For currently standard GHC libraries, see here:

http://www.haskell.org/ghc/docs/latest/html/libraries/index.html

'LibPosix' and 'LibSystem' look like names from before the current hierarchical module system was adopted, so it would seem that code is somewhat outdated.  LibPosix should probably be System.Posix , but I'm not sure what used to be in LibSystem and where it could be found now.  If you're determined to get it to work, try searching the libraries for the names of systemish-looking functions in Hsh.hs, and see if you can find in what modules they now live, and import those.  No promises that the APIs haven't changed, though, so you might still have problems anyway.

The Haskell Report is "definitive" but not very current (it is almost 10 years old at this point).  In practice, there are many extensions to the language and libraries which are fairly widespread and standard but are not documented in the Report.  Hopefully Haskell' will fix that, but no telling when that will be done!

-Brent