A implementation of a zipper filesystem using delimited continuations. Zipper-based File/Operating system with threading and exceptions all realized via delimited continuations. There are no unsafe operations, no GHC (let alone) Unix threads, no concurrency problems. Our threads can't even do IO and can't mutate any global state - and the type system sees to it. To run, type main' fs1 on ghci after loading ZFS.hs. Then from some other terminal, type 'telnet localhost 1503'.