Hi Tim,<div><br></div><div>Thanks for sharing your code.</div><div><br></div><div>Quick, newby question: why do you use "and" instead of "begin" in your progress function? I've seen others do this as well (of course, Eli's "(and...)" idiom above is a whole different animal... and very cool.</div> <div><br></div><div>Thanks,</div><div>-Joe</div><div><br><div class="gmail_quote">On Wed, Mar 21, 2012 at 10:01 AM, Tim Brown <span dir="ltr"><<a href="mailto:tim.brown@cityc.co.uk">tim.brown@cityc.co.uk</a>></span> wrote:<br> <blockquote class="gmail_quote" style="margin:0 0 0 .8ex;border-left:1px #ccc solid;padding-left:1ex">Rodolfo,<br> <br> I started Project Euler with nested (do ...) loops.<br> Which are beyond ugly. It was truly revolutionary<br> finding the for/... forms.<br> <br> Get a hang of them!<br> <br> Also, you might like to use:<br> ;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;<u></u>;;;;;;;;;;;;;;;;;;;<br> (define last-progress-ms #f)<br> ;;; it's global, it's expeident, but it has worked for me so far!<br> (define (progress i period (max-i #f))<br> (when (= (modulo i period) 0)<br> (let* ((now-ms (current-milliseconds))<br> (delta-raw (and last-progress-ms (- now-ms last-progress-ms)))<br> (delta-s (and delta-raw (quotient delta-raw 1000)))<br> (delta-ms (and delta-raw (remainder delta-raw 1000))))<br> (set! last-progress-ms now-ms)<br> (if<br> max-i<br> (and<br> (printf "~a+~a:~a.~a|" i (- max-i i) delta-s delta-ms)<br> (flush-output))<br> (and (printf "~a:~a.~a|" (/ i period) delta-s delta-ms)<br> (flush-output))))))<br> ;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;<u></u>;;;;;;;;;;;;;;;;;;;<br> <br> It's useful in loops like:<br> <br> (let ((stupid-number-youll-find-so-<u></u>often-in-PE(expt 10 1034)))<br> (for*/first<br> (<br> [k (in-range 0 stupid-number-youll-find-so-<u></u>often-in-PE)]<br> #:when (progress (- stupid-number-youll-find-so-<u></u>often-in-PE k) 1000000)<br> [i (in-range 0 10)]<br> [j (in-range 0 10)]<br> ...)))<br> <br> You'll know when you'll need it!<br> #:when (printf ...)<br> will become your friend!<br> <br> Tim<div class="im"><br> <br> Eli Barzilay wrote:<br> <blockquote class="gmail_quote" style="margin:0 0 0 .8ex;border-left:1px #ccc solid;padding-left:1ex"> 20 minutes ago, Rodolfo Carvalho wrote:<br> <blockquote class="gmail_quote" style="margin:0 0 0 .8ex;border-left:1px #ccc solid;padding-left:1ex"> <br> (define (pythagorean-triple/alt n)<br> (for*/first ([a (in-range 1 n)]<br> [b (in-range a n)]<br> [c (in-value (- n a b))]<br> #:when (right-triangle? a b c))<br> (list a b c)))<br> </blockquote> <br> You can also use `for*/or':<br> <br> (define (pythagorean-triple/alt n)<br> (for*/or ([a (in-range 1 n)]<br> [b (in-range a n)])<br> (define c (- n a b))<br> (and (right-triangle? a b c) (list a b c))))<br> <br> </blockquote> <br> <br> -- <br></div> Tim Brown <<a href="mailto:tim.brown@cityc.co.uk" target="_blank">tim.brown@cityc.co.uk</a>> | City Computing Limited |<br> T: <a href="tel:%2B44%2020%208770%202110" value="+442087702110" target="_blank">+44 20 8770 2110</a> | City House, Sutton Park Road |<br> F: <a href="tel:%2B44%2020%208770%202130" value="+442087702130" target="_blank">+44 20 8770 2130</a> | Sutton, Surrey, SM1 2AE, GB |<br> ------------------------------<u></u>------------------------------<u></u>-----------|<br> BEAUTY: What's in your eye when you have a bee in your hand |<br> ------------------------------<u></u>------------------------------<u></u>-----------'<br> City Computing Limited registered in London No. 1767817.<br> Registered Office: City House, Sutton Park Road, Sutton, Surrey, SM1 2AE<br> VAT number 372 8290 34.<div class="HOEnZb"><div class="h5"><br> ____________________<br> Racket Users list:<br> <a href="http://lists.racket-lang.org/users" target="_blank">http://lists.racket-lang.org/<u></u>users</a><br> </div></div></blockquote></div><br></div>