Some read­ers of this book will remem­ber the pro­gram­ming land­scape around 1993, but oth­ers will be too young, so let me tell you a few things that I remem­ber about that time:

So why isn’t every­one already using macros to extend lan­guages? Like garbage col­lec­tion, macros may seem like a cool idea in prin­ci­ple, but with too much over­head to be prac­ti­cal (but with the over­head in pro­gram under­stand­ing, instead of pro­gram exe­cu­tion). Like first-class func­tions, macros add an extra dimen­sion to code that may seem too mind-twist­ing for an aver­age pro­gram­mer. And like a type sys­tem, the the­ory behind hygienic macros may seem too daunt­ing to be worth the extra guar­an­tees that hygiene pro­vides. Maybe so.

But Beau­ti­ful Racket makes the case that the time for lan­guage exten­si­bil­ity has come. That’s why this book is impor­tant. It’s not an abstract argu­ment about the ben­e­fits of macros or a par­tic­u­lar style of macros. Instead, this book shows you, step by step, how to use Racket’s macro sys­tem on real prob­lems and, as a result, get a feel for its ben­e­fits.

Whether you’re already con­vinced, or you’re skep­ti­cal about lan­guage exten­si­bil­ity and macros, the way to know for cer­tain is to give it a try. I think you won’t want to go back.

Matthew But­t­er­ick com­mu­ni­cates the joy that many of us feel when solv­ing prob­lems with exten­si­ble lan­guages and with Racket-style macros. Beau­ti­ful Racket is an enter­tain­ing and uniquely orga­nized book—and it gets to its point faster than you might real­ize. The author’s goal is to teach you to use Racket, but the very first “Racket” pro­gram starts #lang br/quicklanginstead of #lang racket. So, as a reader of this book, you start out by using a cus­tom pro­gram­ming lan­guage, and that’s exactly as it should be. Matthew But­t­er­ick has tried build­ing his own lan­guages, and he won’t go back, not even for the first page.