commit 7daf8fda80e1b47a217ea7c7c82fccceea7d6222
parent 96c20cbade4e6958d63052200561018efaeb0c39
Author: Greg Hendershott <greghendershott@gmail.com>
Date: Mon, 12 Nov 2012 19:48:25 -0500
Regen html
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diff --git a/index.html b/index.html
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<!DOCTYPE html PUBLIC "-//W3C//DTD HTML 4.0 Transitional//EN" "http://www.w3.org/TR/html4/loose.dtd">
-<html><head><meta http-equiv="content-type" content="text-html; charset=utf-8" /><title>Fear of Macros</title><link rel="stylesheet" type="text/css" href="scribble.css" title="default" /><link rel="stylesheet" type="text/css" href="racket.css" title="default" /><link rel="stylesheet" type="text/css" href="scribble-style.css" title="default" /><link rel="stylesheet" type="text/css" href="gh.css" title="default" /><script type="text/javascript" src="scribble-common.js"></script><!--[if IE 6]><style type="text/css">.SIEHidden { overflow: hidden; }</style><![endif]--><meta name="keywords" content="Racket,macros,Scheme"><meta name="description" content="Practical Racket macros"><meta name="author" content="Greg Hendershott"><meta name="charset" content="utf-8"><link href='http://fonts.googleapis.com/css?family=Fenix' rel='stylesheet' type='text/css'><script type="text/javascript">var _gaq = _gaq || [];_gaq.push(['_setAccount', 'UA-29709446-1']);_gaq.push(['_setDomainName', 'greghendershott.com']);_gaq.push(['_trackPageview']);(function() {var ga = document.createElement('script'); ga.type = 'text/javascript'; ga.async = true;ga.src = ('https:' == document.location.protocol ? 'https://ssl' : 'http://www') + '.google-analytics.com/ga.js';var s = document.getElementsByTagName('script')[0]; s.parentNode.insertBefore(ga, s);})();</script></head><body id="scribble-racket-lang-org"><div class="tocset"><div class="tocview"><div class="tocviewlist" style="margin-bottom: 1em;"><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="" class="tocviewselflink" pltdoc="x">Fear of Macros</a></td></tr></table></div><div class="tocviewsublistonly" style="display: none;" id="tocview_0"><table cellspacing="0" cellpadding="0"><tr><td align="right">1 </td><td><a href="#(part._.Preface)" class="tocviewlink" pltdoc="x">Preface</a></td></tr><tr><td align="right">2 </td><td><a href="#(part._.Our_plan_of_attack)" class="tocviewlink" pltdoc="x">Our plan of attack</a></td></tr><tr><td align="right">3 </td><td><a href="#(part._.Transform_)" class="tocviewlink" pltdoc="x">Transform!</a></td></tr><tr><td align="right">4 </td><td><a href="#(part._.Pattern_matching__syntax-case_and_syntax-rules)" class="tocviewlink" pltdoc="x">Pattern matching:<span class="mywbr"> </span> syntax-<wbr></wbr>case and syntax-<wbr></wbr>rules</a></td></tr><tr><td align="right">5 </td><td><a href="#(part._.Syntax_parameters)" class="tocviewlink" pltdoc="x">Syntax parameters</a></td></tr><tr><td align="right">6 </td><td><a href="#(part._.What_s_the_point_of_splicing-let_)" class="tocviewlink" pltdoc="x">What’s the point of <span class="RktSym"><span class="RktStxLink">splicing-<wbr></wbr>let</span></span>?</a></td></tr><tr><td align="right">7 </td><td><a href="#(part._.Robust_macros__syntax-parse)" class="tocviewlink" pltdoc="x">Robust macros:<span class="mywbr"> </span> syntax-<wbr></wbr>parse</a></td></tr><tr><td align="right">8 </td><td><a href="#(part._.References_and_.Acknowledgments)" class="tocviewlink" pltdoc="x">References and Acknowledgments</a></td></tr><tr><td align="right">9 </td><td><a href="#(part._.Epilogue)" class="tocviewlink" pltdoc="x">Epilogue</a></td></tr></table></div></div></div><div class="tocsub"><table class="tocsublist" cellspacing="0"><tr><td><span class="tocsublinknumber">1<tt> </tt></span><a href="#(part._.Preface)" class="tocsubseclink" pltdoc="x">Preface</a></td></tr><tr><td><span class="tocsublinknumber">2<tt> </tt></span><a href="#(part._.Our_plan_of_attack)" class="tocsubseclink" pltdoc="x">Our plan of attack</a></td></tr><tr><td><span class="tocsublinknumber">3<tt> </tt></span><a href="#(part._.Transform_)" class="tocsubseclink" pltdoc="x">Transform!</a></td></tr><tr><td><span class="tocsublinknumber">3.1<tt> </tt></span><a href="#(part._.What_is_a_syntax_transformer_)" class="tocsubseclink" pltdoc="x">What is a syntax transformer?</a></td></tr><tr><td><span class="tocsublinknumber">3.2<tt> </tt></span><a href="#(part._.What_s_the_input_)" class="tocsubseclink" pltdoc="x">What’s the input?</a></td></tr><tr><td><span class="tocsublinknumber">3.3<tt> </tt></span><a href="#(part._.Actually_transforming_the_input)" class="tocsubseclink" pltdoc="x">Actually transforming the input</a></td></tr><tr><td><span class="tocsublinknumber">3.4<tt> </tt></span><a href="#(part._.Compile_time_vs__run_time)" class="tocsubseclink" pltdoc="x">Compile time vs. run time</a></td></tr><tr><td><span class="tocsublinknumber">3.5<tt> </tt></span><a href="#(part._begin-for-syntax)" class="tocsubseclink" pltdoc="x"><span class="RktSym"><span class="RktStxLink">begin-<wbr></wbr>for-<wbr></wbr>syntax</span></span></a></td></tr><tr><td><span class="tocsublinknumber">4<tt> </tt></span><a href="#(part._.Pattern_matching__syntax-case_and_syntax-rules)" class="tocsubseclink" pltdoc="x">Pattern matching:<span class="mywbr"> </span> syntax-<wbr></wbr>case and syntax-<wbr></wbr>rules</a></td></tr><tr><td><span class="tocsublinknumber">4.1<tt> </tt></span><a href="#(part._.Pattern_variable_vs__template---fight_)" class="tocsubseclink" pltdoc="x">Pattern variable vs. template—<wbr></wbr>fight!</a></td></tr><tr><td><span class="tocsublinknumber">4.1.1<tt> </tt></span><a href="#(part._with-syntax)" class="tocsubseclink" pltdoc="x"><span class="RktSym"><span class="RktStxLink">with-<wbr></wbr>syntax</span></span></a></td></tr><tr><td><span class="tocsublinknumber">4.1.2<tt> </tt></span><a href="#(part._format-id)" class="tocsubseclink" pltdoc="x"><span class="RktSym">format-<wbr></wbr>id</span></a></td></tr><tr><td><span class="tocsublinknumber">4.2<tt> </tt></span><a href="#(part._.Making_our_own_struct)" class="tocsubseclink" pltdoc="x">Making our own <span class="RktSym"><span class="RktStxLink">struct</span></span></a></td></tr><tr><td><span class="tocsublinknumber">4.3<tt> </tt></span><a href="#(part._hash..refs)" class="tocsubseclink" pltdoc="x">Using dot notation for nested hash lookups</a></td></tr><tr><td><span class="tocsublinknumber">5<tt> </tt></span><a href="#(part._.Syntax_parameters)" class="tocsubseclink" pltdoc="x">Syntax parameters</a></td></tr><tr><td><span class="tocsublinknumber">6<tt> </tt></span><a href="#(part._.What_s_the_point_of_splicing-let_)" class="tocsubseclink" pltdoc="x">What’s the point of <span class="RktSym"><span class="RktStxLink">splicing-<wbr></wbr>let</span></span>?</a></td></tr><tr><td><span class="tocsublinknumber">7<tt> </tt></span><a href="#(part._.Robust_macros__syntax-parse)" class="tocsubseclink" pltdoc="x">Robust macros:<span class="mywbr"> </span> syntax-<wbr></wbr>parse</a></td></tr><tr><td><span class="tocsublinknumber">7.1<tt> </tt></span><a href="#(part._.Error-handling_strategies_for_functions)" class="tocsubseclink" pltdoc="x">Error-<wbr></wbr>handling strategies for functions</a></td></tr><tr><td><span class="tocsublinknumber">7.2<tt> </tt></span><a href="#(part._.Error-handling_strategies_for_macros)" class="tocsubseclink" pltdoc="x">Error-<wbr></wbr>handling strategies for macros</a></td></tr><tr><td><span class="tocsublinknumber">7.3<tt> </tt></span><a href="#(part._.Using_syntax_parse)" class="tocsubseclink" pltdoc="x">Using <span class="RktSym">syntax/<span class="mywbr"> </span>parse</span></a></td></tr><tr><td><span class="tocsublinknumber">8<tt> </tt></span><a href="#(part._.References_and_.Acknowledgments)" class="tocsubseclink" pltdoc="x">References and Acknowledgments</a></td></tr><tr><td><span class="tocsublinknumber">9<tt> </tt></span><a href="#(part._.Epilogue)" class="tocsubseclink" pltdoc="x">Epilogue</a></td></tr></table></div></div><div class="maincolumn"><div class="main"><h2><a name="(part._.Fear_of_.Macros)"></a>Fear of Macros</h2><div class="SAuthorListBox"><span class="SAuthorList"><p class="author"><a href="http://www.greghendershott.com">Greg Hendershott</a></p></span></div><p><div class="SIntrapara"></div><div class="SIntrapara"><img src="fear-of-macros.jpg" alt="" />
-</div><div class="SIntrapara"><span class="Smaller">Copyright (c) 2012 by Greg Hendershott. All rights reserved.</span></div><div class="SIntrapara"><span class="Smaller">Last updated 2012-11-08 16:16:21</span></div><div class="SIntrapara">Feedback and corrections are <a href="https://github.com/greghendershott/fear-of-macros/issues">welcome here</a>.</div></p><p>Contents:</p><table cellspacing="0"><tr><td><p><span class="hspace"> </span><a href="#(part._.Preface)" class="toptoclink" pltdoc="x">1<span class="hspace"> </span>Preface</a></p></td></tr><tr><td><p><span class="hspace"></span></p></td></tr><tr><td><p><span class="hspace"> </span><a href="#(part._.Our_plan_of_attack)" class="toptoclink" pltdoc="x">2<span class="hspace"> </span>Our plan of attack</a></p></td></tr><tr><td><p><span class="hspace"></span></p></td></tr><tr><td><p><span class="hspace"> </span><a href="#(part._.Transform_)" class="toptoclink" pltdoc="x">3<span class="hspace"> </span>Transform!</a></p></td></tr><tr><td><p><span class="hspace"> </span><a href="#(part._.What_is_a_syntax_transformer_)" class="toclink" pltdoc="x">3.1<span class="hspace"> </span>What is a syntax transformer?</a></p></td></tr><tr><td><p><span class="hspace"> </span><a href="#(part._.What_s_the_input_)" class="toclink" pltdoc="x">3.2<span class="hspace"> </span>What’s the input?</a></p></td></tr><tr><td><p><span class="hspace"> </span><a href="#(part._.Actually_transforming_the_input)" class="toclink" pltdoc="x">3.3<span class="hspace"> </span>Actually transforming the input</a></p></td></tr><tr><td><p><span class="hspace"> </span><a href="#(part._.Compile_time_vs__run_time)" class="toclink" pltdoc="x">3.4<span class="hspace"> </span>Compile time vs. run time</a></p></td></tr><tr><td><p><span class="hspace"> </span><a href="#(part._begin-for-syntax)" class="toclink" pltdoc="x">3.5<span class="hspace"> </span><span class="RktSym"><span class="RktStxLink">begin-for-syntax</span></span></a></p></td></tr><tr><td><p><span class="hspace"></span></p></td></tr><tr><td><p><span class="hspace"> </span><a href="#(part._.Pattern_matching__syntax-case_and_syntax-rules)" class="toptoclink" pltdoc="x">4<span class="hspace"> </span>Pattern matching: syntax-case and syntax-rules</a></p></td></tr><tr><td><p><span class="hspace"> </span><a href="#(part._.Pattern_variable_vs__template---fight_)" class="toclink" pltdoc="x">4.1<span class="hspace"> </span>Pattern variable vs. template—<wbr></wbr>fight!</a></p></td></tr><tr><td><p><span class="hspace"> </span><a href="#(part._with-syntax)" class="toclink" pltdoc="x">4.1.1<span class="hspace"> </span><span class="RktSym"><span class="RktStxLink">with-syntax</span></span></a></p></td></tr><tr><td><p><span class="hspace"> </span><a href="#(part._format-id)" class="toclink" pltdoc="x">4.1.2<span class="hspace"> </span><span class="RktSym">format-id</span></a></p></td></tr><tr><td><p><span class="hspace"> </span><a href="#(part._.Making_our_own_struct)" class="toclink" pltdoc="x">4.2<span class="hspace"> </span>Making our own <span class="RktSym"><span class="RktStxLink">struct</span></span></a></p></td></tr><tr><td><p><span class="hspace"> </span><a href="#(part._hash..refs)" class="toclink" pltdoc="x">4.3<span class="hspace"> </span>Using dot notation for nested hash lookups</a></p></td></tr><tr><td><p><span class="hspace"></span></p></td></tr><tr><td><p><span class="hspace"> </span><a href="#(part._.Syntax_parameters)" class="toptoclink" pltdoc="x">5<span class="hspace"> </span>Syntax parameters</a></p></td></tr><tr><td><p><span class="hspace"></span></p></td></tr><tr><td><p><span class="hspace"> </span><a href="#(part._.What_s_the_point_of_splicing-let_)" class="toptoclink" pltdoc="x">6<span class="hspace"> </span>What’s the point of <span class="RktSym"><span class="RktStxLink">splicing-let</span></span>?</a></p></td></tr><tr><td><p><span class="hspace"></span></p></td></tr><tr><td><p><span class="hspace"> </span><a href="#(part._.Robust_macros__syntax-parse)" class="toptoclink" pltdoc="x">7<span class="hspace"> </span>Robust macros: syntax-parse</a></p></td></tr><tr><td><p><span class="hspace"> </span><a href="#(part._.Error-handling_strategies_for_functions)" class="toclink" pltdoc="x">7.1<span class="hspace"> </span>Error-handling strategies for functions</a></p></td></tr><tr><td><p><span class="hspace"> </span><a href="#(part._.Error-handling_strategies_for_macros)" class="toclink" pltdoc="x">7.2<span class="hspace"> </span>Error-handling strategies for macros</a></p></td></tr><tr><td><p><span class="hspace"> </span><a href="#(part._.Using_syntax_parse)" class="toclink" pltdoc="x">7.3<span class="hspace"> </span>Using <span class="RktSym">syntax/parse</span></a></p></td></tr><tr><td><p><span class="hspace"></span></p></td></tr><tr><td><p><span class="hspace"> </span><a href="#(part._.References_and_.Acknowledgments)" class="toptoclink" pltdoc="x">8<span class="hspace"> </span>References and Acknowledgments</a></p></td></tr><tr><td><p><span class="hspace"></span></p></td></tr><tr><td><p><span class="hspace"> </span><a href="#(part._.Epilogue)" class="toptoclink" pltdoc="x">9<span class="hspace"> </span>Epilogue</a></p></td></tr></table><h3>1<tt> </tt><a name="(part._.Preface)"></a>Preface</h3><p>I learned Racket after 25 years of mostly using C and C++.</p><p>Some psychic whiplash resulted.</p><p>"All the parentheses" was actually not a big deal. Instead, the first
+<html><head><meta http-equiv="content-type" content="text-html; charset=utf-8" /><title>Fear of Macros</title><link rel="stylesheet" type="text/css" href="scribble.css" title="default" /><link rel="stylesheet" type="text/css" href="racket.css" title="default" /><link rel="stylesheet" type="text/css" href="scribble-style.css" title="default" /><link rel="stylesheet" type="text/css" href="gh.css" title="default" /><script type="text/javascript" src="scribble-common.js"></script><!--[if IE 6]><style type="text/css">.SIEHidden { overflow: hidden; }</style><![endif]--><meta name="keywords" content="Racket,macros,Scheme"><meta name="description" content="Practical Racket macros"><meta name="author" content="Greg Hendershott"><meta name="charset" content="utf-8"><link href='http://fonts.googleapis.com/css?family=Fenix' rel='stylesheet' type='text/css'><script type="text/javascript">var _gaq = _gaq || [];_gaq.push(['_setAccount', 'UA-29709446-1']);_gaq.push(['_setDomainName', 'greghendershott.com']);_gaq.push(['_trackPageview']);(function() {var ga = document.createElement('script'); ga.type = 'text/javascript'; ga.async = true;ga.src = ('https:' == document.location.protocol ? 'https://ssl' : 'http://www') + '.google-analytics.com/ga.js';var s = document.getElementsByTagName('script')[0]; s.parentNode.insertBefore(ga, s);})();</script></head><body id="scribble-racket-lang-org"><div class="tocset"><div class="tocview"><div class="tocviewlist" style="margin-bottom: 1em;"><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="" class="tocviewselflink" pltdoc="x">Fear of Macros</a></td></tr></table></div><div class="tocviewsublistonly" style="display: none;" id="tocview_0"><table cellspacing="0" cellpadding="0"><tr><td align="right">1 </td><td><a href="#(part._.Preface)" class="tocviewlink" pltdoc="x">Preface</a></td></tr><tr><td align="right">2 </td><td><a href="#(part._.Our_plan_of_attack)" class="tocviewlink" pltdoc="x">Our plan of attack</a></td></tr><tr><td align="right">3 </td><td><a href="#(part._.Transform_)" class="tocviewlink" pltdoc="x">Transform!</a></td></tr><tr><td align="right">4 </td><td><a href="#(part._.Pattern_matching__syntax-case_and_syntax-rules)" class="tocviewlink" pltdoc="x">Pattern matching:<span class="mywbr"> </span> syntax-<wbr></wbr>case and syntax-<wbr></wbr>rules</a></td></tr><tr><td align="right">5 </td><td><a href="#(part._.Syntax_parameters)" class="tocviewlink" pltdoc="x">Syntax parameters</a></td></tr><tr><td align="right">6 </td><td><a href="#(part._.What_s_the_point_of_splicing-let_)" class="tocviewlink" pltdoc="x">What’s the point of <span class="RktSym"><span class="RktStxLink">splicing-<wbr></wbr>let</span></span>?</a></td></tr><tr><td align="right">7 </td><td><a href="#(part._.Robust_macros__syntax-parse)" class="tocviewlink" pltdoc="x">Robust macros:<span class="mywbr"> </span> syntax-<wbr></wbr>parse</a></td></tr><tr><td align="right">8 </td><td><a href="#(part._.References_and_.Acknowledgments)" class="tocviewlink" pltdoc="x">References and Acknowledgments</a></td></tr><tr><td align="right">9 </td><td><a href="#(part._.Epilogue)" class="tocviewlink" pltdoc="x">Epilogue</a></td></tr></table></div></div></div><div class="tocsub"><table class="tocsublist" cellspacing="0"><tr><td><span class="tocsublinknumber">1<tt> </tt></span><a href="#(part._.Preface)" class="tocsubseclink" pltdoc="x">Preface</a></td></tr><tr><td><span class="tocsublinknumber">2<tt> </tt></span><a href="#(part._.Our_plan_of_attack)" class="tocsubseclink" pltdoc="x">Our plan of attack</a></td></tr><tr><td><span class="tocsublinknumber">3<tt> </tt></span><a href="#(part._.Transform_)" class="tocsubseclink" pltdoc="x">Transform!</a></td></tr><tr><td><span class="tocsublinknumber">3.1<tt> </tt></span><a href="#(part._.What_is_a_syntax_transformer_)" class="tocsubseclink" pltdoc="x">What is a syntax transformer?</a></td></tr><tr><td><span class="tocsublinknumber">3.2<tt> </tt></span><a href="#(part._.What_s_the_input_)" class="tocsubseclink" pltdoc="x">What’s the input?</a></td></tr><tr><td><span class="tocsublinknumber">3.3<tt> </tt></span><a href="#(part._.Actually_transforming_the_input)" class="tocsubseclink" pltdoc="x">Actually transforming the input</a></td></tr><tr><td><span class="tocsublinknumber">3.4<tt> </tt></span><a href="#(part._.Compile_time_vs__run_time)" class="tocsubseclink" pltdoc="x">Compile time vs. run time</a></td></tr><tr><td><span class="tocsublinknumber">3.5<tt> </tt></span><a href="#(part._begin-for-syntax)" class="tocsubseclink" pltdoc="x"><span class="RktSym"><span class="RktStxLink">begin-<wbr></wbr>for-<wbr></wbr>syntax</span></span></a></td></tr><tr><td><span class="tocsublinknumber">4<tt> </tt></span><a href="#(part._.Pattern_matching__syntax-case_and_syntax-rules)" class="tocsubseclink" pltdoc="x">Pattern matching:<span class="mywbr"> </span> syntax-<wbr></wbr>case and syntax-<wbr></wbr>rules</a></td></tr><tr><td><span class="tocsublinknumber">4.1<tt> </tt></span><a href="#(part._.Pattern_variable_vs__template---fight_)" class="tocsubseclink" pltdoc="x">Pattern variable vs. template—<wbr></wbr>fight!</a></td></tr><tr><td><span class="tocsublinknumber">4.1.1<tt> </tt></span><a href="#(part._with-syntax)" class="tocsubseclink" pltdoc="x"><span class="RktSym"><span class="RktStxLink">with-<wbr></wbr>syntax</span></span></a></td></tr><tr><td><span class="tocsublinknumber">4.1.2<tt> </tt></span><a href="#(part._format-id)" class="tocsubseclink" pltdoc="x"><span class="RktSym">format-<wbr></wbr>id</span></a></td></tr><tr><td><span class="tocsublinknumber">4.1.3<tt> </tt></span><a href="#(part._.Another_example)" class="tocsubseclink" pltdoc="x">Another example</a></td></tr><tr><td><span class="tocsublinknumber">4.2<tt> </tt></span><a href="#(part._.Making_our_own_struct)" class="tocsubseclink" pltdoc="x">Making our own <span class="RktSym"><span class="RktStxLink">struct</span></span></a></td></tr><tr><td><span class="tocsublinknumber">4.3<tt> </tt></span><a href="#(part._hash..refs)" class="tocsubseclink" pltdoc="x">Using dot notation for nested hash lookups</a></td></tr><tr><td><span class="tocsublinknumber">5<tt> </tt></span><a href="#(part._.Syntax_parameters)" class="tocsubseclink" pltdoc="x">Syntax parameters</a></td></tr><tr><td><span class="tocsublinknumber">6<tt> </tt></span><a href="#(part._.What_s_the_point_of_splicing-let_)" class="tocsubseclink" pltdoc="x">What’s the point of <span class="RktSym"><span class="RktStxLink">splicing-<wbr></wbr>let</span></span>?</a></td></tr><tr><td><span class="tocsublinknumber">7<tt> </tt></span><a href="#(part._.Robust_macros__syntax-parse)" class="tocsubseclink" pltdoc="x">Robust macros:<span class="mywbr"> </span> syntax-<wbr></wbr>parse</a></td></tr><tr><td><span class="tocsublinknumber">7.1<tt> </tt></span><a href="#(part._.Error-handling_strategies_for_functions)" class="tocsubseclink" pltdoc="x">Error-<wbr></wbr>handling strategies for functions</a></td></tr><tr><td><span class="tocsublinknumber">7.2<tt> </tt></span><a href="#(part._.Error-handling_strategies_for_macros)" class="tocsubseclink" pltdoc="x">Error-<wbr></wbr>handling strategies for macros</a></td></tr><tr><td><span class="tocsublinknumber">7.3<tt> </tt></span><a href="#(part._.Using_syntax_parse)" class="tocsubseclink" pltdoc="x">Using <span class="RktSym">syntax/<span class="mywbr"> </span>parse</span></a></td></tr><tr><td><span class="tocsublinknumber">8<tt> </tt></span><a href="#(part._.References_and_.Acknowledgments)" class="tocsubseclink" pltdoc="x">References and Acknowledgments</a></td></tr><tr><td><span class="tocsublinknumber">9<tt> </tt></span><a href="#(part._.Epilogue)" class="tocsubseclink" pltdoc="x">Epilogue</a></td></tr></table></div></div><div class="maincolumn"><div class="main"><h2><a name="(part._.Fear_of_.Macros)"></a>Fear of Macros</h2><div class="SAuthorListBox"><span class="SAuthorList"><p class="author"><a href="http://www.greghendershott.com">Greg Hendershott</a></p></span></div><p><div class="SIntrapara"></div><div class="SIntrapara"><img src="fear-of-macros.jpg" alt="" />
+</div><div class="SIntrapara"><span class="Smaller">Copyright (c) 2012 by Greg Hendershott. All rights reserved.</span></div><div class="SIntrapara"><span class="Smaller">Last updated 2012-11-12 19:48:10</span></div><div class="SIntrapara">Feedback and corrections are <a href="https://github.com/greghendershott/fear-of-macros/issues">welcome here</a>.</div></p><p>Contents:</p><table cellspacing="0"><tr><td><p><span class="hspace"> </span><a href="#(part._.Preface)" class="toptoclink" pltdoc="x">1<span class="hspace"> </span>Preface</a></p></td></tr><tr><td><p><span class="hspace"></span></p></td></tr><tr><td><p><span class="hspace"> </span><a href="#(part._.Our_plan_of_attack)" class="toptoclink" pltdoc="x">2<span class="hspace"> </span>Our plan of attack</a></p></td></tr><tr><td><p><span class="hspace"></span></p></td></tr><tr><td><p><span class="hspace"> </span><a href="#(part._.Transform_)" class="toptoclink" pltdoc="x">3<span class="hspace"> </span>Transform!</a></p></td></tr><tr><td><p><span class="hspace"> </span><a href="#(part._.What_is_a_syntax_transformer_)" class="toclink" pltdoc="x">3.1<span class="hspace"> </span>What is a syntax transformer?</a></p></td></tr><tr><td><p><span class="hspace"> </span><a href="#(part._.What_s_the_input_)" class="toclink" pltdoc="x">3.2<span class="hspace"> </span>What’s the input?</a></p></td></tr><tr><td><p><span class="hspace"> </span><a href="#(part._.Actually_transforming_the_input)" class="toclink" pltdoc="x">3.3<span class="hspace"> </span>Actually transforming the input</a></p></td></tr><tr><td><p><span class="hspace"> </span><a href="#(part._.Compile_time_vs__run_time)" class="toclink" pltdoc="x">3.4<span class="hspace"> </span>Compile time vs. run time</a></p></td></tr><tr><td><p><span class="hspace"> </span><a href="#(part._begin-for-syntax)" class="toclink" pltdoc="x">3.5<span class="hspace"> </span><span class="RktSym"><span class="RktStxLink">begin-for-syntax</span></span></a></p></td></tr><tr><td><p><span class="hspace"></span></p></td></tr><tr><td><p><span class="hspace"> </span><a href="#(part._.Pattern_matching__syntax-case_and_syntax-rules)" class="toptoclink" pltdoc="x">4<span class="hspace"> </span>Pattern matching: syntax-case and syntax-rules</a></p></td></tr><tr><td><p><span class="hspace"> </span><a href="#(part._.Pattern_variable_vs__template---fight_)" class="toclink" pltdoc="x">4.1<span class="hspace"> </span>Pattern variable vs. template—<wbr></wbr>fight!</a></p></td></tr><tr><td><p><span class="hspace"> </span><a href="#(part._with-syntax)" class="toclink" pltdoc="x">4.1.1<span class="hspace"> </span><span class="RktSym"><span class="RktStxLink">with-syntax</span></span></a></p></td></tr><tr><td><p><span class="hspace"> </span><a href="#(part._format-id)" class="toclink" pltdoc="x">4.1.2<span class="hspace"> </span><span class="RktSym">format-id</span></a></p></td></tr><tr><td><p><span class="hspace"> </span><a href="#(part._.Another_example)" class="toclink" pltdoc="x">4.1.3<span class="hspace"> </span>Another example</a></p></td></tr><tr><td><p><span class="hspace"> </span><a href="#(part._.Making_our_own_struct)" class="toclink" pltdoc="x">4.2<span class="hspace"> </span>Making our own <span class="RktSym"><span class="RktStxLink">struct</span></span></a></p></td></tr><tr><td><p><span class="hspace"> </span><a href="#(part._hash..refs)" class="toclink" pltdoc="x">4.3<span class="hspace"> </span>Using dot notation for nested hash lookups</a></p></td></tr><tr><td><p><span class="hspace"></span></p></td></tr><tr><td><p><span class="hspace"> </span><a href="#(part._.Syntax_parameters)" class="toptoclink" pltdoc="x">5<span class="hspace"> </span>Syntax parameters</a></p></td></tr><tr><td><p><span class="hspace"></span></p></td></tr><tr><td><p><span class="hspace"> </span><a href="#(part._.What_s_the_point_of_splicing-let_)" class="toptoclink" pltdoc="x">6<span class="hspace"> </span>What’s the point of <span class="RktSym"><span class="RktStxLink">splicing-let</span></span>?</a></p></td></tr><tr><td><p><span class="hspace"></span></p></td></tr><tr><td><p><span class="hspace"> </span><a href="#(part._.Robust_macros__syntax-parse)" class="toptoclink" pltdoc="x">7<span class="hspace"> </span>Robust macros: syntax-parse</a></p></td></tr><tr><td><p><span class="hspace"> </span><a href="#(part._.Error-handling_strategies_for_functions)" class="toclink" pltdoc="x">7.1<span class="hspace"> </span>Error-handling strategies for functions</a></p></td></tr><tr><td><p><span class="hspace"> </span><a href="#(part._.Error-handling_strategies_for_macros)" class="toclink" pltdoc="x">7.2<span class="hspace"> </span>Error-handling strategies for macros</a></p></td></tr><tr><td><p><span class="hspace"> </span><a href="#(part._.Using_syntax_parse)" class="toclink" pltdoc="x">7.3<span class="hspace"> </span>Using <span class="RktSym">syntax/parse</span></a></p></td></tr><tr><td><p><span class="hspace"></span></p></td></tr><tr><td><p><span class="hspace"> </span><a href="#(part._.References_and_.Acknowledgments)" class="toptoclink" pltdoc="x">8<span class="hspace"> </span>References and Acknowledgments</a></p></td></tr><tr><td><p><span class="hspace"></span></p></td></tr><tr><td><p><span class="hspace"> </span><a href="#(part._.Epilogue)" class="toptoclink" pltdoc="x">9<span class="hspace"> </span>Epilogue</a></p></td></tr></table><h3>1<tt> </tt><a name="(part._.Preface)"></a>Preface</h3><p>I learned Racket after 25 years of mostly using C and C++.</p><p>Some psychic whiplash resulted.</p><p>"All the parentheses" was actually not a big deal. Instead, the first
mind warp was functional programming. Before long I wrapped my brain
around it, and went on to become comfortable and effective with many
other aspects and features of Racket.</p><p>But two final frontiers remained: Macros and continuations.</p><p>I found that simple macros were easy and understandable, plus there
@@ -84,7 +84,7 @@ given:</p><blockquote class="SCodeFlow"><table cellspacing="0" class="RktBlk"><t
list:</p><blockquote class="SCodeFlow"><table cellspacing="0" class="RktBlk"><tr><td><span class="stt">> </span><span class="RktPn">(</span><span class="RktSym"><a href="http://docs.racket-lang.org/reference/stxops.html#(def._((quote._~23~25kernel)._syntax-~3edatum))" class="RktValLink" pltdoc="x">syntax->datum</a></span><span class="hspace"> </span><span class="RktRdr">#'</span><span class="RktPn">(</span><span class="RktSym">reverse-me</span><span class="hspace"> </span><span class="RktVal">"backwards"</span><span class="hspace"> </span><span class="RktVal">"am"</span><span class="hspace"> </span><span class="RktVal">"i"</span><span class="hspace"> </span><span class="RktSym"><a href="http://docs.racket-lang.org/reference/values.html#(def._((quote._~23~25kernel)._values))" class="RktValLink" pltdoc="x">values</a></span><span class="RktPn">)</span><span class="RktPn">)</span></td></tr><tr><td><p><span class="RktRes">'(reverse-me<span class="stt"> </span>"backwards"<span class="stt"> </span>"am"<span class="stt"> </span>"i"<span class="stt"> </span>values)</span></p></td></tr></table></blockquote><p>Using <span class="RktSym"><a href="http://docs.racket-lang.org/reference/pairs.html#(def._((quote._~23~25kernel)._cdr))" class="RktValLink" pltdoc="x">cdr</a></span> slices off the first item of the list,
<span class="RktSym">reverse-me</span>, leaving the remainder:
<span class="RktPn">(</span><span class="RktVal">"backwards"</span><span class="stt"> </span><span class="RktVal">"am"</span><span class="stt"> </span><span class="RktVal">"i"</span><span class="stt"> </span><span class="RktSym"><a href="http://docs.racket-lang.org/reference/values.html#(def._((quote._~23~25kernel)._values))" class="RktValLink" pltdoc="x">values</a></span><span class="RktPn">)</span>. Passing that to
-<span class="RktSym"><a href="http://docs.racket-lang.org/reference/pairs.html#(def._((lib._racket%2Fprivate%2Flist..rkt)._reverse))" class="RktValLink" pltdoc="x">reverse</a></span> changes it to <span class="RktPn">(</span><span class="RktSym"><a href="http://docs.racket-lang.org/reference/values.html#(def._((quote._~23~25kernel)._values))" class="RktValLink" pltdoc="x">values</a></span><span class="stt"> </span><span class="RktVal">"i"</span><span class="stt"> </span><span class="RktVal">"am"</span><span class="stt"> </span><span class="RktVal">"backwards"</span><span class="RktPn">)</span>:</p><blockquote class="SCodeFlow"><table cellspacing="0" class="RktBlk"><tr><td><span class="stt">> </span><span class="RktPn">(</span><span class="RktSym"><a href="http://docs.racket-lang.org/reference/pairs.html#(def._((lib._racket%2Fprivate%2Flist..rkt)._reverse))" class="RktValLink" pltdoc="x">reverse</a></span><span class="hspace"> </span><span class="RktPn">(</span><span class="RktSym"><a href="http://docs.racket-lang.org/reference/pairs.html#(def._((quote._~23~25kernel)._cdr))" class="RktValLink" pltdoc="x">cdr</a></span><span class="hspace"> </span><span class="RktVal">'</span><span class="RktVal">(</span><span class="RktVal">"backwards"</span><span class="hspace"> </span><span class="RktVal">"am"</span><span class="hspace"> </span><span class="RktVal">"i"</span><span class="hspace"> </span><span class="RktVal">values</span><span class="RktVal">)</span><span class="RktPn">)</span><span class="RktPn">)</span></td></tr><tr><td><p><span class="RktRes">'(values<span class="stt"> </span>"i"<span class="stt"> </span>"am")</span></p></td></tr></table></blockquote><p>Finally we use <span class="RktSym"><a href="http://docs.racket-lang.org/reference/stxops.html#(def._((quote._~23~25kernel)._syntax-~3edatum))" class="RktValLink" pltdoc="x">syntax->datum</a></span> to convert this back to
+<span class="RktSym"><a href="http://docs.racket-lang.org/reference/pairs.html#(def._((lib._racket%2Fprivate%2Flist..rkt)._reverse))" class="RktValLink" pltdoc="x">reverse</a></span> changes it to <span class="RktPn">(</span><span class="RktSym"><a href="http://docs.racket-lang.org/reference/values.html#(def._((quote._~23~25kernel)._values))" class="RktValLink" pltdoc="x">values</a></span><span class="stt"> </span><span class="RktVal">"i"</span><span class="stt"> </span><span class="RktVal">"am"</span><span class="stt"> </span><span class="RktVal">"backwards"</span><span class="RktPn">)</span>:</p><blockquote class="SCodeFlow"><table cellspacing="0" class="RktBlk"><tr><td><span class="stt">> </span><span class="RktPn">(</span><span class="RktSym"><a href="http://docs.racket-lang.org/reference/pairs.html#(def._((lib._racket%2Fprivate%2Flist..rkt)._reverse))" class="RktValLink" pltdoc="x">reverse</a></span><span class="hspace"> </span><span class="RktPn">(</span><span class="RktSym"><a href="http://docs.racket-lang.org/reference/pairs.html#(def._((quote._~23~25kernel)._cdr))" class="RktValLink" pltdoc="x">cdr</a></span><span class="hspace"> </span><span class="RktVal">'</span><span class="RktVal">(</span><span class="RktVal">reverse-me</span><span class="hspace"> </span><span class="RktVal">"backwards"</span><span class="hspace"> </span><span class="RktVal">"am"</span><span class="hspace"> </span><span class="RktVal">"i"</span><span class="hspace"> </span><span class="RktVal">values</span><span class="RktVal">)</span><span class="RktPn">)</span><span class="RktPn">)</span></td></tr><tr><td><p><span class="RktRes">'(values<span class="stt"> </span>"i"<span class="stt"> </span>"am"<span class="stt"> </span>"backwards")</span></p></td></tr></table></blockquote><p>Finally we use <span class="RktSym"><a href="http://docs.racket-lang.org/reference/stxops.html#(def._((quote._~23~25kernel)._datum-~3esyntax))" class="RktValLink" pltdoc="x">datum->syntax</a></span> to convert this back to
<span class="RktSym"><a href="http://docs.racket-lang.org/reference/stx-patterns.html#(form._((lib._racket%2Fprivate%2Fstxcase-scheme..rkt)._syntax))" class="RktStxLink" pltdoc="x">syntax</a></span>:</p><blockquote class="SCodeFlow"><table cellspacing="0" class="RktBlk"><tr><td><span class="stt">> </span><span class="RktPn">(</span><span class="RktSym"><a href="http://docs.racket-lang.org/reference/stxops.html#(def._((quote._~23~25kernel)._datum-~3esyntax))" class="RktValLink" pltdoc="x">datum->syntax</a></span><span class="hspace"> </span><span class="RktVal">#f</span><span class="hspace"> </span><span class="RktVal">'</span><span class="RktVal">(</span><span class="RktVal">values</span><span class="hspace"> </span><span class="RktVal">"i"</span><span class="hspace"> </span><span class="RktVal">"am"</span><span class="hspace"> </span><span class="RktVal">"backwards"</span><span class="RktVal">)</span><span class="RktPn">)</span></td></tr><tr><td><p><span class="RktRes">#<syntax (values "i" "am" "backwards")></span></p></td></tr></table></blockquote><p>That’s what our transformer function gives back to the Racket
compiler, and <span style="font-style: italic">that</span> syntax is evaluated:</p><blockquote class="SCodeFlow"><table cellspacing="0" class="RktBlk"><tr><td><span class="stt">> </span><span class="RktPn">(</span><span class="RktSym"><a href="http://docs.racket-lang.org/reference/values.html#(def._((quote._~23~25kernel)._values))" class="RktValLink" pltdoc="x">values</a></span><span class="hspace"> </span><span class="RktVal">"i"</span><span class="hspace"> </span><span class="RktVal">"am"</span><span class="hspace"> </span><span class="RktVal">"backwards"</span><span class="RktPn">)</span></td></tr><tr><td><p><span class="RktRes">"i"</span></p></td></tr><tr><td><p><span class="RktRes">"am"</span></p></td></tr><tr><td><p><span class="RktRes">"backwards"</span></p></td></tr></table></blockquote><h4>3.4<tt> </tt><a name="(part._.Compile_time_vs__run_time)"></a>Compile time vs. run time</h4><p><table cellspacing="0" class="RktBlk"><tr><td><span class="RktPn">(</span><span class="RktSym"><a href="http://docs.racket-lang.org/reference/define.html#(form._((lib._racket%2Fprivate%2Fbase..rkt)._define-syntax))" class="RktStxLink" pltdoc="x">define-syntax</a></span><span class="RktMeta"></span><span class="hspace"> </span><span class="RktMeta"></span><span class="RktPn">(</span><span class="RktSym">foo</span><span class="RktMeta"></span><span class="hspace"> </span><span class="RktMeta"></span><span class="RktSym">stx</span><span class="RktPn">)</span><span class="RktMeta"></span></td></tr><tr><td><span class="RktMeta"></span><span class="hspace"> </span><span class="RktMeta"></span><span class="RktPn">(</span><span class="RktSym"><a href="http://docs.racket-lang.org/reference/pipeports.html#(def._((quote._~23~25kernel)._make-pipe))" class="RktValLink" pltdoc="x">make-pipe</a></span><span class="RktPn">)</span><span class="RktMeta"></span><span class="hspace"> </span><span class="RktMeta"></span><span class="RktCmt">;Ce</span><span class="hspace"> </span><span class="RktCmt">n'est</span><span class="hspace"> </span><span class="RktCmt">pas</span><span class="hspace"> </span><span class="RktCmt">le</span><span class="hspace"> </span><span class="RktCmt">temps</span><span class="hspace"> </span><span class="RktCmt">d'exécution</span><span class="RktMeta"></span></td></tr><tr><td><span class="RktMeta"></span><span class="hspace"> </span><span class="RktMeta"></span><span class="RktSym"><a href="http://docs.racket-lang.org/reference/stx-patterns.html#(form._((lib._racket%2Fprivate%2Fstxcase-scheme..rkt)._syntax))" class="RktStxLink" pltdoc="x">#'</a></span><span class="RktPn">(</span><span class="RktSym"><a href="http://docs.racket-lang.org/reference/void.html#(def._((quote._~23~25kernel)._void))" class="RktValLink" pltdoc="x">void</a></span><span class="RktPn">)</span><span class="RktPn">)</span><span class="RktMeta"></span></td></tr></table></p><p>Normal Racket code runs at ... run time. Duh.</p><blockquote class="refpara"><blockquote class="refcolumn"><blockquote class="refcontent"><p>Instead of "compile time vs. run time", you may hear it
described as "syntax phase vs. runtime phase". Same difference.</p></blockquote></blockquote></blockquote><p>But a syntax transformer is called by Racket as part of the process of
@@ -223,8 +223,8 @@ mysterious.</p><h5>4.1.2<tt> </tt><a name="(part._format-id)"></a><span cla
succinctly. As we’ve learned, we need to <span class="RktSym"><a href="http://docs.racket-lang.org/reference/require.html#(form._((lib._racket%2Fprivate%2Fbase..rkt)._require))" class="RktStxLink" pltdoc="x">require</a></span> the module
using <span class="RktSym"><a href="http://docs.racket-lang.org/reference/require.html#(form._((lib._racket%2Fprivate%2Fbase..rkt)._for-syntax))" class="RktStxLink" pltdoc="x">for-syntax</a></span>, since we need it at compile time:</p><blockquote class="SCodeFlow"><table cellspacing="0" class="RktBlk"><tr><td><span class="stt">> </span><span class="RktPn">(</span><span class="RktSym"><a href="http://docs.racket-lang.org/reference/require.html#(form._((lib._racket%2Fprivate%2Fbase..rkt)._require))" class="RktStxLink" pltdoc="x">require</a></span><span class="hspace"> </span><span class="RktPn">(</span><span class="RktSym"><a href="http://docs.racket-lang.org/reference/require.html#(form._((lib._racket%2Fprivate%2Fbase..rkt)._for-syntax))" class="RktStxLink" pltdoc="x">for-syntax</a></span><span class="hspace"> </span><span class="RktSym">racket/syntax</span><span class="RktPn">)</span><span class="RktPn">)</span></td></tr><tr><td><table cellspacing="0" class="RktBlk"><tr><td><span class="stt">> </span><span class="RktPn">(</span><span class="RktSym"><a href="http://docs.racket-lang.org/reference/define.html#(form._((lib._racket%2Fprivate%2Fbase..rkt)._define-syntax))" class="RktStxLink" pltdoc="x">define-syntax</a></span><span class="hspace"> </span><span class="RktPn">(</span><span class="RktSym">hyphen-define/ok3</span><span class="hspace"> </span><span class="RktSym">stx</span><span class="RktPn">)</span></td></tr><tr><td><span class="RktPlain"><span class="hspace"> </span></span><span class="hspace"> </span><span class="RktPn">(</span><span class="RktSym"><a href="http://docs.racket-lang.org/reference/stx-patterns.html#(form._((lib._racket%2Fprivate%2Fstxcase-scheme..rkt)._syntax-case))" class="RktStxLink" pltdoc="x">syntax-case</a></span><span class="hspace"> </span><span class="RktSym">stx</span><span class="hspace"> </span><span class="RktPn">(</span><span class="RktPn">)</span></td></tr><tr><td><span class="RktPlain"><span class="hspace"> </span></span><span class="hspace"> </span><span class="RktPn">[</span><span class="RktPn">(</span><span class="RktSym"><a href="http://docs.racket-lang.org/reference/stx-patterns.html#(form._((lib._racket%2Fprivate%2Fstxcase-scheme..rkt).__))" class="RktStxLink" pltdoc="x">_</a></span><span class="hspace"> </span><span class="RktSym">a</span><span class="hspace"> </span><span class="RktSym">b</span><span class="hspace"> </span><span class="RktPn">(</span><span class="RktSym">args</span><span class="hspace"> </span><span class="RktSym"><a href="http://docs.racket-lang.org/reference/stx-patterns.html#(form._((lib._racket%2Fprivate%2Fstxcase-scheme..rkt)._......))" class="RktStxLink" pltdoc="x">...</a></span><span class="RktPn">)</span><span class="hspace"> </span><span class="RktSym">body0</span><span class="hspace"> </span><span class="RktSym">body</span><span class="hspace"> </span><span class="RktSym"><a href="http://docs.racket-lang.org/reference/stx-patterns.html#(form._((lib._racket%2Fprivate%2Fstxcase-scheme..rkt)._......))" class="RktStxLink" pltdoc="x">...</a></span><span class="RktPn">)</span></td></tr><tr><td><span class="RktPlain"><span class="hspace"> </span></span><span class="hspace"> </span><span class="RktPn">(</span><span class="RktSym"><a href="http://docs.racket-lang.org/reference/stx-patterns.html#(form._((lib._racket%2Fprivate%2Fstxcase-scheme..rkt)._with-syntax))" class="RktStxLink" pltdoc="x">with-syntax</a></span><span class="hspace"> </span><span class="RktPn">(</span><span class="RktPn">[</span><span class="RktSym">name</span><span class="hspace"> </span><span class="RktPn">(</span><span class="RktSym">format-id</span><span class="hspace"> </span><span class="RktSym">stx</span><span class="hspace"> </span><span class="RktVal">"~a-~a"</span><span class="hspace"> </span><span class="RktRdr">#'</span><span class="RktSym">a</span><span class="hspace"> </span><span class="RktRdr">#'</span><span class="RktSym">b</span><span class="RktPn">)</span><span class="RktPn">]</span><span class="RktPn">)</span></td></tr><tr><td><span class="RktPlain"><span class="hspace"> </span></span><span class="hspace"> </span><span class="RktRdr">#'</span><span class="RktPn">(</span><span class="RktSym"><a href="http://docs.racket-lang.org/reference/define.html#(form._((lib._racket%2Fprivate%2Fbase..rkt)._define))" class="RktStxLink" pltdoc="x">define</a></span><span class="hspace"> </span><span class="RktPn">(</span><span class="RktSym">name</span><span class="hspace"> </span><span class="RktSym">args</span><span class="hspace"> </span><span class="RktSym"><a href="http://docs.racket-lang.org/reference/stx-patterns.html#(form._((lib._racket%2Fprivate%2Fstxcase-scheme..rkt)._......))" class="RktStxLink" pltdoc="x">...</a></span><span class="RktPn">)</span></td></tr><tr><td><span class="RktPlain"><span class="hspace"> </span></span><span class="hspace"> </span><span class="RktSym">body0</span><span class="hspace"> </span><span class="RktSym">body</span><span class="hspace"> </span><span class="RktSym"><a href="http://docs.racket-lang.org/reference/stx-patterns.html#(form._((lib._racket%2Fprivate%2Fstxcase-scheme..rkt)._......))" class="RktStxLink" pltdoc="x">...</a></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><span class="stt">> </span><span class="RktPn">(</span><span class="RktSym">hyphen-define/ok3</span><span class="hspace"> </span><span class="RktSym">bar</span><span class="hspace"> </span><span class="RktSym">baz</span><span class="hspace"> </span><span class="RktPn">(</span><span class="RktPn">)</span><span class="hspace"> </span><span class="RktVal">#t</span><span class="RktPn">)</span></td></tr><tr><td><span class="stt">> </span><span class="RktPn">(</span><span class="RktSym">bar-baz</span><span class="RktPn">)</span></td></tr><tr><td><p><span class="RktRes">#t</span></p></td></tr></table></blockquote><p>Using <span class="RktSym">format-id</span> is convenient as it handles the tedium of
converting from syntax to symbol datum to string ... and all the way
-back.</p><p>Finally, here’s a variation that accepts any number of name parts that
-are joined with hyphens:</p><blockquote class="SCodeFlow"><table cellspacing="0" class="RktBlk"><tr><td><span class="stt">> </span><span class="RktPn">(</span><span class="RktSym"><a href="http://docs.racket-lang.org/reference/require.html#(form._((lib._racket%2Fprivate%2Fbase..rkt)._require))" class="RktStxLink" pltdoc="x">require</a></span><span class="hspace"> </span><span class="RktPn">(</span><span class="RktSym"><a href="http://docs.racket-lang.org/reference/require.html#(form._((lib._racket%2Fprivate%2Fbase..rkt)._for-syntax))" class="RktStxLink" pltdoc="x">for-syntax</a></span><span class="hspace"> </span><span class="RktSym">racket/string</span><span class="hspace"> </span><span class="RktSym">racket/syntax</span><span class="RktPn">)</span><span class="RktPn">)</span></td></tr><tr><td><table cellspacing="0" class="RktBlk"><tr><td><span class="stt">> </span><span class="RktPn">(</span><span class="RktSym"><a href="http://docs.racket-lang.org/reference/define.html#(form._((lib._racket%2Fprivate%2Fbase..rkt)._define-syntax))" class="RktStxLink" pltdoc="x">define-syntax</a></span><span class="hspace"> </span><span class="RktPn">(</span><span class="RktSym">hyphen-define*</span><span class="hspace"> </span><span class="RktSym">stx</span><span class="RktPn">)</span></td></tr><tr><td><span class="RktPlain"><span class="hspace"> </span></span><span class="hspace"> </span><span class="RktPn">(</span><span class="RktSym"><a href="http://docs.racket-lang.org/reference/stx-patterns.html#(form._((lib._racket%2Fprivate%2Fstxcase-scheme..rkt)._syntax-case))" class="RktStxLink" pltdoc="x">syntax-case</a></span><span class="hspace"> </span><span class="RktSym">stx</span><span class="hspace"> </span><span class="RktPn">(</span><span class="RktPn">)</span></td></tr><tr><td><span class="RktPlain"><span class="hspace"> </span></span><span class="hspace"> </span><span class="RktPn">[</span><span class="RktPn">(</span><span class="RktSym"><a href="http://docs.racket-lang.org/reference/stx-patterns.html#(form._((lib._racket%2Fprivate%2Fstxcase-scheme..rkt).__))" class="RktStxLink" pltdoc="x">_</a></span><span class="hspace"> </span><span class="RktPn">(</span><span class="RktSym">names</span><span class="hspace"> </span><span class="RktSym"><a href="http://docs.racket-lang.org/reference/stx-patterns.html#(form._((lib._racket%2Fprivate%2Fstxcase-scheme..rkt)._......))" class="RktStxLink" pltdoc="x">...</a></span><span class="RktPn">)</span><span class="hspace"> </span><span class="RktPn">(</span><span class="RktSym">args</span><span class="hspace"> </span><span class="RktSym"><a href="http://docs.racket-lang.org/reference/stx-patterns.html#(form._((lib._racket%2Fprivate%2Fstxcase-scheme..rkt)._......))" class="RktStxLink" pltdoc="x">...</a></span><span class="RktPn">)</span><span class="hspace"> </span><span class="RktSym">body0</span><span class="hspace"> </span><span class="RktSym">body</span><span class="hspace"> </span><span class="RktSym"><a href="http://docs.racket-lang.org/reference/stx-patterns.html#(form._((lib._racket%2Fprivate%2Fstxcase-scheme..rkt)._......))" class="RktStxLink" pltdoc="x">...</a></span><span class="RktPn">)</span></td></tr><tr><td><span class="RktPlain"><span class="hspace"> </span></span><span class="hspace"> </span><span class="RktPn">(</span><span class="RktSym"><a href="http://docs.racket-lang.org/reference/let.html#(form._((lib._racket%2Fprivate%2Fletstx-scheme..rkt)._let*))" class="RktStxLink" pltdoc="x">let*</a></span><span class="hspace"> </span><span class="RktPn">(</span><span class="RktPn">[</span><span class="RktSym">names/sym</span><span class="hspace"> </span><span class="RktPn">(</span><span class="RktSym"><a href="http://docs.racket-lang.org/reference/pairs.html#(def._((lib._racket%2Fprivate%2Fmap..rkt)._map))" class="RktValLink" pltdoc="x">map</a></span><span class="hspace"> </span><span class="RktSym"><a href="http://docs.racket-lang.org/reference/stxops.html#(def._((quote._~23~25kernel)._syntax-e))" class="RktValLink" pltdoc="x">syntax-e</a></span><span class="hspace"> </span><span class="RktPn">(</span><span class="RktSym"><a href="http://docs.racket-lang.org/reference/stxops.html#(def._((quote._~23~25kernel)._syntax-~3elist))" class="RktValLink" pltdoc="x">syntax->list</a></span><span class="hspace"> </span><span class="RktRdr">#'</span><span class="RktPn">(</span><span class="RktSym">names</span><span class="hspace"> </span><span class="RktSym"><a href="http://docs.racket-lang.org/reference/stx-patterns.html#(form._((lib._racket%2Fprivate%2Fstxcase-scheme..rkt)._......))" class="RktStxLink" pltdoc="x">...</a></span><span class="RktPn">)</span><span class="RktPn">)</span><span class="RktPn">)</span><span class="RktPn">]</span></td></tr><tr><td><span class="RktPlain"><span class="hspace"> </span></span><span class="hspace"> </span><span class="RktPn">[</span><span class="RktSym">names/str</span><span class="hspace"> </span><span class="RktPn">(</span><span class="RktSym"><a href="http://docs.racket-lang.org/reference/pairs.html#(def._((lib._racket%2Fprivate%2Fmap..rkt)._map))" class="RktValLink" pltdoc="x">map</a></span><span class="hspace"> </span><span class="RktSym"><a href="http://docs.racket-lang.org/reference/symbols.html#(def._((quote._~23~25kernel)._symbol-~3estring))" class="RktValLink" pltdoc="x">symbol->string</a></span><span class="hspace"> </span><span class="RktSym">names/sym</span><span class="RktPn">)</span><span class="RktPn">]</span></td></tr><tr><td><span class="RktPlain"><span class="hspace"> </span></span><span class="hspace"> </span><span class="RktPn">[</span><span class="RktSym">name/str</span><span class="hspace"> </span><span class="RktPn">(</span><span class="RktSym"><a href="http://docs.racket-lang.org/reference/strings.html#(def._((lib._racket%2Fstring..rkt)._string-join))" class="RktValLink" pltdoc="x">string-join</a></span><span class="hspace"> </span><span class="RktSym">names/str</span><span class="hspace"> </span><span class="RktVal">"-"</span><span class="RktPn">)</span><span class="RktPn">]</span></td></tr><tr><td><span class="RktPlain"><span class="hspace"> </span></span><span class="hspace"> </span><span class="RktPn">[</span><span class="RktSym">name/sym</span><span class="hspace"> </span><span class="RktPn">(</span><span class="RktSym"><a href="http://docs.racket-lang.org/reference/symbols.html#(def._((quote._~23~25kernel)._string-~3esymbol))" class="RktValLink" pltdoc="x">string->symbol</a></span><span class="hspace"> </span><span class="RktSym">name/str</span><span class="RktPn">)</span><span class="RktPn">]</span><span class="RktPn">)</span></td></tr><tr><td><span class="RktPlain"><span class="hspace"> </span></span><span class="hspace"> </span><span class="RktPn">(</span><span class="RktSym"><a href="http://docs.racket-lang.org/reference/stx-patterns.html#(form._((lib._racket%2Fprivate%2Fstxcase-scheme..rkt)._with-syntax))" class="RktStxLink" pltdoc="x">with-syntax</a></span><span class="hspace"> </span><span class="RktPn">(</span><span class="RktPn">[</span><span class="RktSym">name</span><span class="hspace"> </span><span class="RktPn">(</span><span class="RktSym"><a href="http://docs.racket-lang.org/reference/stxops.html#(def._((quote._~23~25kernel)._datum-~3esyntax))" class="RktValLink" pltdoc="x">datum->syntax</a></span><span class="hspace"> </span><span class="RktSym">stx</span><span class="hspace"> </span><span class="RktSym">name/sym</span><span class="RktPn">)</span><span class="RktPn">]</span><span class="RktPn">)</span></td></tr><tr><td><span class="RktPlain"><span class="hspace"> </span></span><span class="hspace"> </span><span class="RktRdr">#`</span><span class="RktPn">(</span><span class="RktSym"><a href="http://docs.racket-lang.org/reference/define.html#(form._((lib._racket%2Fprivate%2Fbase..rkt)._define))" class="RktStxLink" pltdoc="x">define</a></span><span class="hspace"> </span><span class="RktPn">(</span><span class="RktSym">name</span><span class="hspace"> </span><span class="RktSym">args</span><span class="hspace"> </span><span class="RktSym"><a href="http://docs.racket-lang.org/reference/stx-patterns.html#(form._((lib._racket%2Fprivate%2Fstxcase-scheme..rkt)._......))" class="RktStxLink" pltdoc="x">...</a></span><span class="RktPn">)</span></td></tr><tr><td><span class="RktPlain"><span class="hspace"> </span></span><span class="hspace"> </span><span class="RktSym">body0</span><span class="hspace"> </span><span class="RktSym">body</span><span class="hspace"> </span><span class="RktSym"><a href="http://docs.racket-lang.org/reference/stx-patterns.html#(form._((lib._racket%2Fprivate%2Fstxcase-scheme..rkt)._......))" class="RktStxLink" pltdoc="x">...</a></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><span class="stt">> </span><span class="RktPn">(</span><span class="RktSym">hyphen-define*</span><span class="hspace"> </span><span class="RktPn">(</span><span class="RktSym">foo</span><span class="hspace"> </span><span class="RktSym">bar</span><span class="hspace"> </span><span class="RktSym">baz</span><span class="RktPn">)</span><span class="hspace"> </span><span class="RktPn">(</span><span class="RktSym">v</span><span class="RktPn">)</span><span class="hspace"> </span><span class="RktPn">(</span><span class="RktSym"><a href="http://docs.racket-lang.org/reference/generic-numbers.html#(def._((quote._~23~25kernel)._*))" class="RktValLink" pltdoc="x">*</a></span><span class="hspace"> </span><span class="RktVal">2</span><span class="hspace"> </span><span class="RktSym">v</span><span class="RktPn">)</span><span class="RktPn">)</span></td></tr><tr><td><span class="stt">> </span><span class="RktPn">(</span><span class="RktSym">foo-bar-baz</span><span class="hspace"> </span><span class="RktVal">50</span><span class="RktPn">)</span></td></tr><tr><td><p><span class="RktRes">100</span></p></td></tr></table></blockquote><p>To review:</p><ul><li><p>You can’t use a pattern variable outside of a template. But
+back.</p><h5>4.1.3<tt> </tt><a name="(part._.Another_example)"></a>Another example</h5><p>Finally, here’s a variation that accepts an arbitary number of name
+parts to be joined with hyphens:</p><blockquote class="SCodeFlow"><table cellspacing="0" class="RktBlk"><tr><td><span class="stt">> </span><span class="RktPn">(</span><span class="RktSym"><a href="http://docs.racket-lang.org/reference/require.html#(form._((lib._racket%2Fprivate%2Fbase..rkt)._require))" class="RktStxLink" pltdoc="x">require</a></span><span class="hspace"> </span><span class="RktPn">(</span><span class="RktSym"><a href="http://docs.racket-lang.org/reference/require.html#(form._((lib._racket%2Fprivate%2Fbase..rkt)._for-syntax))" class="RktStxLink" pltdoc="x">for-syntax</a></span><span class="hspace"> </span><span class="RktSym">racket/string</span><span class="hspace"> </span><span class="RktSym">racket/syntax</span><span class="RktPn">)</span><span class="RktPn">)</span></td></tr><tr><td><table cellspacing="0" class="RktBlk"><tr><td><span class="stt">> </span><span class="RktPn">(</span><span class="RktSym"><a href="http://docs.racket-lang.org/reference/define.html#(form._((lib._racket%2Fprivate%2Fbase..rkt)._define-syntax))" class="RktStxLink" pltdoc="x">define-syntax</a></span><span class="hspace"> </span><span class="RktPn">(</span><span class="RktSym">hyphen-define*</span><span class="hspace"> </span><span class="RktSym">stx</span><span class="RktPn">)</span></td></tr><tr><td><span class="RktPlain"><span class="hspace"> </span></span><span class="hspace"> </span><span class="RktPn">(</span><span class="RktSym"><a href="http://docs.racket-lang.org/reference/stx-patterns.html#(form._((lib._racket%2Fprivate%2Fstxcase-scheme..rkt)._syntax-case))" class="RktStxLink" pltdoc="x">syntax-case</a></span><span class="hspace"> </span><span class="RktSym">stx</span><span class="hspace"> </span><span class="RktPn">(</span><span class="RktPn">)</span></td></tr><tr><td><span class="RktPlain"><span class="hspace"> </span></span><span class="hspace"> </span><span class="RktPn">[</span><span class="RktPn">(</span><span class="RktSym"><a href="http://docs.racket-lang.org/reference/stx-patterns.html#(form._((lib._racket%2Fprivate%2Fstxcase-scheme..rkt).__))" class="RktStxLink" pltdoc="x">_</a></span><span class="hspace"> </span><span class="RktPn">(</span><span class="RktSym">names</span><span class="hspace"> </span><span class="RktSym"><a href="http://docs.racket-lang.org/reference/stx-patterns.html#(form._((lib._racket%2Fprivate%2Fstxcase-scheme..rkt)._......))" class="RktStxLink" pltdoc="x">...</a></span><span class="RktPn">)</span><span class="hspace"> </span><span class="RktPn">(</span><span class="RktSym">args</span><span class="hspace"> </span><span class="RktSym"><a href="http://docs.racket-lang.org/reference/stx-patterns.html#(form._((lib._racket%2Fprivate%2Fstxcase-scheme..rkt)._......))" class="RktStxLink" pltdoc="x">...</a></span><span class="RktPn">)</span><span class="hspace"> </span><span class="RktSym">body0</span><span class="hspace"> </span><span class="RktSym">body</span><span class="hspace"> </span><span class="RktSym"><a href="http://docs.racket-lang.org/reference/stx-patterns.html#(form._((lib._racket%2Fprivate%2Fstxcase-scheme..rkt)._......))" class="RktStxLink" pltdoc="x">...</a></span><span class="RktPn">)</span></td></tr><tr><td><span class="RktPlain"><span class="hspace"> </span></span><span class="hspace"> </span><span class="RktPn">(</span><span class="RktSym"><a href="http://docs.racket-lang.org/reference/let.html#(form._((lib._racket%2Fprivate%2Fletstx-scheme..rkt)._let*))" class="RktStxLink" pltdoc="x">let*</a></span><span class="hspace"> </span><span class="RktPn">(</span><span class="RktPn">[</span><span class="RktSym">names/sym</span><span class="hspace"> </span><span class="RktPn">(</span><span class="RktSym"><a href="http://docs.racket-lang.org/reference/pairs.html#(def._((lib._racket%2Fprivate%2Fmap..rkt)._map))" class="RktValLink" pltdoc="x">map</a></span><span class="hspace"> </span><span class="RktSym"><a href="http://docs.racket-lang.org/reference/stxops.html#(def._((quote._~23~25kernel)._syntax-e))" class="RktValLink" pltdoc="x">syntax-e</a></span><span class="hspace"> </span><span class="RktPn">(</span><span class="RktSym"><a href="http://docs.racket-lang.org/reference/stxops.html#(def._((quote._~23~25kernel)._syntax-~3elist))" class="RktValLink" pltdoc="x">syntax->list</a></span><span class="hspace"> </span><span class="RktRdr">#'</span><span class="RktPn">(</span><span class="RktSym">names</span><span class="hspace"> </span><span class="RktSym"><a href="http://docs.racket-lang.org/reference/stx-patterns.html#(form._((lib._racket%2Fprivate%2Fstxcase-scheme..rkt)._......))" class="RktStxLink" pltdoc="x">...</a></span><span class="RktPn">)</span><span class="RktPn">)</span><span class="RktPn">)</span><span class="RktPn">]</span></td></tr><tr><td><span class="RktPlain"><span class="hspace"> </span></span><span class="hspace"> </span><span class="RktPn">[</span><span class="RktSym">names/str</span><span class="hspace"> </span><span class="RktPn">(</span><span class="RktSym"><a href="http://docs.racket-lang.org/reference/pairs.html#(def._((lib._racket%2Fprivate%2Fmap..rkt)._map))" class="RktValLink" pltdoc="x">map</a></span><span class="hspace"> </span><span class="RktSym"><a href="http://docs.racket-lang.org/reference/symbols.html#(def._((quote._~23~25kernel)._symbol-~3estring))" class="RktValLink" pltdoc="x">symbol->string</a></span><span class="hspace"> </span><span class="RktSym">names/sym</span><span class="RktPn">)</span><span class="RktPn">]</span></td></tr><tr><td><span class="RktPlain"><span class="hspace"> </span></span><span class="hspace"> </span><span class="RktPn">[</span><span class="RktSym">name/str</span><span class="hspace"> </span><span class="RktPn">(</span><span class="RktSym"><a href="http://docs.racket-lang.org/reference/strings.html#(def._((lib._racket%2Fstring..rkt)._string-join))" class="RktValLink" pltdoc="x">string-join</a></span><span class="hspace"> </span><span class="RktSym">names/str</span><span class="hspace"> </span><span class="RktVal">"-"</span><span class="RktPn">)</span><span class="RktPn">]</span></td></tr><tr><td><span class="RktPlain"><span class="hspace"> </span></span><span class="hspace"> </span><span class="RktPn">[</span><span class="RktSym">name/sym</span><span class="hspace"> </span><span class="RktPn">(</span><span class="RktSym"><a href="http://docs.racket-lang.org/reference/symbols.html#(def._((quote._~23~25kernel)._string-~3esymbol))" class="RktValLink" pltdoc="x">string->symbol</a></span><span class="hspace"> </span><span class="RktSym">name/str</span><span class="RktPn">)</span><span class="RktPn">]</span><span class="RktPn">)</span></td></tr><tr><td><span class="RktPlain"><span class="hspace"> </span></span><span class="hspace"> </span><span class="RktPn">(</span><span class="RktSym"><a href="http://docs.racket-lang.org/reference/stx-patterns.html#(form._((lib._racket%2Fprivate%2Fstxcase-scheme..rkt)._with-syntax))" class="RktStxLink" pltdoc="x">with-syntax</a></span><span class="hspace"> </span><span class="RktPn">(</span><span class="RktPn">[</span><span class="RktSym">name</span><span class="hspace"> </span><span class="RktPn">(</span><span class="RktSym"><a href="http://docs.racket-lang.org/reference/stxops.html#(def._((quote._~23~25kernel)._datum-~3esyntax))" class="RktValLink" pltdoc="x">datum->syntax</a></span><span class="hspace"> </span><span class="RktSym">stx</span><span class="hspace"> </span><span class="RktSym">name/sym</span><span class="RktPn">)</span><span class="RktPn">]</span><span class="RktPn">)</span></td></tr><tr><td><span class="RktPlain"><span class="hspace"> </span></span><span class="hspace"> </span><span class="RktRdr">#`</span><span class="RktPn">(</span><span class="RktSym"><a href="http://docs.racket-lang.org/reference/define.html#(form._((lib._racket%2Fprivate%2Fbase..rkt)._define))" class="RktStxLink" pltdoc="x">define</a></span><span class="hspace"> </span><span class="RktPn">(</span><span class="RktSym">name</span><span class="hspace"> </span><span class="RktSym">args</span><span class="hspace"> </span><span class="RktSym"><a href="http://docs.racket-lang.org/reference/stx-patterns.html#(form._((lib._racket%2Fprivate%2Fstxcase-scheme..rkt)._......))" class="RktStxLink" pltdoc="x">...</a></span><span class="RktPn">)</span></td></tr><tr><td><span class="RktPlain"><span class="hspace"> </span></span><span class="hspace"> </span><span class="RktSym">body0</span><span class="hspace"> </span><span class="RktSym">body</span><span class="hspace"> </span><span class="RktSym"><a href="http://docs.racket-lang.org/reference/stx-patterns.html#(form._((lib._racket%2Fprivate%2Fstxcase-scheme..rkt)._......))" class="RktStxLink" pltdoc="x">...</a></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><span class="stt">> </span><span class="RktPn">(</span><span class="RktSym">hyphen-define*</span><span class="hspace"> </span><span class="RktPn">(</span><span class="RktSym">foo</span><span class="hspace"> </span><span class="RktSym">bar</span><span class="hspace"> </span><span class="RktSym">baz</span><span class="RktPn">)</span><span class="hspace"> </span><span class="RktPn">(</span><span class="RktSym">v</span><span class="RktPn">)</span><span class="hspace"> </span><span class="RktPn">(</span><span class="RktSym"><a href="http://docs.racket-lang.org/reference/generic-numbers.html#(def._((quote._~23~25kernel)._*))" class="RktValLink" pltdoc="x">*</a></span><span class="hspace"> </span><span class="RktVal">2</span><span class="hspace"> </span><span class="RktSym">v</span><span class="RktPn">)</span><span class="RktPn">)</span></td></tr><tr><td><span class="stt">> </span><span class="RktPn">(</span><span class="RktSym">foo-bar-baz</span><span class="hspace"> </span><span class="RktVal">50</span><span class="RktPn">)</span></td></tr><tr><td><p><span class="RktRes">100</span></p></td></tr></table></blockquote><p>To review:</p><ul><li><p>You can’t use a pattern variable outside of a template. But
you can use <span class="RktSym"><a href="http://docs.racket-lang.org/reference/stx-patterns.html#(form._((lib._racket%2Fprivate%2Fstxcase-scheme..rkt)._syntax))" class="RktStxLink" pltdoc="x">syntax</a></span> or <span class="stt">#</span><span class="stt">’</span><span class="stt"></span> on a pattern variable to make
an ad hoc, "fun size" template.</p></li><li><p>If you want to munge pattern variables for use in the
template, <span class="RktSym"><a href="http://docs.racket-lang.org/reference/stx-patterns.html#(form._((lib._racket%2Fprivate%2Fstxcase-scheme..rkt)._with-syntax))" class="RktStxLink" pltdoc="x">with-syntax</a></span> is your friend, because it lets you
@@ -343,7 +343,8 @@ early draft and encouraged me to keep going. Sam Tobin-Hochstadt and
Robby Findler also encouraged me. Matthew Flatt showed me how to make
a Scribble <span class="RktSym">interaction</span> print <span class="RktSym"><a href="http://docs.racket-lang.org/reference/stx-patterns.html#(form._((lib._racket%2Fprivate%2Fstxcase-scheme..rkt)._syntax))" class="RktStxLink" pltdoc="x">syntax</a></span> as
<span class="RktVal">"syntax"</span> rather than as <span class="RktVal">"#'"</span>. Jay McCarthy helped me
-catch some mistakes and confusions.</p><p>Finally, I noticed something strange. After writing much of this, when
+catch some mistakes and confusions. Jon Rafkind pointed out some
+problems. Kieron Hardy reported a font issue and some typos.</p><p>Finally, I noticed something strange. After writing much of this, when
I returned to some parts of the Racket documentation, I noticed it had
improved since I last read it. Of course, it was the same. I’d
changed. It’s interesting how much of what we already know is
