[Jscheme-user] generating xml

[Ken A. <kan...@bb...>]

There are at least 3 ways to generate XML in JScheme.

Way 1 - use quasistring:

I'm going to use an example of generating OWL.

(define (datatypeProperty name doc class type)
  {<owl:DatatypeProperty <rdf:ID>="[name]">
[doc]
 <rdfs:domain rdf:resource="[class]">
 <rdfs:range rdf:resource="[(: xsd type)]">
</owl:DatatypeProperty>})

The advantage is you can start with an example of the xml you want and
replace with varible parts with [...].
The disadvantage is your still writing XML mixed with Scheme.

Way 2 - Use a macro like the <> macro in elf/html-gen.scm (which works for html, not xml):

(<> (owl:DatatypeProperty (rdf:ID ,name))
  (<> (rdfs:domain (rdf:resource ,class))
    (<> (rdfs:range rdf:resource ,(: xsd type)))))

The advantage is you just use s-expressions, using ,name to extract
the value of the name variable from Scheme.  The disadvantage is you
have to type <> all the time and understand what "," does.

Way 3 - Geoffrey showed me this approach for his html generation:

(owl:DatatypeProperty (rdf:ID name)
                      doc
                      (rdfs:domain (rdf:resource class))
                      (rdfs:range (rdf:resource (: xsd type))))

Basically you define a procedure with arguments (attributes . contents)
for each tag, and (value) for each attribute.

The advantage is you're completely in Scheme, and evaluating the code
will error if you've made a typo like saying rdf:range.
Static typing in JScheme - who knew!
The disadvantage is you need to write all the functions

Or, just write a macro to generate them:

(define (xtag tag)
  (let ((start {<[tag] })
        (end {</[tag]>\n}))
    (lambda (as . bs)
      (if (null? bs) {[start][as]/>\n}
          {[start][as]>[bs][end]}))))

(define (xatt name) (lambda (x)
                      {[name]="[x]"}))

;;; xml attributes - wrap this around more than one attribute.
(define xas string-append)

(define-macro (defxtags . tags)
  `(begin
     ,@(map (lambda (tag) `(define ,tag (xtag ,(.toString tag)))) tags)))

(define-macro (defxatts . tags)
  `(begin
     ,@(map (lambda (tag) `(define ,tag (xatt ,(.toString tag)))) tags)))

(defxtags
  owl:Class
  owl:DatatypeProperty
  owl:ObjectProperty
  rdfs:comment
  rdfs:domain
  rdfs:range
  rdfs:subClassOf
  )

(defxatts
  rdf:datatype
  rdf:ID
  rdf:resource
  )