[Jscheme-user] hack of the day 2 - building debugging tools

[Timothy J. H. <tim...@ma...>]

Nice example!

Maybe we should create a webpage of Jscheme snippets on the  
jscheme.sourceforge.net site.
This one  could be titled something like

    * generate a sort list of selected fields from tab-separated file of  
records...


Here's an example I wrote today.
Its a servlet that generates a webpage showing all of the symbols that  
are defined

If you call it with a "which" parameters, e.g.
       show_bindings.servlet?new
it will filter out all of the primitives, all of the javadot, and all  
those symbols defined in elf/basic.scm

;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;; 
;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;
;;; show_bindings.servlet
(servlet (new)
   (define js (jscheme.JScheme.))
   (define mod (.eval js '(use-module "elf/basic.scm")))

   (define (getBindings env)  (.rep$# env))
   (define jsenv (.INTERACTION_ENVIRONMENT$ (.evaluator$# js)))

   (define primitives
      (getBindings jsenv))
   (define currentbindings
      (getBindings (.INTERACTION_ENVIRONMENT$  
(jsint.Scheme.currentEvaluator))))

   (define newbindings
      (filter
           (lambda(x)
               (or (equal? which #null)
                 (and
                    (equal? #null (.get primitives x))
                    (= -1 (.indexOf (.toString x) "."))  )))
          (map* (lambda(x) x) (.keys currentbindings))))

   (define (show-bindings)
     {<ol>[
       (map*
         (lambda(x){<li>[x] </li>\n})
         (sort newbindings (comparator string<? .toString)))
          ]
     </ol>})

(show-bindings)
)
;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;; 
;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;


This is somewhat fragile code however since it uses the jsint package  
and things may change
more rapidly in jsint than in jscheme (witness the disappearance of  
jsint.Version.java!)

---Tim---

On Jun 23, 2004, at 7:10 PM, Ken Anderson wrote:

> I wrote this piece of code today and it struck me:
>
> (define (readCountryData)
>   (sort
>    (remove-duplicates
>     (readingTabData
>      (File. "../dafif/Dafift/AppC/appc_cc_icao.txt")
>      (lambda (country country_name icao_rgn usage)
>        (list country country_name))))
>    (comparator string<? car)))
>
> (define (readingTabData file f)
>   (map* (lambda (r) (apply f (vector->list (.split r "\t"))))
>         (BufferedReader. (FileReader. file))))
>
> Now, this code can be improved in a lot of ways, but it did what i  
> wanted - grind over a tab separated file, extract the fields i wanted,  
> and sort the result.  It also abstracted out readinging from a tab  
> separated file so it can be resused.
>
> While you might argue that i should have produced an iterator to be  
> Java compatible, to do it in Java, you'd need  an interface with  
> methods call and apply, and each of the 4 loops would require at least  
> 50% more lines of code.
>
>
>
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