<table cellspacing="0" cellpadding="0" border="0" ><tr><td valign="top" style="font: inherit;">What is the "Module" language? Don't see it in any of the language selection menus. Michael --- On Tue, 12/29/09, Robby Findler <robby@eecs.northwestern.edu> wrote: <blockquote style="border-left: 2px solid rgb(16, 16, 255); margin-left: 5px; padding-left: 5px;"> From: Robby Findler <robby@eecs.northwestern.edu> Subject: Re: [plt-scheme] Not so hygienic macros? To: "michael rice" <nowgate@yahoo.com> Cc: plt-scheme@list.cs.brown.edu Date: Tuesday, December 29, 2009, 2:21 AM <div class="plainMail">On Mon, Dec 28, 2009 at 9:02 PM, michael rice <<a ymailto="mailto:nowgate@yahoo.com" href="/mc/compose?to=nowgate@yahoo.com">nowgate@yahoo.com</a>> wrote: > OK, here's some code (at bottom) to work with. Use of MATCH seems to cause a lot of > problems. Code is actually Scheme translation of some Logo code from an old TLC Logo > book (for the Mattel Aquarius no less) authored by John R. Allen. I think you're running into what Matthew calls "hopeless top-level problems". Eli can probably say more about what is going on with the Swindle language that leads to these precise results. In the meatime, I think that if you use the module language, I think you'll find that the program behaves much more sanely. That is, get rid of the eopl require, prefix the program with "#lang scheme", and use the "Module" language to run the program in DrScheme. When I do that, both versions of the program, the one you posted, and the one below, behave identically on the example inputs you send, namely producing #f for both of these calls:   (compare '(likes desi lucy) db)   (compare '(likes romeo juliet) db) hth, Robby #lang scheme (define match   (λ (pat1 pat2)     (if (null? pat1)         (null? pat2)         (if (null? pat2)             #f             (if (match-first (car pat1) (car pat2))                 (match (cdr pat1) (cdr pat2))                 #f))))) (define match-first   (λ (pat1 pat2)     (if (symbol? pat1)         (if (symbol? pat2)             (equal? pat1 pat2)             #f)         (cond ((symbol? pat2) #f)               ((match-first pat1 (car pat2)) (match (cdr pat1) (cdr pat2)))               (else #f))))) (define compare   (λ (q db)     (cond ((null? db) #f)           (else (cond ((match q (car db)) #t)                       (else (compare q (cdr db)))))))) (define db '((likes minnie mickey) (likes jack jill) (likes daisy donald))) </div></blockquote></td></tr></table>