[Haskell-cafe] Cont, ContT and IO()

Hi, I've got an IO action, some file system IO, traversing one level only and iterating over files found. I wish to build in an "early" exit, ie. if an IO action in the loop encounters a particular value I want it to abort the loop. Now so far, pls don't shoot, I have done this by throwing IO Exceptions and catching them. I'm trying to rewrite this using Continuatios / callCC but can't figure out where to place what. I certainly don't have the intuition yet and funny enough not even in RWH I could find some Cont/ContT examples. Would someone please draw me an example? Günther