Fwd: Creating a list of procedures in a file.

[Daniel Ridge]

On Nov 19, 2009, at 5:41 PM, Neil Jerram wrote:

> Alternatively, assuming that it is safe to do so - i.e. that there are
> no possible side-effects from reading - you could just read and  
> process
> the script.  Something like:
>
> (with-input-from-file FILENAME
> (lambda ()
>   (let loop ((x (read)) (defs '()))
>     (if (eof-object? x)
>         defs
>         (loop (read) (if (and (list? x)
>                               (>= (length x) 3)
>                               (eq? (car x) 'define)
>                               (pair? (cadr x)))
>                          (cons (caadr x) defs)
>                          defs))))))

I go back and forth between this totally static analysis and runtime  
introspection and I usually
come out favoring runtime introspection. Guile's fantastic  
introspection facilities are one of
the key reasons that I use Guile.

In the static case, above, you win on:

(define (x y) (+ y 5))

but lose on:

(define x (lambda (y) (+ y 5)))

and on:
(begin
 (define (x y) (+ y 5))
)

and on a dozen other top-level forms.

As for (current-module) vs. (resolve-interface '(bogo)), I think the  
answer is not necessarily so simple.

(module-public-interface (current-module)) might be more appropriate  
if the goal was to enumerate public interfaces.

On a distantly related note, I encourage interested Guilers to try out  
a snapshot of my interactive Scheme
system 'Proverb'. Its the web-based AJAX Guile shell I use every day  
(almost all day).

A rough snapshot is available at http://www.cqctworld.org/snap/proverb.tgz 
. I use it currently with guile-1.8.x and firefox 1.0 - 3.0.x. To run,  
unpack the tarball and run ./proverb and point your firefox browser at  
the URL printed on the console.

An online demo of just the Javascript shell portion is available  
online at: http://www.cqctworld.org/jsshell/jsshell.html
This online version is a REPL for Javascript only and not backed by a  
Scheme system.

To connect Proverb with the present topic, you could type:

(xhtml-find-undefined-in-module (resolve-interface '(guile)))

at the Proverb prompt and see some of the benefits of Guile  
introspection.

Cheers,
        Dan