System.Path

A more type-safe version of file paths

This module provides the basic Path abstraction. See also System.Path.IO which extends this module by thin wrappers wrappers around common IO operations.

Paths

newtype Path a

Paths

A Path is simply a FilePath with a type-level tag indicating where this path is rooted (relative to the current directory, absolute path, relative to a web domain, whatever). Most operations on Path are just lifted versions of the operations on the underlying FilePath. The tag however allows us to give a lot of operations a more meaningful type. For instance, it does not make sense to append two absolute paths together; instead, we can only append an unrooted path to another path. It also means we avoid bugs where we use one kind of path where we expect another.

Constructors

Path FilePath

Instances

Eq (Path a)

Methods

(==) :: Path a -> Path a -> Bool

(/=) :: Path a -> Path a -> Bool

Ord (Path a)

Methods

compare :: Path a -> Path a -> Ordering

(<) :: Path a -> Path a -> Bool

(<=) :: Path a -> Path a -> Bool

(>) :: Path a -> Path a -> Bool

(>=) :: Path a -> Path a -> Bool

max :: Path a -> Path a -> Path a

min :: Path a -> Path a -> Path a

Show (Path a)

Methods

showsPrec :: Int -> Path a -> ShowS

show :: Path a -> String

showList :: [Path a] -> ShowS

NFData (Path a)

Methods

rnf :: Path a -> ()

castRoot :: Path root -> Path root'

Reinterpret the root of a path

This literally just changes the type-level tag; use with caution!

FilePath-like operations on paths with arbitrary roots

takeDirectory :: Path a -> Path a

Wrapped takeDirectory

takeFileName :: Path a -> String

Wrapped takeFileName

(<.>) :: Path a -> String -> Path a

Wrapped <.>

splitExtension :: Path a -> (Path a, String)

Wrapped splitExtension

takeExtension :: Path a -> String

Wrapped takeExtension

Unrooted paths

data Unrooted

Type-level tag for unrooted paths

Unrooted paths need a root before they can be interpreted.

(</>) :: Path a -> Path Unrooted -> Path a

Wrapped </>

rootPath :: Path Unrooted -> Path root

Reinterpret an unrooted path

This is an alias for castRoot; see comments there.

unrootPath :: Path root -> Path Unrooted

Forget a path's root

This is an alias for castRoot; see comments there.

toUnrootedFilePath :: Path Unrooted -> FilePath

Convert a relative/unrooted Path to a FilePath (using POSIX style directory separators).

See also toAbsoluteFilePath

fromUnrootedFilePath :: FilePath -> Path Unrooted

Convert from a relative/unrooted FilePath (using POSIX style directory separators).

fragment :: String -> Path Unrooted

A path fragment (like a single directory or filename)

joinFragments :: [String] -> Path Unrooted

Wrapped joinPath

splitFragments :: Path Unrooted -> [String]

Wrapped splitDirectories

File-system paths

class FsRoot root where

A file system root can be interpreted as an (absolute) FilePath

Minimal complete definition

toAbsoluteFilePath

Methods

toAbsoluteFilePath :: Path root -> IO FilePath

Convert a Path to an absolute FilePath (using native style directory separators).

Instances

FsRoot HomeDir

Methods

toAbsoluteFilePath :: Path HomeDir -> IO FilePath

FsRoot Absolute

Methods

toAbsoluteFilePath :: Path Absolute -> IO FilePath

FsRoot Relative

Methods

toAbsoluteFilePath :: Path Relative -> IO FilePath

data FsPath

Abstract over a file system root

see fromFilePath

Constructors

FsRoot root => FsPath (Path root)

Instances

NFData FsPath

Methods

rnf :: FsPath -> ()

data Relative

Instances

FsRoot Relative

Methods

toAbsoluteFilePath :: Path Relative -> IO FilePath

data Absolute

Instances

FsRoot Absolute

Methods

toAbsoluteFilePath :: Path Absolute -> IO FilePath

data HomeDir

Instances

FsRoot HomeDir

Methods

toAbsoluteFilePath :: Path HomeDir -> IO FilePath

Conversions

toFilePath :: Path Absolute -> FilePath

fromFilePath :: FilePath -> FsPath

makeAbsolute :: FsPath -> IO (Path Absolute)

fromAbsoluteFilePath :: FilePath -> Path Absolute