[plt-scheme] foldl, map, filter with sequences?

Hi,

I have a rather large list which would be handled best if I wouldn't
need to create it as one big thing but rather compute on need (it is
the output of string-tokenize applied on a 350 MB file). As I am using
foldl in my program, I don't need all items at once. Is there a way to
feed a sequence into foldl? Or maybe there a sequence-foldl?

regards,
Marek