<html><head></head><body style="word-wrap: break-word; -webkit-nbsp-mode: space; -webkit-line-break: after-white-space; "><br><div><div>On May 26, 2012, at 10:32 AM, Don Green wrote:</div><br class="Apple-interchange-newline"><blockquote type="cite"><span class="Apple-style-span" style="border-collapse: separate; font-family: 'Lucida Grande'; font-style: normal; font-variant: normal; font-weight: normal; letter-spacing: normal; line-height: normal; orphans: 2; text-align: -webkit-auto; text-indent: 0px; text-transform: none; white-space: normal; widows: 2; word-spacing: 0px; -webkit-border-horizontal-spacing: 0px; -webkit-border-vertical-spacing: 0px; -webkit-text-decorations-in-effect: none; -webkit-text-size-adjust: auto; -webkit-text-stroke-width: 0px; font-size: medium; ">(with-output-to-file file<br> #:exists 'replace<br> (lambda ()<br> (for ((ch content)) (display ch)))) ;<<<<<<<<<<<<<<<<<<what is ch?<br></span></blockquote><div><br></div><div><br></div><div>Like all languages, Racket for loops specify a variable _ch_ that run over some compound data structure, in this case the string in _content_ . </div><div><br></div><br><blockquote type="cite"><span class="Apple-style-span" style="border-collapse: separate; font-family: 'Lucida Grande'; font-style: normal; font-variant: normal; font-weight: normal; letter-spacing: normal; line-height: normal; orphans: 2; text-align: -webkit-auto; text-indent: 0px; text-transform: none; white-space: normal; widows: 2; word-spacing: 0px; -webkit-border-horizontal-spacing: 0px; -webkit-border-vertical-spacing: 0px; -webkit-text-decorations-in-effect: none; -webkit-text-size-adjust: auto; -webkit-text-stroke-width: 0px; font-size: medium; ">;; --- test<br>(check-equal? (with-output-to-string<br> (lambda ()<br> (for ((ln (answer file)))<br> (displayln (string-join ln))))) ;<<<<<procedure string-join: expects 2 arguments, given 1: '("Do" "you" "think" "it" "is" "long" "enough?")<br> expected)</span></blockquote><br></div><div>I assume you're running a version of DrRacket that's a bit behind. Add " " as the second argument. </div><div><br></div><div><br></div><br></body></html>