Talking from Scheme to Maxima



Hi, I posted this question in the comp.sci.symbolic newsgroup from a  
friend account and was redirected here.
I need from DrScheme to ask Maxima (MacOS-X) to compute - say - a  
series or an integral. I would like to :

i) produce in Scheme the lisp internal coding of my expression, say  
(/ x (+ (* x x) 1)) in the Maxima Lisp internal format ((MQUOTIENT)  
$X ((MPLUS) ((MTIMES) $X $X) 1)) ? I can do that if I know precisely  
this format. Rational functions and sin, cos will be enough.

ii) send this Maxima Lisp datum to a maxima startup file (is there  
one ??)

iii) to use from Scheme a system call to the Unix command line:
           (system "maxima")
     which launches Maxima, which reads the startup file, computes  
AND send the result in Lisp format in a text file maxima.out !

iv) read from Scheme the Lisp result in the file and translate it in  
Scheme.

I must confess that the complexity of Maxima hurts me, and I don't  
plan now to use Maxima for more than this. I know how to do that in  
Maple (not free, and even if i must parse, alas) but Maxima  
information seems to be burried deep...

Help needed mainly for points ii) and iii).

Moreover, to train myself to Lisp internal format, how can i see the  
internal format of Maxima expression like (x^2-3)/x, like the  
FullForm of Mathematica for example, at the toplevel ?

Thanks for all,

     Jean-Paul