<html dir="ltr"> <head> <meta http-equiv="Content-Type" content="text/html; charset=iso-8859-1"> <style type="text/css" id="owaParaStyle"></style> </head> <body style="word-wrap:break-word" fpstyle="1" ocsi="0"> <div style="direction: ltr;font-family: Tahoma;color: #000000;font-size: 10pt;">Well this is what I got so far... <div><br> </div> <div> <div>(define deleteNth</div> <div>    (lambda(N LS)</div> <div>    (cond</div> <div>      (null? LS) LS)</div> <div>         ((= N 0)(cdr LS))</div> <div>         (else(cons(car LS)(deleteNth(- N 1)(cdr LS))))))</div> <div><br> </div> <div>and it keeps giving me the error of "cond: bad syntax (clause is not a test-value pair) in: ls"</div> <div style="font-family: Times New Roman; color: #000000; font-size: 16px"> <hr tabindex="-1"> <div id="divRpF503536" style="direction: ltr; "><font face="Tahoma" size="2" color="#000000"><b>From:</b> Matthias Felleisen [matthias@ccs.neu.edu]<br> <b>Sent:</b> Monday, October 08, 2012 9:51 AM<br> <b>To:</b> Ashley Fowler<br> <b>Cc:</b> users@racket-lang.org<br> <b>Subject:</b> Re: [racket] Delete Nth Term<br> </font><br> </div> <div></div> <div> <div><br> </div> <div>3 versions, all pass the test suite. Now write the function </div> <div><br> </div> <div> pick-one-of-three : [List X X X] -> X </div> <div><br> </div> <div>and turn in. </div> <div><br> </div> <div><br> </div> <div><br> </div> <div><br> </div> <div> <div>#lang racket</div> <div><br> </div> <div>(require rackunit)</div> <div><br> </div> <div>;; Nat [Listof X] -> [Listof X]</div> <div>;; delete the n-th item from l, if there is one </div> <div><br> </div> <div>(module+ </div> <div>  test</div> <div>  (check-equal? (deleteNth 4 '()) '())</div> <div>  (check-equal? (deleteNth 0 '(a b c)) '(b c))</div> <div>  (check-equal? (deleteNth 3 '(a b c)) '(a b c))</div> <div>  (check-equal? (deleteNth 2 '(a b c)) '(a b)) )</div> <div><br> </div> <div>(define (deleteNth n l)</div> <div>  (cond</div> <div>    [(= n 0) (rest l)]</div> <div>    [(< n (length l)) (append (take l n) (rest (drop l n)))]</div> <div>    [else l])</div> <div>  #;</div> <div>  (cond </div> <div>    [(empty? l) l]</div> <div>    [(zero? n) (rest l)]</div> <div>    [else (cons (first l) (deleteNth (sub1 n) (rest l)))])</div> <div>  #;</div> <div>  (cond</div> <div>    [(and (zero? n) (empty? l)) l]</div> <div>    [(and (positive? n) (empty? l)) l]</div> <div>    [(and (zero? n) (cons? l)) (rest l)]</div> <div>    [(and (positive? n) (cons? l)) (cons (first l) (deleteNth (sub1 n) (rest l)))]))</div> <div><br> </div> <div><br> </div> </div> <div><br> </div> <div><br> </div> <br> <div> <div>On Oct 7, 2012, at 10:03 PM, Ashley Fowler wrote:</div> <br class="Apple-interchange-newline"> <blockquote type="cite"> <div> <div style="direction:ltr; font-family:Tahoma; color:rgb(0,0,0); font-size:10pt"> I need help with making a function that deletes the nth term from a list.(<span style="white-space:pre-wrap">list LS with its Nth element (with indexes </span><span style="white-space:pre-wrap">starting at 0) deleted)</span> <div>So far I have </div> <div><br> </div> <div> <div>(define (deleteNth N ls)</div> <div>    (if (null? ls)</div> <div>        ls</div> <div>        (deleteNth (- N 1) (cdr ls))))</div> </div> <div><br> </div> <div>The results should be ...</div> <div><br> </div> <div> <pre style="word-wrap:break-word; white-space:pre-wrap">(deleteNth 4 '()) returns () (deleteNth 0 '(a b c)) returns (b c) (deleteNth 3 '(a b c)) returns (a b c)</pre> </div> </div> ____________________<br>  Racket Users list:<br>  <a href="http://lists.racket-lang.org/users" target="_blank">http://lists.racket-lang.org/users</a><br> </div> </blockquote> </div> <br> </div> </div> </div> </div> </body> </html>