System.FilePath.Extra module

Currently introduces following functions:

dropPrefix :: FilePath -> FilePath -> Maybe FilePath
unsafeDropPrefix :: FilePath -> FilePath -> FilePath
changePrefixTo :: FilePath -> FilePath -> FilePath -> Maybe FilePath
unsafeChangePrefixTo :: FilePath -> FilePath -> FilePath -> FilePath
hasPrefix :: FilePath -> FilePath -> Bool
dropDirectories :: Int -> FilePath -> FilePath
takeDirectories :: Int -> FilePath -> FilePath
Dependency on filepath library