Haskell is great at manipulating tree structures, but I can't seem to find anything representing a directory tree. A simple representation would be something like this: data Dir = Dir {dirName :: String, subDirectories :: [Dir], files :: [File]} data File = File {fileName :: String, fileSize :: Int} Maybe these would need to be parametrized to allow a function splitting files by extension or that kind of thing. Anyway, the whole idea would be to abstract as much of the file stuff out of the IO monad as possible. I haven't used the "Scrap Your Boilerplate" stuff yet, but it seems like that could fit in here naturally to traverse a Dir and make changes at specified points. The only problem I can see (so far) with the approach is that it might make "big changes" to the directory tree too easy to make. I'm not sure immediately how to deal with that, or if the answer is just to post a "be careful" disclaimer. So, what do you think? Do you know of any work in this direction? Is there a way to make "dangerous 1-liners" safe? Is there a fundamental flaw with the approach I'm missing? Thanks much, Chad