How to make System Calls in NHC98?

Hi :) ,  I am creating a tiny app in Haskell to search for a directory 
in the tree and change the current shell directory just to learn to 
program better in Haskell and I've always used the Win/Hugs98 
interpreter but I've just moved to FreeBSD/NHC98 because I want binary 
code and the thing is I can't find a function in NHC98 to make a pipe to 
comunicate with the shell (csh in my case) and that's the question: are 
the FreeBSD pipes functionality available in NHC98? By the way, can one 
make arbitrary System Calls in NHC98 by any means? if no, how can I 
change the shell's current directory?

Regards,
Alberto Dominguez  (Spain)