On Mon, Jan 29, 2007 at 08:14:55PM +0100, Michael Roth wrote:
Hello list,
Hi! Just to simplify one function...
logdir = "/var/log" ... makeOldname :: String -> String makeOldname fn = logdir ++ '/' : fn ... main :: IO () main = do files <- liftM (filter isLogfile) (getDirectoryContents logdir) let oldnames = map makeOldname files times <- mapM getModificationTime oldnames
main = do files <- liftM (filter isLogfile) (getDirectoryContents logdir) times <- mapM (getModificationTime . ("/var/log/"++)) files (also consider) main = do files <- filter isLogfile `fmap` getDirectoryContents logdir times <- (getModificationTime . ("/var/log/"++)) `mapM` files If you count reindenting of the first line of the do statement and removal of type signatures, I've eliminated six out of eight lines, and the resulting function doesn't need to be read like spaghetti, looking back and forth to find out what makeOldname and logdir are. Of course, if you expect to change logdir or use it elsewhere in the code, you still might want to give it a name. But my versions I'd say are more readable and much more compact. On large projects it's worthwhile using type declarations for top-level functions, and it's worth adding them while debugging (to get better error messages), or for tricky functions where the types aren't obvious. But for code like this, they just make it harder to read. -- David Roundy Department of Physics Oregon State University