><tr><td style="width: 1em;"><a href="javascript:void(0);" title="Expand/Collapse" class="tocviewtoggle" onclick="TocviewToggle(this,"tocview_2");">▼</a></td><td>4.14 </td><td><a href="sequences_streams.html" class="tocviewlink" data-pltdoc="x">Sequences and Streams</a></td></tr></table><div class="tocviewsublist" style="display: block;" id="tocview_2"><table cellspacing="0" cellpadding="0"><tr><td align="right">4.14.1 </td><td><a href="" class="tocviewselflink" data-pltdoc="x">Sequences</a></td></tr><tr><td align="right">4.14.2 </td><td><a href="streams.html" class="tocviewlink" data-pltdoc="x">Streams</a></td></tr><tr><td align="right">4.14.3 </td><td><a href="Generators.html" class="tocviewlink" data-pltdoc="x">Generators</a></td></tr></table></div></div><div class="tocviewlist"><table cellspacing="0" cellpadding="0"><tr><td style="width: 1em;"><a href="javascript:void(0);" title="Expand/Collapse" class="tocviewtoggle" onclick="TocviewToggle(this,"tocview_3");">►</a></td><td>4.14.1 </td><td><a href="" class="tocviewselflink" data-pltdoc="x">Sequences</a></td></tr></table><div class="tocviewsublistbottom" style="display: none;" id="tocview_3"><table cellspacing="0" cellpadding="0"><tr><td align="right">4.14.1.1 </td><td><a href="#%28part._.Sequence_.Predicate_and_.Constructors%29" class="tocviewlink" data-pltdoc="x">Sequence Predicate and Constructors</a></td></tr><tr><td align="right">4.14.1.2 </td><td><a href="#%28part._.Sequence_.Conversion%29" class="tocviewlink" data-pltdoc="x">Sequence Conversion</a></td></tr><tr><td align="right">4.14.1.3 </td><td><a href="#%28part._more-sequences%29" class="tocviewlink" data-pltdoc="x">Sequence Combinations</a></td></tr></table></div></div></div><div class="tocsub"><div class="tocsubtitle">On this page:</div><table class="tocsublist" cellspacing="0"><tr><td><span class="tocsublinknumber">4.14.1.1<tt> </tt></span><a href="#%28part._.Sequence_.Predicate_and_.Constructors%29" class="tocsubseclink" data-pltdoc="x">Sequence Predicate and Constructors</a></td></tr><tr><td><a href="#%28def._%28%28lib._racket%2Fprivate%2Fbase..rkt%29._sequence~3f%29%29" class="tocsubnonseclink" data-pltdoc="x"><span class="RktSym"><span class="RktValLink">sequence?</span></span></a></td></tr><tr><td><a href="#%28def._%28%28lib._racket%2Fprivate%2Fbase..rkt%29._in-range%29%29" class="tocsubnonseclink" data-pltdoc="x"><span class="RktSym"><span class="RktValLink">in-<wbr></wbr>range</span></span></a></td></tr><tr><td><a href="#%28def._%28%28lib._racket%2Fprivate%2Fbase..rkt%29._in-naturals%29%29" class="tocsubnonseclink" data-pltdoc="x"><span class="RktSym"><span class="RktValLink">in-<wbr></wbr>naturals</span></span></a></td></tr><tr><td><a href="#%28def._%28%28lib._racket%2Fprivate%2Fbase..rkt%29._in-list%29%29" class="tocsubnonseclink" data-pltdoc="x"><span class="RktSym"><span class="RktValLink">in-<wbr></wbr>list</span></span></a></td></tr><tr><td><a href="#%28def._%28%28lib._racket%2Fprivate%2Fbase..rkt%29._in-mlist%29%29" class="tocsubnonseclink" data-pltdoc="x"><span class="RktSym"><span class="RktValLink">in-<wbr></wbr>mlist</span></span></a></td></tr><tr><td><a href="#%28def._%28%28lib._racket%2Fprivate%2Fbase..rkt%29._in-vector%29%29" class="tocsubnonseclink" data-pltdoc="x"><span class="RktSym"><span class="RktValLink">in-<wbr></wbr>vector</span></span></a></td></tr><tr><td><a href="#%28def._%28%28lib._racket%2Fprivate%2Fbase..rkt%29._in-string%29%29" class="tocsubnonseclink" data-pltdoc="x"><span class="RktSym"><span class="RktValLink">in-<wbr></wbr>string</span></span></a></td></tr><tr><td><a href="#%28def._%28%28lib._racket%2Fprivate%2Fbase..rkt%29._in-bytes%29%29" class="tocsubnonseclink" data-pltdoc="x"><span class="RktSym"><span class="RktValLink">in-<wbr></wbr>bytes</span></span></a></td></tr><tr><td><a href="#%28def._%28%28lib._racket%2Fprivate%2Fbase..rkt%29._in-port%29%29" class="tocsubnonseclink" data-pltdoc="x"><span class="RktSym"><span class="RktValLink">in-<wbr></wbr>port</span></span></a></td></tr><tr><td><a href="#%28def._%28%28lib._racket%2Fprivate%2Fbase..rkt%29._in-input-port-bytes%29%29" class="tocsubnonseclink" data-pltdoc="x"><span class="RktSym"><span class="RktValLink">in-<wbr></wbr>input-<wbr></wbr>port-<wbr></wbr>bytes</span></span></a></td></tr><tr><td><a href="#%28def._%28%28lib._racket%2Fprivate%2Fbase..rkt%29._in-input-port-chars%29%29" class="tocsubnonseclink" data-pltdoc="x"><span class="RktSym"><span class="RktValLink">in-<wbr></wbr>input-<wbr></wbr>port-<wbr></wbr>chars</span></span></a></td></tr><tr><td><a href="#%28def._%28%28lib._racket%2Fprivate%2Fbase..rkt%29._in-lines%29%29" class="tocsubnonseclink" data-pltdoc="x"><span class="RktSym"><span class="RktValLink">in-<wbr></wbr>lines</span></span></a></td></tr><tr><td><a href="#%28def._%28%28lib._racket%2Fprivate%2Fbase..rkt%29._in-bytes-lines%29%29" class="tocsubnonseclink" data-pltdoc="x"><span class="RktSym"><span class="RktValLink">in-<wbr></wbr>bytes-<wbr></wbr>lines</span></span></a></td></tr><tr><td><a href="#%28def._%28%28lib._racket%2Fprivate%2Fbase..rkt%29._in-hash%29%29" class="tocsubnonseclink" data-pltdoc="x"><span class="RktSym"><span class="RktValLink">in-<wbr></wbr>hash</span></span></a></td></tr><tr><td><a href="#%28def._%28%28lib._racket%2Fprivate%2Fbase..rkt%29._in-hash-keys%29%29" class="tocsubnonseclink" data-pltdoc="x"><span class="RktSym"><span class="RktValLink">in-<wbr></wbr>hash-<wbr></wbr>keys</span></span></a></td></tr><tr><td><a href="#%28def._%28%28lib._racket%2Fprivate%2Fbase..rkt%29._in-hash-values%29%29" class="tocsubnonseclink" data-pltdoc="x"><span class="RktSym"><span class="RktValLink">in-<wbr></wbr>hash-<wbr></wbr>values</span></span></a></td></tr><tr><td><a href="#%28def._%28%28lib._racket%2Fprivate%2Fbase..rkt%29._in-hash-pairs%29%29" class="tocsubnonseclink" data-pltdoc="x"><span class="RktSym"><span class="RktValLink">in-<wbr></wbr>hash-<wbr></wbr>pairs</span></span></a></td></tr><tr><td><a href="#%28def._%28%28lib._racket%2Fprivate%2Fbase..rkt%29._in-directory%29%29" class="tocsubnonseclink" data-pltdoc="x"><span class="RktSym"><span class="RktValLink">in-<wbr></wbr>directory</span></span></a></td></tr><tr><td><a href="#%28def._%28%28lib._racket%2Fprivate%2Fbase..rkt%29._in-producer%29%29" class="tocsubnonseclink" data-pltdoc="x"><span class="RktSym"><span class="RktValLink">in-<wbr></wbr>producer</span></span></a></td></tr><tr><td><a href="#%28def._%28%28lib._racket%2Fprivate%2Fbase..rkt%29._in-value%29%29" class="tocsubnonseclink" data-pltdoc="x"><span class="RktSym"><span class="RktValLink">in-<wbr></wbr>value</span></span></a></td></tr><tr><td><a href="#%28def._%28%28lib._racket%2Fprivate%2Fbase..rkt%29._in-indexed%29%29" class="tocsubnonseclink" data-pltdoc="x"><span class="RktSym"><span class="RktValLink">in-<wbr></wbr>indexed</span></span></a></td></tr><tr><td><a href="#%28def._%28%28lib._racket%2Fprivate%2Fbase..rkt%29._in-sequences%29%29" class="tocsubnonseclink" data-pltdoc="x"><span class="RktSym"><span class="RktValLink">in-<wbr></wbr>sequences</span></span></a></td></tr><tr><td><a href="#%28def._%28%28lib._racket%2Fprivate%2Fbase..rkt%29._in-cycle%29%29" class="tocsubnonseclink" data-pltdoc="x"><span class="RktSym"><span class="RktValLink">in-<wbr></wbr>cycle</span></span></a></td></tr><tr><td><a href="#%28def._%28%28lib._racket%2Fprivate%2Fbase..rkt%29._in-parallel%29%29" class="tocsubnonseclink" data-pltdoc="x"><span class="RktSym"><span class="RktValLink">in-<wbr></wbr>parallel</span></span></a></td></tr><tr><td><a href="#%28def._%28%28lib._racket%2Fprivate%2Fbase..rkt%29._in-values-sequence%29%29" class="tocsubnonseclink" data-pltdoc="x"><span class="RktSym"><span class="RktValLink">in-<wbr></wbr>values-<wbr></wbr>sequence</span></span></a></td></tr><tr><td><a href="#%28def._%28%28lib._racket%2Fprivate%2Fbase..rkt%29._in-values%2A-sequence%29%29" class="tocsubnonseclink" data-pltdoc="x"><span class="RktSym"><span class="RktValLink">in-<wbr></wbr>values*-<wbr></wbr>sequence</span></span></a></td></tr><tr><td><a href="#%28def._%28%28lib._racket%2Fprivate%2Fbase..rkt%29._stop-before%29%29" class="tocsubnonseclink" data-pltdoc="x"><span class="RktSym"><span class="RktValLink">stop-<wbr></wbr>before</span></span></a></td></tr><tr><td><a href="#%28def._%28%28lib._racket%2Fprivate%2Fbase..rkt%29._stop-after%29%29" class="tocsubnonseclink" data-pltdoc="x"><span class="RktSym"><span class="RktValLink">stop-<wbr></wbr>after</span></span></a></td></tr><tr><td><a href="#%28def._%28%28lib._racket%2Fprivate%2Fbase..rkt%29._make-do-sequence%29%29" class="tocsubnonseclink" data-pltdoc="x"><span class="RktSym"><span class="RktValLink">make-<wbr></wbr>do-<wbr></wbr>sequence</span></span></a></td></tr><tr><td><a href="#%28def._%28%28lib._racket%2Fprivate%2Fbase..rkt%29._prop~3asequence%29%29" class="tocsubnonseclink" data-pltdoc="x"><span class="RktSym"><span class="RktValLink">prop:<span class="mywbr"> </span>sequence</span></span></a></td></tr><tr><td><span class="tocsublinknumber">4.14.1.2<tt> </tt></span><a href="#%28part._.Sequence_.Conversion%29" class="tocsubseclink" data-pltdoc="x">Sequence Conversion</a></td></tr><tr><td><a href="#%28def._%28%28lib._racket%2Fprivate%2Fbase..rkt%29._sequence-~3estream%29%29" class="tocsubnonseclink" data-pltdoc="x"><span class="RktSym"><span class="RktValLink">sequence-<wbr></wbr>>stream</span></span></a></td></tr><tr><td><a href="#%28def._%28%28lib._racket%2Fprivate%2Fbase..rkt%29._sequence-generate%29%29" class="tocsubnonseclink" data-pltdoc="x"><span class="RktSym"><span class="RktValLink">sequence-<wbr></wbr>generate</span></span></a></td></tr><tr><td><a href="#%28def._%28%28lib._racket%2Fprivate%2Fbase..rkt%29._sequence-generate%2A%29%29" class="tocsubnonseclink" data-pltdoc="x"><span class="RktSym"><span class="RktValLink">sequence-<wbr></wbr>generate*</span></span></a></td></tr><tr><td><span class="tocsublinknumber">4.14.1.3<tt> </tt></span><a href="#%28part._more-sequences%29" class="tocsubseclink" data-pltdoc="x">Sequence Combinations</a></td></tr><tr><td><a href="#%28def._%28%28lib._racket%2Fsequence..rkt%29._empty-sequence%29%29" class="tocsubnonseclink" data-pltdoc="x"><span class="RktSym"><span class="RktValLink">empty-<wbr></wbr>sequence</span></span></a></td></tr><tr><td><a href="#%28def._%28%28lib._racket%2Fsequence..rkt%29._sequence-~3elist%29%29" class="tocsubnonseclink" data-pltdoc="x"><span class="RktSym"><span class="RktValLink">sequence-<wbr></wbr>>list</span></span></a></td></tr><tr><td><a href="#%28def._%28%28lib._racket%2Fsequence..rkt%29._sequence-length%29%29" class="tocsubnonseclink" data-pltdoc="x"><span class="RktSym"><span class="RktValLink">sequence-<wbr></wbr>length</span></span></a></td></tr><tr><td><a href="#%28def._%28%28lib._racket%2Fsequence..rkt%29._sequence-ref%29%29" class="tocsubnonseclink" data-pltdoc="x"><span class="RktSym"><span class="RktValLink">sequence-<wbr></wbr>ref</span></span></a></td></tr><tr><td><a href="#%28def._%28%28lib._racket%2Fsequence..rkt%29._sequence-tail%29%29" class="tocsubnonseclink" data-pltdoc="x"><span class="RktSym"><span class="RktValLink">sequence-<wbr></wbr>tail</span></span></a></td></tr><tr><td><a href="#%28def._%28%28lib._racket%2Fsequence..rkt%29._sequence-append%29%29" class="tocsubnonseclink" data-pltdoc="x"><span class="RktSym"><span class="RktValLink">sequence-<wbr></wbr>append</span></span></a></td></tr><tr><td><a href="#%28def._%28%28lib._racket%2Fsequence..rkt%29._sequence-map%29%29" class="tocsubnonseclink" data-pltdoc="x"><span class="RktSym"><span class="RktValLink">sequence-<wbr></wbr>map</span></span></a></td></tr><tr><td><a href="#%28def._%28%28lib._racket%2Fsequence..rkt%29._sequence-andmap%29%29" class="tocsubnonseclink" data-pltdoc="x"><span class="RktSym"><span class="RktValLink">sequence-<wbr></wbr>andmap</span></span></a></td></tr><tr><td><a href="#%28def._%28%28lib._racket%2Fsequence..rkt%29._sequence-ormap%29%29" class="tocsubnonseclink" data-pltdoc="x"><span class="RktSym"><span class="RktValLink">sequence-<wbr></wbr>ormap</span></span></a></td></tr><tr><td><a href="#%28def._%28%28lib._racket%2Fsequence..rkt%29._sequence-for-each%29%29" class="tocsubnonseclink" data-pltdoc="x"><span class="RktSym"><span class="RktValLink">sequence-<wbr></wbr>for-<wbr></wbr>each</span></span></a></td></tr><tr><td><a href="#%28def._%28%28lib._racket%2Fsequence..rkt%29._sequence-fold%29%29" class="tocsubnonseclink" data-pltdoc="x"><span class="RktSym"><span class="RktValLink">sequence-<wbr></wbr>fold</span></span></a></td></tr><tr><td><a href="#%28def._%28%28lib._racket%2Fsequence..rkt%29._sequence-count%29%29" class="tocsubnonseclink" data-pltdoc="x"><span class="RktSym"><span class="RktValLink">sequence-<wbr></wbr>count</span></span></a></td></tr><tr><td><a href="#%28def._%28%28lib._racket%2Fsequence..rkt%29._sequence-filter%29%29" class="tocsubnonseclink" data-pltdoc="x"><span class="RktSym"><span class="RktValLink">sequence-<wbr></wbr>filter</span></span></a></td></tr><tr><td><a href="#%28def._%28%28lib._racket%2Fsequence..rkt%29._sequence-add-between%29%29" class="tocsubnonseclink" data-pltdoc="x"><span class="RktSym"><span class="RktValLink">sequence-<wbr></wbr>add-<wbr></wbr>between</span></span></a></td></tr></table></div></div><div class="maincolumn"><div class="main"><div class="navsettop"><span class="navleft"><form class="searchform"><input class="searchbox" style="color: #888;" type="text" value="...search manuals..." title="Enter a search string to search the manuals" onkeypress="return DoSearchKey(event, this, "6.1", "../");" onfocus="this.style.color="black"; this.style.textAlign="left"; if (this.value == "...search manuals...") this.value="";" onblur="if (this.value.match(/^ *$/)) { this.style.color="#888"; this.style.textAlign="center"; this.value="...search manuals..."; }"/></form> <a href="../index.html" title="up to the documentation top" data-pltdoc="x" onclick="return GotoPLTRoot("6.1");">top</a></span><span class="navright"> <a href="sequences_streams.html" title="backward to "4.14 Sequences and Streams"" data-pltdoc="x">← prev</a> <a href="sequences_streams.html" title="up to "4.14 Sequences and Streams"" data-pltdoc="x">up</a> <a href="streams.html" title="forward to "4.14.2 Streams"" data-pltdoc="x">next →</a></span> </div><h5 x-source-module="(lib "scribblings/reference/reference.scrbl")" x-part-tag=""sequences"">4.14.1<tt> </tt><a name="(part._sequences)"></a>Sequences</h5><blockquote class="refpara"><blockquote class="refcolumn"><blockquote class="refcontent"><p><span class="imageleft"><img src="finger.png" alt="+" width="24" height="24"/></span><a href="http://download.racket-lang.org/docs/6.1/html/local-redirect/index.html?doc=guide&rel=for.html%23%2528part._sequences%2529&version=6.1" class="Sq" data-pltdoc="x">Sequence Constructors</a> in <a href="http://download.racket-lang.org/docs/6.1/html/local-redirect/index.html?doc=guide&rel=index.html&version=6.1" class="Sq" data-pltdoc="x"><span style="font-weight: bold">The Racket Guide</span></a> introduces sequences.</p></blockquote></blockquote></blockquote><p>A <a name="(tech._sequence)"></a><span style="font-style: italic">sequence</span> encapsulates an ordered collection of values.
The elements of a sequence can be extracted with one of the
<span class="RktSym"><a href="for.html#%28form._%28%28lib._racket%2Fprivate%2Fbase..rkt%29._for%29%29" class="RktStxLink" data-pltdoc="x">for</a></span> syntactic forms, with the procedures returned by
<span class="RktSym"><a href="#%28def._%28%28lib._racket%2Fprivate%2Fbase..rkt%29._sequence-generate%29%29" class="RktValLink" data-pltdoc="x">sequence-generate</a></span>, or by converting the sequence into a
<a href="streams.html#%28tech._stream%29" class="techoutside" data-pltdoc="x"><span class="techinside">stream</span></a>.</p><p>The sequence datatype overlaps with many other datatypes. Among
built-in datatypes, the sequence datatype includes the following:</p><ul><li><p>exact nonnegative integers (see below)</p></li><li><p>strings (see <a href="strings.html" data-pltdoc="x">Strings</a>)</p></li><li><p>byte strings (see <a href="bytestrings.html" data-pltdoc="x">Byte Strings</a>)</p></li><li><p>lists (see <a href="pairs.html" data-pltdoc="x">Pairs and Lists</a>)</p></li><li><p>mutable lists (see <a href="mpairs.html" data-pltdoc="x">Mutable Pairs and Lists</a>)</p></li><li><p>vectors (see <a href="vectors.html" data-pltdoc="x">Vectors</a>)</p></li><li><p>flvectors (see <a href="flonums.html#%28part._flvectors%29" data-pltdoc="x">Flonum Vectors</a>)</p></li><li><p>fxvectors (see <a href="fixnums.html#%28part._fxvectors%29" data-pltdoc="x">Fixnum Vectors</a>)</p></li><li><p>hash tables (see <a href="hashtables.html" data-pltdoc="x">Hash Tables</a>)</p></li><li><p>dictionaries (see <a href="dicts.html" data-pltdoc="x">Dictionaries</a>)</p></li><li><p>sets (see <a href="sets.html" data-pltdoc="x">Sets</a>)</p></li><li><p>input ports (see <a href="ports.html" data-pltdoc="x">Ports</a>)</p></li><li><p>streams (see <a href="streams.html" data-pltdoc="x">Streams</a>)</p></li></ul><p>An <a href="numbers.html#%28tech._exact._number%29" class="techoutside" data-pltdoc="x"><span class="techinside">exact number</span></a> <span class="RktVar">k</span> that is a non-negative
<a href="numbers.html#%28tech._integer%29" class="techoutside" data-pltdoc="x"><span class="techinside">integer</span></a> acts as a sequence similar to <span class="RktPn">(</span><span class="RktSym"><a href="#%28def._%28%28lib._racket%2Fprivate%2Fbase..rkt%29._in-range%29%29" class="RktValLink" data-pltdoc="x">in-range</a></span><span class="stt"> </span><span class="RktVar">k</span><span class="RktPn">)</span>,
except that <span class="RktVar">k</span> by itself is not a <a href="streams.html#%28tech._stream%29" class="techoutside" data-pltdoc="x"><span class="techinside">stream</span></a>.</p><p>Custom sequences can be defined using structure type properties. The
easiest method to define a custom sequence is to use the
<span class="RktSym"><a href="streams.html#%28def._%28%28lib._racket%2Fstream..rkt%29._gen~3astream%29%29" class="RktValLink" data-pltdoc="x">gen:stream</a></span> <a href="struct-generics.html#%28tech._generic._interface%29" class="techoutside" data-pltdoc="x"><span class="techinside">generic interface</span></a>. Streams are a suitable
abstraction for data structures that are directly iterable. For
example, a list is directly iterable with <span class="RktSym"><a href="pairs.html#%28def._%28%28lib._racket%2Flist..rkt%29._first%29%29" class="RktValLink" data-pltdoc="x">first</a></span> and
<span class="RktSym"><a href="pairs.html#%28def._%28%28lib._racket%2Flist..rkt%29._rest%29%29" class="RktValLink" data-pltdoc="x">rest</a></span>. On the other hand, vectors are not directly iterable:
iteration has to go through an index. For data structures that are not
directly iterable, the <a name="(tech._iterator)"></a><span style="font-style: italic">iterator</span> for the data structure can
be defined to be a stream (e.g., a structure containing the index of a
vector).</p><p>For example, unrolled linked lists (represented as a list of vectors)
themselves do not fit the stream abstraction, but have index-based
iterators that can be represented as streams:</p><p><table cellspacing="0" cellpadding="0" class="RktBlk"><tr><td><p>Examples:</p></td></tr><tr><td><blockquote class="SCodeFlow"><table cellspacing="0" cellpadding="0" class="RktBlk"><tr><td><table cellspacing="0" cellpadding="0" class="RktBlk"><tr><td><span class="stt">> </span><span class="RktPn">(</span><span class="RktSym"><a href="define-struct.html#%28form._%28%28lib._racket%2Fprivate%2Fbase..rkt%29._struct%29%29" class="RktStxLink" data-pltdoc="x">struct</a></span><span class="hspace"> </span><span class="RktSym">unrolled-list-iterator</span><span class="hspace"> </span><span class="RktPn">(</span><span class="RktSym">idx</span><span class="hspace"> </span><span class="RktSym">lst</span><span class="RktPn">)</span></td></tr><tr><td><span class="hspace"> </span><span class="hspace"> </span><span class="RktPn">#:methods</span><span class="hspace"> </span><span class="RktSym"><a href="streams.html#%28def._%28%28lib._racket%2Fstream..rkt%29._gen~3astream%29%29" class="RktValLink" data-pltdoc="x">gen:stream</a></span></td></tr><tr><td><span class="hspace"> </span><span class="hspace"> </span><span class="RktPn">[</span><span class="RktPn">(</span><span class="RktSym"><a href="define.html#%28form._%28%28lib._racket%2Fprivate%2Fbase..rkt%29._define%29%29" class="RktStxLink" data-pltdoc="x">define</a></span><span class="hspace"> </span><span class="RktPn">(</span><span class="RktSym"><a href="streams.html#%28def._%28%28lib._racket%2Fstream..rkt%29._stream-empty~3f%29%29" class="RktValLink" data-pltdoc="x">stream-empty?</a></span><span class="hspace"> </span><span class="RktSym">iter</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="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">lst</span><span class="hspace"> </span><span class="RktPn">(</span><span class="RktSym">unrolled-list-iterator-lst</span><span class="hspace"> </span><span class="RktSym">iter</span><span class="RktPn">)</span><span class="RktPn">)</span></td></tr><tr><td><span class="hspace"> </span><span class="hspace"> </span><span class="RktPn">(</span><span class="RktSym"><a href="if.html#%28form._%28%28lib._racket%2Fprivate%2Fletstx-scheme..rkt%29._or%29%29" class="RktStxLink" data-pltdoc="x">or</a></span><span class="hspace"> </span><span class="RktPn">(</span><span class="RktSym"><a href="pairs.html#%28def._%28%28quote._~23~25kernel%29._null~3f%29%29" class="RktValLink" data-pltdoc="x">null?</a></span><span class="hspace"> </span><span class="RktSym">lst</span><span class="RktPn">)</span></td></tr><tr><td><span class="hspace"> </span><span class="hspace"> </span><span class="RktPn">(</span><span class="RktSym"><a href="if.html#%28form._%28%28lib._racket%2Fprivate%2Fletstx-scheme..rkt%29._and%29%29" class="RktStxLink" data-pltdoc="x">and</a></span><span class="hspace"> </span><span class="RktPn">(</span><span class="RktSym"><a href="generic-numbers.html#%28def._%28%28quote._~23~25kernel%29._~3e~3d%29%29" class="RktValLink" data-pltdoc="x">>=</a></span><span class="hspace"> </span><span class="RktPn">(</span><span class="RktSym">unrolled-list-iterator-idx</span><span class="hspace"> </span><span class="RktSym">iter</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="vectors.html#%28def._%28%28quote._~23~25kernel%29._vector-length%29%29" class="RktValLink" data-pltdoc="x">vector-length</a></span><span class="hspace"> </span><span class="RktPn">(</span><span class="RktSym"><a href="pairs.html#%28def._%28%28lib._racket%2Flist..rkt%29._first%29%29" class="RktValLink" data-pltdoc="x">first</a></span><span class="hspace"> </span><span class="RktSym">lst</span><span class="RktPn">)</span><span class="RktPn">)</span><span class="RktPn">)</span></td></tr><tr><td><span class="hspace"> </span><span class="hspace"> </span><span class="RktPn">(</span><span class="RktSym"><a href="pairs.html#%28def._%28%28quote._~23~25kernel%29._null~3f%29%29" class="RktValLink" data-pltdoc="x">null?</a></span><span class="hspace"> </span><span class="RktPn">(</span><span class="RktSym"><a href="pairs.html#%28def._%28%28lib._racket%2Flist..rkt%29._rest%29%29" class="RktValLink" data-pltdoc="x">rest</a></span><span class="hspace"> </span><span class="RktSym">lst</span><span class="RktPn">)</span><span class="RktPn">)</span><span class="RktPn">)</span><span class="RktPn">)</span><span class="RktPn">)</span></td></tr><tr><td><span class="hspace"> </span><span class="hspace"> </span><span class="RktPn">(</span><span class="RktSym"><a href="define.html#%28form._%28%28lib._racket%2Fprivate%2Fbase..rkt%29._define%29%29" class="RktStxLink" data-pltdoc="x">define</a></span><span class="hspace"> </span><span class="RktPn">(</span><span class="RktSym"><a href="streams.html#%28def._%28%28lib._racket%2Fstream..rkt%29._stream-first%29%29" class="RktValLink" data-pltdoc="x">stream-first</a></span><span class="hspace"> </span><span class="RktSym">iter</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="vectors.html#%28def._%28%28quote._~23~25kernel%29._vector-ref%29%29" class="RktValLink" data-pltdoc="x">vector-ref</a></span><span class="hspace"> </span><span class="RktPn">(</span><span class="RktSym"><a href="pairs.html#%28def._%28%28lib._racket%2Flist..rkt%29._first%29%29" class="RktValLink" data-pltdoc="x">first</a></span><span class="hspace"> </span><span class="RktPn">(</span><span class="RktSym">unrolled-list-iterator-lst</span><span class="hspace"> </span><span class="RktSym">iter</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">unrolled-list-iterator-idx</span><span class="hspace"> </span><span class="RktSym">iter</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="define.html#%28form._%28%28lib._racket%2Fprivate%2Fbase..rkt%29._define%29%29" class="RktStxLink" data-pltdoc="x">define</a></span><span class="hspace"> </span><span class="RktPn">(</span><span class="RktSym"><a href="streams.html#%28def._%28%28lib._racket%2Fstream..rkt%29._stream-rest%29%29" class="RktValLink" data-pltdoc="x">stream-rest</a></span><span class="hspace"> </span><span class="RktSym">iter</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="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">idx</span><span class="hspace"> </span><span class="RktPn">(</span><span class="RktSym">unrolled-list-iterator-idx</span><span class="hspace"> </span><span class="RktSym">iter</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="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">lst</span><span class="hspace"> </span><span class="RktPn">(</span><span class="RktSym">unrolled-list-iterator-lst</span><span class="hspace"> </span><span class="RktSym">iter</span><span class="RktPn">)</span><span class="RktPn">)</span></td></tr><tr><td><span class="hspace"> </span><span class="hspace"> </span><span class="RktPn">(</span><span class="RktSym"><a href="if.html#%28form._%28%28quote._~23~25kernel%29._if%29%29" class="RktStxLink" data-pltdoc="x">if</a></span><span class="hspace"> </span><span class="RktPn">(</span><span class="RktSym"><a href="generic-numbers.html#%28def._%28%28quote._~23~25kernel%29._~3e~3d%29%29" class="RktValLink" data-pltdoc="x">>=</a></span><span class="hspace"> </span><span class="RktSym">idx</span><span class="hspace"> </span><span class="RktPn">(</span><span class="RktSym"><a href="generic-numbers.html#%28def._%28%28quote._~23~25kernel%29._sub1%29%29" class="RktValLink" data-pltdoc="x">sub1</a></span><span class="hspace"> </span><span class="RktPn">(</span><span class="RktSym"><a href="vectors.html#%28def._%28%28quote._~23~25kernel%29._vector-length%29%29" class="RktValLink" data-pltdoc="x">vector-length</a></span><span class="hspace"> </span><span class="RktPn">(</span><span class="RktSym"><a href="pairs.html#%28def._%28%28lib._racket%2Flist..rkt%29._first%29%29" class="RktValLink" data-pltdoc="x">first</a></span><span class="hspace"> </span><span class="RktSym">lst</span><span class="RktPn">)</span><span class="RktPn">)</span><span class="RktPn">)</span><span class="RktPn">)</span></td></tr><tr><td><span class="hspace"> </span><span class="hspace"> </span><span class="RktPn">(</span><span class="RktSym">unrolled-list-iterator</span><span class="hspace"> </span><span class="RktVal">0</span><span class="hspace"> </span><span class="RktPn">(</span><span class="RktSym"><a href="pairs.html#%28def._%28%28lib._racket%2Flist..rkt%29._rest%29%29" class="RktValLink" data-pltdoc="x">rest</a></span><span class="hspace"> </span><span class="RktSym">lst</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">unrolled-list-iterator</span><span class="hspace"> </span><span class="RktPn">(</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="RktSym">idx</span><span class="RktPn">)</span><span class="hspace"> </span><span class="RktSym">lst</span><span class="RktPn">)</span><span class="RktPn">)</span><span class="RktPn">)</span><span class="RktPn">]</span><span class="RktPn">)</span></td></tr></table></td></tr><tr><td><table cellspacing="0" cellpadding="0"><tr><td></td></tr></table></td></tr><tr><td><table cellspacing="0" cellpadding="0" class="RktBlk"><tr><td><span class="stt">> </span><span class="RktPn">(</span><span class="RktSym"><a href="define.html#%28form._%28%28lib._racket%2Fprivate%2Fbase..rkt%29._define%29%29" class="RktStxLink" data-pltdoc="x">define</a></span><span class="hspace"> </span><span class="RktPn">(</span><span class="RktSym">make-unrolled-list-iterator</span><span class="hspace"> </span><span class="RktSym">ul</span><span class="RktPn">)</span></td></tr><tr><td><span class="hspace"> </span><span class="hspace"> </span><span class="RktPn">(</span><span class="RktSym">unrolled-list-iterator</span><span class="hspace"> </span><span class="RktVal">0</span><span class="hspace"> </span><span class="RktPn">(</span><span class="RktSym">unrolled-list-lov</span><span class="hspace"> </span><span class="RktSym">ul</span><span class="RktPn">)</span><span class="RktPn">)</span><span class="RktPn">)</span></td></tr></table></td></tr><tr><td><table cellspacing="0" cellpadding="0"><tr><td></td></tr></table></td></tr><tr><td><table cellspacing="0" cellpadding="0" class="RktBlk"><tr><td><span class="stt">> </span><span class="RktPn">(</span><span class="RktSym"><a href="define-struct.html#%28form._%28%28lib._racket%2Fprivate%2Fbase..rkt%29._struct%29%29" class="RktStxLink" data-pltdoc="x">struct</a></span><span class="hspace"> </span><span class="RktSym">unrolled-list</span><span class="hspace"> </span><span class="RktPn">(</span><span class="RktSym">lov</span><span class="RktPn">)</span></td></tr><tr><td><span class="hspace"> </span><span class="hspace"> </span><span class="RktPn">#:property</span><span class="hspace"> </span><span class="RktSym"><a href="#%28def._%28%28lib._racket%2Fprivate%2Fbase..rkt%29._prop~3asequence%29%29" class="RktValLink" data-pltdoc="x">prop:sequence</a></span></td></tr><tr><td><span class="hspace"> </span><span class="hspace"> </span><span class="RktSym">make-unrolled-list-iterator</span><span class="RktPn">)</span></td></tr></table></td></tr><tr><td><table cellspacing="0" cellpadding="0"><tr><td></td></tr></table></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">ul1</span><span class="hspace"> </span><span class="RktPn">(</span><span class="RktSym">unrolled-list</span><span class="hspace"> </span><span class="RktVal">'</span><span class="RktVal">(</span><span class="RktVal">#</span><span class="RktVal">(</span><span class="RktVal">cracker</span><span class="hspace"> </span><span class="RktVal">biscuit</span><span class="RktVal">)</span><span class="hspace"> </span><span class="RktVal">#</span><span class="RktVal">(</span><span class="RktVal">cookie</span><span class="hspace"> </span><span class="RktVal">scone</span><span class="RktVal">)</span><span class="RktVal">)</span><span class="RktPn">)</span><span class="RktPn">)</span></td></tr><tr><td><table cellspacing="0" cellpadding="0"><tr><td></td></tr></table></td></tr><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">x</span><span class="hspace"> </span><span class="RktSym">ul1</span><span class="RktPn">]</span><span class="RktPn">)</span><span class="hspace"> </span><span class="RktSym">x</span><span class="RktPn">)</span></td></tr><tr><td><p><span class="RktRes">'(cracker biscuit cookie scone)</span></p></td></tr></table></blockquote></td></tr></table></p><p>The <span class="RktSym"><a href="#%28def._%28%28lib._racket%2Fprivate%2Fbase..rkt%29._prop~3asequence%29%29" class="RktValLink" data-pltdoc="x">prop:sequence</a></span> property provides more flexibility in
specifying iteration, such as when a pre-processing step is needed to
prepare the data for iteration. The <span class="RktSym"><a href="#%28def._%28%28lib._racket%2Fprivate%2Fbase..rkt%29._make-do-sequence%29%29" class="RktValLink" data-pltdoc="x">make-do-sequence</a></span>
function creates a sequence given a thunk that returns procedures to
implement a sequence, and the <span class="RktSym"><a href="#%28def._%28%28lib._racket%2Fprivate%2Fbase..rkt%29._prop~3asequence%29%29" class="RktValLink" data-pltdoc="x">prop:sequence</a></span> property can be
associated with a structure type to implement its implicit conversion
to a sequence.</p><p>For most sequence types, extracting elements from a sequence has no
side-effect on the original sequence value; for example, extracting
the sequence of elements from a list does not change the list. For
other sequence types, each extraction implies a side effect; for
example, extracting the sequence of bytes from a port causes the bytes
to be read from the port. A sequence’s state may either span all uses
of the sequence, as for a port, or it may be confined to each distinct
time that a sequence is <a name="(tech._initiate)"></a><span style="font-style: italic">initiate</span>d by a <span class="RktSym"><a href="for.html#%28form._%28%28lib._racket%2Fprivate%2Fbase..rkt%29._for%29%29" class="RktStxLink" data-pltdoc="x">for</a></span> form,
<span class="RktSym"><a href="#%28def._%28%28lib._racket%2Fprivate%2Fbase..rkt%29._sequence-~3estream%29%29" class="RktValLink" data-pltdoc="x">sequence->stream</a></span>, <span class="RktSym"><a href="#%28def._%28%28lib._racket%2Fprivate%2Fbase..rkt%29._sequence-generate%29%29" class="RktValLink" data-pltdoc="x">sequence-generate</a></span>, or
<span class="RktSym"><a href="#%28def._%28%28lib._racket%2Fprivate%2Fbase..rkt%29._sequence-generate%2A%29%29" class="RktValLink" data-pltdoc="x">sequence-generate*</a></span>. Concretely, the thunk passed to
<span class="RktSym"><a href="#%28def._%28%28lib._racket%2Fprivate%2Fbase..rkt%29._make-do-sequence%29%29" class="RktValLink" data-pltdoc="x">make-do-sequence</a></span> is called to <a href="#%28tech._initiate%29" class="techoutside" data-pltdoc="x"><span class="techinside">initiate</span></a> the sequence
each time the sequence is used.</p><p>Individual elements of a sequence typically correspond to single
values, but an element may also correspond to multiple values. For
example, a hash table generates two values—<wbr></wbr>a key and its value—<wbr></wbr>for
each element in the sequence.</p><h5 x-source-module="(lib "scribblings/reference/reference.scrbl")" x-part-tag=""Sequence_Predicate_and_Constructors"">4.14.1.1<tt> </tt><a name="(part._.Sequence_.Predicate_and_.Constructors)"></a>Sequence Predicate and Constructors</h5><p><div class="SIntrapara"><blockquote class="SVInsetFlow"><table cellspacing="0" cellpadding="0" class="boxed RBoxed"><tr><td><blockquote class="SubFlow"><div class="RBackgroundLabel SIEHidden"><div class="RBackgroundLabelInner"><p>procedure</p></div></div><p class="RForeground"><span class="RktPn">(</span><a name="(def._((lib._racket/private/base..rkt)._sequence~3f))"></a><span title="Provided from: racket/base, racket | Package: base"><span class="RktSym"><a href="#%28def._%28%28lib._racket%2Fprivate%2Fbase..rkt%29._sequence~3f%29%29" class="RktValDef RktValLink" data-pltdoc="x">sequence?</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> can be used as a <a href="#%28tech._sequence%29" class="techoutside" data-pltdoc="x"><span class="techinside">sequence</span></a>,
<span class="RktVal">#f</span> otherwise.</div></p><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="#%28def._%28%28lib._racket%2Fprivate%2Fbase..rkt%29._sequence~3f%29%29" class="RktValLink" data-pltdoc="x">sequence?</a></span><span class="hspace"> </span><span class="RktVal">42</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="#%28def._%28%28lib._racket%2Fprivate%2Fbase..rkt%29._sequence~3f%29%29" class="RktValLink" data-pltdoc="x">sequence?</a></span><span class="hspace"> </span><span class="RktVal">'</span><span class="RktVal">(</span><span class="RktVal">a</span><span class="hspace"> </span><span class="RktVal">b</span><span class="hspace"> </span><span class="RktVal">c</span><span class="RktVal">)</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="#%28def._%28%28lib._racket%2Fprivate%2Fbase..rkt%29._sequence~3f%29%29" class="RktValLink" data-pltdoc="x">sequence?</a></span><span class="hspace"> </span><span class="RktVal">"word"</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="#%28def._%28%28lib._racket%2Fprivate%2Fbase..rkt%29._sequence~3f%29%29" class="RktValLink" data-pltdoc="x">sequence?</a></span><span class="hspace"> </span><span class="RktVal">#\x</span><span class="RktPn">)</span></td></tr><tr><td><p><span class="RktRes">#f</span></p></td></tr></table></blockquote><p><div class="SIntrapara"><blockquote class="SVInsetFlow"><table cellspacing="0" cellpadding="0" class="boxed RBoxed"><tr><td><blockquote class="SubFlow"><div class="RBackgroundLabel SIEHidden"><div class="RBackgroundLabelInner"><p>procedure</p></div></div><p class="RForeground"><span class="RktPn">(</span><a name="(def._((lib._racket/private/base..rkt)._in-range))"></a><span title="Provided from: racket/base, racket | Package: base"><span class="RktSym"><a href="#%28def._%28%28lib._racket%2Fprivate%2Fbase..rkt%29._in-range%29%29" class="RktValDef RktValLink" data-pltdoc="x">in-range</a></span></span><span class="hspace"> </span><span class="RktVar">end</span><span class="RktPn">)</span><span class="hspace"> </span>→<span class="hspace"> </span><span class="RktSym"><a href="streams.html#%28def._%28%28lib._racket%2Fstream..rkt%29._stream~3f%29%29" class="RktValLink" data-pltdoc="x">stream?</a></span></p></blockquote></td></tr><tr><td><span class="hspace"> </span><span class="RktVar">end</span><span class="hspace"> </span>:<span class="hspace"> </span><span class="RktSym"><a href="number-types.html#%28def._%28%28quote._~23~25kernel%29._number~3f%29%29" class="RktValLink" data-pltdoc="x">number?</a></span></td></tr><tr><td><span class="RktPn">(</span><span title="Provided from: racket/base, racket | Package: base"><span class="RktSym"><a href="#%28def._%28%28lib._racket%2Fprivate%2Fbase..rkt%29._in-range%29%29" class="RktValDef RktValLink" data-pltdoc="x">in-range</a></span></span><span class="hspace"> </span><span class="RktVar">start</span><span class="hspace"> </span><span class="RktVar">end</span><span class="hspace"> </span>[<span class="RktVar">step</span>]<span class="RktPn">)</span><span class="hspace"> </span>→<span class="hspace"> </span><span class="RktSym"><a href="streams.html#%28def._%28%28lib._racket%2Fstream..rkt%29._stream~3f%29%29" class="RktValLink" data-pltdoc="x">stream?</a></span></td></tr><tr><td><span class="hspace"> </span><span class="RktVar">start</span><span class="hspace"> </span>:<span class="hspace"> </span><span class="RktSym"><a href="number-types.html#%28def._%28%28quote._~23~25kernel%29._number~3f%29%29" class="RktValLink" data-pltdoc="x">number?</a></span></td></tr><tr><td><span class="hspace"> </span><span class="RktVar">end</span><span class="hspace"> </span>:<span class="hspace"> </span><span class="RktSym"><a href="number-types.html#%28def._%28%28quote._~23~25kernel%29._number~3f%29%29" class="RktValLink" data-pltdoc="x">number?</a></span></td></tr><tr><td><span class="hspace"> </span><span class="RktVar">step</span><span class="hspace"> </span>:<span class="hspace"> </span><span class="RktSym"><a href="number-types.html#%28def._%28%28quote._~23~25kernel%29._number~3f%29%29" class="RktValLink" data-pltdoc="x">number?</a></span><span class="hspace"> </span>=<span class="hspace"> </span><span class="RktVal">1</span></td></tr></table></blockquote></div><div class="SIntrapara">Returns a sequence (that is also a <a href="streams.html#%28tech._stream%29" class="techoutside" data-pltdoc="x"><span class="techinside">stream</span></a>) whose elements are
numbers. The single-argument case <span class="RktPn">(</span><span class="RktSym"><a href="#%28def._%28%28lib._racket%2Fprivate%2Fbase..rkt%29._in-range%29%29" class="RktValLink" data-pltdoc="x">in-range</a></span><span class="stt"> </span><span class="RktVar">end</span><span class="RktPn">)</span> is
equivalent to <span class="RktPn">(</span><span class="RktSym"><a href="#%28def._%28%28lib._racket%2Fprivate%2Fbase..rkt%29._in-range%29%29" class="RktValLink" data-pltdoc="x">in-range</a></span><span class="stt"> </span><span class="RktVal">0</span><span class="stt"> </span><span class="RktVar">end</span><span class="stt"> </span><span class="RktVal">1</span><span class="RktPn">)</span>. The first number in the
sequence is <span class="RktVar">start</span>, and each successive element is generated
by adding <span class="RktVar">step</span> to the previous element. The sequence stops
before an element that would be greater or equal to <span class="RktVar">end</span> if
<span class="RktVar">step</span> is non-negative, or less or equal to <span class="RktVar">end</span> if
<span class="RktVar">step</span> is negative. </div><div class="SIntrapara">An <span class="RktSym"><a href="#%28def._%28%28lib._racket%2Fprivate%2Fbase..rkt%29._in-range%29%29" class="RktValLink" data-pltdoc="x">in-range</a></span> application can provide better performance for number iteration when it appears directly in a <span class="RktSym"><a href="for.html#%28form._%28%28lib._racket%2Fprivate%2Fbase..rkt%29._for%29%29" class="RktStxLink" data-pltdoc="x">for</a></span> clause.</div></p><p><div class="SIntrapara">Example: gaussian sum
</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="for.html#%28form._%28%28lib._racket%2Fprivate%2Fbase..rkt%29._for%2Fsum%29%29" class="RktStxLink" data-pltdoc="x">for/sum</a></span><span class="hspace"> </span><span class="RktPn">(</span><span class="RktPn">[</span><span class="RktSym">x</span><span class="hspace"> </span><span class="RktPn">(</span><span class="RktSym"><a href="#%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><span class="hspace"> </span><span class="RktSym">x</span><span class="RktPn">)</span></td></tr><tr><td><p><span class="RktRes">45</span></p></td></tr></table></blockquote></div></p><p><div class="SIntrapara">Example: sum of even numbers
</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="for.html#%28form._%28%28lib._racket%2Fprivate%2Fbase..rkt%29._for%2Fsum%29%29" class="RktStxLink" data-pltdoc="x">for/sum</a></span><span class="hspace"> </span><span class="RktPn">(</span><span class="RktPn">[</span><span class="RktSym">x</span><span class="hspace"> </span><span class="RktPn">(</span><span class="RktSym"><a href="#%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">0</span><span class="hspace"> </span><span class="RktVal">100</span><span class="hspace"> </span><span class="RktVal">2</span><span class="RktPn">)</span><span class="RktPn">]</span><span class="RktPn">)</span><span class="hspace"> </span><span class="RktSym">x</span><span class="RktPn">)</span></td></tr><tr><td><p><span class="RktRes">2450</span></p></td></tr></table></blockquote></div></p><p><div class="SIntrapara"><blockquote class="SVInsetFlow"><table cellspacing="0" cellpadding="0" class="boxed RBoxed"><tr><td><blockquote class="SubFlow"><div class="RBackgroundLabel SIEHidden"><div class="RBackgroundLabelInner"><p>procedure</p></div></div><p class="RForeground"><span class="RktPn">(</span><a name="(def._((lib._racket/private/base..rkt)._in-naturals))"></a><span title="Provided from: racket/base, racket | Package: base"><span class="RktSym"><a href="#%28def._%28%28lib._racket%2Fprivate%2Fbase..rkt%29._in-naturals%29%29" class="RktValDef RktValLink" data-pltdoc="x">in-naturals</a></span></span><span class="hspace"> </span>[<span class="RktVar">start</span>]<span class="RktPn">)</span><span class="hspace"> </span>→<span class="hspace"> </span><span class="RktSym"><a href="streams.html#%28def._%28%28lib._racket%2Fstream..rkt%29._stream~3f%29%29" class="RktValLink" data-pltdoc="x">stream?</a></span></p></blockquote></td></tr><tr><td><span class="hspace"> </span><span class="RktVar">start</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><span class="hspace"> </span>=<span class="hspace"> </span><span class="RktVal">0</span></td></tr></table></blockquote></div><div class="SIntrapara">Returns an infinite sequence (that is also a <a href="streams.html#%28tech._stream%29" class="techoutside" data-pltdoc="x"><span class="techinside">stream</span></a>) of exact
integers starting with <span class="RktVar">start</span>, where each element is one
more than the preceding element. </div><div class="SIntrapara">An <span class="RktSym"><a href="#%28def._%28%28lib._racket%2Fprivate%2Fbase..rkt%29._in-naturals%29%29" class="RktValLink" data-pltdoc="x">in-naturals</a></span> application can provide better performance for integer iteration when it appears directly in a <span class="RktSym"><a href="for.html#%28form._%28%28lib._racket%2Fprivate%2Fbase..rkt%29._for%29%29" class="RktStxLink" data-pltdoc="x">for</a></span> clause.</div></p><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">k</span><span class="hspace"> </span><span class="RktPn">(</span><span class="RktSym"><a href="#%28def._%28%28lib._racket%2Fprivate%2Fbase..rkt%29._in-naturals%29%29" class="RktValLink" data-pltdoc="x">in-naturals</a></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">x</span><span class="hspace"> </span><span class="RktPn">(</span><span class="RktSym"><a href="#%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="pairs.html#%28def._%28%28quote._~23~25kernel%29._list%29%29" class="RktValLink" data-pltdoc="x">list</a></span><span class="hspace"> </span><span class="RktSym">k</span><span class="hspace"> </span><span class="RktSym">x</span><span class="RktPn">)</span><span class="RktPn">)</span></td></tr></table></td></tr><tr><td><p><span class="RktRes">'((0 0) (1 1) (2 2) (3 3) (4 4) (5 5) (6 6) (7 7) (8 8) (9 9))</span></p></td></tr></table></blockquote><p><div class="SIntrapara"><blockquote class="SVInsetFlow"><table cellspacing="0" cellpadding="0" class="boxed RBoxed"><tr><td><blockquote class="SubFlow"><div class="RBackgroundLabel SIEHidden"><div class="RBackgroundLabelInner"><p>procedure</p></div></div><p class="RForeground"><span class="RktPn">(</span><a name="(def._((lib._racket/private/base..rkt)._in-list))"></a><span title="Provided from: racket/base, racket | Package: base"><span class="RktSym"><a href="#%28def._%28%28lib._racket%2Fprivate%2Fbase..rkt%29._in-list%29%29" class="RktValDef RktValLink" data-pltdoc="x">in-list</a></span></span><span class="hspace"> </span><span class="RktVar">lst</span><span class="RktPn">)</span><span class="hspace"> </span>→<span class="hspace"> </span><span class="RktSym"><a href="streams.html#%28def._%28%28lib._racket%2Fstream..rkt%29._stream~3f%29%29" class="RktValLink" data-pltdoc="x">stream?</a></span></p></blockquote></td></tr><tr><td><span class="hspace"> </span><span class="RktVar">lst</span><span class="hspace"> </span>:<span class="hspace"> </span><span class="RktSym"><a href="pairs.html#%28def._%28%28quote._~23~25kernel%29._list~3f%29%29" class="RktValLink" data-pltdoc="x">list?</a></span></td></tr></table></blockquote></div><div class="SIntrapara">Returns a sequence (that is also a <a href="streams.html#%28tech._stream%29" class="techoutside" data-pltdoc="x"><span class="techinside">stream</span></a>) that is equivalent
to using <span class="RktVar">lst</span> directly as a sequence.
</div><div class="SIntrapara"><blockquote class="refpara"><blockquote class="refcolumn"><blockquote class="refcontent"><p>See <a href="pairs.html" data-pltdoc="x">Pairs and Lists</a> for information on using lists as
sequences.</p></blockquote></blockquote></blockquote></div><div class="SIntrapara">An <span class="RktSym"><a href="#%28def._%28%28lib._racket%2Fprivate%2Fbase..rkt%29._in-list%29%29" class="RktValLink" data-pltdoc="x">in-list</a></span> application can provide better performance for list iteration when it appears directly in a <span class="RktSym"><a href="for.html#%28form._%28%28lib._racket%2Fprivate%2Fbase..rkt%29._for%29%29" class="RktStxLink" data-pltdoc="x">for</a></span> clause.</div></p><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">x</span><span class="hspace"> </span><span class="RktPn">(</span><span class="RktSym"><a href="#%28def._%28%28lib._racket%2Fprivate%2Fbase..rkt%29._in-list%29%29" class="RktValLink" data-pltdoc="x">in-list</a></span><span class="hspace"> </span><span class="RktVal">'</span><span class="RktVal">(</span><span class="RktVal">3</span><span class="hspace"> </span><span class="RktVal">1</span><span class="hspace"> </span><span class="RktVal">4</span><span class="RktVal">)</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="RktVal">`</span><span class="RktVal">(</span><span class="RktRdr">,</span><span class="RktSym">x</span><span class="hspace"> </span><span class="RktRdr">,</span><span class="RktPn">(</span><span class="RktSym"><a href="generic-numbers.html#%28def._%28%28quote._~23~25kernel%29._%2A%29%29" class="RktValLink" data-pltdoc="x">*</a></span><span class="hspace"> </span><span class="RktSym">x</span><span class="hspace"> </span><span class="RktSym">x</span><span class="RktPn">)</span><span class="RktVal">)</span><span class="RktPn">)</span></td></tr></table></td></tr><tr><td><p><span class="RktRes">'((3 9) (1 1) (4 16))</span></p></td></tr></table></blockquote><p><div class="SIntrapara"><blockquote class="SVInsetFlow"><table cellspacing="0" cellpadding="0" class="boxed RBoxed"><tr><td><blockquote class="SubFlow"><div class="RBackgroundLabel SIEHidden"><div class="RBackgroundLabelInner"><p>procedure</p></div></div><p class="RForeground"><span class="RktPn">(</span><a name="(def._((lib._racket/private/base..rkt)._in-mlist))"></a><span title="Provided from: racket/base, racket | Package: base"><span class="RktSym"><a href="#%28def._%28%28lib._racket%2Fprivate%2Fbase..rkt%29._in-mlist%29%29" class="RktValDef RktValLink" data-pltdoc="x">in-mlist</a></span></span><span class="hspace"> </span><span class="RktVar">mlst</span><span class="RktPn">)</span><span class="hspace"> </span>→<span class="hspace"> </span><span class="RktSym"><a href="#%28def._%28%28lib._racket%2Fprivate%2Fbase..rkt%29._sequence~3f%29%29" class="RktValLink" data-pltdoc="x">sequence?</a></span></p></blockquote></td></tr><tr><td><span class="hspace"> </span><span class="RktVar">mlst</span><span class="hspace"> </span>:<span class="hspace"> </span><span class="RktSym"><a href="http://download.racket-lang.org/docs/6.1/html/local-redirect/index.html?doc=compatibility&rel=mlists.html%23%2528def._%2528%2528lib._compatibility%252Fmlist..rkt%2529._mlist%7E3f%2529%2529&version=6.1" class="RktValLink Sq" data-pltdoc="x">mlist?</a></span></td></tr></table></blockquote></div><div class="SIntrapara">Returns a sequence equivalent to <span class="RktVar">mlst</span>.
</div><div class="SIntrapara"><blockquote class="refpara"><blockquote class="refcolumn"><blockquote class="refcontent"><p>See <a href="mpairs.html" data-pltdoc="x">Mutable Pairs and Lists</a> for information on using mutable lists as
sequences.</p></blockquote></blockquote></blockquote></div><div class="SIntrapara">An <span class="RktSym"><a href="#%28def._%28%28lib._racket%2Fprivate%2Fbase..rkt%29._in-mlist%29%29" class="RktValLink" data-pltdoc="x">in-mlist</a></span> application can provide better performance for mutable list iteration when it appears directly in a <span class="RktSym"><a href="for.html#%28form._%28%28lib._racket%2Fprivate%2Fbase..rkt%29._for%29%29" class="RktStxLink" data-pltdoc="x">for</a></span> clause.</div></p><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">x</span><span class="hspace"> </span><span class="RktPn">(</span><span class="RktSym"><a href="#%28def._%28%28lib._racket%2Fprivate%2Fbase..rkt%29._in-mlist%29%29" class="RktValLink" data-pltdoc="x">in-mlist</a></span><span class="hspace"> </span><span class="RktPn">(</span><span class="RktSym"><a href="mpairs.html#%28def._%28%28quote._~23~25kernel%29._mcons%29%29" class="RktValLink" data-pltdoc="x">mcons</a></span><span class="hspace"> </span><span class="RktVal">"RACKET"</span><span class="hspace"> </span><span class="RktPn">(</span><span class="RktSym"><a href="mpairs.html#%28def._%28%28quote._~23~25kernel%29._mcons%29%29" class="RktValLink" data-pltdoc="x">mcons</a></span><span class="hspace"> </span><span class="RktVal">"LANG"</span><span class="hspace"> </span><span class="RktVal">'</span><span class="RktVal">(</span><span class="RktVal">)</span><span class="RktPn">)</span><span class="RktPn">)</span><span class="RktPn">)</span><span class="RktPn">]</span><span class="RktPn">)</span></td></tr><tr><td><span class="hspace"> </span><span class="hspace"> </span><span class="RktPn">(</span><span class="RktSym"><a href="strings.html#%28def._%28%28quote._~23~25kernel%29._string-length%29%29" class="RktValLink" data-pltdoc="x">string-length</a></span><span class="hspace"> </span><span class="RktSym">x</span><span class="RktPn">)</span><span class="RktPn">)</span></td></tr></table></td></tr><tr><td><p><span class="RktRes">'(6 4)</span></p></td></tr></table></blockquote><p><div class="SIntrapara"><blockquote class="SVInsetFlow"><table cellspacing="0" cellpadding="0" class="boxed RBoxed"><tr><td><blockquote class="SubFlow"><div class="RBackgroundLabel SIEHidden"><div class="RBackgroundLabelInner"><p>procedure</p></div></div><p class="RForeground"><span class="RktPn">(</span><a name="(def._((lib._racket/private/base..rkt)._in-vector))"></a><span title="Provided from: racket/base, racket | Package: base"><span class="RktSym"><a href="#%28def._%28%28lib._racket%2Fprivate%2Fbase..rkt%29._in-vector%29%29" class="RktValDef RktValLink" data-pltdoc="x">in-vector</a></span></span><span class="hspace"> </span><span class="RktVar">vec</span><span class="hspace"> </span>[<span class="RktVar">start</span><span class="hspace"> </span><span class="RktVar">stop</span><span class="hspace"> </span><span class="RktVar">step</span>]<span class="RktPn">)</span><span class="hspace"> </span>→<span class="hspace"> </span><span class="RktSym"><a href="#%28def._%28%28lib._racket%2Fprivate%2Fbase..rkt%29._sequence~3f%29%29" class="RktValLink" data-pltdoc="x">sequence?</a></span></p></blockquote></td></tr><tr><td><span class="hspace"> </span><span class="RktVar">vec</span><span class="hspace"> </span>:<span class="hspace"> </span><span class="RktSym"><a href="vectors.html#%28def._%28%28quote._~23~25kernel%29._vector~3f%29%29" class="RktValLink" data-pltdoc="x">vector?</a></span></td></tr><tr><td><span class="hspace"> </span><span class="RktVar">start</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><span class="hspace"> </span>=<span class="hspace"> </span><span class="RktVal">0</span></td></tr><tr><td><span class="hspace"> </span><span class="RktVar">stop</span><span class="hspace"> </span>:<span class="hspace"> </span><span class="RktPn">(</span><span class="RktSym"><a href="data-structure-contracts.html#%28def._%28%28lib._racket%2Fcontract%2Fbase..rkt%29._or%2Fc%29%29" class="RktValLink" data-pltdoc="x">or/c</a></span><span class="hspace"> </span><span class="RktSym"><a href="number-types.html#%28def._%28%28quote._~23~25kernel%29._exact-integer~3f%29%29" class="RktValLink" data-pltdoc="x">exact-integer?</a></span><span class="hspace"> </span><span class="RktVal">#f</span><span class="RktPn">)</span><span class="hspace"> </span>=<span class="hspace"> </span><span class="RktVal">#f</span></td></tr><tr><td><span class="hspace"> </span><span class="RktVar">step</span><span class="hspace"> </span>:<span class="hspace"> </span><span class="RktPn">(</span><span class="RktSym"><a href="data-structure-contracts.html#%28def._%28%28lib._racket%2Fcontract%2Fprivate%2Fmisc..rkt%29._and%2Fc%29%29" class="RktValLink" data-pltdoc="x">and/c</a></span><span class="hspace"> </span><span class="RktSym"><a href="number-types.html#%28def._%28%28quote._~23~25kernel%29._exact-integer~3f%29%29" class="RktValLink" data-pltdoc="x">exact-integer?</a></span><span class="hspace"> </span><span class="RktPn">(</span><span class="RktSym"><a href="data-structure-contracts.html#%28def._%28%28lib._racket%2Fcontract%2Fprivate%2Fmisc..rkt%29._not%2Fc%29%29" class="RktValLink" data-pltdoc="x">not/c</a></span><span class="hspace"> </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="RktPn">)</span><span class="RktPn">)</span><span class="hspace"> </span>=<span class="hspace"> </span><span class="RktVal">1</span></td></tr></table></blockquote></div><div class="SIntrapara">Returns a sequence equivalent to <span class="RktVar">vec</span> when no optional
arguments are supplied.</div></p><blockquote class="refpara"><blockquote class="refcolumn"><blockquote class="refcontent"><p>See <a href="vectors.html" data-pltdoc="x">Vectors</a> for information on using vectors as
sequences.</p></blockquote></blockquote></blockquote><p>The optional arguments <span class="RktVar">start</span>, <span class="RktVar">stop</span>, and
<span class="RktVar">step</span> are analogous to <span class="RktSym"><a href="#%28def._%28%28lib._racket%2Fprivate%2Fbase..rkt%29._in-range%29%29" class="RktValLink" data-pltdoc="x">in-range</a></span>, except that a
<span class="RktVal">#f</span> value for <span class="RktVar">stop</span> is equivalent to
<span class="RktPn">(</span><span class="RktSym"><a href="vectors.html#%28def._%28%28quote._~23~25kernel%29._vector-length%29%29" class="RktValLink" data-pltdoc="x">vector-length</a></span><span class="stt"> </span><span class="RktVar">vec</span><span class="RktPn">)</span>. That is, the first element in the
sequence is <span class="RktPn">(</span><span class="RktSym"><a href="vectors.html#%28def._%28%28quote._~23~25kernel%29._vector-ref%29%29" class="RktValLink" data-pltdoc="x">vector-ref</a></span><span class="stt"> </span><span class="RktVar">vec</span><span class="stt"> </span><span class="RktVar">start</span><span class="RktPn">)</span>, and each successive
element is generated by adding <span class="RktVar">step</span> to index of the
previous element. The sequence stops before an index that would be
greater or equal to <span class="RktSym">end</span> if <span class="RktVar">step</span> is non-negative,
or less or equal to <span class="RktSym">end</span> if <span class="RktVar">step</span> is negative.</p><p>If <span class="RktVar">start</span> is not a valid index, or <span class="RktVar">stop</span> is not in
[-1, <span class="RktPn">(</span><span class="RktSym"><a href="vectors.html#%28def._%28%28quote._~23~25kernel%29._vector-length%29%29" class="RktValLink" data-pltdoc="x">vector-length</a></span><span class="stt"> </span><span class="RktVar">vec</span><span class="RktPn">)</span>] then the
<span class="RktSym"><a href="exns.html#%28def._%28%28lib._racket%2Fprivate%2Fbase..rkt%29._exn~3afail~3acontract%29%29" class="RktValLink" data-pltdoc="x">exn:fail:contract</a></span> exception is raised. If <span class="RktVar">start</span> is less than
<span class="RktVar">stop</span> and <span class="RktVar">step</span> is negative, then the
<span class="RktSym">exn:fail:contract:mismatch</span> exception is raised. Similarly, if <span class="RktVar">start</span>
is more than <span class="RktVar">stop</span> and <span class="RktVar">step</span> is positive, then the
<span class="RktSym">exn:fail:contract:mismatch</span> exception is raised.</p><p>An <span class="RktSym"><a href="#%28def._%28%28lib._racket%2Fprivate%2Fbase..rkt%29._in-vector%29%29" class="RktValLink" data-pltdoc="x">in-vector</a></span> application can provide better performance for vector iteration when it appears directly in a <span class="RktSym"><a href="for.html#%28form._%28%28lib._racket%2Fprivate%2Fbase..rkt%29._for%29%29" class="RktStxLink" data-pltdoc="x">for</a></span> clause.</p><blockquote class="SCodeFlow"><table cellspacing="0" cellpadding="0" class="RktBlk"><tr><td><table cellspacing="0" cellpadding="0" class="RktBlk"><tr><td><span class="stt">> </span><span class="RktPn">(</span><span class="RktSym"><a href="define.html#%28form._%28%28lib._racket%2Fprivate%2Fbase..rkt%29._define%29%29" class="RktStxLink" data-pltdoc="x">define</a></span><span class="hspace"> </span><span class="RktPn">(</span><span class="RktSym">histogram</span><span class="hspace"> </span><span class="RktSym">vector-of-words</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="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">a-hash</span><span class="hspace"> </span><span class="RktPn">(</span><span class="RktSym"><a href="hashtables.html#%28def._%28%28quote._~23~25kernel%29._hash%29%29" class="RktValLink" data-pltdoc="x">hash</a></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="for.html#%28form._%28%28lib._racket%2Fprivate%2Fbase..rkt%29._for%29%29" class="RktStxLink" data-pltdoc="x">for</a></span><span class="hspace"> </span><span class="RktPn">(</span><span class="RktPn">[</span><span class="RktSym">word</span><span class="hspace"> </span><span class="RktPn">(</span><span class="RktSym"><a href="#%28def._%28%28lib._racket%2Fprivate%2Fbase..rkt%29._in-vector%29%29" class="RktValLink" data-pltdoc="x">in-vector</a></span><span class="hspace"> </span><span class="RktSym">vector-of-words</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="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">a-hash</span><span class="hspace"> </span><span class="RktSym">word</span><span class="hspace"> </span><span class="RktPn">(</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="RktPn">(</span><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="hspace"> </span><span class="RktSym">a-hash</span><span class="hspace"> </span><span class="RktSym">word</span><span class="hspace"> </span><span class="RktVal">0</span><span class="RktPn">)</span><span class="RktPn">)</span><span class="RktPn">)</span><span class="RktPn">)</span></td></tr><tr><td><span class="hspace"> </span><span class="hspace"> </span><span class="RktSym">a-hash</span><span class="RktPn">)</span></td></tr></table></td></tr><tr><td><table cellspacing="0" cellpadding="0"><tr><td></td></tr></table></td></tr><tr><td><span class="stt">> </span><span class="RktPn">(</span><span class="RktSym">histogram</span><span class="hspace"> </span><span class="RktVal">#</span><span class="RktVal">(</span><span class="RktVal">"hello"</span><span class="hspace"> </span><span class="RktVal">"world"</span><span class="hspace"> </span><span class="RktVal">"hello"</span><span class="hspace"> </span><span class="RktVal">"sunshine"</span><span class="RktVal">)</span><span class="RktPn">)</span></td></tr><tr><td><p><span class="RktErr">hash-set!: contract violation</span></p></td></tr><tr><td><p><span class="RktErr"></span><span class="hspace"> </span><span class="RktErr">expected: (and/c hash? (not/c immutable?))</span></p></td></tr><tr><td><p><span class="RktErr"></span><span class="hspace"> </span><span class="RktErr">given: '#hash()</span></p></td></tr><tr><td><p><span class="RktErr"></span><span class="hspace"> </span><span class="RktErr">argument position: 1st</span></p></td></tr><tr><td><p><span class="RktErr"></span><span class="hspace"> </span><span class="RktErr">other arguments...:</span></p></td></tr><tr><td><p><span class="RktErr"></span><span class="hspace"> </span><span class="RktErr"></span><span class="hspace"> </span><span class="RktErr">"hello"</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">1</span></p></td></tr></table></blockquote><p><div class="SIntrapara"><blockquote class="SVInsetFlow"><table cellspacing="0" cellpadding="0" class="boxed RBoxed"><tr><td><blockquote class="SubFlow"><div class="RBackgroundLabel SIEHidden"><div class="RBackgroundLabelInner"><p>procedure</p></div></div><p class="RForeground"><span class="RktPn">(</span><a name="(def._((lib._racket/private/base..rkt)._in-string))"></a><span title="Provided from: racket/base, racket | Package: base"><span class="RktSym"><a href="#%28def._%28%28lib._racket%2Fprivate%2Fbase..rkt%29._in-string%29%29" class="RktValDef RktValLink" data-pltdoc="x">in-string</a></span></span><span class="hspace"> </span><span class="RktVar">str</span><span class="hspace"> </span>[<span class="RktVar">start</span><span class="hspace"> </span><span class="RktVar">stop</span><span class="hspace"> </span><span class="RktVar">step</span>]<span class="RktPn">)</span><span class="hspace"> </span>→<span class="hspace"> </span><span class="RktSym"><a href="#%28def._%28%28lib._racket%2Fprivate%2Fbase..rkt%29._sequence~3f%29%29" class="RktValLink" data-pltdoc="x">sequence?</a></span></p></blockquote></td></tr><tr><td><span class="hspace"> </span><span class="RktVar">str</span><span class="hspace"> </span>:<span class="hspace"> </span><span class="RktSym"><a href="strings.html#%28def._%28%28quote._~23~25kernel%29._string~3f%29%29" class="RktValLink" data-pltdoc="x">string?</a></span></td></tr><tr><td><span class="hspace"> </span><span class="RktVar">start</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><span class="hspace"> </span>=<span class="hspace"> </span><span class="RktVal">0</span></td></tr><tr><td><span class="hspace"> </span><span class="RktVar">stop</span><span class="hspace"> </span>:<span class="hspace"> </span><span class="RktPn">(</span><span class="RktSym"><a href="data-structure-contracts.html#%28def._%28%28lib._racket%2Fcontract%2Fbase..rkt%29._or%2Fc%29%29" class="RktValLink" data-pltdoc="x">or/c</a></span><span class="hspace"> </span><span class="RktSym"><a href="number-types.html#%28def._%28%28quote._~23~25kernel%29._exact-integer~3f%29%29" class="RktValLink" data-pltdoc="x">exact-integer?</a></span><span class="hspace"> </span><span class="RktVal">#f</span><span class="RktPn">)</span><span class="hspace"> </span>=<span class="hspace"> </span><span class="RktVal">#f</span></td></tr><tr><td><span class="hspace"> </span><span class="RktVar">step</span><span class="hspace"> </span>:<span class="hspace"> </span><span class="RktPn">(</span><span class="RktSym"><a href="data-structure-contracts.html#%28def._%28%28lib._racket%2Fcontract%2Fprivate%2Fmisc..rkt%29._and%2Fc%29%29" class="RktValLink" data-pltdoc="x">and/c</a></span><span class="hspace"> </span><span class="RktSym"><a href="number-types.html#%28def._%28%28quote._~23~25kernel%29._exact-integer~3f%29%29" class="RktValLink" data-pltdoc="x">exact-integer?</a></span><span class="hspace"> </span><span class="RktPn">(</span><span class="RktSym"><a href="data-structure-contracts.html#%28def._%28%28lib._racket%2Fcontract%2Fprivate%2Fmisc..rkt%29._not%2Fc%29%29" class="RktValLink" data-pltdoc="x">not/c</a></span><span class="hspace"> </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="RktPn">)</span><span class="RktPn">)</span><span class="hspace"> </span>=<span class="hspace"> </span><span class="RktVal">1</span></td></tr></table></blockquote></div><div class="SIntrapara">Returns a sequence equivalent to <span class="RktVar">str</span> when no optional
arguments are supplied.</div></p><blockquote class="refpara"><blockquote class="refcolumn"><blockquote class="refcontent"><p>See <a href="strings.html" data-pltdoc="x">Strings</a> for information on using strings as
sequences.</p></blockquote></blockquote></blockquote><p>The optional arguments <span class="RktVar">start</span>, <span class="RktVar">stop</span>, and
<span class="RktVar">step</span> are as in <span class="RktSym"><a href="#%28def._%28%28lib._racket%2Fprivate%2Fbase..rkt%29._in-vector%29%29" class="RktValLink" data-pltdoc="x">in-vector</a></span>.</p><p>An <span class="RktSym"><a href="#%28def._%28%28lib._racket%2Fprivate%2Fbase..rkt%29._in-string%29%29" class="RktValLink" data-pltdoc="x">in-string</a></span> application can provide better performance for string iteration when it appears directly in a <span class="RktSym"><a href="for.html#%28form._%28%28lib._racket%2Fprivate%2Fbase..rkt%29._for%29%29" class="RktStxLink" data-pltdoc="x">for</a></span> clause.</p><blockquote class="SCodeFlow"><table cellspacing="0" cellpadding="0" class="RktBlk"><tr><td><table cellspacing="0" cellpadding="0" class="RktBlk"><tr><td><span class="stt">> </span><span class="RktPn">(</span><span class="RktSym"><a href="define.html#%28form._%28%28lib._racket%2Fprivate%2Fbase..rkt%29._define%29%29" class="RktStxLink" data-pltdoc="x">define</a></span><span class="hspace"> </span><span class="RktPn">(</span><span class="RktSym">line-count</span><span class="hspace"> </span><span class="RktVar">str</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="for.html#%28form._%28%28lib._racket%2Fprivate%2Fbase..rkt%29._for%2Fsum%29%29" class="RktStxLink" data-pltdoc="x">for/sum</a></span><span class="hspace"> </span><span class="RktPn">(</span><span class="RktPn">[</span><span class="RktSym">ch</span><span class="hspace"> </span><span class="RktPn">(</span><span class="RktSym"><a href="#%28def._%28%28lib._racket%2Fprivate%2Fbase..rkt%29._in-string%29%29" class="RktValLink" data-pltdoc="x">in-string</a></span><span class="hspace"> </span><span class="RktVar">str</span><span class="RktPn">)</span><span class="RktPn">]</span><span class="RktPn">)</span></td></tr><tr><td><span class="hspace"> </span><span class="hspace"> </span><span class="RktPn">(</span><span class="RktSym"><a href="if.html#%28form._%28%28quote._~23~25kernel%29._if%29%29" class="RktStxLink" data-pltdoc="x">if</a></span><span class="hspace"> </span><span class="RktPn">(</span><span class="RktSym"><a href="characters.html#%28def._%28%28quote._~23~25kernel%29._char~3d~3f%29%29" class="RktValLink" data-pltdoc="x">char=?</a></span><span class="hspace"> </span><span class="RktVal">#\newline</span><span class="hspace"> </span><span class="RktSym">ch</span><span class="RktPn">)</span><span class="hspace"> </span><span class="RktVal">1</span><span class="hspace"> </span><span class="RktVal">0</span><span class="RktPn">)</span><span class="RktPn">)</span><span class="RktPn">)</span></td></tr></table></td></tr><tr><td><table cellspacing="0" cellpadding="0"><tr><td></td></tr></table></td></tr><tr><td><span class="stt">> </span><span class="RktPn">(</span><span class="RktSym">line-count</span><span class="hspace"> </span><span class="RktVal">"this string\nhas\nthree \nnewlines"</span><span class="RktPn">)</span></td></tr><tr><td><p><span class="RktRes">3</span></p></td></tr></table></blockquote><p><div class="SIntrapara"><blockquote class="SVInsetFlow"><table cellspacing="0" cellpadding="0" class="boxed RBoxed"><tr><td><blockquote class="SubFlow"><div class="RBackgroundLabel SIEHidden"><div class="RBackgroundLabelInner"><p>procedure</p></div></div><p class="RForeground"><span class="RktPn">(</span><a name="(def._((lib._racket/private/base..rkt)._in-bytes))"></a><span title="Provided from: racket/base, racket | Package: base"><span class="RktSym"><a href="#%28def._%28%28lib._racket%2Fprivate%2Fbase..rkt%29._in-bytes%29%29" class="RktValDef RktValLink" data-pltdoc="x">in-bytes</a></span></span><span class="hspace"> </span><span class="RktVar">bstr</span><span class="hspace"> </span>[<span class="RktVar">start</span><span class="hspace"> </span><span class="RktVar">stop</span><span class="hspace"> </span><span class="RktVar">step</span>]<span class="RktPn">)</span><span class="hspace"> </span>→<span class="hspace"> </span><span class="RktSym"><a href="#%28def._%28%28lib._racket%2Fprivate%2Fbase..rkt%29._sequence~3f%29%29" class="RktValLink" data-pltdoc="x">sequence?</a></span></p></blockquote></td></tr><tr><td><span class="hspace"> </span><span class="RktVar">bstr</span><span class="hspace"> </span>:<span class="hspace"> </span><span class="RktSym"><a href="bytestrings.html#%28def._%28%28quote._~23~25kernel%29._bytes~3f%29%29" class="RktValLink" data-pltdoc="x">bytes?</a></span></td></tr><tr><td><span class="hspace"> </span><span class="RktVar">start</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><span class="hspace"> </span>=<span class="hspace"> </span><span class="RktVal">0</span></td></tr><tr><td><span class="hspace"> </span><span class="RktVar">stop</span><span class="hspace"> </span>:<span class="hspace"> </span><span class="RktPn">(</span><span class="RktSym"><a href="data-structure-contracts.html#%28def._%28%28lib._racket%2Fcontract%2Fbase..rkt%29._or%2Fc%29%29" class="RktValLink" data-pltdoc="x">or/c</a></span><span class="hspace"> </span><span class="RktSym"><a href="number-types.html#%28def._%28%28quote._~23~25kernel%29._exact-integer~3f%29%29" class="RktValLink" data-pltdoc="x">exact-integer?</a></span><span class="hspace"> </span><span class="RktVal">#f</span><span class="RktPn">)</span><span class="hspace"> </span>=<span class="hspace"> </span><span class="RktVal">#f</span></td></tr><tr><td><span class="hspace"> </span><span class="RktVar">step</span><span class="hspace"> </span>:<span class="hspace"> </span><span class="RktPn">(</span><span class="RktSym"><a href="data-structure-contracts.html#%28def._%28%28lib._racket%2Fcontract%2Fprivate%2Fmisc..rkt%29._and%2Fc%29%29" class="RktValLink" data-pltdoc="x">and/c</a></span><span class="hspace"> </span><span class="RktSym"><a href="number-types.html#%28def._%28%28quote._~23~25kernel%29._exact-integer~3f%29%29" class="RktValLink" data-pltdoc="x">exact-integer?</a></span><span class="hspace"> </span><span class="RktPn">(</span><span class="RktSym"><a href="data-structure-contracts.html#%28def._%28%28lib._racket%2Fcontract%2Fprivate%2Fmisc..rkt%29._not%2Fc%29%29" class="RktValLink" data-pltdoc="x">not/c</a></span><span class="hspace"> </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="RktPn">)</span><span class="RktPn">)</span><span class="hspace"> </span>=<span class="hspace"> </span><span class="RktVal">1</span></td></tr></table></blockquote></div><div class="SIntrapara">Returns a sequence equivalent to <span class="RktVar">bstr</span> when no optional
arguments are supplied.</div></p><blockquote class="refpara"><blockquote class="refcolumn"><blockquote class="refcontent"><p>See <a href="bytestrings.html" data-pltdoc="x">Byte Strings</a> for information on using byte strings as
sequences.</p></blockquote></blockquote></blockquote><p>The optional arguments <span class="RktVar">start</span>, <span class="RktVar">stop</span>, and
<span class="RktVar">step</span> are as in <span class="RktSym"><a href="#%28def._%28%28lib._racket%2Fprivate%2Fbase..rkt%29._in-vector%29%29" class="RktValLink" data-pltdoc="x">in-vector</a></span>.</p><p>An <span class="RktSym"><a href="#%28def._%28%28lib._racket%2Fprivate%2Fbase..rkt%29._in-bytes%29%29" class="RktValLink" data-pltdoc="x">in-bytes</a></span> application can provide better performance for byte string iteration when it appears directly in a <span class="RktSym"><a href="for.html#%28form._%28%28lib._racket%2Fprivate%2Fbase..rkt%29._for%29%29" class="RktStxLink" data-pltdoc="x">for</a></span> clause.</p><blockquote class="SCodeFlow"><table cellspacing="0" cellpadding="0" class="RktBlk"><tr><td><table cellspacing="0" cellpadding="0" class="RktBlk"><tr><td><span class="stt">> </span><span class="RktPn">(</span><span class="RktSym"><a href="define.html#%28form._%28%28lib._racket%2Fprivate%2Fbase..rkt%29._define%29%29" class="RktStxLink" data-pltdoc="x">define</a></span><span class="hspace"> </span><span class="RktPn">(</span><span class="RktSym">has-eof?</span><span class="hspace"> </span><span class="RktSym">bs</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="for.html#%28form._%28%28lib._racket%2Fprivate%2Fbase..rkt%29._for%2For%29%29" class="RktStxLink" data-pltdoc="x">for/or</a></span><span class="hspace"> </span><span class="RktPn">(</span><span class="RktPn">[</span><span class="RktSym">ch</span><span class="hspace"> </span><span class="RktPn">(</span><span class="RktSym"><a href="#%28def._%28%28lib._racket%2Fprivate%2Fbase..rkt%29._in-bytes%29%29" class="RktValLink" data-pltdoc="x">in-bytes</a></span><span class="hspace"> </span><span class="RktSym">bs</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="generic-numbers.html#%28def._%28%28quote._~23~25kernel%29._~3d%29%29" class="RktValLink" data-pltdoc="x">=</a></span><span class="hspace"> </span><span class="RktSym">ch</span><span class="hspace"> </span><span class="RktVal">0</span><span class="RktPn">)</span><span class="RktPn">)</span><span class="RktPn">)</span></td></tr></table></td></tr><tr><td><table cellspacing="0" cellpadding="0"><tr><td></td></tr></table></td></tr><tr><td><span class="stt">> </span><span class="RktPn">(</span><span class="RktSym">has-eof?</span><span class="hspace"> </span><span class="RktVal">#"this byte string has an \0embedded zero byte"</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">has-eof?</span><span class="hspace"> </span><span class="RktVal">#"this byte string does not"</span><span class="RktPn">)</span></td></tr><tr><td><p><span class="RktRes">#f</span></p></td></tr></table></blockquote><p><div class="SIntrapara"><blockquote class="SVInsetFlow"><table cellspacing="0" cellpadding="0" class="boxed RBoxed"><tr><td><blockquote class="SubFlow"><div class="RBackgroundLabel SIEHidden"><div class="RBackgroundLabelInner"><p>procedure</p></div></div><p class="RForeground"><span class="RktPn">(</span><a name="(def._((lib._racket/private/base..rkt)._in-port))"></a><span title="Provided from: racket/base, racket | Package: base"><span class="RktSym"><a href="#%28def._%28%28lib._racket%2Fprivate%2Fbase..rkt%29._in-port%29%29" class="RktValDef RktValLink" data-pltdoc="x">in-port</a></span></span><span class="hspace"> </span>[<span class="RktVar">r</span><span class="hspace"> </span><span class="RktVar">in</span>]<span class="RktPn">)</span><span class="hspace"> </span>→<span class="hspace"> </span><span class="RktSym"><a href="#%28def._%28%28lib._racket%2Fprivate%2Fbase..rkt%29._sequence~3f%29%29" class="RktValLink" data-pltdoc="x">sequence?</a></span></p></blockquote></td></tr><tr><td><span class="hspace"> </span><span class="RktVar">r</span><span class="hspace"> </span>:<span class="hspace"> </span><span class="RktPn">(</span><span class="RktSym"><a href="port-ops.html#%28def._%28%28quote._~23~25kernel%29._input-port~3f%29%29" class="RktValLink" data-pltdoc="x">input-port?</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><span class="hspace"> </span>=<span class="hspace"> </span><span class="RktSym"><a href="Reading.html#%28def._%28%28quote._~23~25kernel%29._read%29%29" class="RktValLink" data-pltdoc="x">read</a></span></td></tr><tr><td><span class="hspace"> </span><span class="RktVar">in</span><span class="hspace"> </span>:<span class="hspace"> </span><span class="RktSym"><a href="port-ops.html#%28def._%28%28quote._~23~25kernel%29._input-port~3f%29%29" class="RktValLink" data-pltdoc="x">input-port?</a></span><span class="hspace"> </span>=<span class="hspace"> </span><span class="RktPn">(</span><span class="RktSym"><a href="port-ops.html#%28def._%28%28quote._~23~25kernel%29._current-input-port%29%29" class="RktValLink" data-pltdoc="x">current-input-port</a></span><span class="RktPn">)</span></td></tr></table></blockquote></div><div class="SIntrapara">Returns a sequence whose elements are produced by calling <span class="RktVar">r</span>
on <span class="RktVar">in</span> until it produces <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>.</div></p><p><div class="SIntrapara"><blockquote class="SVInsetFlow"><table cellspacing="0" cellpadding="0" class="boxed RBoxed"><tr><td><blockquote class="SubFlow"><div class="RBackgroundLabel SIEHidden"><div class="RBackgroundLabelInner"><p>procedure</p></div></div><p class="RForeground"><span class="RktPn">(</span><a name="(def._((lib._racket/private/base..rkt)._in-input-port-bytes))"></a><span title="Provided from: racket/base, racket | Package: base"><span class="RktSym"><a href="#%28def._%28%28lib._racket%2Fprivate%2Fbase..rkt%29._in-input-port-bytes%29%29" class="RktValDef RktValLink" data-pltdoc="x">in-input-port-bytes</a></span></span><span class="hspace"> </span><span class="RktVar">in</span><span class="RktPn">)</span><span class="hspace"> </span>→<span class="hspace"> </span><span class="RktSym"><a href="#%28def._%28%28lib._racket%2Fprivate%2Fbase..rkt%29._sequence~3f%29%29" class="RktValLink" data-pltdoc="x">sequence?</a></span></p></blockquote></td></tr><tr><td><span class="hspace"> </span><span class="RktVar">in</span><span class="hspace"> </span>:<span class="hspace"> </span><span class="RktSym"><a href="port-ops.html#%28def._%28%28quote._~23~25kernel%29._input-port~3f%29%29" class="RktValLink" data-pltdoc="x">input-port?</a></span></td></tr></table></blockquote></div><div class="SIntrapara">Returns a sequence equivalent to <span class="RktPn">(</span><span class="RktSym"><a href="#%28def._%28%28lib._racket%2Fprivate%2Fbase..rkt%29._in-port%29%29" class="RktValLink" data-pltdoc="x">in-port</a></span><span class="stt"> </span><span class="RktSym"><a href="Byte_and_String_Input.html#%28def._%28%28quote._~23~25kernel%29._read-byte%29%29" class="RktValLink" data-pltdoc="x">read-byte</a></span><span class="stt"> </span><span class="RktVar">in</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._((lib._racket/private/base..rkt)._in-input-port-chars))"></a><span title="Provided from: racket/base, racket | Package: base"><span class="RktSym"><a href="#%28def._%28%28lib._racket%2Fprivate%2Fbase..rkt%29._in-input-port-chars%29%29" class="RktValDef RktValLink" data-pltdoc="x">in-input-port-chars</a></span></span><span class="hspace"> </span><span class="RktVar">in</span><span class="RktPn">)</span><span class="hspace"> </span>→<span class="hspace"> </span><span class="RktSym"><a href="#%28def._%28%28lib._racket%2Fprivate%2Fbase..rkt%29._sequence~3f%29%29" class="RktValLink" data-pltdoc="x">sequence?</a></span></p></blockquote></td></tr><tr><td><span class="hspace"> </span><span class="RktVar">in</span><span class="hspace"> </span>:<span class="hspace"> </span><span class="RktSym"><a href="port-ops.html#%28def._%28%28quote._~23~25kernel%29._input-port~3f%29%29" class="RktValLink" data-pltdoc="x">input-port?</a></span></td></tr></table></blockquote></div><div class="SIntrapara">Returns a sequence whose elements are read as characters from
<span class="RktVar">in</span> (equivalent to <span class="RktPn">(</span><span class="RktSym"><a href="#%28def._%28%28lib._racket%2Fprivate%2Fbase..rkt%29._in-port%29%29" class="RktValLink" data-pltdoc="x">in-port</a></span><span class="stt"> </span><span class="RktSym"><a href="Byte_and_String_Input.html#%28def._%28%28quote._~23~25kernel%29._read-char%29%29" class="RktValLink" data-pltdoc="x">read-char</a></span><span class="stt"> </span><span class="RktVar">in</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._((lib._racket/private/base..rkt)._in-lines))"></a><span title="Provided from: racket/base, racket | Package: base"><span class="RktSym"><a href="#%28def._%28%28lib._racket%2Fprivate%2Fbase..rkt%29._in-lines%29%29" class="RktValDef RktValLink" data-pltdoc="x">in-lines</a></span></span><span class="hspace"> </span>[<span class="RktVar">in</span><span class="hspace"> </span><span class="RktVar">mode</span>]<span class="RktPn">)</span><span class="hspace"> </span>→<span class="hspace"> </span><span class="RktSym"><a href="#%28def._%28%28lib._racket%2Fprivate%2Fbase..rkt%29._sequence~3f%29%29" class="RktValLink" data-pltdoc="x">sequence?</a></span></p></blockquote></td></tr><tr><td><span class="hspace"> </span><span class="RktVar">in</span><span class="hspace"> </span>:<span class="hspace"> </span><span class="RktSym"><a href="port-ops.html#%28def._%28%28quote._~23~25kernel%29._input-port~3f%29%29" class="RktValLink" data-pltdoc="x">input-port?</a></span><span class="hspace"> </span>=<span class="hspace"> </span><span class="RktPn">(</span><span class="RktSym"><a href="port-ops.html#%28def._%28%28quote._~23~25kernel%29._current-input-port%29%29" class="RktValLink" data-pltdoc="x">current-input-port</a></span><span class="RktPn">)</span></td></tr><tr><td><table cellspacing="0" cellpadding="0" class="argcontract"><tr><td><span class="hspace"> </span></td><td><span class="RktVar">mode</span></td><td><span class="hspace"> </span></td><td>:</td><td><span class="hspace"> </span></td><td><span class="RktPn">(</span><span class="RktSym"><a href="data-structure-contracts.html#%28def._%28%28lib._racket%2Fcontract%2Fbase..rkt%29._or%2Fc%29%29" class="RktValLink" data-pltdoc="x">or/c</a></span><span class="hspace"> </span><span class="RktVal">'</span><span class="RktVal">linefeed</span><span class="hspace"> </span><span class="RktVal">'</span><span class="RktVal">return</span><span class="hspace"> </span><span class="RktVal">'</span><span class="RktVal">return-linefeed</span><span class="hspace"> </span><span class="RktVal">'</span><span class="RktVal">any</span><span class="hspace"> </span><span class="RktVal">'</span><span class="RktVal">any-one</span><span class="RktPn">)</span></td></tr><tr><td><span class="hspace"> </span></td><td><span class="hspace"> </span></td><td><span class="hspace"> </span></td><td>=</td><td><span class="hspace"> </span></td><td><span class="RktVal">'</span><span class="RktVal">any</span></td></tr></table></td></tr></table></blockquote></div><div class="SIntrapara">Returns a sequence equivalent to
<span class="RktPn">(</span><span class="RktSym"><a href="#%28def._%28%28lib._racket%2Fprivate%2Fbase..rkt%29._in-port%29%29" class="RktValLink" data-pltdoc="x">in-port</a></span><span class="stt"> </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="stt"> </span><span class="RktPn">(</span><span class="RktSym">p</span><span class="RktPn">)</span><span class="stt"> </span><span class="RktPn">(</span><span class="RktSym"><a href="Byte_and_String_Input.html#%28def._%28%28quote._~23~25kernel%29._read-line%29%29" class="RktValLink" data-pltdoc="x">read-line</a></span><span class="stt"> </span><span class="RktSym">p</span><span class="stt"> </span><span class="RktVar">mode</span><span class="RktPn">)</span><span class="RktPn">)</span><span class="stt"> </span><span class="RktVar">in</span><span class="RktPn">)</span>. Note that
the default mode is <span class="RktVal">'</span><span class="RktVal">any</span>, whereas the default mode of
<span class="RktSym"><a href="Byte_and_String_Input.html#%28def._%28%28quote._~23~25kernel%29._read-line%29%29" class="RktValLink" data-pltdoc="x">read-line</a></span> is <span class="RktVal">'</span><span class="RktVal">linefeed</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._((lib._racket/private/base..rkt)._in-bytes-lines))"></a><span title="Provided from: racket/base, racket | Package: base"><span class="RktSym"><a href="#%28def._%28%28lib._racket%2Fprivate%2Fbase..rkt%29._in-bytes-lines%29%29" class="RktValDef RktValLink" data-pltdoc="x">in-bytes-lines</a></span></span><span class="hspace"> </span>[<span class="RktVar">in</span><span class="hspace"> </span><span class="RktVar">mode</span>]<span class="RktPn">)</span><span class="hspace"> </span>→<span class="hspace"> </span><span class="RktSym"><a href="#%28def._%28%28lib._racket%2Fprivate%2Fbase..rkt%29._sequence~3f%29%29" class="RktValLink" data-pltdoc="x">sequence?</a></span></p></blockquote></td></tr><tr><td><span class="hspace"> </span><span class="RktVar">in</span><span class="hspace"> </span>:<span class="hspace"> </span><span class="RktSym"><a href="port-ops.html#%28def._%28%28quote._~23~25kernel%29._input-port~3f%29%29" class="RktValLink" data-pltdoc="x">input-port?</a></span><span class="hspace"> </span>=<span class="hspace"> </span><span class="RktPn">(</span><span class="RktSym"><a href="port-ops.html#%28def._%28%28quote._~23~25kernel%29._current-input-port%29%29" class="RktValLink" data-pltdoc="x">current-input-port</a></span><span class="RktPn">)</span></td></tr><tr><td><table cellspacing="0" cellpadding="0" class="argcontract"><tr><td><span class="hspace"> </span></td><td><span class="RktVar">mode</span></td><td><span class="hspace"> </span></td><td>:</td><td><span class="hspace"> </span></td><td><span class="RktPn">(</span><span class="RktSym"><a href="data-structure-contracts.html#%28def._%28%28lib._racket%2Fcontract%2Fbase..rkt%29._or%2Fc%29%29" class="RktValLink" data-pltdoc="x">or/c</a></span><span class="hspace"> </span><span class="RktVal">'</span><span class="RktVal">linefeed</span><span class="hspace"> </span><span class="RktVal">'</span><span class="RktVal">return</span><span class="hspace"> </span><span class="RktVal">'</span><span class="RktVal">return-linefeed</span><span class="hspace"> </span><span class="RktVal">'</span><span class="RktVal">any</span><span class="hspace"> </span><span class="RktVal">'</span><span class="RktVal">any-one</span><span class="RktPn">)</span></td></tr><tr><td><span class="hspace"> </span></td><td><span class="hspace"> </span></td><td><span class="hspace"> </span></td><td>=</td><td><span class="hspace"> </span></td><td><span class="RktVal">'</span><span class="RktVal">any</span></td></tr></table></td></tr></table></blockquote></div><div class="SIntrapara">Returns a sequence equivalent to
<span class="RktPn">(</span><span class="RktSym"><a href="#%28def._%28%28lib._racket%2Fprivate%2Fbase..rkt%29._in-port%29%29" class="RktValLink" data-pltdoc="x">in-port</a></span><span class="stt"> </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="stt"> </span><span class="RktPn">(</span><span class="RktSym">p</span><span class="RktPn">)</span><span class="stt"> </span><span class="RktPn">(</span><span class="RktSym"><a href="Byte_and_String_Input.html#%28def._%28%28quote._~23~25kernel%29._read-bytes-line%29%29" class="RktValLink" data-pltdoc="x">read-bytes-line</a></span><span class="stt"> </span><span class="RktSym">p</span><span class="stt"> </span><span class="RktVar">mode</span><span class="RktPn">)</span><span class="RktPn">)</span><span class="stt"> </span><span class="RktVar">in</span><span class="RktPn">)</span>. Note
that the default mode is <span class="RktVal">'</span><span class="RktVal">any</span>, whereas the default mode of
<span class="RktSym"><a href="Byte_and_String_Input.html#%28def._%28%28quote._~23~25kernel%29._read-bytes-line%29%29" class="RktValLink" data-pltdoc="x">read-bytes-line</a></span> is <span class="RktVal">'</span><span class="RktVal">linefeed</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._((lib._racket/private/base..rkt)._in-hash))"></a><span title="Provided from: racket/base, racket | Package: base"><span class="RktSym"><a href="#%28def._%28%28lib._racket%2Fprivate%2Fbase..rkt%29._in-hash%29%29" class="RktValDef RktValLink" data-pltdoc="x">in-hash</a></span></span><span class="hspace"> </span><span class="RktVar">hash</span><span class="RktPn">)</span><span class="hspace"> </span>→<span class="hspace"> </span><span class="RktSym"><a href="#%28def._%28%28lib._racket%2Fprivate%2Fbase..rkt%29._sequence~3f%29%29" class="RktValLink" data-pltdoc="x">sequence?</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 a sequence equivalent to <span class="RktVar">hash</span>.</div></p><p><table cellspacing="0" cellpadding="0" class="RktBlk"><tr><td><p>Examples:</p></td></tr><tr><td><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">table</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">1</span><span class="hspace"> </span><span class="RktVal">'</span><span class="RktVal">b</span><span class="hspace"> </span><span class="RktVal">2</span><span class="RktPn">)</span><span class="RktPn">)</span></td></tr><tr><td><table cellspacing="0" cellpadding="0"><tr><td></td></tr></table></td></tr><tr><td><table cellspacing="0" cellpadding="0" class="RktBlk"><tr><td><span class="stt">> </span><span class="RktPn">(</span><span class="RktSym"><a href="for.html#%28form._%28%28lib._racket%2Fprivate%2Fbase..rkt%29._for%29%29" class="RktStxLink" data-pltdoc="x">for</a></span><span class="hspace"> </span><span class="RktPn">(</span><span class="RktPn">[</span><span class="RktPn">(</span><span class="RktSym">key</span><span class="hspace"> </span><span class="RktSym">value</span><span class="RktPn">)</span><span class="hspace"> </span><span class="RktPn">(</span><span class="RktSym"><a href="#%28def._%28%28lib._racket%2Fprivate%2Fbase..rkt%29._in-hash%29%29" class="RktValLink" data-pltdoc="x">in-hash</a></span><span class="hspace"> </span><span class="RktSym">table</span><span class="RktPn">)</span><span class="RktPn">]</span><span class="RktPn">)</span></td></tr><tr><td><span class="hspace"> </span><span class="hspace"> </span><span class="RktPn">(</span><span class="RktSym"><a href="Writing.html#%28def._%28%28quote._~23~25kernel%29._printf%29%29" class="RktValLink" data-pltdoc="x">printf</a></span><span class="hspace"> </span><span class="RktVal">"key: ~a value: ~a\n"</span><span class="hspace"> </span><span class="RktSym">key</span><span class="hspace"> </span><span class="RktSym">value</span><span class="RktPn">)</span><span class="RktPn">)</span></td></tr></table></td></tr><tr><td><table cellspacing="0" cellpadding="0"><tr><td><p><span class="RktOut">key: b value: 2</span></p></td></tr><tr><td><p><span class="RktOut">key: a value: 1</span></p></td></tr></table></td></tr><tr><td><table cellspacing="0" cellpadding="0"><tr><td></td></tr></table></td></tr></table></blockquote></td></tr></table></p><blockquote class="refpara"><blockquote class="refcolumn"><blockquote class="refcontent"><p>See <a href="hashtables.html" data-pltdoc="x">Hash Tables</a> for information on using hash tables as
sequences.</p></blockquote></blockquote></blockquote><p><div class="SIntrapara"><blockquote class="SVInsetFlow"><table cellspacing="0" cellpadding="0" class="boxed RBoxed"><tr><td><blockquote class="SubFlow"><div class="RBackgroundLabel SIEHidden"><div class="RBackgroundLabelInner"><p>procedure</p></div></div><p class="RForeground"><span class="RktPn">(</span><a name="(def._((lib._racket/private/base..rkt)._in-hash-keys))"></a><span title="Provided from: racket/base, racket | Package: base"><span class="RktSym"><a href="#%28def._%28%28lib._racket%2Fprivate%2Fbase..rkt%29._in-hash-keys%29%29" class="RktValDef RktValLink" data-pltdoc="x">in-hash-keys</a></span></span><span class="hspace"> </span><span class="RktVar">hash</span><span class="RktPn">)</span><span class="hspace"> </span>→<span class="hspace"> </span><span class="RktSym"><a href="#%28def._%28%28lib._racket%2Fprivate%2Fbase..rkt%29._sequence~3f%29%29" class="RktValLink" data-pltdoc="x">sequence?</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 a sequence whose elements are the keys of <span class="RktVar">hash</span>.</div></p><p><table cellspacing="0" cellpadding="0" class="RktBlk"><tr><td><p>Examples:</p></td></tr><tr><td><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">table</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">1</span><span class="hspace"> </span><span class="RktVal">'</span><span class="RktVal">b</span><span class="hspace"> </span><span class="RktVal">2</span><span class="RktPn">)</span><span class="RktPn">)</span></td></tr><tr><td><table cellspacing="0" cellpadding="0"><tr><td></td></tr></table></td></tr><tr><td><table cellspacing="0" cellpadding="0" class="RktBlk"><tr><td><span class="stt">> </span><span class="RktPn">(</span><span class="RktSym"><a href="for.html#%28form._%28%28lib._racket%2Fprivate%2Fbase..rkt%29._for%29%29" class="RktStxLink" data-pltdoc="x">for</a></span><span class="hspace"> </span><span class="RktPn">(</span><span class="RktPn">[</span><span class="RktSym">key</span><span class="hspace"> </span><span class="RktPn">(</span><span class="RktSym"><a href="#%28def._%28%28lib._racket%2Fprivate%2Fbase..rkt%29._in-hash-keys%29%29" class="RktValLink" data-pltdoc="x">in-hash-keys</a></span><span class="hspace"> </span><span class="RktSym">table</span><span class="RktPn">)</span><span class="RktPn">]</span><span class="RktPn">)</span></td></tr><tr><td><span class="hspace"> </span><span class="hspace"> </span><span class="RktPn">(</span><span class="RktSym"><a href="Writing.html#%28def._%28%28quote._~23~25kernel%29._printf%29%29" class="RktValLink" data-pltdoc="x">printf</a></span><span class="hspace"> </span><span class="RktVal">"key: ~a\n"</span><span class="hspace"> </span><span class="RktSym">key</span><span class="RktPn">)</span><span class="RktPn">)</span></td></tr></table></td></tr><tr><td><table cellspacing="0" cellpadding="0"><tr><td><p><span class="RktOut">key: b</span></p></td></tr><tr><td><p><span class="RktOut">key: a</span></p></td></tr></table></td></tr><tr><td><table cellspacing="0" cellpadding="0"><tr><td></td></tr></table></td></tr></table></blockquote></td></tr></table></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)._in-hash-values))"></a><span title="Provided from: racket/base, racket | Package: base"><span class="RktSym"><a href="#%28def._%28%28lib._racket%2Fprivate%2Fbase..rkt%29._in-hash-values%29%29" class="RktValDef RktValLink" data-pltdoc="x">in-hash-values</a></span></span><span class="hspace"> </span><span class="RktVar">hash</span><span class="RktPn">)</span><span class="hspace"> </span>→<span class="hspace"> </span><span class="RktSym"><a href="#%28def._%28%28lib._racket%2Fprivate%2Fbase..rkt%29._sequence~3f%29%29" class="RktValLink" data-pltdoc="x">sequence?</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 a sequence whose elements are the values of <span class="RktVar">hash</span>.</div></p><p><table cellspacing="0" cellpadding="0" class="RktBlk"><tr><td><p>Examples:</p></td></tr><tr><td><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">table</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">1</span><span class="hspace"> </span><span class="RktVal">'</span><span class="RktVal">b</span><span class="hspace"> </span><span class="RktVal">2</span><span class="RktPn">)</span><span class="RktPn">)</span></td></tr><tr><td><table cellspacing="0" cellpadding="0"><tr><td></td></tr></table></td></tr><tr><td><table cellspacing="0" cellpadding="0" class="RktBlk"><tr><td><span class="stt">> </span><span class="RktPn">(</span><span class="RktSym"><a href="for.html#%28form._%28%28lib._racket%2Fprivate%2Fbase..rkt%29._for%29%29" class="RktStxLink" data-pltdoc="x">for</a></span><span class="hspace"> </span><span class="RktPn">(</span><span class="RktPn">[</span><span class="RktSym">value</span><span class="hspace"> </span><span class="RktPn">(</span><span class="RktSym"><a href="#%28def._%28%28lib._racket%2Fprivate%2Fbase..rkt%29._in-hash-values%29%29" class="RktValLink" data-pltdoc="x">in-hash-values</a></span><span class="hspace"> </span><span class="RktSym">table</span><span class="RktPn">)</span><span class="RktPn">]</span><span class="RktPn">)</span></td></tr><tr><td><span class="hspace"> </span><span class="hspace"> </span><span class="RktPn">(</span><span class="RktSym"><a href="Writing.html#%28def._%28%28quote._~23~25kernel%29._printf%29%29" class="RktValLink" data-pltdoc="x">printf</a></span><span class="hspace"> </span><span class="RktVal">"value: ~a\n"</span><span class="hspace"> </span><span class="RktSym">value</span><span class="RktPn">)</span><span class="RktPn">)</span></td></tr></table></td></tr><tr><td><table cellspacing="0" cellpadding="0"><tr><td><p><span class="RktOut">value: 2</span></p></td></tr><tr><td><p><span class="RktOut">value: 1</span></p></td></tr></table></td></tr><tr><td><table cellspacing="0" cellpadding="0"><tr><td></td></tr></table></td></tr></table></blockquote></td></tr></table></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)._in-hash-pairs))"></a><span title="Provided from: racket/base, racket | Package: base"><span class="RktSym"><a href="#%28def._%28%28lib._racket%2Fprivate%2Fbase..rkt%29._in-hash-pairs%29%29" class="RktValDef RktValLink" data-pltdoc="x">in-hash-pairs</a></span></span><span class="hspace"> </span><span class="RktVar">hash</span><span class="RktPn">)</span><span class="hspace"> </span>→<span class="hspace"> </span><span class="RktSym"><a href="#%28def._%28%28lib._racket%2Fprivate%2Fbase..rkt%29._sequence~3f%29%29" class="RktValLink" data-pltdoc="x">sequence?</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 a sequence whose elements are pairs, each containing a key
and its value from <span class="RktVar">hash</span> (as opposed to using <span class="RktVar">hash</span>
directly as a sequence to get the key and value as separate values
for each element).</div></p><p><table cellspacing="0" cellpadding="0" class="RktBlk"><tr><td><p>Examples:</p></td></tr><tr><td><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">table</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">1</span><span class="hspace"> </span><span class="RktVal">'</span><span class="RktVal">b</span><span class="hspace"> </span><span class="RktVal">2</span><span class="RktPn">)</span><span class="RktPn">)</span></td></tr><tr><td><table cellspacing="0" cellpadding="0"><tr><td></td></tr></table></td></tr><tr><td><table cellspacing="0" cellpadding="0" class="RktBlk"><tr><td><span class="stt">> </span><span class="RktPn">(</span><span class="RktSym"><a href="for.html#%28form._%28%28lib._racket%2Fprivate%2Fbase..rkt%29._for%29%29" class="RktStxLink" data-pltdoc="x">for</a></span><span class="hspace"> </span><span class="RktPn">(</span><span class="RktPn">[</span><span class="RktSym">key+value</span><span class="hspace"> </span><span class="RktPn">(</span><span class="RktSym"><a href="#%28def._%28%28lib._racket%2Fprivate%2Fbase..rkt%29._in-hash-pairs%29%29" class="RktValLink" data-pltdoc="x">in-hash-pairs</a></span><span class="hspace"> </span><span class="RktSym">table</span><span class="RktPn">)</span><span class="RktPn">]</span><span class="RktPn">)</span></td></tr><tr><td><span class="hspace"> </span><span class="hspace"> </span><span class="RktPn">(</span><span class="RktSym"><a href="Writing.html#%28def._%28%28quote._~23~25kernel%29._printf%29%29" class="RktValLink" data-pltdoc="x">printf</a></span><span class="hspace"> </span><span class="RktVal">"key and value: ~a\n"</span><span class="hspace"> </span><span class="RktSym">key+value</span><span class="RktPn">)</span><span class="RktPn">)</span></td></tr></table></td></tr><tr><td><table cellspacing="0" cellpadding="0"><tr><td><p><span class="RktOut">key and value: (b . 2)</span></p></td></tr><tr><td><p><span class="RktOut">key and value: (a . 1)</span></p></td></tr></table></td></tr><tr><td><table cellspacing="0" cellpadding="0"><tr><td></td></tr></table></td></tr></table></blockquote></td></tr></table></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)._in-directory))"></a><span title="Provided from: racket/base, racket | Package: base"><span class="RktSym"><a href="#%28def._%28%28lib._racket%2Fprivate%2Fbase..rkt%29._in-directory%29%29" class="RktValDef RktValLink" data-pltdoc="x">in-directory</a></span></span><span class="hspace"> </span>[<span class="RktVar">dir</span><span class="hspace"> </span><span class="RktVar">use-dir?</span>]<span class="RktPn">)</span><span class="hspace"> </span>→<span class="hspace"> </span><span class="RktSym"><a href="#%28def._%28%28lib._racket%2Fprivate%2Fbase..rkt%29._sequence~3f%29%29" class="RktValLink" data-pltdoc="x">sequence?</a></span></p></blockquote></td></tr><tr><td><span class="hspace"> </span><span class="RktVar">dir</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="RktSym"><a href="Manipulating_Paths.html#%28def._%28%28lib._racket%2Fprivate%2Fmisc..rkt%29._path-string~3f%29%29" class="RktValLink" data-pltdoc="x">path-string?</a></span><span class="RktPn">)</span><span class="hspace"> </span>=<span class="hspace"> </span><span class="RktVal">#f</span></td></tr><tr><td><table cellspacing="0" cellpadding="0" class="argcontract"><tr><td><span class="hspace"> </span></td><td><span class="RktVar">use-dir?</span></td><td><span class="hspace"> </span></td><td>:</td><td><span class="hspace"> </span></td><td><span class="RktPn">(</span><span class="RktPn">(</span><span class="RktSym"><a href="data-structure-contracts.html#%28def._%28%28lib._racket%2Fcontract%2Fprivate%2Fmisc..rkt%29._and%2Fc%29%29" class="RktValLink" data-pltdoc="x">and/c</a></span><span class="hspace"> </span><span class="RktSym"><a href="Manipulating_Paths.html#%28def._%28%28quote._~23~25kernel%29._path~3f%29%29" class="RktValLink" data-pltdoc="x">path?</a></span><span class="hspace"> </span><span class="RktSym"><a href="Manipulating_Paths.html#%28def._%28%28quote._~23~25kernel%29._complete-path~3f%29%29" class="RktValLink" data-pltdoc="x">complete-path?</a></span><span class="RktPn">)</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></td><td><span class="hspace"> </span></td><td><span class="hspace"> </span></td><td>=</td><td><span class="hspace"> </span></td><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="RktSym">dir-path</span><span class="RktPn">)</span><span class="hspace"> </span><span class="RktVal">#t</span><span class="RktPn">)</span></td></tr></table></td></tr></table></blockquote></div><div class="SIntrapara">Returns a sequence that produces all of the paths for files,
directories, and links within <span class="RktVar">dir</span>, except for the
contents of any directory for which <span class="RktVar">use-dir?</span> returns
<span class="RktVal">#f</span>. If <span class="RktVar">dir</span> is not
<span class="RktVal">#f</span>, then every produced path starts with <span class="RktVar">dir</span> as
its prefix. If <span class="RktVar">dir</span> is <span class="RktVal">#f</span>, then paths in and
relative to the current directory are produced.</div></p><p>An <span class="RktSym"><a href="#%28def._%28%28lib._racket%2Fprivate%2Fbase..rkt%29._in-directory%29%29" class="RktValLink" data-pltdoc="x">in-directory</a></span> sequence traverses nested subdirectories
recursively (filtered by <span class="RktVar">use-dir?</span>).
To generate a sequence that includes only the immediate
content of a directory, use the result of <span class="RktSym"><a href="Filesystem.html#%28def._%28%28lib._racket%2Fprivate%2Fbase..rkt%29._directory-list%29%29" class="RktValLink" data-pltdoc="x">directory-list</a></span> as
a sequence.</p><p class="SHistory">Changed in version 6.0.0.1 of package <span class="stt">base</span>: Added <span class="RktVar">use-dir?</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)._in-producer))"></a><span title="Provided from: racket/base, racket | Package: base"><span class="RktSym"><a href="#%28def._%28%28lib._racket%2Fprivate%2Fbase..rkt%29._in-producer%29%29" class="RktValDef RktValLink" data-pltdoc="x">in-producer</a></span></span><span class="hspace"> </span><span class="RktVar">producer</span><span class="RktPn">)</span><span class="hspace"> </span>→<span class="hspace"> </span><span class="RktSym"><a href="#%28def._%28%28lib._racket%2Fprivate%2Fbase..rkt%29._sequence~3f%29%29" class="RktValLink" data-pltdoc="x">sequence?</a></span></p></blockquote></td></tr><tr><td><span class="hspace"> </span><span class="RktVar">producer</span><span class="hspace"> </span>:<span class="hspace"> </span><span class="RktSym"><a href="procedures.html#%28def._%28%28quote._~23~25kernel%29._procedure~3f%29%29" class="RktValLink" data-pltdoc="x">procedure?</a></span></td></tr><tr><td><span class="RktPn">(</span><span title="Provided from: racket/base, racket | Package: base"><span class="RktSym"><a href="#%28def._%28%28lib._racket%2Fprivate%2Fbase..rkt%29._in-producer%29%29" class="RktValDef RktValLink" data-pltdoc="x">in-producer</a></span></span><span class="hspace"> </span><span class="RktVar">producer</span><span class="hspace"> </span><span class="RktVar">stop</span><span class="hspace"> </span><span class="RktVar">arg</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="#%28def._%28%28lib._racket%2Fprivate%2Fbase..rkt%29._sequence~3f%29%29" class="RktValLink" data-pltdoc="x">sequence?</a></span></td></tr><tr><td><span class="hspace"> </span><span class="RktVar">producer</span><span class="hspace"> </span>:<span class="hspace"> </span><span class="RktSym"><a href="procedures.html#%28def._%28%28quote._~23~25kernel%29._procedure~3f%29%29" class="RktValLink" data-pltdoc="x">procedure?</a></span></td></tr><tr><td><span class="hspace"> </span><span class="RktVar">stop</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">arg</span><span class="hspace"> </span>:<span class="hspace"> </span><span class="RktSym"><a href="data-structure-contracts.html#%28def._%28%28lib._racket%2Fcontract%2Fprivate%2Fmisc..rkt%29._any%2Fc%29%29" class="RktValLink" data-pltdoc="x">any/c</a></span></td></tr></table></blockquote></div><div class="SIntrapara">Returns a sequence that contains values from sequential calls to
<span class="RktVar">producer</span>, which would usually use some state to do its work.</div></p><p>If a <span class="RktVar">stop</span> value is not given, the sequence goes on
infinitely, and therefore it common to use it with a finite sequence
or using <span class="RktPn">#:break</span> etc. If a <span class="RktVar">stop</span> value is given, it
is used to identify a value that marks the end of the sequence (and
the <span class="RktVar">stop</span> value is not included in the sequence);
<span class="RktVar">stop</span> can be a predicate that is applied to the results of
<span class="RktVar">producer</span>, or it can be a value that is tested against the
result of with <span class="RktSym"><a href="booleans.html#%28def._%28%28quote._~23~25kernel%29._eq~3f%29%29" class="RktValLink" data-pltdoc="x">eq?</a></span>. (The <span class="RktVar">stop</span> argument must be a
predicate if the stop value is itself a function or if
<span class="RktVar">producer</span> returns multiple values.)</p><p>If additional <span class="RktVar">arg</span>s are specified, they are passed to every
call to <span class="RktVar">producer</span>.</p><p><table cellspacing="0" cellpadding="0" class="RktBlk"><tr><td><p>Examples:</p></td></tr><tr><td><blockquote class="SCodeFlow"><table cellspacing="0" cellpadding="0" class="RktBlk"><tr><td><table cellspacing="0" cellpadding="0" class="RktBlk"><tr><td><span class="stt">> </span><span class="RktPn">(</span><span class="RktSym"><a href="define.html#%28form._%28%28lib._racket%2Fprivate%2Fbase..rkt%29._define%29%29" class="RktStxLink" data-pltdoc="x">define</a></span><span class="hspace"> </span><span class="RktPn">(</span><span class="RktSym">counter</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="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">n</span><span class="hspace"> </span><span class="RktVal">0</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="RktPn">[</span><span class="RktSym">d</span><span class="hspace"> </span><span class="RktVal">1</span><span class="RktPn">]</span><span class="RktPn">)</span><span class="hspace"> </span><span class="RktPn">(</span><span class="RktSym"><a href="set_.html#%28form._%28%28quote._~23~25kernel%29._set%21%29%29" class="RktStxLink" data-pltdoc="x">set!</a></span><span class="hspace"> </span><span class="RktSym">n</span><span class="hspace"> </span><span class="RktPn">(</span><span class="RktSym"><a href="generic-numbers.html#%28def._%28%28quote._~23~25kernel%29._%2B%29%29" class="RktValLink" data-pltdoc="x">+</a></span><span class="hspace"> </span><span class="RktSym">d</span><span class="hspace"> </span><span class="RktSym">n</span><span class="RktPn">)</span><span class="RktPn">)</span><span class="hspace"> </span><span class="RktSym">n</span><span class="RktPn">)</span><span class="RktPn">)</span></td></tr></table></td></tr><tr><td><table cellspacing="0" cellpadding="0"><tr><td></td></tr></table></td></tr><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">x</span><span class="hspace"> </span><span class="RktPn">(</span><span class="RktSym"><a href="#%28def._%28%28lib._racket%2Fprivate%2Fbase..rkt%29._in-producer%29%29" class="RktValLink" data-pltdoc="x">in-producer</a></span><span class="hspace"> </span><span class="RktPn">(</span><span class="RktSym">counter</span><span class="RktPn">)</span><span class="RktPn">)</span><span class="RktPn">]</span><span class="hspace"> </span><span class="RktPn">[</span><span class="RktSym">y</span><span class="hspace"> </span><span class="RktPn">(</span><span class="RktSym"><a href="#%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">4</span><span class="RktPn">)</span><span class="RktPn">]</span><span class="RktPn">)</span><span class="hspace"> </span><span class="RktSym">x</span><span class="RktPn">)</span></td></tr><tr><td><p><span class="RktRes">'(1 2 3 4)</span></p></td></tr><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">x</span><span class="hspace"> </span><span class="RktPn">(</span><span class="RktSym"><a href="#%28def._%28%28lib._racket%2Fprivate%2Fbase..rkt%29._in-producer%29%29" class="RktValLink" data-pltdoc="x">in-producer</a></span><span class="hspace"> </span><span class="RktPn">(</span><span class="RktSym">counter</span><span class="RktPn">)</span><span class="RktPn">)</span><span class="RktPn">]</span><span class="hspace"> </span><span class="RktPn">#:break</span><span class="hspace"> </span><span class="RktPn">(</span><span class="RktSym"><a href="generic-numbers.html#%28def._%28%28quote._~23~25kernel%29._~3d%29%29" class="RktValLink" data-pltdoc="x">=</a></span><span class="hspace"> </span><span class="RktSym">x</span><span class="hspace"> </span><span class="RktVal">5</span><span class="RktPn">)</span><span class="RktPn">)</span><span class="hspace"> </span><span class="RktSym">x</span><span class="RktPn">)</span></td></tr><tr><td><p><span class="RktRes">'(1 2 3 4)</span></p></td></tr><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">x</span><span class="hspace"> </span><span class="RktPn">(</span><span class="RktSym"><a href="#%28def._%28%28lib._racket%2Fprivate%2Fbase..rkt%29._in-producer%29%29" class="RktValLink" data-pltdoc="x">in-producer</a></span><span class="hspace"> </span><span class="RktPn">(</span><span class="RktSym">counter</span><span class="RktPn">)</span><span class="hspace"> </span><span class="RktVal">5</span><span class="RktPn">)</span><span class="RktPn">]</span><span class="RktPn">)</span><span class="hspace"> </span><span class="RktSym">x</span><span class="RktPn">)</span></td></tr><tr><td><p><span class="RktRes">'(1 2 3 4)</span></p></td></tr><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">x</span><span class="hspace"> </span><span class="RktPn">(</span><span class="RktSym"><a href="#%28def._%28%28lib._racket%2Fprivate%2Fbase..rkt%29._in-producer%29%29" class="RktValLink" data-pltdoc="x">in-producer</a></span><span class="hspace"> </span><span class="RktPn">(</span><span class="RktSym">counter</span><span class="RktPn">)</span><span class="hspace"> </span><span class="RktVal">5</span><span class="hspace"> </span><span class="RktVal">1/2</span><span class="RktPn">)</span><span class="RktPn">]</span><span class="RktPn">)</span><span class="hspace"> </span><span class="RktSym">x</span><span class="RktPn">)</span></td></tr><tr><td><p><span class="RktRes">'(1/2 1 3/2 2 5/2 3 7/2 4 9/2)</span></p></td></tr><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">x</span><span class="hspace"> </span><span class="RktPn">(</span><span class="RktSym"><a href="#%28def._%28%28lib._racket%2Fprivate%2Fbase..rkt%29._in-producer%29%29" class="RktValLink" data-pltdoc="x">in-producer</a></span><span class="hspace"> </span><span class="RktSym"><a href="Reading.html#%28def._%28%28quote._~23~25kernel%29._read%29%29" class="RktValLink" data-pltdoc="x">read</a></span><span class="hspace"> </span><span class="RktSym"><a href="port-ops.html#%28def._%28%28quote._~23~25kernel%29._eof%29%29" class="RktValLink" data-pltdoc="x">eof</a></span><span class="hspace"> </span><span class="RktPn">(</span><span class="RktSym"><a href="stringport.html#%28def._%28%28quote._~23~25kernel%29._open-input-string%29%29" class="RktValLink" data-pltdoc="x">open-input-string</a></span><span class="hspace"> </span><span class="RktVal">"1 2 3"</span><span class="RktPn">)</span><span class="RktPn">)</span><span class="RktPn">]</span><span class="RktPn">)</span><span class="hspace"> </span><span class="RktSym">x</span><span class="RktPn">)</span></td></tr><tr><td><p><span class="RktRes">'(1 2 3)</span></p></td></tr></table></blockquote></td></tr></table></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)._in-value))"></a><span title="Provided from: racket/base, racket | Package: base"><span class="RktSym"><a href="#%28def._%28%28lib._racket%2Fprivate%2Fbase..rkt%29._in-value%29%29" class="RktValDef RktValLink" data-pltdoc="x">in-value</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="#%28def._%28%28lib._racket%2Fprivate%2Fbase..rkt%29._sequence~3f%29%29" class="RktValLink" data-pltdoc="x">sequence?</a></span></p></blockquote></td></tr><tr><td><span class="hspace"> </span><span class="RktVar">v</span><span class="hspace"> </span>:<span class="hspace"> </span><span class="RktSym"><a href="data-structure-contracts.html#%28def._%28%28lib._racket%2Fcontract%2Fprivate%2Fmisc..rkt%29._any%2Fc%29%29" class="RktValLink" data-pltdoc="x">any/c</a></span></td></tr></table></blockquote></div><div class="SIntrapara">Returns a sequence that produces a single value: <span class="RktVar">v</span>. This
form is mostly useful for <span class="RktSym"><a href="let.html#%28form._%28%28lib._racket%2Fprivate%2Fletstx-scheme..rkt%29._let%29%29" class="RktStxLink" data-pltdoc="x">let</a></span>-like bindings in forms such
as <span class="RktSym"><a href="for.html#%28form._%28%28lib._racket%2Fprivate%2Fbase..rkt%29._for%2A%2Flist%29%29" class="RktStxLink" data-pltdoc="x">for*/list</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._((lib._racket/private/base..rkt)._in-indexed))"></a><span title="Provided from: racket/base, racket | Package: base"><span class="RktSym"><a href="#%28def._%28%28lib._racket%2Fprivate%2Fbase..rkt%29._in-indexed%29%29" class="RktValDef RktValLink" data-pltdoc="x">in-indexed</a></span></span><span class="hspace"> </span><span class="RktVar">seq</span><span class="RktPn">)</span><span class="hspace"> </span>→<span class="hspace"> </span><span class="RktSym"><a href="#%28def._%28%28lib._racket%2Fprivate%2Fbase..rkt%29._sequence~3f%29%29" class="RktValLink" data-pltdoc="x">sequence?</a></span></p></blockquote></td></tr><tr><td><span class="hspace"> </span><span class="RktVar">seq</span><span class="hspace"> </span>:<span class="hspace"> </span><span class="RktSym"><a href="#%28def._%28%28lib._racket%2Fprivate%2Fbase..rkt%29._sequence~3f%29%29" class="RktValLink" data-pltdoc="x">sequence?</a></span></td></tr></table></blockquote></div><div class="SIntrapara">Returns a sequence where each element has two values: the value
produced by <span class="RktVar">seq</span>, and a non-negative exact integer starting
with <span class="RktVal">0</span>. The elements of <span class="RktVar">seq</span> must be
single-valued.</div></p><p><div class="SIntrapara"><blockquote class="SVInsetFlow"><table cellspacing="0" cellpadding="0" class="boxed RBoxed"><tr><td><blockquote class="SubFlow"><div class="RBackgroundLabel SIEHidden"><div class="RBackgroundLabelInner"><p>procedure</p></div></div><p class="RForeground"><span class="RktPn">(</span><a name="(def._((lib._racket/private/base..rkt)._in-sequences))"></a><span title="Provided from: racket/base, racket | Package: base"><span class="RktSym"><a href="#%28def._%28%28lib._racket%2Fprivate%2Fbase..rkt%29._in-sequences%29%29" class="RktValDef RktValLink" data-pltdoc="x">in-sequences</a></span></span><span class="hspace"> </span><span class="RktVar">seq</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="#%28def._%28%28lib._racket%2Fprivate%2Fbase..rkt%29._sequence~3f%29%29" class="RktValLink" data-pltdoc="x">sequence?</a></span></p></blockquote></td></tr><tr><td><span class="hspace"> </span><span class="RktVar">seq</span><span class="hspace"> </span>:<span class="hspace"> </span><span class="RktSym"><a href="#%28def._%28%28lib._racket%2Fprivate%2Fbase..rkt%29._sequence~3f%29%29" class="RktValLink" data-pltdoc="x">sequence?</a></span></td></tr></table></blockquote></div><div class="SIntrapara">Returns a sequence that is made of all input sequences, one after
the other. Each <span class="RktVar">seq</span> is <a href="#%28tech._initiate%29" class="techoutside" data-pltdoc="x"><span class="techinside">initiate</span></a>d only after the
preceding <span class="RktVar">seq</span> is exhausted. If a single <span class="RktVar">seq</span> is
provided, then <span class="RktVar">seq</span> is returned; otherwise, the elements of
each <span class="RktVar">seq</span> must all have the same number of values.</div></p><p><div class="SIntrapara"><blockquote class="SVInsetFlow"><table cellspacing="0" cellpadding="0" class="boxed RBoxed"><tr><td><blockquote class="SubFlow"><div class="RBackgroundLabel SIEHidden"><div class="RBackgroundLabelInner"><p>procedure</p></div></div><p class="RForeground"><span class="RktPn">(</span><a name="(def._((lib._racket/private/base..rkt)._in-cycle))"></a><span title="Provided from: racket/base, racket | Package: base"><span class="RktSym"><a href="#%28def._%28%28lib._racket%2Fprivate%2Fbase..rkt%29._in-cycle%29%29" class="RktValDef RktValLink" data-pltdoc="x">in-cycle</a></span></span><span class="hspace"> </span><span class="RktVar">seq</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="#%28def._%28%28lib._racket%2Fprivate%2Fbase..rkt%29._sequence~3f%29%29" class="RktValLink" data-pltdoc="x">sequence?</a></span></p></blockquote></td></tr><tr><td><span class="hspace"> </span><span class="RktVar">seq</span><span class="hspace"> </span>:<span class="hspace"> </span><span class="RktSym"><a href="#%28def._%28%28lib._racket%2Fprivate%2Fbase..rkt%29._sequence~3f%29%29" class="RktValLink" data-pltdoc="x">sequence?</a></span></td></tr></table></blockquote></div><div class="SIntrapara">Similar to <span class="RktSym"><a href="#%28def._%28%28lib._racket%2Fprivate%2Fbase..rkt%29._in-sequences%29%29" class="RktValLink" data-pltdoc="x">in-sequences</a></span>, but the sequences are repeated in
an infinite cycle, where each <span class="RktVar">seq</span> is <a href="#%28tech._initiate%29" class="techoutside" data-pltdoc="x"><span class="techinside">initiate</span></a>d
afresh in each iteration. Beware that if no <span class="RktVar">seq</span>s are
provided or if all <span class="RktVar">seq</span>s become empty, then the sequence
produced by <span class="RktSym"><a href="#%28def._%28%28lib._racket%2Fprivate%2Fbase..rkt%29._in-cycle%29%29" class="RktValLink" data-pltdoc="x">in-cycle</a></span> never returns when an element is
demanded—<wbr></wbr>or even when the sequence is <a href="#%28tech._initiate%29" class="techoutside" data-pltdoc="x"><span class="techinside">initiate</span></a>d, if all
<span class="RktVar">seq</span>s are initially empty.</div></p><p><div class="SIntrapara"><blockquote class="SVInsetFlow"><table cellspacing="0" cellpadding="0" class="boxed RBoxed"><tr><td><blockquote class="SubFlow"><div class="RBackgroundLabel SIEHidden"><div class="RBackgroundLabelInner"><p>procedure</p></div></div><p class="RForeground"><span class="RktPn">(</span><a name="(def._((lib._racket/private/base..rkt)._in-parallel))"></a><span title="Provided from: racket/base, racket | Package: base"><span class="RktSym"><a href="#%28def._%28%28lib._racket%2Fprivate%2Fbase..rkt%29._in-parallel%29%29" class="RktValDef RktValLink" data-pltdoc="x">in-parallel</a></span></span><span class="hspace"> </span><span class="RktVar">seq</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="#%28def._%28%28lib._racket%2Fprivate%2Fbase..rkt%29._sequence~3f%29%29" class="RktValLink" data-pltdoc="x">sequence?</a></span></p></blockquote></td></tr><tr><td><span class="hspace"> </span><span class="RktVar">seq</span><span class="hspace"> </span>:<span class="hspace"> </span><span class="RktSym"><a href="#%28def._%28%28lib._racket%2Fprivate%2Fbase..rkt%29._sequence~3f%29%29" class="RktValLink" data-pltdoc="x">sequence?</a></span></td></tr></table></blockquote></div><div class="SIntrapara">Returns a sequence where each element has as many values as the
number of supplied <span class="RktVar">seq</span>s; the values, in order, are the
values of each <span class="RktVar">seq</span>. The elements of each <span class="RktVar">seq</span> must
be single-valued.</div></p><p><div class="SIntrapara"><blockquote class="SVInsetFlow"><table cellspacing="0" cellpadding="0" class="boxed RBoxed"><tr><td><blockquote class="SubFlow"><div class="RBackgroundLabel SIEHidden"><div class="RBackgroundLabelInner"><p>procedure</p></div></div><p class="RForeground"><span class="RktPn">(</span><a name="(def._((lib._racket/private/base..rkt)._in-values-sequence))"></a><span title="Provided from: racket/base, racket | Package: base"><span class="RktSym"><a href="#%28def._%28%28lib._racket%2Fprivate%2Fbase..rkt%29._in-values-sequence%29%29" class="RktValDef RktValLink" data-pltdoc="x">in-values-sequence</a></span></span><span class="hspace"> </span><span class="RktVar">seq</span><span class="RktPn">)</span><span class="hspace"> </span>→<span class="hspace"> </span><span class="RktSym"><a href="#%28def._%28%28lib._racket%2Fprivate%2Fbase..rkt%29._sequence~3f%29%29" class="RktValLink" data-pltdoc="x">sequence?</a></span></p></blockquote></td></tr><tr><td><span class="hspace"> </span><span class="RktVar">seq</span><span class="hspace"> </span>:<span class="hspace"> </span><span class="RktSym"><a href="#%28def._%28%28lib._racket%2Fprivate%2Fbase..rkt%29._sequence~3f%29%29" class="RktValLink" data-pltdoc="x">sequence?</a></span></td></tr></table></blockquote></div><div class="SIntrapara">Returns a sequence that is like <span class="RktVar">seq</span>, but it combines
multiple values for each element from <span class="RktVar">seq</span> as a list of
elements.</div></p><p><div class="SIntrapara"><blockquote class="SVInsetFlow"><table cellspacing="0" cellpadding="0" class="boxed RBoxed"><tr><td><blockquote class="SubFlow"><div class="RBackgroundLabel SIEHidden"><div class="RBackgroundLabelInner"><p>procedure</p></div></div><p class="RForeground"><span class="RktPn">(</span><a name="(def._((lib._racket/private/base..rkt)._in-values*-sequence))"></a><span title="Provided from: racket/base, racket | Package: base"><span class="RktSym"><a href="#%28def._%28%28lib._racket%2Fprivate%2Fbase..rkt%29._in-values%2A-sequence%29%29" class="RktValDef RktValLink" data-pltdoc="x">in-values*-sequence</a></span></span><span class="hspace"> </span><span class="RktVar">seq</span><span class="RktPn">)</span><span class="hspace"> </span>→<span class="hspace"> </span><span class="RktSym"><a href="#%28def._%28%28lib._racket%2Fprivate%2Fbase..rkt%29._sequence~3f%29%29" class="RktValLink" data-pltdoc="x">sequence?</a></span></p></blockquote></td></tr><tr><td><span class="hspace"> </span><span class="RktVar">seq</span><span class="hspace"> </span>:<span class="hspace"> </span><span class="RktSym"><a href="#%28def._%28%28lib._racket%2Fprivate%2Fbase..rkt%29._sequence~3f%29%29" class="RktValLink" data-pltdoc="x">sequence?</a></span></td></tr></table></blockquote></div><div class="SIntrapara">Returns a sequence that is like <span class="RktVar">seq</span>, but when an element of
<span class="RktVar">seq</span> has multiple values or a single list value, then the
values are combined in a list. In other words,
<span class="RktSym"><a href="#%28def._%28%28lib._racket%2Fprivate%2Fbase..rkt%29._in-values%2A-sequence%29%29" class="RktValLink" data-pltdoc="x">in-values*-sequence</a></span> is like <span class="RktSym"><a href="#%28def._%28%28lib._racket%2Fprivate%2Fbase..rkt%29._in-values-sequence%29%29" class="RktValLink" data-pltdoc="x">in-values-sequence</a></span>,
except that non-list, single-valued elements are not wrapped in a
list.</div></p><p><div class="SIntrapara"><blockquote class="SVInsetFlow"><table cellspacing="0" cellpadding="0" class="boxed RBoxed"><tr><td><blockquote class="SubFlow"><div class="RBackgroundLabel SIEHidden"><div class="RBackgroundLabelInner"><p>procedure</p></div></div><p class="RForeground"><span class="RktPn">(</span><a name="(def._((lib._racket/private/base..rkt)._stop-before))"></a><span title="Provided from: racket/base, racket | Package: base"><span class="RktSym"><a href="#%28def._%28%28lib._racket%2Fprivate%2Fbase..rkt%29._stop-before%29%29" class="RktValDef RktValLink" data-pltdoc="x">stop-before</a></span></span><span class="hspace"> </span><span class="RktVar">seq</span><span class="hspace"> </span><span class="RktVar">pred</span><span class="RktPn">)</span><span class="hspace"> </span>→<span class="hspace"> </span><span class="RktSym"><a href="#%28def._%28%28lib._racket%2Fprivate%2Fbase..rkt%29._sequence~3f%29%29" class="RktValLink" data-pltdoc="x">sequence?</a></span></p></blockquote></td></tr><tr><td><span class="hspace"> </span><span class="RktVar">seq</span><span class="hspace"> </span>:<span class="hspace"> </span><span class="RktSym"><a href="#%28def._%28%28lib._racket%2Fprivate%2Fbase..rkt%29._sequence~3f%29%29" class="RktValLink" data-pltdoc="x">sequence?</a></span></td></tr><tr><td><span class="hspace"> </span><span class="RktVar">pred</span><span class="hspace"> </span>:<span class="hspace"> </span><span class="RktPn">(</span><span class="RktSym"><a href="data-structure-contracts.html#%28def._%28%28lib._racket%2Fcontract%2Fprivate%2Fmisc..rkt%29._any%2Fc%29%29" class="RktValLink" data-pltdoc="x">any/c</a></span><span class="hspace"> </span><span class="RktPn">. </span><span class="RktSym"><a href="function-contracts.html#%28form._%28%28lib._racket%2Fcontract%2Fbase..rkt%29._-~3e%29%29" class="RktStxLink" data-pltdoc="x"><span class="nobreak">-></span></a></span><span class="RktPn"> .</span><span class="hspace"> </span><span class="RktSym"><a href="data-structure-contracts.html#%28form._%28%28lib._racket%2Fcontract%2Fprivate%2Fmisc..rkt%29._any%29%29" class="RktStxLink" data-pltdoc="x">any</a></span><span class="RktPn">)</span></td></tr></table></blockquote></div><div class="SIntrapara">Returns a sequence that contains the elements of <span class="RktVar">seq</span> (which
must be single-valued), but only until the last element for which
applying <span class="RktVar">pred</span> to the element produces <span class="RktVal">#t</span>, after
which the sequence ends.</div></p><p><div class="SIntrapara"><blockquote class="SVInsetFlow"><table cellspacing="0" cellpadding="0" class="boxed RBoxed"><tr><td><blockquote class="SubFlow"><div class="RBackgroundLabel SIEHidden"><div class="RBackgroundLabelInner"><p>procedure</p></div></div><p class="RForeground"><span class="RktPn">(</span><a name="(def._((lib._racket/private/base..rkt)._stop-after))"></a><span title="Provided from: racket/base, racket | Package: base"><span class="RktSym"><a href="#%28def._%28%28lib._racket%2Fprivate%2Fbase..rkt%29._stop-after%29%29" class="RktValDef RktValLink" data-pltdoc="x">stop-after</a></span></span><span class="hspace"> </span><span class="RktVar">seq</span><span class="hspace"> </span><span class="RktVar">pred</span><span class="RktPn">)</span><span class="hspace"> </span>→<span class="hspace"> </span><span class="RktSym"><a href="#%28def._%28%28lib._racket%2Fprivate%2Fbase..rkt%29._sequence~3f%29%29" class="RktValLink" data-pltdoc="x">sequence?</a></span></p></blockquote></td></tr><tr><td><span class="hspace"> </span><span class="RktVar">seq</span><span class="hspace"> </span>:<span class="hspace"> </span><span class="RktSym"><a href="#%28def._%28%28lib._racket%2Fprivate%2Fbase..rkt%29._sequence~3f%29%29" class="RktValLink" data-pltdoc="x">sequence?</a></span></td></tr><tr><td><span class="hspace"> </span><span class="RktVar">pred</span><span class="hspace"> </span>:<span class="hspace"> </span><span class="RktPn">(</span><span class="RktSym"><a href="data-structure-contracts.html#%28def._%28%28lib._racket%2Fcontract%2Fprivate%2Fmisc..rkt%29._any%2Fc%29%29" class="RktValLink" data-pltdoc="x">any/c</a></span><span class="hspace"> </span><span class="RktPn">. </span><span class="RktSym"><a href="function-contracts.html#%28form._%28%28lib._racket%2Fcontract%2Fbase..rkt%29._-~3e%29%29" class="RktStxLink" data-pltdoc="x"><span class="nobreak">-></span></a></span><span class="RktPn"> .</span><span class="hspace"> </span><span class="RktSym"><a href="data-structure-contracts.html#%28form._%28%28lib._racket%2Fcontract%2Fprivate%2Fmisc..rkt%29._any%29%29" class="RktStxLink" data-pltdoc="x">any</a></span><span class="RktPn">)</span></td></tr></table></blockquote></div><div class="SIntrapara">Returns a sequence that contains the elements of <span class="RktVar">seq</span> (which
must be single-valued), but only until the element (inclusive) for
which applying <span class="RktVar">pred</span> to the element produces <span class="RktVal">#t</span>,
after which the sequence ends.</div></p><p><div class="SIntrapara"><blockquote class="SVInsetFlow"><table cellspacing="0" cellpadding="0" class="boxed RBoxed"><tr><td><blockquote class="SubFlow"><div class="RBackgroundLabel SIEHidden"><div class="RBackgroundLabelInner"><p>procedure</p></div></div><p class="RForeground"><span class="RktPn">(</span><a name="(def._((lib._racket/private/base..rkt)._make-do-sequence))"></a><span title="Provided from: racket/base, racket | Package: base"><span class="RktSym"><a href="#%28def._%28%28lib._racket%2Fprivate%2Fbase..rkt%29._make-do-sequence%29%29" class="RktValDef RktValLink" data-pltdoc="x">make-do-sequence</a></span></span><span class="hspace"> </span><span class="RktVar">thunk</span><span class="RktPn">)</span><span class="hspace"> </span>→<span class="hspace"> </span><span class="RktSym"><a href="#%28def._%28%28lib._racket%2Fprivate%2Fbase..rkt%29._sequence~3f%29%29" class="RktValLink" data-pltdoc="x">sequence?</a></span></p></blockquote></td></tr><tr><td><table cellspacing="0" cellpadding="0" class="argcontract"><tr><td><span class="hspace"> </span></td><td><span class="RktVar">thunk</span></td><td><span class="hspace"> </span></td><td>:</td><td><span class="hspace"> </span></td><td><table cellspacing="0" cellpadding="0" class="RktBlk"><tr><td><span class="RktPn">(</span><span class="RktSym"><a href="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="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="RktPn">(</span><span class="RktSym"><a href="data-structure-contracts.html#%28def._%28%28lib._racket%2Fcontract%2Fprivate%2Fmisc..rkt%29._any%2Fc%29%29" class="RktValLink" data-pltdoc="x">any/c</a></span><span class="hspace"> </span><span class="RktPn">. </span><span class="RktSym"><a href="function-contracts.html#%28form._%28%28lib._racket%2Fcontract%2Fbase..rkt%29._-~3e%29%29" class="RktStxLink" data-pltdoc="x"><span class="nobreak">-></span></a></span><span class="RktPn"> .</span><span class="hspace"> </span><span class="RktSym"><a href="data-structure-contracts.html#%28form._%28%28lib._racket%2Fcontract%2Fprivate%2Fmisc..rkt%29._any%29%29" class="RktStxLink" data-pltdoc="x">any</a></span><span class="RktPn">)</span></td></tr><tr><td><span class="hspace"> </span><span class="RktPn">(</span><span class="RktSym"><a href="data-structure-contracts.html#%28def._%28%28lib._racket%2Fcontract%2Fprivate%2Fmisc..rkt%29._any%2Fc%29%29" class="RktValLink" data-pltdoc="x">any/c</a></span><span class="hspace"> </span><span class="RktPn">. </span><span class="RktSym"><a href="function-contracts.html#%28form._%28%28lib._racket%2Fcontract%2Fbase..rkt%29._-~3e%29%29" class="RktStxLink" data-pltdoc="x"><span class="nobreak">-></span></a></span><span class="RktPn"> .</span><span class="hspace"> </span><span class="RktSym"><a href="data-structure-contracts.html#%28def._%28%28lib._racket%2Fcontract%2Fprivate%2Fmisc..rkt%29._any%2Fc%29%29" class="RktValLink" data-pltdoc="x">any/c</a></span><span class="RktPn">)</span></td></tr><tr><td><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="RktPn">(</span><span class="RktSym"><a href="data-structure-contracts.html#%28def._%28%28lib._racket%2Fcontract%2Fbase..rkt%29._or%2Fc%29%29" class="RktValLink" data-pltdoc="x">or/c</a></span><span class="hspace"> </span><span class="RktPn">(</span><span class="RktSym"><a href="data-structure-contracts.html#%28def._%28%28lib._racket%2Fcontract%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><span class="hspace"> </span><span class="RktVal">#f</span><span class="RktPn">)</span></td></tr><tr><td><span class="hspace"> </span><span class="RktPn">(</span><span class="RktSym"><a href="data-structure-contracts.html#%28def._%28%28lib._racket%2Fcontract%2Fbase..rkt%29._or%2Fc%29%29" class="RktValLink" data-pltdoc="x">or/c</a></span><span class="hspace"> </span><span class="RktPn">(</span><span class="RktPn">(</span><span class="RktPn">)</span><span class="hspace"> </span><span class="RktPn">(</span><span class="RktPn">)</span><span class="hspace"> </span><span class="RktPn">#:rest</span><span class="hspace"> </span><span class="RktSym"><a href="pairs.html#%28def._%28%28quote._~23~25kernel%29._list~3f%29%29" class="RktValLink" data-pltdoc="x">list?</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%2A%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><span class="hspace"> </span><span class="RktVal">#f</span><span class="RktPn">)</span></td></tr><tr><td><span class="hspace"> </span><span class="RktPn">(</span><span class="RktSym"><a href="data-structure-contracts.html#%28def._%28%28lib._racket%2Fcontract%2Fbase..rkt%29._or%2Fc%29%29" class="RktValLink" data-pltdoc="x">or/c</a></span><span class="hspace"> </span><span class="RktPn">(</span><span class="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="RktPn">)</span><span class="hspace"> </span><span class="RktPn">(</span><span class="RktPn">)</span><span class="hspace"> </span><span class="RktPn">#:rest</span><span class="hspace"> </span><span class="RktSym"><a href="pairs.html#%28def._%28%28quote._~23~25kernel%29._list~3f%29%29" class="RktValLink" data-pltdoc="x">list?</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%2A%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><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></table></td></tr></table></blockquote></div><div class="SIntrapara">Returns a sequence whose elements are generated by the procedures
and initial value returned by the thunk, which is called to
<a href="#%28tech._initiate%29" class="techoutside" data-pltdoc="x"><span class="techinside">initiate</span></a> the sequence. The initiated sequence is defined in
terms of a <span style="font-style: italic">position</span>, which is initialized to the third
result of the thunk, and the <span style="font-style: italic">element</span>, which may consist of
multiple values.</div></p><p><div class="SIntrapara">The <span class="RktVar">thunk</span> results define the generated elements as follows:
</div><div class="SIntrapara"><ul><li><p>The first result is a <span class="RktVar">pos->element</span> procedure that
takes the current position and returns the value(s) for the
current element.</p></li><li><p>The second result is a <span class="RktVar">next-pos</span> procedure that
takes the current position and returns the next position.</p></li><li><p>The third result is the initial position.</p></li><li><p>The fourth result is a <span class="RktVar">continue-with-pos?</span> function
that takes the current position and returns a true result if the
sequence includes the value(s) for the current position, and
false if the sequence should end instead of including the
value(s). Alternatively, the fourth result can be <span class="RktVal">#f</span> to
indicate that the sequence should always include the current
value(s).</p></li><li><p>The fifth result is a <span class="RktVar">continue-with-val?</span> function
that is like the fourth result, but it takes the current element
value(s) instead of the current position. Alternatively, the
fifth result can be <span class="RktVal">#f</span> to indicate that the sequence
should always include the value(s) at the current position.</p></li><li><p>The sixth result is a <span class="RktVar">continue-after-pos+val?</span>
procedure that takes both the current position and the current
element value(s) and determines whether the sequence ends after
the current element is already included in the sequence.
Alternatively, the sixth result can be <span class="RktVal">#f</span> to indicate
that the sequence can always continue after the current
value(s).</p></li></ul></div></p><p>Each of the procedures listed above is called only once per
position. Among the last three procedures, as soon as one of the
procedures returns <span class="RktVal">#f</span>, the sequence ends, and none are
called again. Typically, one of the functions determines the end
condition, and <span class="RktVal">#f</span> is used in place of the other two
functions.</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/private/base..rkt)._prop~3asequence))"></a><span title="Provided from: racket/base, racket | Package: base"><span class="RktSym"><a href="#%28def._%28%28lib._racket%2Fprivate%2Fbase..rkt%29._prop~3asequence%29%29" class="RktValDef RktValLink" data-pltdoc="x">prop:sequence</a></span></span><span class="hspace"> </span>:<span class="hspace"> </span><span class="RktSym"><a href="structprops.html#%28def._%28%28quote._~23~25kernel%29._struct-type-property~3f%29%29" class="RktValLink" data-pltdoc="x">struct-type-property?</a></span></p></blockquote></td></tr></table></blockquote></div><div class="SIntrapara">Associates a procedure to a structure type that takes an instance of
the structure and returns a sequence. If <span class="RktSym">v</span> is an instance
of a structure type with this property, then <span class="RktPn">(</span><span class="RktSym"><a href="#%28def._%28%28lib._racket%2Fprivate%2Fbase..rkt%29._sequence~3f%29%29" class="RktValLink" data-pltdoc="x">sequence?</a></span><span class="stt"> </span><span class="RktSym">v</span><span class="RktPn">)</span>
produces <span class="RktVal">#t</span>.</div></p><p>Using a pre-existing sequence:</p><p><table cellspacing="0" cellpadding="0" class="RktBlk"><tr><td><p>Examples:</p></td></tr><tr><td><blockquote class="SCodeFlow"><table cellspacing="0" cellpadding="0" class="RktBlk"><tr><td><table cellspacing="0" cellpadding="0" class="RktBlk"><tr><td><span class="stt">> </span><span class="RktPn">(</span><span class="RktSym"><a href="define-struct.html#%28form._%28%28lib._racket%2Fprivate%2Fbase..rkt%29._struct%29%29" class="RktStxLink" data-pltdoc="x">struct</a></span><span class="hspace"> </span><span class="RktSym">my-set</span><span class="hspace"> </span><span class="RktPn">(</span><span class="RktSym">table</span><span class="RktPn">)</span></td></tr><tr><td><span class="hspace"> </span><span class="hspace"> </span><span class="RktPn">#:property</span><span class="hspace"> </span><span class="RktSym"><a href="#%28def._%28%28lib._racket%2Fprivate%2Fbase..rkt%29._prop~3asequence%29%29" class="RktValLink" data-pltdoc="x">prop:sequence</a></span></td></tr><tr><td><span class="hspace"> </span><span class="hspace"> </span><span class="RktPn">(</span><span class="RktSym"><a href="lambda.html#%28form._%28%28lib._racket%2Fprivate%2Fbase..rkt%29._lambda%29%29" class="RktStxLink" data-pltdoc="x">lambda</a></span><span class="hspace"> </span><span class="RktPn">(</span><span class="RktSym">s</span><span class="RktPn">)</span></td></tr><tr><td><span class="hspace"> </span><span class="hspace"> </span><span class="RktPn">(</span><span class="RktSym"><a href="#%28def._%28%28lib._racket%2Fprivate%2Fbase..rkt%29._in-hash-keys%29%29" class="RktValLink" data-pltdoc="x">in-hash-keys</a></span><span class="hspace"> </span><span class="RktPn">(</span><span class="RktSym">my-set-table</span><span class="hspace"> </span><span class="RktSym">s</span><span class="RktPn">)</span><span class="RktPn">)</span><span class="RktPn">)</span><span class="RktPn">)</span></td></tr></table></td></tr><tr><td><table cellspacing="0" cellpadding="0"><tr><td></td></tr></table></td></tr><tr><td><table cellspacing="0" cellpadding="0" class="RktBlk"><tr><td><span class="stt">> </span><span class="RktPn">(</span><span class="RktSym"><a href="define.html#%28form._%28%28lib._racket%2Fprivate%2Fbase..rkt%29._define%29%29" class="RktStxLink" data-pltdoc="x">define</a></span><span class="hspace"> </span><span class="RktPn">(</span><span class="RktSym">make-set</span><span class="hspace"> </span><span class="RktPn">. </span><span class="RktSym">xs</span><span class="RktPn">)</span></td></tr><tr><td><span class="hspace"> </span><span class="hspace"> </span><span class="RktPn">(</span><span class="RktSym">my-set</span><span class="hspace"> </span><span class="RktPn">(</span><span class="RktSym"><a href="for.html#%28form._%28%28lib._racket%2Fprivate%2Fbase..rkt%29._for%2Fhash%29%29" class="RktStxLink" data-pltdoc="x">for/hash</a></span><span class="hspace"> </span><span class="RktPn">(</span><span class="RktPn">[</span><span class="RktSym">x</span><span class="hspace"> </span><span class="RktPn">(</span><span class="RktSym"><a href="#%28def._%28%28lib._racket%2Fprivate%2Fbase..rkt%29._in-list%29%29" class="RktValLink" data-pltdoc="x">in-list</a></span><span class="hspace"> </span><span class="RktSym">xs</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="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">x</span><span class="hspace"> </span><span class="RktVal">#t</span><span class="RktPn">)</span><span class="RktPn">)</span><span class="RktPn">)</span><span class="RktPn">)</span></td></tr></table></td></tr><tr><td><table cellspacing="0" cellpadding="0"><tr><td></td></tr></table></td></tr><tr><td><table cellspacing="0" cellpadding="0" class="RktBlk"><tr><td><span class="stt">> </span><span class="RktPn">(</span><span class="RktSym"><a href="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">c</span><span class="hspace"> </span><span class="RktPn">(</span><span class="RktSym">make-set</span><span class="hspace"> </span><span class="RktVal">'</span><span class="RktVal">celeriac</span><span class="hspace"> </span><span class="RktVal">'</span><span class="RktVal">carrot</span><span class="hspace"> </span><span class="RktVal">'</span><span class="RktVal">potato</span><span class="RktPn">)</span><span class="RktPn">]</span><span class="RktPn">)</span></td></tr><tr><td><span class="hspace"> </span><span class="hspace"> </span><span class="RktSym">c</span><span class="RktPn">)</span></td></tr></table></td></tr><tr><td><p><span class="RktRes">'(celeriac carrot potato)</span></p></td></tr></table></blockquote></td></tr></table></p><p>Using <span class="RktSym"><a href="#%28def._%28%28lib._racket%2Fprivate%2Fbase..rkt%29._make-do-sequence%29%29" class="RktValLink" data-pltdoc="x">make-do-sequence</a></span>:</p><p><table cellspacing="0" cellpadding="0" class="RktBlk"><tr><td><p>Examples:</p></td></tr><tr><td><blockquote class="SCodeFlow"><table cellspacing="0" cellpadding="0" class="RktBlk"><tr><td><table cellspacing="0" cellpadding="0" class="RktBlk"><tr><td><span class="stt">> </span><span class="RktPn">(</span><span class="RktSym"><a href="define-struct.html#%28form._%28%28lib._racket%2Fprivate%2Fbase..rkt%29._define-struct%29%29" class="RktStxLink" data-pltdoc="x">define-struct</a></span><span class="hspace"> </span><span class="RktSym">train</span><span class="hspace"> </span><span class="RktPn">(</span><span class="RktSym">car</span><span class="hspace"> </span><span class="RktSym">next</span><span class="RktPn">)</span></td></tr><tr><td><span class="hspace"> </span><span class="hspace"> </span><span class="RktPn">#:property</span><span class="hspace"> </span><span class="RktSym"><a href="#%28def._%28%28lib._racket%2Fprivate%2Fbase..rkt%29._prop~3asequence%29%29" class="RktValLink" data-pltdoc="x">prop:sequence</a></span></td></tr><tr><td><span class="hspace"> </span><span class="hspace"> </span><span class="RktPn">(</span><span class="RktSym"><a href="lambda.html#%28form._%28%28lib._racket%2Fprivate%2Fbase..rkt%29._lambda%29%29" class="RktStxLink" data-pltdoc="x">lambda</a></span><span class="hspace"> </span><span class="RktPn">(</span><span class="RktSym">t</span><span class="RktPn">)</span></td></tr><tr><td><span class="hspace"> </span><span class="hspace"> </span><span class="RktPn">(</span><span class="RktSym"><a href="#%28def._%28%28lib._racket%2Fprivate%2Fbase..rkt%29._make-do-sequence%29%29" class="RktValLink" data-pltdoc="x">make-do-sequence</a></span></td></tr><tr><td><span class="hspace"> </span><span class="hspace"> </span><span class="RktPn">(</span><span class="RktSym"><a href="lambda.html#%28form._%28%28lib._racket%2Fprivate%2Fbase..rkt%29._lambda%29%29" class="RktStxLink" data-pltdoc="x">lambda</a></span><span class="hspace"> </span><span class="RktPn">(</span><span class="RktPn">)</span></td></tr><tr><td><span class="hspace"> </span><span class="hspace"> </span><span class="RktPn">(</span><span class="RktSym"><a href="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">train-car</span><span class="hspace"> </span><span class="RktSym">train-next</span><span class="hspace"> </span><span class="RktSym">t</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">t</span><span class="RktPn">)</span><span class="hspace"> </span><span class="RktSym">t</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">v</span><span class="RktPn">)</span><span class="hspace"> </span><span class="RktVal">#t</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">t</span><span class="hspace"> </span><span class="RktSym">v</span><span class="RktPn">)</span><span class="hspace"> </span><span class="RktVal">#t</span><span class="RktPn">)</span><span class="RktPn">)</span><span class="RktPn">)</span><span class="RktPn">)</span><span class="RktPn">)</span><span class="RktPn">)</span></td></tr></table></td></tr><tr><td><table cellspacing="0" cellpadding="0"><tr><td></td></tr></table></td></tr><tr><td><table cellspacing="0" cellpadding="0" class="RktBlk"><tr><td><span class="stt">> </span><span class="RktPn">(</span><span class="RktSym"><a href="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">c</span><span class="hspace"> </span><span class="RktPn">(</span><span class="RktSym">make-train</span><span class="hspace"> </span><span class="RktVal">'</span><span class="RktVal">engine</span></td></tr><tr><td><span class="hspace"> </span><span class="hspace"> </span><span class="RktPn">(</span><span class="RktSym">make-train</span><span class="hspace"> </span><span class="RktVal">'</span><span class="RktVal">boxcar</span></td></tr><tr><td><span class="hspace"> </span><span class="hspace"> </span><span class="RktPn">(</span><span class="RktSym">make-train</span><span class="hspace"> </span><span class="RktVal">'</span><span class="RktVal">caboose</span></td></tr><tr><td><span class="hspace"> </span><span class="hspace"> </span><span class="RktVal">#f</span><span class="RktPn">)</span><span class="RktPn">)</span><span class="RktPn">)</span><span class="RktPn">]</span><span class="RktPn">)</span></td></tr><tr><td><span class="hspace"> </span><span class="hspace"> </span><span class="RktSym">c</span><span class="RktPn">)</span></td></tr></table></td></tr><tr><td><p><span class="RktRes">'(engine boxcar caboose)</span></p></td></tr></table></blockquote></td></tr></table></p><h5 x-source-module="(lib "scribblings/reference/reference.scrbl")" x-part-tag=""Sequence_Conversion"">4.14.1.2<tt> </tt><a name="(part._.Sequence_.Conversion)"></a>Sequence Conversion</h5><p><div class="SIntrapara"><blockquote class="SVInsetFlow"><table cellspacing="0" cellpadding="0" class="boxed RBoxed"><tr><td><blockquote class="SubFlow"><div class="RBackgroundLabel SIEHidden"><div class="RBackgroundLabelInner"><p>procedure</p></div></div><p class="RForeground"><span class="RktPn">(</span><a name="(def._((lib._racket/private/base..rkt)._sequence-~3estream))"></a><span title="Provided from: racket/base, racket | Package: base"><span class="RktSym"><a href="#%28def._%28%28lib._racket%2Fprivate%2Fbase..rkt%29._sequence-~3estream%29%29" class="RktValDef RktValLink" data-pltdoc="x">sequence->stream</a></span></span><span class="hspace"> </span><span class="RktVar">seq</span><span class="RktPn">)</span><span class="hspace"> </span>→<span class="hspace"> </span><span class="RktSym"><a href="streams.html#%28def._%28%28lib._racket%2Fstream..rkt%29._stream~3f%29%29" class="RktValLink" data-pltdoc="x">stream?</a></span></p></blockquote></td></tr><tr><td><span class="hspace"> </span><span class="RktVar">seq</span><span class="hspace"> </span>:<span class="hspace"> </span><span class="RktSym"><a href="#%28def._%28%28lib._racket%2Fprivate%2Fbase..rkt%29._sequence~3f%29%29" class="RktValLink" data-pltdoc="x">sequence?</a></span></td></tr></table></blockquote></div><div class="SIntrapara">Coverts a sequence to a <a href="streams.html#%28tech._stream%29" class="techoutside" data-pltdoc="x"><span class="techinside">stream</span></a>, which supports the
<span class="RktSym"><a href="streams.html#%28def._%28%28lib._racket%2Fstream..rkt%29._stream-first%29%29" class="RktValLink" data-pltdoc="x">stream-first</a></span> and <span class="RktSym"><a href="streams.html#%28def._%28%28lib._racket%2Fstream..rkt%29._stream-rest%29%29" class="RktValLink" data-pltdoc="x">stream-rest</a></span> operations. Creation
of the stream eagerly <a href="#%28tech._initiate%29" class="techoutside" data-pltdoc="x"><span class="techinside">initiates</span></a> the sequence, but the stream
lazily draws elements from the sequence, caching each element so
that <span class="RktSym"><a href="streams.html#%28def._%28%28lib._racket%2Fstream..rkt%29._stream-first%29%29" class="RktValLink" data-pltdoc="x">stream-first</a></span> produces the same result each time is
applied to a stream.</div></p><p>If extracting an element from <span class="RktVar">seq</span> involves a side-effect,
then the effect is performed each time that either
<span class="RktSym"><a href="streams.html#%28def._%28%28lib._racket%2Fstream..rkt%29._stream-first%29%29" class="RktValLink" data-pltdoc="x">stream-first</a></span> or <span class="RktSym"><a href="streams.html#%28def._%28%28lib._racket%2Fstream..rkt%29._stream-rest%29%29" class="RktValLink" data-pltdoc="x">stream-rest</a></span> is first used to
access or skip an element.</p><p><div class="SIntrapara"><blockquote class="SVInsetFlow"><table cellspacing="0" cellpadding="0" class="boxed RBoxed"><tr><td><blockquote class="SubFlow"><div class="RBackgroundLabel SIEHidden"><div class="RBackgroundLabelInner"><p>procedure</p></div></div><table cellspacing="0" cellpadding="0" class="prototype RForeground"><tr><td><span class="RktPn">(</span><a name="(def._((lib._racket/private/base..rkt)._sequence-generate))"></a><span title="Provided from: racket/base, racket | Package: base"><span class="RktSym"><a href="#%28def._%28%28lib._racket%2Fprivate%2Fbase..rkt%29._sequence-generate%29%29" class="RktValDef RktValLink" data-pltdoc="x">sequence-generate</a></span></span><span class="hspace"> </span><span class="RktVar">seq</span><span class="RktPn">)</span></td><td><span class="hspace"> </span></td><td>→</td><td><span class="hspace"> </span></td><td><table cellspacing="0" cellpadding="0"><tr><td><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="booleans.html#%28def._%28%28quote._~23~25kernel%29._boolean~3f%29%29" class="RktValLink" data-pltdoc="x">boolean?</a></span><span class="RktPn">)</span></td><td><span class="hspace"> </span></td><td><span class="RktPn">(</span><span class="RktSym"><a href="function-contracts.html#%28form._%28%28lib._racket%2Fcontract%2Fbase..rkt%29._-~3e%29%29" class="RktStxLink" data-pltdoc="x"><span class="nobreak">-></span></a></span><span class="hspace"> </span><span class="RktSym"><a href="data-structure-contracts.html#%28form._%28%28lib._racket%2Fcontract%2Fprivate%2Fmisc..rkt%29._any%29%29" class="RktStxLink" data-pltdoc="x">any</a></span><span class="RktPn">)</span></td></tr></table></td></tr></table></blockquote></td></tr><tr><td><span class="hspace"> </span><span class="RktVar">seq</span><span class="hspace"> </span>:<span class="hspace"> </span><span class="RktSym"><a href="#%28def._%28%28lib._racket%2Fprivate%2Fbase..rkt%29._sequence~3f%29%29" class="RktValLink" data-pltdoc="x">sequence?</a></span></td></tr></table></blockquote></div><div class="SIntrapara"><a href="#%28tech._initiate%29" class="techoutside" data-pltdoc="x"><span class="techinside">Initiates</span></a> a sequence and returns two thunks to extract
elements from the sequence. The first returns <span class="RktVal">#t</span> if more
values are available for the sequence. The second returns the next
element (which may be multiple values) from the sequence; if no more
elements are available, the <span class="RktSym"><a href="exns.html#%28def._%28%28lib._racket%2Fprivate%2Fbase..rkt%29._exn~3afail~3acontract%29%29" class="RktValLink" data-pltdoc="x">exn:fail:contract</a></span> exception is raised.</div></p><p><div class="SIntrapara"><blockquote class="SVInsetFlow"><table cellspacing="0" cellpadding="0" class="boxed RBoxed"><tr><td><blockquote class="SubFlow"><div class="RBackgroundLabel SIEHidden"><div class="RBackgroundLabelInner"><p>procedure</p></div></div><p class="RForeground"><span class="RktPn">(</span><a name="(def._((lib._racket/private/base..rkt)._sequence-generate*))"></a><span title="Provided from: racket/base, racket | Package: base"><span class="RktSym"><a href="#%28def._%28%28lib._racket%2Fprivate%2Fbase..rkt%29._sequence-generate%2A%29%29" class="RktValDef RktValLink" data-pltdoc="x">sequence-generate*</a></span></span><span class="hspace"> </span><span class="RktVar">seq</span><span class="RktPn">)</span></p></blockquote></td></tr><tr><td><table cellspacing="0" cellpadding="0" class="prototype"><tr><td><span class="hspace"> </span></td><td>→</td><td><span class="hspace"> </span></td><td><table cellspacing="0" cellpadding="0"><tr><td><span class="RktPn">(</span><span class="RktSym"><a href="data-structure-contracts.html#%28def._%28%28lib._racket%2Fcontract%2Fbase..rkt%29._or%2Fc%29%29" class="RktValLink" data-pltdoc="x">or/c</a></span><span class="hspace"> </span><span class="RktSym"><a href="pairs.html#%28def._%28%28quote._~23~25kernel%29._list~3f%29%29" class="RktValLink" data-pltdoc="x">list?</a></span><span class="hspace"> </span><span class="RktVal">#f</span><span class="RktPn">)</span></td></tr><tr><td><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="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="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="pairs.html#%28def._%28%28quote._~23~25kernel%29._list~3f%29%29" class="RktValLink" data-pltdoc="x">list?</a></span><span class="hspace"> </span><span class="RktVal">#f</span><span class="RktPn">)</span><span class="hspace"> </span><span class="RktSym"><a href="procedures.html#%28def._%28%28quote._~23~25kernel%29._procedure~3f%29%29" class="RktValLink" data-pltdoc="x">procedure?</a></span><span class="RktPn">)</span><span class="RktPn">)</span></td></tr></table></td></tr></table></td></tr><tr><td><span class="hspace"> </span><span class="RktVar">seq</span><span class="hspace"> </span>:<span class="hspace"> </span><span class="RktSym"><a href="#%28def._%28%28lib._racket%2Fprivate%2Fbase..rkt%29._sequence~3f%29%29" class="RktValLink" data-pltdoc="x">sequence?</a></span></td></tr></table></blockquote></div><div class="SIntrapara">Like <span class="RktSym"><a href="#%28def._%28%28lib._racket%2Fprivate%2Fbase..rkt%29._sequence-generate%29%29" class="RktValLink" data-pltdoc="x">sequence-generate</a></span>, but avoids state (aside from any
inherent in the sequence) by returning a list of values for the
sequence’s first element—<wbr></wbr>or <span class="RktVal">#f</span> if the sequence is
empty—<wbr></wbr>and a thunk to continue with the sequence; the result of the
thunk is the same as the result of <span class="RktSym"><a href="#%28def._%28%28lib._racket%2Fprivate%2Fbase..rkt%29._sequence-generate%2A%29%29" class="RktValLink" data-pltdoc="x">sequence-generate*</a></span>, but
for the second element of the sequence, and so on. If the thunk is
called when the element result is <span class="RktVal">#f</span> (indicating no further
values in the sequence), the <span class="RktSym"><a href="exns.html#%28def._%28%28lib._racket%2Fprivate%2Fbase..rkt%29._exn~3afail~3acontract%29%29" class="RktValLink" data-pltdoc="x">exn:fail:contract</a></span> exception is raised.</div></p><h5 x-source-module="(lib "scribblings/reference/reference.scrbl")" x-part-tag=""more-sequences"">4.14.1.3<tt> </tt><a name="(part._more-sequences)"></a><a name="(mod-path._racket/sequence)"></a>Sequence Combinations</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="#%28mod-path._racket%2Fsequence%29" class="RktModLink" data-pltdoc="x"><span class="RktSym">racket/sequence</span></a><span class="RktPn">)</span></td><td align="right"><span class="RpackageSpec"><span class="Smaller"> package:</span> <span class="stt">base</span></span></td></tr></table></div><div class="SIntrapara">The bindings documented in this section are provided by the <a href="#%28mod-path._racket%2Fsequence%29" class="RktModLink" data-pltdoc="x"><span class="RktSym">racket/sequence</span></a> and <a href="index.html" class="RktModLink" data-pltdoc="x"><span class="RktSym">racket</span></a> libraries, but not <a href="index.html" class="RktModLink" data-pltdoc="x"><span class="RktSym">racket/base</span></a>.</div></p><p><div class="SIntrapara"><blockquote class="SVInsetFlow"><table cellspacing="0" cellpadding="0" class="boxed RBoxed"><tr><td><blockquote class="SubFlow"><div class="RBackgroundLabel SIEHidden"><div class="RBackgroundLabelInner"><p>value</p></div></div><p class="RForeground"><a name="(def._((lib._racket/sequence..rkt)._empty-sequence))"></a><span title="Provided from: racket/sequence, racket | Package: base"><span class="RktSym"><a href="#%28def._%28%28lib._racket%2Fsequence..rkt%29._empty-sequence%29%29" class="RktValDef RktValLink" data-pltdoc="x">empty-sequence</a></span></span><span class="hspace"> </span>:<span class="hspace"> </span><span class="RktSym"><a href="#%28def._%28%28lib._racket%2Fprivate%2Fbase..rkt%29._sequence~3f%29%29" class="RktValLink" data-pltdoc="x">sequence?</a></span></p></blockquote></td></tr></table></blockquote></div><div class="SIntrapara">A sequence with no elements.</div></p><p><div class="SIntrapara"><blockquote class="SVInsetFlow"><table cellspacing="0" cellpadding="0" class="boxed RBoxed"><tr><td><blockquote class="SubFlow"><div class="RBackgroundLabel SIEHidden"><div class="RBackgroundLabelInner"><p>procedure</p></div></div><p class="RForeground"><span class="RktPn">(</span><a name="(def._((lib._racket/sequence..rkt)._sequence-~3elist))"></a><span title="Provided from: racket/sequence, racket | Package: base"><span class="RktSym"><a href="#%28def._%28%28lib._racket%2Fsequence..rkt%29._sequence-~3elist%29%29" class="RktValDef RktValLink" data-pltdoc="x">sequence->list</a></span></span><span class="hspace"> </span><span class="RktVar">s</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._list~3f%29%29" class="RktValLink" data-pltdoc="x">list?</a></span></p></blockquote></td></tr><tr><td><span class="hspace"> </span><span class="RktVar">s</span><span class="hspace"> </span>:<span class="hspace"> </span><span class="RktSym"><a href="#%28def._%28%28lib._racket%2Fprivate%2Fbase..rkt%29._sequence~3f%29%29" class="RktValLink" data-pltdoc="x">sequence?</a></span></td></tr></table></blockquote></div><div class="SIntrapara">Returns a list whose elements are the elements of <span class="RktVar">s</span>, each
of which must be a single value. If <span class="RktVar">s</span> is infinite, this
function does not terminate.</div></p><p><div class="SIntrapara"><blockquote class="SVInsetFlow"><table cellspacing="0" cellpadding="0" class="boxed RBoxed"><tr><td><blockquote class="SubFlow"><div class="RBackgroundLabel SIEHidden"><div class="RBackgroundLabelInner"><p>procedure</p></div></div><p class="RForeground"><span class="RktPn">(</span><a name="(def._((lib._racket/sequence..rkt)._sequence-length))"></a><span title="Provided from: racket/sequence, racket | Package: base"><span class="RktSym"><a href="#%28def._%28%28lib._racket%2Fsequence..rkt%29._sequence-length%29%29" class="RktValDef RktValLink" data-pltdoc="x">sequence-length</a></span></span><span class="hspace"> </span><span class="RktVar">s</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">s</span><span class="hspace"> </span>:<span class="hspace"> </span><span class="RktSym"><a href="#%28def._%28%28lib._racket%2Fprivate%2Fbase..rkt%29._sequence~3f%29%29" class="RktValLink" data-pltdoc="x">sequence?</a></span></td></tr></table></blockquote></div><div class="SIntrapara">Returns the number of elements of <span class="RktVar">s</span> by extracting and
discarding all of them. If <span class="RktVar">s</span> is infinite, this function
does not terminate.</div></p><p><div class="SIntrapara"><blockquote class="SVInsetFlow"><table cellspacing="0" cellpadding="0" class="boxed RBoxed"><tr><td><blockquote class="SubFlow"><div class="RBackgroundLabel SIEHidden"><div class="RBackgroundLabelInner"><p>procedure</p></div></div><p class="RForeground"><span class="RktPn">(</span><a name="(def._((lib._racket/sequence..rkt)._sequence-ref))"></a><span title="Provided from: racket/sequence, racket | Package: base"><span class="RktSym"><a href="#%28def._%28%28lib._racket%2Fsequence..rkt%29._sequence-ref%29%29" class="RktValDef RktValLink" data-pltdoc="x">sequence-ref</a></span></span><span class="hspace"> </span><span class="RktVar">s</span><span class="hspace"> </span><span class="RktVar">i</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">s</span><span class="hspace"> </span>:<span class="hspace"> </span><span class="RktSym"><a href="#%28def._%28%28lib._racket%2Fprivate%2Fbase..rkt%29._sequence~3f%29%29" class="RktValLink" data-pltdoc="x">sequence?</a></span></td></tr><tr><td><span class="hspace"> </span><span class="RktVar">i</span><span class="hspace"> </span>:<span class="hspace"> </span><span class="RktSym"><a href="number-types.html#%28def._%28%28quote._~23~25kernel%29._exact-nonnegative-integer~3f%29%29" class="RktValLink" data-pltdoc="x">exact-nonnegative-integer?</a></span></td></tr></table></blockquote></div><div class="SIntrapara">Returns the <span class="RktVar">i</span>th element of <span class="RktVar">s</span> (which may be
multiple values).</div></p><p><div class="SIntrapara"><blockquote class="SVInsetFlow"><table cellspacing="0" cellpadding="0" class="boxed RBoxed"><tr><td><blockquote class="SubFlow"><div class="RBackgroundLabel SIEHidden"><div class="RBackgroundLabelInner"><p>procedure</p></div></div><p class="RForeground"><span class="RktPn">(</span><a name="(def._((lib._racket/sequence..rkt)._sequence-tail))"></a><span title="Provided from: racket/sequence, racket | Package: base"><span class="RktSym"><a href="#%28def._%28%28lib._racket%2Fsequence..rkt%29._sequence-tail%29%29" class="RktValDef RktValLink" data-pltdoc="x">sequence-tail</a></span></span><span class="hspace"> </span><span class="RktVar">s</span><span class="hspace"> </span><span class="RktVar">i</span><span class="RktPn">)</span><span class="hspace"> </span>→<span class="hspace"> </span><span class="RktSym"><a href="#%28def._%28%28lib._racket%2Fprivate%2Fbase..rkt%29._sequence~3f%29%29" class="RktValLink" data-pltdoc="x">sequence?</a></span></p></blockquote></td></tr><tr><td><span class="hspace"> </span><span class="RktVar">s</span><span class="hspace"> </span>:<span class="hspace"> </span><span class="RktSym"><a href="#%28def._%28%28lib._racket%2Fprivate%2Fbase..rkt%29._sequence~3f%29%29" class="RktValLink" data-pltdoc="x">sequence?</a></span></td></tr><tr><td><span class="hspace"> </span><span class="RktVar">i</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 a sequence equivalent to <span class="RktVar">s</span>, except that the first
<span class="RktVar">i</span> elements are omitted.</div></p><p>In case <a href="#%28tech._initiate%29" class="techoutside" data-pltdoc="x"><span class="techinside">initiating</span></a> <span class="RktVar">s</span> involves a
side effect, the sequence <span class="RktVar">s</span> is not <a href="#%28tech._initiate%29" class="techoutside" data-pltdoc="x"><span class="techinside">initiate</span></a>d until
the resulting sequence is <a href="#%28tech._initiate%29" class="techoutside" data-pltdoc="x"><span class="techinside">initiate</span></a>d, at which point the first
<span class="RktVar">i</span> elements are extracted from the sequence.</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/sequence..rkt)._sequence-append))"></a><span title="Provided from: racket/sequence, racket | Package: base"><span class="RktSym"><a href="#%28def._%28%28lib._racket%2Fsequence..rkt%29._sequence-append%29%29" class="RktValDef RktValLink" data-pltdoc="x">sequence-append</a></span></span><span class="hspace"> </span><span class="RktVar">s</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="#%28def._%28%28lib._racket%2Fprivate%2Fbase..rkt%29._sequence~3f%29%29" class="RktValLink" data-pltdoc="x">sequence?</a></span></p></blockquote></td></tr><tr><td><span class="hspace"> </span><span class="RktVar">s</span><span class="hspace"> </span>:<span class="hspace"> </span><span class="RktSym"><a href="#%28def._%28%28lib._racket%2Fprivate%2Fbase..rkt%29._sequence~3f%29%29" class="RktValLink" data-pltdoc="x">sequence?</a></span></td></tr></table></blockquote></div><div class="SIntrapara">Returns a sequence that contains all elements of each sequence in
the order they appear in the original sequences. The new sequence
is constructed lazily.</div></p><p>If all given <span class="RktVar">s</span>s are <a href="streams.html#%28tech._stream%29" class="techoutside" data-pltdoc="x"><span class="techinside">streams</span></a>, the result is also a
<a href="streams.html#%28tech._stream%29" class="techoutside" data-pltdoc="x"><span class="techinside">stream</span></a>.</p><p><div class="SIntrapara"><blockquote class="SVInsetFlow"><table cellspacing="0" cellpadding="0" class="boxed RBoxed"><tr><td><blockquote class="SubFlow"><div class="RBackgroundLabel SIEHidden"><div class="RBackgroundLabelInner"><p>procedure</p></div></div><p class="RForeground"><span class="RktPn">(</span><a name="(def._((lib._racket/sequence..rkt)._sequence-map))"></a><span title="Provided from: racket/sequence, racket | Package: base"><span class="RktSym"><a href="#%28def._%28%28lib._racket%2Fsequence..rkt%29._sequence-map%29%29" class="RktValDef RktValLink" data-pltdoc="x">sequence-map</a></span></span><span class="hspace"> </span><span class="RktVar">f</span><span class="hspace"> </span><span class="RktVar">s</span><span class="RktPn">)</span><span class="hspace"> </span>→<span class="hspace"> </span><span class="RktSym"><a href="#%28def._%28%28lib._racket%2Fprivate%2Fbase..rkt%29._sequence~3f%29%29" class="RktValLink" data-pltdoc="x">sequence?</a></span></p></blockquote></td></tr><tr><td><span class="hspace"> </span><span class="RktVar">f</span><span class="hspace"> </span>:<span class="hspace"> </span><span class="RktSym"><a href="procedures.html#%28def._%28%28quote._~23~25kernel%29._procedure~3f%29%29" class="RktValLink" data-pltdoc="x">procedure?</a></span></td></tr><tr><td><span class="hspace"> </span><span class="RktVar">s</span><span class="hspace"> </span>:<span class="hspace"> </span><span class="RktSym"><a href="#%28def._%28%28lib._racket%2Fprivate%2Fbase..rkt%29._sequence~3f%29%29" class="RktValLink" data-pltdoc="x">sequence?</a></span></td></tr></table></blockquote></div><div class="SIntrapara">Returns a sequence that contains <span class="RktVar">f</span> applied to each element
of <span class="RktVar">s</span>. The new sequence is constructed lazily.</div></p><p>If <span class="RktVar">s</span> is a <a href="streams.html#%28tech._stream%29" class="techoutside" data-pltdoc="x"><span class="techinside">stream</span></a>, then the result is also a
<a href="streams.html#%28tech._stream%29" class="techoutside" data-pltdoc="x"><span class="techinside">stream</span></a>.</p><p><div class="SIntrapara"><blockquote class="SVInsetFlow"><table cellspacing="0" cellpadding="0" class="boxed RBoxed"><tr><td><blockquote class="SubFlow"><div class="RBackgroundLabel SIEHidden"><div class="RBackgroundLabelInner"><p>procedure</p></div></div><p class="RForeground"><span class="RktPn">(</span><a name="(def._((lib._racket/sequence..rkt)._sequence-andmap))"></a><span title="Provided from: racket/sequence, racket | Package: base"><span class="RktSym"><a href="#%28def._%28%28lib._racket%2Fsequence..rkt%29._sequence-andmap%29%29" class="RktValDef RktValLink" data-pltdoc="x">sequence-andmap</a></span></span><span class="hspace"> </span><span class="RktVar">f</span><span class="hspace"> </span><span class="RktVar">s</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">f</span><span class="hspace"> </span>:<span class="hspace"> </span><span class="RktPn">(</span><span class="RktSym"><a href="function-contracts.html#%28form._%28%28lib._racket%2Fcontract%2Fbase..rkt%29._-~3e%29%29" class="RktStxLink" data-pltdoc="x"><span class="nobreak">-></span></a></span><span class="hspace"> </span><span class="RktSym"><a href="data-structure-contracts.html#%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="stx-patterns.html#%28form._%28%28lib._racket%2Fprivate%2Fstxcase-scheme..rkt%29._......%29%29" class="RktStxLink" data-pltdoc="x">...</a></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><span class="RktPn">)</span></td></tr><tr><td><span class="hspace"> </span><span class="RktVar">s</span><span class="hspace"> </span>:<span class="hspace"> </span><span class="RktSym"><a href="#%28def._%28%28lib._racket%2Fprivate%2Fbase..rkt%29._sequence~3f%29%29" class="RktValLink" data-pltdoc="x">sequence?</a></span></td></tr></table></blockquote></div><div class="SIntrapara">Returns <span class="RktVal">#t</span> if <span class="RktVar">f</span> returns a true result on every
element of <span class="RktVar">s</span>. If <span class="RktVar">s</span> is infinite and <span class="RktVar">f</span>
never returns a false result, this function does not terminate.</div></p><p><div class="SIntrapara"><blockquote class="SVInsetFlow"><table cellspacing="0" cellpadding="0" class="boxed RBoxed"><tr><td><blockquote class="SubFlow"><div class="RBackgroundLabel SIEHidden"><div class="RBackgroundLabelInner"><p>procedure</p></div></div><p class="RForeground"><span class="RktPn">(</span><a name="(def._((lib._racket/sequence..rkt)._sequence-ormap))"></a><span title="Provided from: racket/sequence, racket | Package: base"><span class="RktSym"><a href="#%28def._%28%28lib._racket%2Fsequence..rkt%29._sequence-ormap%29%29" class="RktValDef RktValLink" data-pltdoc="x">sequence-ormap</a></span></span><span class="hspace"> </span><span class="RktVar">f</span><span class="hspace"> </span><span class="RktVar">s</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">f</span><span class="hspace"> </span>:<span class="hspace"> </span><span class="RktPn">(</span><span class="RktSym"><a href="function-contracts.html#%28form._%28%28lib._racket%2Fcontract%2Fbase..rkt%29._-~3e%29%29" class="RktStxLink" data-pltdoc="x"><span class="nobreak">-></span></a></span><span class="hspace"> </span><span class="RktSym"><a href="data-structure-contracts.html#%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="stx-patterns.html#%28form._%28%28lib._racket%2Fprivate%2Fstxcase-scheme..rkt%29._......%29%29" class="RktStxLink" data-pltdoc="x">...</a></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><span class="RktPn">)</span></td></tr><tr><td><span class="hspace"> </span><span class="RktVar">s</span><span class="hspace"> </span>:<span class="hspace"> </span><span class="RktSym"><a href="#%28def._%28%28lib._racket%2Fprivate%2Fbase..rkt%29._sequence~3f%29%29" class="RktValLink" data-pltdoc="x">sequence?</a></span></td></tr></table></blockquote></div><div class="SIntrapara">Returns <span class="RktVal">#t</span> if <span class="RktVar">f</span> returns a true result on some
element of <span class="RktVar">s</span>. If <span class="RktVar">s</span> is infinite and <span class="RktVar">f</span>
never returns a true result, this function does not terminate.</div></p><p><div class="SIntrapara"><blockquote class="SVInsetFlow"><table cellspacing="0" cellpadding="0" class="boxed RBoxed"><tr><td><blockquote class="SubFlow"><div class="RBackgroundLabel SIEHidden"><div class="RBackgroundLabelInner"><p>procedure</p></div></div><p class="RForeground"><span class="RktPn">(</span><a name="(def._((lib._racket/sequence..rkt)._sequence-for-each))"></a><span title="Provided from: racket/sequence, racket | Package: base"><span class="RktSym"><a href="#%28def._%28%28lib._racket%2Fsequence..rkt%29._sequence-for-each%29%29" class="RktValDef RktValLink" data-pltdoc="x">sequence-for-each</a></span></span><span class="hspace"> </span><span class="RktVar">f</span><span class="hspace"> </span><span class="RktVar">s</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">f</span><span class="hspace"> </span>:<span class="hspace"> </span><span class="RktPn">(</span><span class="RktSym"><a href="function-contracts.html#%28form._%28%28lib._racket%2Fcontract%2Fbase..rkt%29._-~3e%29%29" class="RktStxLink" data-pltdoc="x"><span class="nobreak">-></span></a></span><span class="hspace"> </span><span class="RktSym"><a href="data-structure-contracts.html#%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="stx-patterns.html#%28form._%28%28lib._racket%2Fprivate%2Fstxcase-scheme..rkt%29._......%29%29" class="RktStxLink" data-pltdoc="x">...</a></span><span class="hspace"> </span><span class="RktSym"><a href="data-structure-contracts.html#%28form._%28%28lib._racket%2Fcontract%2Fprivate%2Fmisc..rkt%29._any%29%29" class="RktStxLink" data-pltdoc="x">any</a></span><span class="RktPn">)</span></td></tr><tr><td><span class="hspace"> </span><span class="RktVar">s</span><span class="hspace"> </span>:<span class="hspace"> </span><span class="RktSym"><a href="#%28def._%28%28lib._racket%2Fprivate%2Fbase..rkt%29._sequence~3f%29%29" class="RktValLink" data-pltdoc="x">sequence?</a></span></td></tr></table></blockquote></div><div class="SIntrapara">Applies <span class="RktVar">f</span> to each element of <span class="RktVar">s</span>. If <span class="RktVar">s</span> is
infinite, this function does not terminate.</div></p><p><div class="SIntrapara"><blockquote class="SVInsetFlow"><table cellspacing="0" cellpadding="0" class="boxed RBoxed"><tr><td><blockquote class="SubFlow"><div class="RBackgroundLabel SIEHidden"><div class="RBackgroundLabelInner"><p>procedure</p></div></div><p class="RForeground"><span class="RktPn">(</span><a name="(def._((lib._racket/sequence..rkt)._sequence-fold))"></a><span title="Provided from: racket/sequence, racket | Package: base"><span class="RktSym"><a href="#%28def._%28%28lib._racket%2Fsequence..rkt%29._sequence-fold%29%29" class="RktValDef RktValLink" data-pltdoc="x">sequence-fold</a></span></span><span class="hspace"> </span><span class="RktVar">f</span><span class="hspace"> </span><span class="RktVar">i</span><span class="hspace"> </span><span class="RktVar">s</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">f</span><span class="hspace"> </span>:<span class="hspace"> </span><span class="RktPn">(</span><span class="RktSym"><a href="function-contracts.html#%28form._%28%28lib._racket%2Fcontract%2Fbase..rkt%29._-~3e%29%29" class="RktStxLink" data-pltdoc="x"><span class="nobreak">-></span></a></span><span class="hspace"> </span><span class="RktSym"><a href="data-structure-contracts.html#%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="RktSym"><a href="stx-patterns.html#%28form._%28%28lib._racket%2Fprivate%2Fstxcase-scheme..rkt%29._......%29%29" class="RktStxLink" data-pltdoc="x">...</a></span><span class="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">i</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">s</span><span class="hspace"> </span>:<span class="hspace"> </span><span class="RktSym"><a href="#%28def._%28%28lib._racket%2Fprivate%2Fbase..rkt%29._sequence~3f%29%29" class="RktValLink" data-pltdoc="x">sequence?</a></span></td></tr></table></blockquote></div><div class="SIntrapara">Folds <span class="RktVar">f</span> over each element of <span class="RktVar">s</span> with <span class="RktVar">i</span> as
the initial accumulator. If <span class="RktVar">s</span> is infinite, this function
does not terminate. The <span class="RktVar">f</span> function takes the accumulator as
its first argument and the next sequence element as its second.</div></p><p><div class="SIntrapara"><blockquote class="SVInsetFlow"><table cellspacing="0" cellpadding="0" class="boxed RBoxed"><tr><td><blockquote class="SubFlow"><div class="RBackgroundLabel SIEHidden"><div class="RBackgroundLabelInner"><p>procedure</p></div></div><p class="RForeground"><span class="RktPn">(</span><a name="(def._((lib._racket/sequence..rkt)._sequence-count))"></a><span title="Provided from: racket/sequence, racket | Package: base"><span class="RktSym"><a href="#%28def._%28%28lib._racket%2Fsequence..rkt%29._sequence-count%29%29" class="RktValDef RktValLink" data-pltdoc="x">sequence-count</a></span></span><span class="hspace"> </span><span class="RktVar">f</span><span class="hspace"> </span><span class="RktVar">s</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">f</span><span class="hspace"> </span>:<span class="hspace"> </span><span class="RktSym"><a href="procedures.html#%28def._%28%28quote._~23~25kernel%29._procedure~3f%29%29" class="RktValLink" data-pltdoc="x">procedure?</a></span></td></tr><tr><td><span class="hspace"> </span><span class="RktVar">s</span><span class="hspace"> </span>:<span class="hspace"> </span><span class="RktSym"><a href="#%28def._%28%28lib._racket%2Fprivate%2Fbase..rkt%29._sequence~3f%29%29" class="RktValLink" data-pltdoc="x">sequence?</a></span></td></tr></table></blockquote></div><div class="SIntrapara">Returns the number of elements in <span class="RktVar">s</span> for which <span class="RktVar">f</span>
returns a true result. If <span class="RktVar">s</span> is infinite, this function
does not terminate.</div></p><p><div class="SIntrapara"><blockquote class="SVInsetFlow"><table cellspacing="0" cellpadding="0" class="boxed RBoxed"><tr><td><blockquote class="SubFlow"><div class="RBackgroundLabel SIEHidden"><div class="RBackgroundLabelInner"><p>procedure</p></div></div><p class="RForeground"><span class="RktPn">(</span><a name="(def._((lib._racket/sequence..rkt)._sequence-filter))"></a><span title="Provided from: racket/sequence, racket | Package: base"><span class="RktSym"><a href="#%28def._%28%28lib._racket%2Fsequence..rkt%29._sequence-filter%29%29" class="RktValDef RktValLink" data-pltdoc="x">sequence-filter</a></span></span><span class="hspace"> </span><span class="RktVar">f</span><span class="hspace"> </span><span class="RktVar">s</span><span class="RktPn">)</span><span class="hspace"> </span>→<span class="hspace"> </span><span class="RktSym"><a href="#%28def._%28%28lib._racket%2Fprivate%2Fbase..rkt%29._sequence~3f%29%29" class="RktValLink" data-pltdoc="x">sequence?</a></span></p></blockquote></td></tr><tr><td><span class="hspace"> </span><span class="RktVar">f</span><span class="hspace"> </span>:<span class="hspace"> </span><span class="RktPn">(</span><span class="RktSym"><a href="function-contracts.html#%28form._%28%28lib._racket%2Fcontract%2Fbase..rkt%29._-~3e%29%29" class="RktStxLink" data-pltdoc="x"><span class="nobreak">-></span></a></span><span class="hspace"> </span><span class="RktSym"><a href="data-structure-contracts.html#%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="stx-patterns.html#%28form._%28%28lib._racket%2Fprivate%2Fstxcase-scheme..rkt%29._......%29%29" class="RktStxLink" data-pltdoc="x">...</a></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><span class="RktPn">)</span></td></tr><tr><td><span class="hspace"> </span><span class="RktVar">s</span><span class="hspace"> </span>:<span class="hspace"> </span><span class="RktSym"><a href="#%28def._%28%28lib._racket%2Fprivate%2Fbase..rkt%29._sequence~3f%29%29" class="RktValLink" data-pltdoc="x">sequence?</a></span></td></tr></table></blockquote></div><div class="SIntrapara">Returns a sequence whose elements are the elements of <span class="RktVar">s</span> for
which <span class="RktVar">f</span> returns a true result. Although the new sequence
is constructed lazily, if <span class="RktVar">s</span> has an infinite number of
elements where <span class="RktVar">f</span> returns a false result in between two
elements where <span class="RktVar">f</span> returns a true result, then operations on
this sequence will not terminate during the infinite sub-sequence.</div></p><p>If <span class="RktVar">s</span> is a <a href="streams.html#%28tech._stream%29" class="techoutside" data-pltdoc="x"><span class="techinside">stream</span></a>, then the result is also a
<a href="streams.html#%28tech._stream%29" class="techoutside" data-pltdoc="x"><span class="techinside">stream</span></a>.</p><p><div class="SIntrapara"><blockquote class="SVInsetFlow"><table cellspacing="0" cellpadding="0" class="boxed RBoxed"><tr><td><blockquote class="SubFlow"><div class="RBackgroundLabel SIEHidden"><div class="RBackgroundLabelInner"><p>procedure</p></div></div><p class="RForeground"><span class="RktPn">(</span><a name="(def._((lib._racket/sequence..rkt)._sequence-add-between))"></a><span title="Provided from: racket/sequence, racket | Package: base"><span class="RktSym"><a href="#%28def._%28%28lib._racket%2Fsequence..rkt%29._sequence-add-between%29%29" class="RktValDef RktValLink" data-pltdoc="x">sequence-add-between</a></span></span><span class="hspace"> </span><span class="RktVar">s</span><span class="hspace"> </span><span class="RktVar">e</span><span class="RktPn">)</span><span class="hspace"> </span>→<span class="hspace"> </span><span class="RktSym"><a href="#%28def._%28%28lib._racket%2Fprivate%2Fbase..rkt%29._sequence~3f%29%29" class="RktValLink" data-pltdoc="x">sequence?</a></span></p></blockquote></td></tr><tr><td><span class="hspace"> </span><span class="RktVar">s</span><span class="hspace"> </span>:<span class="hspace"> </span><span class="RktSym"><a href="#%28def._%28%28lib._racket%2Fprivate%2Fbase..rkt%29._sequence~3f%29%29" class="RktValLink" data-pltdoc="x">sequence?</a></span></td></tr><tr><td><span class="hspace"> </span><span class="RktVar">e</span><span class="hspace"> </span>:<span class="hspace"> </span><span class="RktSym"><a href="data-structure-contracts.html#%28def._%28%28lib._racket%2Fcontract%2Fprivate%2Fmisc..rkt%29._any%2Fc%29%29" class="RktValLink" data-pltdoc="x">any/c</a></span></td></tr></table></blockquote></div><div class="SIntrapara">Returns a sequence whose elements are the elements of <span class="RktVar">s</span>,
but with <span class="RktVar">e</span> between each pair of elements in <span class="RktVar">s</span>.
The new sequence is constructed lazily.</div></p><p>If <span class="RktVar">s</span> is a <a href="streams.html#%28tech._stream%29" class="techoutside" data-pltdoc="x"><span class="techinside">stream</span></a>, then the result is also a
<a href="streams.html#%28tech._stream%29" class="techoutside" data-pltdoc="x"><span class="techinside">stream</span></a>.</p><p><table cellspacing="0" cellpadding="0" class="RktBlk"><tr><td><p>Examples:</p></td></tr><tr><td><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="let.html#%28form._%28%28lib._racket%2Fprivate%2Fletstx-scheme..rkt%29._let%2A%29%29" class="RktStxLink" data-pltdoc="x">let*</a></span><span class="hspace"> </span><span class="RktPn">(</span><span class="RktPn">[</span><span class="RktSym">all-reds</span><span class="hspace"> </span><span class="RktPn">(</span><span class="RktSym"><a href="#%28def._%28%28lib._racket%2Fprivate%2Fbase..rkt%29._in-cycle%29%29" class="RktValLink" data-pltdoc="x">in-cycle</a></span><span class="hspace"> </span><span class="RktVal">'</span><span class="RktVal">(</span><span class="RktVal">"red"</span><span class="RktVal">)</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">red-and-blues</span><span class="hspace"> </span><span class="RktPn">(</span><span class="RktSym"><a href="#%28def._%28%28lib._racket%2Fsequence..rkt%29._sequence-add-between%29%29" class="RktValLink" data-pltdoc="x">sequence-add-between</a></span><span class="hspace"> </span><span class="RktSym">all-reds</span><span class="hspace"> </span><span class="RktVal">"blue"</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="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">n</span><span class="hspace"> </span><span class="RktPn">(</span><span class="RktSym"><a href="#%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></td></tr><tr><td><span class="hspace"> </span><span class="hspace"> </span><span class="RktPn">[</span><span class="RktSym">elt</span><span class="hspace"> </span><span class="RktSym">red-and-blues</span><span class="RktPn">]</span><span class="RktPn">)</span></td></tr><tr><td><span class="hspace"> </span><span class="hspace"> </span><span class="RktSym">elt</span><span class="RktPn">)</span><span class="RktPn">)</span></td></tr></table></td></tr><tr><td><p><span class="RktRes">'("red" "blue" "red" "blue" "red" "blue" "red" "blue" "red" "blue")</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="for.html#%28form._%28%28lib._racket%2Fprivate%2Fbase..rkt%29._for%29%29" class="RktStxLink" data-pltdoc="x">for</a></span><span class="hspace"> </span><span class="RktPn">(</span><span class="RktPn">[</span><span class="RktSym">text</span><span class="hspace"> </span><span class="RktPn">(</span><span class="RktSym"><a href="#%28def._%28%28lib._racket%2Fsequence..rkt%29._sequence-add-between%29%29" class="RktValLink" data-pltdoc="x">sequence-add-between</a></span><span class="hspace"> </span><span class="RktVal">'</span><span class="RktVal">(</span><span class="RktVal">"veni"</span><span class="hspace"> </span><span class="RktVal">"vidi"</span><span class="hspace"> </span><span class="RktVal">"duci"</span><span class="RktVal">)</span><span class="hspace"> </span><span class="RktVal">", "</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="Writing.html#%28def._%28%28quote._~23~25kernel%29._display%29%29" class="RktValLink" data-pltdoc="x">display</a></span><span class="hspace"> </span><span class="RktSym">text</span><span class="RktPn">)</span><span class="RktPn">)</span></td></tr></table></td></tr><tr><td><p><span class="RktOut">veni, vidi, duci</span></p></td></tr><tr><td><table cellspacing="0" cellpadding="0"><tr><td></td></tr></table></td></tr></table></blockquote></td></tr></table></p><div class="navsetbottom"><span class="navleft"><form class="searchform"><input class="searchbox" style="color: #888;" type="text" value="...search manuals..." title="Enter a search string to search the manuals" onkeypress="return DoSearchKey(event, this, "6.1", "../");" onfocus="this.style.color="black"; this.style.textAlign="left"; if (this.value == "...search manuals...") this.value="";" onblur="if (this.value.match(/^ *$/)) { this.style.color="#888"; this.style.textAlign="center"; this.value="...search manuals..."; }"/></form> <a href="../index.html" title="up to the documentation top" data-pltdoc="x" onclick="return GotoPLTRoot("6.1");">top</a></span><span class="navright"> <a href="sequences_streams.html" title="backward to "4.14 Sequences and Streams"" data-pltdoc="x">← prev</a> <a href="sequences_streams.html" title="up to "4.14 Sequences and Streams"" data-pltdoc="x">up</a> <a href="streams.html" title="forward to "4.14.2 Streams"" data-pltdoc="x">next →</a></span> </div></div></div><div id="contextindicator"> </div></body></html>
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