MissingH- Large utility library

MaintainerJohn Goerzen <jgoerzen@complete.org>
Safe HaskellNone




Haskell Virtual FS -- generic support for real or virtual filesystem in Haskell

Copyright (c) 2004-2005 John Goerzen, jgoerzen@complete.org

The idea of this module is to provide virtualization of filesystem calls. In addition to the "real" system filesystem, you can also provide access to other, virtual, filesystems using the same set of calls. Examples of such virtual filesystems might include a remote FTP server, WebDAV server, a local Hashtable, a ConfigParser object, or any other data structure you can represent as a tree of named nodes containing strings.

Each HVFS function takes a HVFS "handle" (HVFS instance) as its first parameter. If you wish to operate on the standard system filesystem, you can just use SystemFS.

The MissingH.HVFS.IO.InstanceHelpers module contains some code to help you make your own HVFS instances.

The HVFSOpenable class works together with the System.IO.HVIO module to provide a complete virtual filesystem and I/O model that allows you to open up virtual filesystem files and act upon them in a manner similar to standard Handles.


Implementation Classes / Types

class Show a => HVFS a whereSource

The main HVFS class.

Default implementations of these functions are provided:

Default implementations of all other functions will generate an isIllegalOperation error, since they are assumed to be un-implemented.

You should always provide at least a vGetFileStatus call, and almost certainly several of the others.

Most of these functions correspond to functions in System.Directory or System.Posix.Files. Please see detailed documentation on them there.


vGetCurrentDirectory :: a -> IO FilePathSource

vSetCurrentDirectory :: a -> FilePath -> IO ()Source

vGetDirectoryContents :: a -> FilePath -> IO [FilePath]Source

vDoesFileExist :: a -> FilePath -> IO BoolSource

vDoesDirectoryExist :: a -> FilePath -> IO BoolSource

vDoesExist :: a -> FilePath -> IO BoolSource

True if the file exists, regardless of what type it is. This is even True if the given path is a broken symlink.

vCreateDirectory :: a -> FilePath -> IO ()Source

vRemoveDirectory :: a -> FilePath -> IO ()Source

vRenameDirectory :: a -> FilePath -> FilePath -> IO ()Source

vRemoveFile :: a -> FilePath -> IO ()Source

vRenameFile :: a -> FilePath -> FilePath -> IO ()Source

vGetFileStatus :: a -> FilePath -> IO HVFSStatEncapSource

vGetSymbolicLinkStatus :: a -> FilePath -> IO HVFSStatEncapSource

vGetModificationTime :: a -> FilePath -> IO ClockTimeSource

vRaiseError :: a -> IOErrorType -> String -> Maybe FilePath -> IO cSource

Raise an error relating to actions on this class.

vCreateSymbolicLink :: a -> FilePath -> FilePath -> IO ()Source

vReadSymbolicLink :: a -> FilePath -> IO FilePathSource

vCreateLink :: a -> FilePath -> FilePath -> IO ()Source

class Show a => HVFSStat a whereSource

Evaluating types of files and information about them.

This corresponds to the System.Posix.Types.FileStatus type, and indeed, that is one instance of this class.

Inplementators must, at minimum, implement vIsDirectory and vIsRegularFile.

Default implementations of everything else are provided, returning reasonable values.

A default implementation of this is not currently present on Windows.

class HVFS a => HVFSOpenable a whereSource

Types that can open a HVIO object should be instances of this class. You need only implement vOpen.

data HVFSOpenEncap Source

Similar to HVFSStatEncap, but for vOpen result.


forall a . HVIO a => HVFSOpenEncap a 

data HVFSStatEncap Source

Encapsulate a HVFSStat result. This is required due to Haskell typing restrictions. You can get at it with:

 case encap of
    HVFSStatEncap x -> -- now use x


forall a . HVFSStat a => HVFSStatEncap a 

withStat :: forall b. HVFSStatEncap -> (forall a. HVFSStat a => a -> b) -> bSource

Convenience function for working with stat -- takes a stat result and a function that uses it, and returns the result.

Here is an example from the HVFS source:

    vGetModificationTime fs fp = 
       do s <- vGetFileStatus fs fp
          return $ epochToClockTime (withStat s vModificationTime)

See epochToClockTime for more information.

withOpen :: forall b. HVFSOpenEncap -> (forall a. HVIO a => a -> b) -> bSource

Similar to withStat, but for the vOpen result.

Re-exported types from other modules

type FilePath = String

File and directory names are values of type String, whose precise meaning is operating system dependent. Files can be opened, yielding a handle which can then be used to operate on the contents of that file.

type DeviceID = CDev

type FileID = CIno

type UserID = CUid

type GroupID = CGid