Re: [racket-users] A couple of questions about Neil's html reader/writer
.. the conversion for neil's xexpr .. at this point the two converters can be abstracted by passing in two lambdas, is-at-list predicate, and extract-at-list. Neil can you comment on what other differences I might expect to find? (define (neil-xexpr-tok-tree an-xexpr) (define (is-at-list e) (and (pair? e) (eqv? '@ (car e (define (extract-at-list e) (cdr e) ) (cond [(null? an-xexpr) an-xexpr] [(not (pair? an-xexpr)) (tok-make 'tok:value `((value ,an-xexpr)))] [else (let( [tag (car an-xexpr)] [r1 (cdr an-xexpr)] ) (cond [(null? r1) an-xexpr] [else (let( [first-element (car r1)] [r2 (cdr r1)] ) (cond [(is-at-list first-element) (cons tag (cons (extract-at-list first-element) (map neil-xexpr-tok-tree r2)))] [else (cons tag (cons '() (map neil-xexpr-tok-tree r1)))] ))]))])) (define (test-neil-xexpr-tok-tree-0) (equal? (neil-xexpr-tok-tree '(html (head (title My Title)) (body (@ (bgcolor white)) (h1 My Heading) (p (@ (style default)) This is a paragraph.) (p This is another paragraph. '(html () (head () (title () (tok:value ((value My Title) (body ((bgcolor white)) (h1 () (tok:value ((value My Heading (p ((style default)) (tok:value ((value This is a paragraph. (p () (tok:value ((value This is another paragraph.) ))) An example: (define (test-neil-xexpr-tok-tree-0) (equal? (neil-xexpr-tok-tree '(html (head (title My Title)) (body (@ (bgcolor white)) (h1 My Heading) (p (@ (style default)) This is a paragraph.) (p This is another paragraph. '(html () (head () (title () (tok:value ((value My Title) (body ((bgcolor white)) (h1 () (tok:value ((value My Heading (p ((style default)) (tok:value ((value This is a paragraph. (p () (tok:value ((value This is another paragraph.) ))) On Wed, Jul 29, 2015 at 7:56 PM, Thomas Lynch thomas.ly...@reasoningtechnology.com wrote: I wrote primitive conversion routines to bring the xexpr or Neil's xexpr into ... oh gosh, my parser token format, which by coincidence is very close. Just playing with this now .. In my target format token children are always other tokens. All values given as attributes in value tokens. I use an empty list if there are no attributes. The conversion routines are very simple, though I'm just playing with this, there will be other cases I missed, I suspect: (define (xexpr-tok-tree an-xexpr) (define (is-at-list e) (and (pair? e) (pair? (car e (cond [(null? an-xexpr) an-xexpr] [(not (pair? an-xexpr)) (tok-make 'tok:value `((value ,an-xexpr)))] ; actually diff toks for diff types [else (let( [tag (car an-xexpr)] [r1 (cdr an-xexpr)] ) (cond [(null? r1) an-xexpr] [else (let( [first-element (car r1)] [r2 (cdr r1)] ) (cond [(is-at-list first-element) (cons tag (cons first-element (map xexpr-tok-tree r2)))] [else (cons tag (cons '() (map xexpr-tok-tree r1)))] ))]))])) (define (test-xexpr-tok-tree-0) (equal? (xexpr-tok-tree '(html (head (title My Title)) (body ((bgcolor white)) (h1 My Heading) (p ((style default)) This is a paragraph.) (p This is another paragraph. '(html () (head () (title () (tok:value ((value My Title) (body ((bgcolor white)) (h1 () (tok:value ((value My Heading (p ((style default)) (tok:value ((value This is a paragraph. (p () (tok:value ((value This is another paragraph.) ))) On Wed, Jul 29, 2015 at 7:05 AM, Matthew Butterick m...@mbtype.com wrote: Yes, more or less. In an X-expression, an attribute list is the only element that's a list made of sublists. A list of embedded X-expressions, OTOH, will start with a symbol. To look at it another way, (cons symbol (list xexpr ...)) really amounts to (list symbol xexpr ...) which is just (list symbol (list (list symbol string) ...) xexpr ...) but without the attribute list, cf. '(p foo bar) '(p ((style default)) foo bar) A recurring annoyance in X-expressions is distinguishing these two cases on input, because the second element can be either an
Re: [racket-users] A couple of questions about Neil's html reader/writer
Alexander, you will notice I pulled a couple lambdas to the top, and added a test routine at the bottom take those out ... then the code you sent isn't shorter. I am also expecting to have to add more code to the intermediate points. I like seeing those named. I think it is easy to read. ... What advantage do you see in using match? So I have been thinking about this, have come to this conclusion, what do you think: In general grammar driven parsing is elegant against well formed input data. However a complication enters because the error grammar explodes in size in comparison. Where as if one builds a match with cascading let (naming the parts) and cond (doing the match), all end conditions are exposed and can be handled. As an example, I will have to check the tag to see if it aliases against tags the parser is using, so that people can't send in poison xml statement. The alternative would be to first run the xml through a well formed checker, but that would just move the complication to the checker, just so the parse can look pretty. In addition, I'm concerned about the stream behavior of racket's match - something I've promised to work on. Notice, what happens if you try to match pattern delineated by paren literals within nested parens, because it does a greedy match, and it will wait for the end of stream to complete that match using the outside most right paren. So I don't understand match behavior enough yet to be completely comfortable with it yet. Independent, in this case I suspect I like the cascading cond/let match. Be glad to hear your thoughts on this. Be glad to learn more about match. On Wed, Jul 29, 2015 at 10:56 PM, Alexander D. Knauth alexan...@knauth.org wrote: Would it be easier using match? (define (xexpr-tok-tree an-xexpr) (match as-xexpr ['() '()] [(not (cons _ _)) (tok-make ...)] [(list tag) (list tag)] [(list-rest tag (? is-at-list at-list) r2) ] )) On Jul 29, 2015, at 7:56 AM, Thomas Lynch thomas.ly...@reasoningtechnology.com wrote: I wrote primitive conversion routines to bring the xexpr or Neil's xexpr into ... oh gosh, my parser token format, which by coincidence is very close. Just playing with this now .. In my target format token children are always other tokens. All values given as attributes in value tokens. I use an empty list if there are no attributes. The conversion routines are very simple, though I'm just playing with this, there will be other cases I missed, I suspect: (define (xexpr-tok-tree an-xexpr) (define (is-at-list e) (and (pair? e) (pair? (car e (cond [(null? an-xexpr) an-xexpr] [(not (pair? an-xexpr)) (tok-make 'tok:value `((value ,an-xexpr)))] ; actually diff toks for diff types [else (let( [tag (car an-xexpr)] [r1 (cdr an-xexpr)] ) (cond [(null? r1) an-xexpr] [else (let( [first-element (car r1)] [r2 (cdr r1)] ) (cond [(is-at-list first-element) (cons tag (cons first-element (map xexpr-tok-tree r2)))] [else (cons tag (cons '() (map xexpr-tok-tree r1)))] ))]))])) (define (test-xexpr-tok-tree-0) (equal? (xexpr-tok-tree '(html (head (title My Title)) (body ((bgcolor white)) (h1 My Heading) (p ((style default)) This is a paragraph.) (p This is another paragraph. '(html () (head () (title () (tok:value ((value My Title) (body ((bgcolor white)) (h1 () (tok:value ((value My Heading (p ((style default)) (tok:value ((value This is a paragraph. (p () (tok:value ((value This is another paragraph.) ))) On Wed, Jul 29, 2015 at 7:05 AM, Matthew Butterick m...@mbtype.com wrote: Yes, more or less. In an X-expression, an attribute list is the only element that's a list made of sublists. A list of embedded X-expressions, OTOH, will start with a symbol. To look at it another way, (cons symbol (list xexpr ...)) really amounts to (list symbol xexpr ...) which is just (list symbol (list (list symbol string) ...) xexpr ...) but without the attribute list, cf. '(p foo bar) '(p ((style default)) foo bar) A recurring annoyance in X-expressions is distinguishing these two cases on input, because the second element can be either an attribute list or nested X-expression. You can use `xexpr-drop-empty-attributes` to force an attribute list (even empty). My `txexpr` package also has utilities for handling them. Here is the syntax for an xexp from xexp? in the reference: xexpr = string | (list
Re: [racket-users] A couple of questions about Neil's html reader/writer
Thomas Lynch wrote on 07/29/2015 11:22 PM: The most obvious difference between racket's xexpr and yours is the '@' as the head of the attributes list. Any idea where else I will see divergences? You might not be able to implement a tool that works correctly with all conforming SXML, until you read Oleg's SXML spec. It is often helpful to assume that Oleg is smarter than all of us. After you understand Oleg's stuff, there might be something in the implementation notes I posted that is a small bit of additional help. Or, consider not doing these conversion kludges, after all, and just pick an HTML/XML representation and stick with that one exclusively. This problem does not rate the amount of energy being flung at it. Stupid engineering situations often beget stupid, the stupid can compound, and pretty soon we've all degenerated to smearing out code on the wall. -- You received this message because you are subscribed to the Google Groups Racket Users group. To unsubscribe from this group and stop receiving emails from it, send an email to racket-users+unsubscr...@googlegroups.com. For more options, visit https://groups.google.com/d/optout.
Re: [racket-users] A couple of questions about Neil's html reader/writer
Great! thanks Neil! On Thu, Jul 30, 2015 at 11:02 AM, Neil Van Dyke n...@neilvandyke.org wrote: Thomas Lynch wrote on 07/29/2015 10:25 PM: Neil can you comment on what other differences I might expect to find? Are the below 2 messages to the list helpful? * Historical background on SXML and Racket xexpr: https://groups.google.com/d/msg/racket-users/yaOtPkd_qvs/8ruIg-Smr7cJ * Technical notes on implementing conversion kludge functions between SXML and Racket xexpr: https://groups.google.com/d/msg/racket-users/yaOtPkd_qvs/vhvAi90_CgAJ The historical one should also clarify why not to say neil-xexpr in identifiers. (I'll have to earn some better claim to fame.) Good luck. I and many others have been using SXML tools happily for over a decade, and at this point I'm sure we all wish the xexpr people best of luck with whatever their problem is. :) Neil V. -- You received this message because you are subscribed to the Google Groups Racket Users group. To unsubscribe from this group and stop receiving emails from it, send an email to racket-users+unsubscr...@googlegroups.com. For more options, visit https://groups.google.com/d/optout.
Re: [racket-users] A couple of questions about Neil's html reader/writer
On Thu, Jul 30, 2015 at 11:09 AM, Thomas Lynch thomas.ly...@reasoningtechnology.com wrote: Great! thanks Neil! Ah spoke too soon! Those links just point back into this very same thread! The most obvious difference between racket's xexpr and yours is the '@' as the head of the attributes list. Any idea where else I will see divergences? On Thu, Jul 30, 2015 at 11:02 AM, Neil Van Dyke n...@neilvandyke.org wrote: Thomas Lynch wrote on 07/29/2015 10:25 PM: Neil can you comment on what other differences I might expect to find? Are the below 2 messages to the list helpful? * Historical background on SXML and Racket xexpr: https://groups.google.com/d/msg/racket-users/yaOtPkd_qvs/8ruIg-Smr7cJ * Technical notes on implementing conversion kludge functions between SXML and Racket xexpr: https://groups.google.com/d/msg/racket-users/yaOtPkd_qvs/vhvAi90_CgAJ The historical one should also clarify why not to say neil-xexpr in identifiers. (I'll have to earn some better claim to fame.) Good luck. I and many others have been using SXML tools happily for over a decade, and at this point I'm sure we all wish the xexpr people best of luck with whatever their problem is. :) Neil V. -- You received this message because you are subscribed to the Google Groups Racket Users group. To unsubscribe from this group and stop receiving emails from it, send an email to racket-users+unsubscr...@googlegroups.com. For more options, visit https://groups.google.com/d/optout.
Re: [racket-users] A couple of questions about Neil's html reader/writer
I wrote primitive conversion routines to bring the xexpr or Neil's xexpr into ... oh gosh, my parser token format, which by coincidence is very close. Just playing with this now .. In my target format token children are always other tokens. All values given as attributes in value tokens. I use an empty list if there are no attributes. The conversion routines are very simple, though I'm just playing with this, there will be other cases I missed, I suspect: (define (xexpr-tok-tree an-xexpr) (define (is-at-list e) (and (pair? e) (pair? (car e (cond [(null? an-xexpr) an-xexpr] [(not (pair? an-xexpr)) (tok-make 'tok:value `((value ,an-xexpr)))] ; actually diff toks for diff types [else (let( [tag (car an-xexpr)] [r1 (cdr an-xexpr)] ) (cond [(null? r1) an-xexpr] [else (let( [first-element (car r1)] [r2 (cdr r1)] ) (cond [(is-at-list first-element) (cons tag (cons first-element (map xexpr-tok-tree r2)))] [else (cons tag (cons '() (map xexpr-tok-tree r1)))] ))]))])) (define (test-xexpr-tok-tree-0) (equal? (xexpr-tok-tree '(html (head (title My Title)) (body ((bgcolor white)) (h1 My Heading) (p ((style default)) This is a paragraph.) (p This is another paragraph. '(html () (head () (title () (tok:value ((value My Title) (body ((bgcolor white)) (h1 () (tok:value ((value My Heading (p ((style default)) (tok:value ((value This is a paragraph. (p () (tok:value ((value This is another paragraph.) ))) On Wed, Jul 29, 2015 at 7:05 AM, Matthew Butterick m...@mbtype.com wrote: Yes, more or less. In an X-expression, an attribute list is the only element that's a list made of sublists. A list of embedded X-expressions, OTOH, will start with a symbol. To look at it another way, (cons symbol (list xexpr ...)) really amounts to (list symbol xexpr ...) which is just (list symbol (list (list symbol string) ...) xexpr ...) but without the attribute list, cf. '(p foo bar) '(p ((style default)) foo bar) A recurring annoyance in X-expressions is distinguishing these two cases on input, because the second element can be either an attribute list or nested X-expression. You can use `xexpr-drop-empty-attributes` to force an attribute list (even empty). My `txexpr` package also has utilities for handling them. Here is the syntax for an xexp from xexp? in the reference: xexpr = string | (list http://pkg-build.racket-lang.org/doc/reference/pairs.html#%28def._%28%28quote._~23~25kernel%29._list%29%29 symbol (list http://pkg-build.racket-lang.org/doc/reference/pairs.html#%28def._%28%28quote._~23~25kernel%29._list%29%29 (list http://pkg-build.racket-lang.org/doc/reference/pairs.html#%28def._%28%28quote._~23~25kernel%29._list%29%29 symbol string) ...) xexpr ...) | (cons http://pkg-build.racket-lang.org/doc/reference/pairs.html#%28def._%28%28quote._~23~25kernel%29._cons%29%29 symbol (list http://pkg-build.racket-lang.org/doc/reference/pairs.html#%28def._%28%28quote._~23~25kernel%29._list%29%29 xexpr ...)) | symbol | valid-char? http://pkg-build.racket-lang.org/doc/xml/index.html#%28def._%28%28lib._xml%2Fmain..rkt%29._valid-char~3f%29%29 | cdata | misc And in this latter syntax, how is the attribute list distinguished from a list of embedded xexps? Is it due to the nesting in the attribute list? -- You received this message because you are subscribed to the Google Groups Racket Users group. To unsubscribe from this group and stop receiving emails from it, send an email to racket-users+unsubscr...@googlegroups.com. For more options, visit https://groups.google.com/d/optout.
Re: [racket-users] A couple of questions about Neil's html reader/writer
Would it be easier using match? (define (xexpr-tok-tree an-xexpr) (match as-xexpr ['() '()] [(not (cons _ _)) (tok-make ...)] [(list tag) (list tag)] [(list-rest tag (? is-at-list at-list) r2) ] )) On Jul 29, 2015, at 7:56 AM, Thomas Lynch thomas.ly...@reasoningtechnology.com wrote: I wrote primitive conversion routines to bring the xexpr or Neil's xexpr into ... oh gosh, my parser token format, which by coincidence is very close. Just playing with this now .. In my target format token children are always other tokens. All values given as attributes in value tokens. I use an empty list if there are no attributes. The conversion routines are very simple, though I'm just playing with this, there will be other cases I missed, I suspect: (define (xexpr-tok-tree an-xexpr) (define (is-at-list e) (and (pair? e) (pair? (car e (cond [(null? an-xexpr) an-xexpr] [(not (pair? an-xexpr)) (tok-make 'tok:value `((value ,an-xexpr)))] ; actually diff toks for diff types [else (let( [tag (car an-xexpr)] [r1 (cdr an-xexpr)] ) (cond [(null? r1) an-xexpr] [else (let( [first-element (car r1)] [r2 (cdr r1)] ) (cond [(is-at-list first-element) (cons tag (cons first-element (map xexpr-tok-tree r2)))] [else (cons tag (cons '() (map xexpr-tok-tree r1)))] ))]))])) (define (test-xexpr-tok-tree-0) (equal? (xexpr-tok-tree '(html (head (title My Title)) (body ((bgcolor white)) (h1 My Heading) (p ((style default)) This is a paragraph.) (p This is another paragraph. '(html () (head () (title () (tok:value ((value My Title) (body ((bgcolor white)) (h1 () (tok:value ((value My Heading (p ((style default)) (tok:value ((value This is a paragraph. (p () (tok:value ((value This is another paragraph.) ))) On Wed, Jul 29, 2015 at 7:05 AM, Matthew Butterick m...@mbtype.com wrote: Yes, more or less. In an X-expression, an attribute list is the only element that's a list made of sublists. A list of embedded X-expressions, OTOH, will start with a symbol. To look at it another way, (cons symbol (list xexpr ...)) really amounts to (list symbol xexpr ...) which is just (list symbol (list (list symbol string) ...) xexpr ...) but without the attribute list, cf. '(p foo bar) '(p ((style default)) foo bar) A recurring annoyance in X-expressions is distinguishing these two cases on input, because the second element can be either an attribute list or nested X-expression. You can use `xexpr-drop-empty-attributes` to force an attribute list (even empty). My `txexpr` package also has utilities for handling them. Here is the syntax for an xexp from xexp? in the reference: xexpr = string | (list symbol (list (list symbol string) ...) xexpr ...) | (cons symbol (list xexpr ...)) | symbol | valid-char? | cdata | misc And in this latter syntax, how is the attribute list distinguished from a list of embedded xexps? Is it due to the nesting in the attribute list? -- You received this message because you are subscribed to the Google Groups Racket Users group. To unsubscribe from this group and stop receiving emails from it, send an email to racket-users+unsubscr...@googlegroups.com. For more options, visit https://groups.google.com/d/optout. -- You received this message because you are subscribed to the Google Groups Racket Users group. To unsubscribe from this group and stop receiving emails from it, send an email to racket-users+unsubscr...@googlegroups.com. For more options, visit https://groups.google.com/d/optout.
[racket-users] A couple of questions about Neil's html reader/writer
Is Neil's xexp format different that the one being used in racket due to the attribute list beginning with an '@'? (write-html '((html (head (title My Title)) (body (@ (bgcolor white)) (h1 My Heading) (p This is a paragraph.) (p This is another paragraph. ( current-output-port)) Here is an example xexp from some guys homework assignment ( http://web.cs.wpi.edu/~cs1102/a12/Assignments/Hwk7/html.html) (form ((action http://localhost:8088/hello;)) What is your first name? (input ((type text) (name firstName))) (input ((type submit) (value Click Here Here is the syntax for an xexp from xexp? in the reference: xexpr = string | (list http://pkg-build.racket-lang.org/doc/reference/pairs.html#%28def._%28%28quote._~23~25kernel%29._list%29%29 symbol (list http://pkg-build.racket-lang.org/doc/reference/pairs.html#%28def._%28%28quote._~23~25kernel%29._list%29%29 (list http://pkg-build.racket-lang.org/doc/reference/pairs.html#%28def._%28%28quote._~23~25kernel%29._list%29%29 symbol string) ...) xexpr ...) | (cons http://pkg-build.racket-lang.org/doc/reference/pairs.html#%28def._%28%28quote._~23~25kernel%29._cons%29%29 symbol (list http://pkg-build.racket-lang.org/doc/reference/pairs.html#%28def._%28%28quote._~23~25kernel%29._list%29%29 xexpr ...)) | symbol | valid-char? http://pkg-build.racket-lang.org/doc/xml/index.html#%28def._%28%28lib._xml%2Fmain..rkt%29._valid-char~3f%29%29 | cdata | misc And in this latter syntax, how is the attribute list distinguished from a list of embedded xexps? Is it due to the nesting in the attribute list? Another question, the racket manuals show xexp-string being used to generate html. Neil has a separate write-html function. Why the divergence? Thanks in advance! -- You received this message because you are subscribed to the Google Groups Racket Users group. To unsubscribe from this group and stop receiving emails from it, send an email to racket-users+unsubscr...@googlegroups.com. For more options, visit https://groups.google.com/d/optout.
