[Haskell] A opportunity to lern (parsing huge binary file)

[Skeptic .]

Hi,
I finally have an opportunity to learn Haskell (I'm a day-to-day Java programmer, but I'm also at ease with Scheme), parsing a huge (i.e. up to 50 go) binary file. The encoding is very stable, but it's not a flat struct array (i.e. it uses flags). 
Different outputs (i.e. text files) will be needed, some unknown at this time. 
Sounds to me a perfect "real-world" task to see what Haskell can offer.

Any suggestions at how to structure the code or on which packages to look at is welcome.

Thanks.