This is a Cabalized and somewhat modernized/cleaned-up package containing Oleg's famous ZipperFS. For details, see <http://lambda-the-ultimate.org/node/1036>.

A demonstration of how to use it is contained in zfs.pdf. The short of the matter is:

       "Load ZFS.hs into GHCi
       Start up the system: main at the GHCi prompt
       From some terminal: 'telnet localhost 1503'"

And then you can play around with it.

This package also comes with an old implementation of delimited continuations. Ideally it would be updated to use the maintained package, CC-Delcont <http://hackage.haskell.org/cgi-bin/hackage-scripts/package/CC-delcont>. But I don't know how.