| Portability | portable |
|---|---|
| Stability | experimental |
| Maintainer | Brandon Simmons <brandon.m.simmons@gmail.com> |
System.Directory.Tree
Contents
Description
Provides a simple data structure mirroring a directory tree on the filesystem, as well as useful functions for reading and writing file and directory structures in the IO monad.
Errors are caught in a special constructor in the DirTree type.
Defined instances of Functor, Traversable and Foldable allow for easily operating on a directory of files. For example, you could use Foldable.foldr to create a hash of the entire contents of a directory.
The AnchoredDirTree type is a simple wrapper for DirTree to keep track of a base directory context for the DirTree.
Please send me any requests, bugs, or other feedback on this module!
- data DirTree a
- data AnchoredDirTree a = FilePath :/ (DirTree a)
- type FileName = String
- readDirectory :: FilePath -> IO (AnchoredDirTree String)
- readDirectoryWith :: (FilePath -> IO a) -> FilePath -> IO (AnchoredDirTree a)
- writeDirectory :: AnchoredDirTree String -> IO ()
- writeDirectoryWith :: (FilePath -> a -> IO ()) -> AnchoredDirTree a -> IO ()
- zipPaths :: AnchoredDirTree a -> DirTree (FilePath, a)
- build :: FilePath -> IO (AnchoredDirTree FilePath)
- openDirectory :: FilePath -> IOMode -> IO (AnchoredDirTree Handle)
- writeJustDirs :: AnchoredDirTree a -> IO ()
- successful :: DirTree a -> Bool
- anyFailed :: DirTree a -> Bool
- failures :: DirTree a -> [DirTree a]
- failedMap :: (FileName -> IOException -> DirTree a) -> DirTree a -> DirTree a
- free :: AnchoredDirTree a -> DirTree a
Data types for representing directory trees
data DirTree a
the String in the name field is always a file name, never a full path.
The free type variable is used in the File constructor and can hold Handles,
Strings representing a file's contents or anything else you can think of.
We catch any IO errors in the Failed constructor. an Exception can be
converted to a String with show.
data AnchoredDirTree a
a simple wrapper to hold a base directory name, which can be either an absolute or relative path. This lets us give the DirTree a context, while still letting us store only directory and file NAMES (not full paths) in the DirTree. (uses an infix constructor; don't be scared)
Instances
| Eq a => Eq (AnchoredDirTree a) | |
| Ord a => Ord (AnchoredDirTree a) | |
| Show a => Show (AnchoredDirTree a) |
High level IO functions
readDirectory :: FilePath -> IO (AnchoredDirTree String)
build an AnchoredDirTree, given the path to a directory, opening the files using readFile.
readDirectoryWith :: (FilePath -> IO a) -> FilePath -> IO (AnchoredDirTree a)
same as readDirectory but allows us to, for example, use ByteString.readFile to return a tree of ByteStrings.
writeDirectory :: AnchoredDirTree String -> IO ()
write a DirTree of strings to disk. clobbers files of the same name. doesn't affect files in the directories (if any already exist) with different names:
writeDirectoryWith :: (FilePath -> a -> IO ()) -> AnchoredDirTree a -> IO ()
writes the directory structure to disc, then uses the provided function to write the contents of Files to disc.
Lower level functions
zipPaths :: AnchoredDirTree a -> DirTree (FilePath, a)
tuple up the complete filename with the File contents, by building up the path, trie-style, from the root. The filepath will be relative to the current directory. This allows us to, for example, mapM_ 'uncurry writeFile' over a DirTree of strings.
build :: FilePath -> IO (AnchoredDirTree FilePath)
builds a DirTree from the contents of the directory passed to it, saving
the base directory in the Anchored* wrapper. Errors are caught in the tree in
the Failed constructor. The file fields initially are populated with full
paths to the files they are abstracting.
openDirectory :: FilePath -> IOMode -> IO (AnchoredDirTree Handle)
a simple application of readDirectoryWith openFile:
writeJustDirs :: AnchoredDirTree a -> IO ()
writes the directory structure (not files) of a DirTree to the anchored directory. can be preparation for writing files:
Utility functions
Handling failure
successful :: DirTree a -> Bool
True if there are no Failed constructors in the tree
failedMap :: (FileName -> IOException -> DirTree a) -> DirTree a -> DirTree a
maps a function to convert Failed DirTrees to Files or Dirs
Misc.
free :: AnchoredDirTree a -> DirTree a
strips away base directory wrapper: