<html xmlns:o="urn:schemas-microsoft-com:office:office" xmlns:w="urn:schemas-microsoft-com:office:word" xmlns:st1="urn:schemas-microsoft-com:office:smarttags" xmlns="http://www.w3.org/TR/REC-html40"> <head> <meta http-equiv=Content-Type content="text/html; charset=us-ascii"> <meta name=Generator content="Microsoft Word 11 (filtered medium)"> <o:SmartTagType namespaceuri="urn:schemas-microsoft-com:office:smarttags" name="Street"/> <o:SmartTagType namespaceuri="urn:schemas-microsoft-com:office:smarttags" name="address"/> <o:SmartTagType namespaceuri="urn:schemas-microsoft-com:office:smarttags" name="PlaceType"/> <o:SmartTagType namespaceuri="urn:schemas-microsoft-com:office:smarttags" name="PlaceName"/> <o:SmartTagType namespaceuri="urn:schemas-microsoft-com:office:smarttags" name="country-region"/> <o:SmartTagType namespaceuri="urn:schemas-microsoft-com:office:smarttags" name="City"/> <o:SmartTagType namespaceuri="urn:schemas-microsoft-com:office:smarttags" name="place"/>  <style>  </style> </head> <body lang=EN-GB link=blue vlink=purple> <div class=Section1> Dear Matt and Danny,<o:p></o:p> <o:p> </o:p> Oh dear, I am really sorry, I have received Danny's email but have missed it as I do get a lot of emails! I have had a flue since the weekend and still trying to recover. I’ve been trying to work from my bed, but not doing a good job L<o:p></o:p> I am not an expert programmer but I’m learning and I do appreciate your detailed analysis and your time for helping. I will go through it in detail and will reply back if you don’t mind please.<o:p></o:p> <o:p> </o:p> Thank you very much.<o:p></o:p> HZBilal.<o:p></o:p> <o:p> </o:p> <o:p> </o:p> ---<o:p></o:p> Mr Haider Zuhair Bilal BEng MSc MIEE MIEEE MBCS<o:p></o:p> PhD Research Scholar<o:p></o:p> Centre for Systems and Software Engineering<o:p></o:p> Faculty of Business, Computing and Information Management<o:p></o:p> <st1:place w:st="on"><st1:PlaceName w:st="on">London</st1:PlaceName> <st1:PlaceName w:st="on">South</st1:PlaceName> <st1:PlaceName w:st="on">Bank</st1:PlaceName> <st1:PlaceType w:st="on">University</st1:PlaceType></st1:place><o:p></o:p> <st1:Street w:st="on"><st1:address w:st="on">103 Borough Road</st1:address></st1:Street><o:p></o:p> <st1:City w:st="on"><st1:place w:st="on">London</st1:place></st1:City> SE1 0AA<o:p></o:p> <st1:country-region w:st="on"><st1:place w:st="on">UK</st1:place></st1:country-region><o:p></o:p>  <o:p></o:p> Tel: +44(0)20 7815 7473<o:p></o:p> Fax: +44(0)20 7815 7550<o:p></o:p> <st1:City w:st="on"><st1:place w:st="on">Mobile</st1:place></st1:City>: +44(0)7887 598355<o:p></o:p>  <o:p></o:p> http://myweb.lsbu.ac.uk/~bilalhz/<o:p></o:p>  <o:p></o:p>  <o:p></o:p> -----Original Message----- From: Matt Jadud [mailto:mcj4@kent.ac.uk] Sent: 11 October 2006 09:57 To: Bilal, Haider Z Cc: Danny Yoo Subject: [Fwd: Re: [plt-scheme] Scheme Program]<o:p></o:p> <o:p> </o:p> Hi Bilal,<o:p></o:p> <o:p> </o:p> Danny gave you a good, thoughtful reply just a few days ago. If you're <o:p></o:p> subscribed to the list, and you're asking questions to the list, you <o:p></o:p> should watch for replies to your messages.<o:p></o:p> <o:p> </o:p> Danny has already outlined a number of steps you can take, and I suggest <o:p></o:p> you take everything he said on-board. His advice is, in my experience, <o:p></o:p> usually quite good. When it isn't "quite good", it's bordering on <o:p></o:p> "excellent". If that seems over-the-top, then I'll claim that the word <o:p></o:p> "thorough" always applies to the answers he provides on-list.<o:p></o:p> <o:p> </o:p> Cheers,<o:p></o:p> Matt<o:p></o:p> <o:p> </o:p> -------- Original Message --------<o:p></o:p> Subject: Re: [plt-scheme] Scheme Program<o:p></o:p> Date: Mon, 2 Oct 2006 14:29:16 -0700 (PDT)<o:p></o:p> From: Danny Yoo <dyoo@hkn.eecs.berkeley.edu><o:p></o:p> To: Bilal, Haider Z <bilalhz@lsbu.ac.uk><o:p></o:p> CC: plt-scheme@flux.utah.edu<o:p></o:p> References: <o:p></o:p> <9FFEE39DADA4A442B06FB5673765F41002847F77@CSD-EXBE-VS1.lsbu.ac.uk><o:p></o:p> <o:p> </o:p> > However, this section of the code is not working properly and giving me <o:p></o:p> > the following error: apply: bad procedure: #[undefined]<o:p></o:p> <o:p> </o:p> Hi Haider,<o:p></o:p> <o:p> </o:p> The following is a code review of the code.  Please don't take any of the<o:p></o:p> comments as condemnation against your own person. I'll try to keep<o:p></o:p> criticism directed at the code.<o:p></o:p> <o:p> </o:p> <o:p> </o:p> Code review comments:<o:p></o:p> <o:p> </o:p>      * I tried reading your program.  I suppose I'm not be a Schemer yet,<o:p></o:p>        but I think the program is, frankly, hard to read.  It's way too<o:p></o:p>        nested for me to read comfortably, and the indentation is in places<o:p></o:p>        that does not seem natural.  Double-spacing Scheme code is not<o:p></o:p>        common.<o:p></o:p> <o:p> </o:p>      * There are superfluous expressions.  Doing a test like:<o:p></o:p> <o:p> </o:p>            (not (equal? (pdg-vertex-ids-killed v) #f))<o:p></o:p> <o:p> </o:p>        can be more simply expressed as:<o:p></o:p> <o:p> </o:p>            (pdg-vertex-ids-killed v)<o:p></o:p> <o:p> </o:p>      * There's a <st1:place w:st="on">LOT</st1:place> of mutation going on in the code.  Are you sure you<o:p></o:p>        want to do that?  It's really making the code more complicated than<o:p></o:p>        it needs to be.<o:p></o:p> <o:p> </o:p>      * There are subexpressions that basically look like big copy-and-paste<o:p></o:p>        blocks.  Don't copy-and-paste: abstract!  Concretely, the only<o:p></o:p>        difference I see between<o:p></o:p> <o:p> </o:p>                    (if (pdg-vertex-ids-killed v)<o:p></o:p>                        (abs-loc-set-traverse<o:p></o:p>                         (pdg-vertex-ids-killed v)<o:p></o:p>                         (lambda (y)<o:p></o:p>                           (let*<o:p></o:p>                               ((line-num<o:p></o:p>                                 (file-get-line-num fileuid offset)))<o:p></o:p>                             (set! linelist<o:p></o:p>                                   (cons (list line-num y v)<o:p></o:p>                                         linelist)))<o:p></o:p>                           #t)))<o:p></o:p> <o:p> </o:p>        and:<o:p></o:p> <o:p> </o:p>                    (if (pdg-vertex-ids-used v)<o:p></o:p>                        (abs-loc-set-traverse<o:p></o:p>                         (pdg-vertex-ids-used v)<o:p></o:p>                         (lambda (y)<o:p></o:p>                           (let*<o:p></o:p>                               ((line-num<o:p></o:p>                                 (file-get-line-num fileuid offset)))<o:p></o:p>                             (set! linelist<o:p></o:p>                                   (cons (list line-num y v)<o:p></o:p>                                         linelist)))<o:p></o:p>                           #t)))<o:p></o:p> <o:p> </o:p>        is just one minor subexpression.<o:p></o:p> <o:p> </o:p>      * Everything seems to be stuffed in one gargantuan function.  Consider<o:p></o:p>        writing helper functions where it will clarify the code's intent.<o:p></o:p> <o:p> </o:p>      * I see no direct use of APPLY in your code, so something else must be<o:p></o:p>        calling it.  Actually, I see a few type errors in the code.<o:p></o:p> <o:p> </o:p>        Concretely: what's the "contract" of ABS-LOC-SET-TRAVERSE?  Check<o:p></o:p>        your usages of that function: the code is definitely violating <o:p></o:p> its use of<o:p></o:p>        ABS-LOC-SET-TRAVERSE in a few places.<o:p></o:p> <o:p> </o:p> <o:p> </o:p> <o:p> </o:p> You made the comment:<o:p></o:p> <o:p> </o:p> > However, it gave me wrong output, some had TO and FROM both listed <o:p></o:p> > together:<o:p></o:p> <o:p> </o:p> What in the program prevents from happening? From the sequence of<o:p></o:p> subexpressions:<o:p></o:p> <o:p> </o:p>      (if (pdg-vertex-ids-killed (caddr z))<o:p></o:p>          (abs-loc-set-traverse ...))<o:p></o:p>      (if (pdg-vertex-ids-used (caddr z))<o:p></o:p>          (abs-loc-set-traverse ...))<o:p></o:p> <o:p> </o:p> there's nothing in the code that excludes both PDG-VERTEX-IDS-KILLED and<o:p></o:p> PDG-VERTEX-IDS-USED to return true values.<o:p></o:p> <o:p> </o:p> <o:p> </o:p> If you are going to write more Scheme code, you might also want to<o:p></o:p> consider doing a read-through a textbook like HTDP:<o:p></o:p> <o:p> </o:p>      http://htdp.org<o:p></o:p> <o:p> </o:p> If you do so, your programs will tend to have a better design.<o:p></o:p> <o:p> </o:p> <o:p> </o:p> <o:p> </o:p> I've reformatted your code as best as I can in the context of a PLT Scheme<o:p></o:p> module, to be able to use the Syntax Check tool as well as better see the<o:p></o:p> structure of the program.<o:p></o:p> <o:p> </o:p> ;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;<o:p></o:p> <o:p> </o:p> (module pdg mzscheme<o:p></o:p>    ;; Unknown: the following definitions are here only so I can run<o:p></o:p>    ;; check syntax and see where values are coming from.<o:p></o:p>    (define (pdg-vertex-set-traverse l f) (void))<o:p></o:p>    (define (int-pair-set-traverse l f) (void))<o:p></o:p>    (define (abs-loc-set-traverse l f) (void))<o:p></o:p>    (define (pdg-vertices pdg) (void))<o:p></o:p>    (define (pdg-compilation-uid pdg) (void))<o:p></o:p>    (define (pdg-vertex-pdg pdg) (void))<o:p></o:p>    (define (pdg-kind pdg) (void))<o:p></o:p>    (define (pdg-vertex-charpos pdg) (void))<o:p></o:p>    (define (pdg-vertex-ids-killed pdg) (void))<o:p></o:p>    (define (pdg-vertex-ids-used pdg) (void))<o:p></o:p>    (define (file-get-line-num x y) (void))<o:p></o:p>    (define (sort l cmp) (void))<o:p></o:p>    (define (sdg-pdgs) (void))<o:p></o:p> <o:p> </o:p> <o:p> </o:p>    (define (assignments)<o:p></o:p> <o:p> </o:p>      (define filenumber 1)<o:p></o:p> <o:p> </o:p>      (define (process-pdg pdg)<o:p></o:p>        (when (eqv? (pdg-kind pdg) 'user-defined)<o:p></o:p>          (let* ((out-port<o:p></o:p>                  (open-output-file<o:p></o:p>                   (string-append "Fun"<o:p></o:p>                                  (number->string filenumber)<o:p></o:p>                                  "_V.dat")))<o:p></o:p>                 (linelist ()))<o:p></o:p>            (pdg-vertex-set-traverse<o:p></o:p>             (pdg-vertices pdg)<o:p></o:p>             (lambda (v)<o:p></o:p>               (let* ((fileuid<o:p></o:p>                       (pdg-compilation-uid<o:p></o:p>                        (pdg-vertex-pdg v))))<o:p></o:p>                 (int-pair-set-traverse<o:p></o:p>                  (pdg-vertex-charpos v)<o:p></o:p>                  (lambda (offset w)<o:p></o:p>                    (if (pdg-vertex-ids-killed v)<o:p></o:p>                        (abs-loc-set-traverse<o:p></o:p>                         (pdg-vertex-ids-killed v)<o:p></o:p>                         (lambda (y)<o:p></o:p>                           (let*<o:p></o:p>                               ((line-num<o:p></o:p>                                 (file-get-line-num<o:p></o:p>                                  fileuid offset)))<o:p></o:p>                             (set! linelist<o:p></o:p>                                   (cons (list line-num y v)<o:p></o:p>                                         linelist)))<o:p></o:p>                           #t)))<o:p></o:p> <o:p> </o:p>                    (if (pdg-vertex-ids-used v)<o:p></o:p>                        (abs-loc-set-traverse<o:p></o:p>                         (pdg-vertex-ids-used v)<o:p></o:p>                         (lambda (y)<o:p></o:p>                           (let*<o:p></o:p>                               ((line-num<o:p></o:p>                                 (file-get-line-num<o:p></o:p>                                  fileuid offset)))<o:p></o:p>                             (set! linelist<o:p></o:p>                                   (cons (list line-num y v)<o:p></o:p>                                         linelist)))<o:p></o:p>                           #t)))<o:p></o:p>                    #t)))<o:p></o:p>               #t))<o:p></o:p> <o:p> </o:p>            (set! linelist<o:p></o:p>                  (sort linelist<o:p></o:p>                        (lambda (a b)<o:p></o:p>                          (< (cadar a) (cadar b)))))<o:p></o:p> <o:p> </o:p>            (for-each (lambda (z)<o:p></o:p>                        (let<o:p></o:p>                            ((linenum (car z)))<o:p></o:p>                          (define line-num (car z))<o:p></o:p>                          (display (cdr line-num) out-port)<o:p></o:p>                          (write-char #\tab out-port)<o:p></o:p> <o:p> </o:p>                          (if (pdg-vertex-ids-killed (caddr z))<o:p></o:p>                              (abs-loc-set-traverse<o:p></o:p>                               (pdg-vertex-ids-killed (caddr z))<o:p></o:p>                               (display "to" out-port)))<o:p></o:p> <o:p> </o:p>                          (if (pdg-vertex-ids-used (caddr z))<o:p></o:p>                              (abs-loc-set-traverse<o:p></o:p>                               (pdg-vertex-ids-used (caddr z))<o:p></o:p>                               (display "from" out-port)))<o:p></o:p> <o:p> </o:p>                          (newline out-port)))<o:p></o:p>                      linelist)<o:p></o:p> <o:p> </o:p>            (close-output-port out-port))<o:p></o:p> <o:p> </o:p>          (set! filenumber (+ filenumber 1))))<o:p></o:p> <o:p> </o:p>      (for-each process-pdg (sdg-pdgs)))<o:p></o:p> <o:p> </o:p>    (assignments))<o:p></o:p> _________________________________________________<o:p></o:p>   For list-related administrative tasks:<o:p></o:p>   http://list.cs.brown.edu/mailman/listinfo/plt-scheme<o:p></o:p> </div> This e-mail message may be confidential and is intended only for the use of the individual(s) to whom it is addressed. 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