| Haskell Hierarchical Libraries (filepath package) | Source code | Contents | Index

System.FilePath.Posix

Portability | portable
Stability | stable
Maintainer | libraries@haskell.org

Contents

Separator predicates
Path methods (environment $PATH)
Extension methods
Operations on a FilePath, as a list of directories
Low level FilePath operators
File name manipulators

Description
A library for FilePath manipulations, using Posix style paths on all platforms. Importing System.FilePath is usually better.
Synopsis

FilePath
pathSeparator :: Char
pathSeparators :: [Char]
isPathSeparator :: Char -> Bool
searchPathSeparator :: Char
isSearchPathSeparator :: Char -> Bool
extSeparator :: Char
isExtSeparator :: Char -> Bool
splitSearchPath :: String -> [FilePath]
getSearchPath :: IO [FilePath]
splitExtension :: FilePath -> (String, String)
takeExtension :: FilePath -> String
replaceExtension :: FilePath -> String -> FilePath
dropExtension :: FilePath -> FilePath
addExtension :: FilePath -> String -> FilePath
hasExtension :: FilePath -> Bool
(<.>) :: FilePath -> String -> FilePath
splitExtensions :: FilePath -> (FilePath, String)
dropExtensions :: FilePath -> FilePath
takeExtensions :: FilePath -> String
splitFileName :: FilePath -> (String, String)
takeFileName :: FilePath -> FilePath
replaceFileName :: FilePath -> String -> FilePath
dropFileName :: FilePath -> FilePath
takeBaseName :: FilePath -> String
replaceBaseName :: FilePath -> String -> FilePath
takeDirectory :: FilePath -> FilePath
replaceDirectory :: FilePath -> String -> FilePath
combine :: FilePath -> FilePath -> FilePath
(</>) :: FilePath -> FilePath -> FilePath
splitPath :: FilePath -> [FilePath]
joinPath :: [FilePath] -> FilePath
splitDirectories :: FilePath -> [FilePath]
hasTrailingPathSeparator :: FilePath -> Bool
addTrailingPathSeparator :: FilePath -> FilePath
dropTrailingPathSeparator :: FilePath -> FilePath
normalise :: FilePath -> FilePath
equalFilePath :: FilePath -> FilePath -> Bool
makeRelativeToCurrentDirectory :: FilePath -> IO FilePath
makeRelative :: FilePath -> FilePath -> FilePath
isRelative :: FilePath -> Bool
isAbsolute :: FilePath -> Bool
isValid :: FilePath -> Bool
makeValid :: FilePath -> FilePath

Separator predicates
FilePath
pathSeparator :: Char

The character that separates directories. In the case where more than one character is possible, `pathSeparator` is the 'ideal' one.

     Windows: pathSeparator == '\\'
     Posix:   pathSeparator ==  '/'
     isPathSeparator pathSeparator

pathSeparators :: [Char]

The list of all possible separators.

     Windows: pathSeparators == ['\\', '/']
     Posix:   pathSeparators == ['/']
     pathSeparator `elem` pathSeparators

isPathSeparator :: Char -> Bool

Rather than using `(== `pathSeparator`)`, use this. Test if something is a path separator.

     isPathSeparator a == (a `elem` pathSeparators)

searchPathSeparator :: Char

The character that is used to separate the entries in the $PATH environment variable.

     Windows: searchPathSeparator == ';'
     Posix:   searchPathSeparator == ':'

isSearchPathSeparator :: Char -> Bool

Is the character a file separator?

     isSearchPathSeparator a == (a == searchPathSeparator)

extSeparator :: Char

File extension character

     extSeparator == '.'

isExtSeparator :: Char -> Bool

Is the character an extension character?

     isExtSeparator a == (a == extSeparator)

Path methods (environment $PATH)
splitSearchPath :: String -> [FilePath]

Take a string, split it on the `searchPathSeparator` character.

     Windows: splitSearchPath "File1;File2;File3" == ["File1","File2","File3"]
     Posix:   splitSearchPath "File1:File2:File3" == ["File1","File2","File3"]

getSearchPath :: IO [FilePath]
Get a list of filepaths in the $PATH.
Extension methods
splitExtension :: FilePath -> (String, String)

Split on the extension. `addExtension` is the inverse.

     uncurry (++) (splitExtension x) == x
     uncurry addExtension (splitExtension x) == x
     splitExtension "file.txt" == ("file",".txt")
     splitExtension "file" == ("file","")
     splitExtension "file/file.txt" == ("file/file",".txt")
     splitExtension "file.txt/boris" == ("file.txt/boris","")
     splitExtension "file.txt/boris.ext" == ("file.txt/boris",".ext")
     splitExtension "file/path.txt.bob.fred" == ("file/path.txt.bob",".fred")
     splitExtension "file/path.txt/" == ("file/path.txt/","")

takeExtension :: FilePath -> String

Get the extension of a file, returns `""` for no extension, `.ext` otherwise.

     takeExtension x == snd (splitExtension x)
     takeExtension (addExtension x "ext") == ".ext"
     takeExtension (replaceExtension x "ext") == ".ext"

replaceExtension :: FilePath -> String -> FilePath

Set the extension of a file, overwriting one if already present.

     replaceExtension "file.txt" ".bob" == "file.bob"
     replaceExtension "file.txt" "bob" == "file.bob"
     replaceExtension "file" ".bob" == "file.bob"
     replaceExtension "file.txt" "" == "file"
     replaceExtension "file.fred.bob" "txt" == "file.fred.txt"

dropExtension :: FilePath -> FilePath

Remove last extension, and the "." preceding it.

     dropExtension x == fst (splitExtension x)

addExtension :: FilePath -> String -> FilePath

Add an extension, even if there is already one there. E.g. `addExtension "foo.txt" "bat" -> "foo.txt.bat"`.

     addExtension "file.txt" "bib" == "file.txt.bib"
     addExtension "file." ".bib" == "file..bib"
     addExtension "file" ".bib" == "file.bib"
     addExtension "/" "x" == "/.x"
     takeFileName (addExtension (addTrailingPathSeparator x) "ext") == ".ext"
     Windows: addExtension "\\\\share" ".txt" == "\\\\share\\.txt"

hasExtension :: FilePath -> Bool

Does the given filename have an extension?

     null (takeExtension x) == not (hasExtension x)

(<.>) :: FilePath -> String -> FilePath
Alias to `addExtension`, for people who like that sort of thing.
splitExtensions :: FilePath -> (FilePath, String)

Split on all extensions

     splitExtensions "file.tar.gz" == ("file",".tar.gz")

dropExtensions :: FilePath -> FilePath

Drop all extensions

     not $ hasExtension (dropExtensions x)

takeExtensions :: FilePath -> String
Get all extensions
Operations on a FilePath, as a list of directories
splitFileName :: FilePath -> (String, String)

Split a filename into directory and file. `combine` is the inverse.

     uncurry (++) (splitFileName x) == x
     uncurry combine (splitFileName (makeValid x)) == (makeValid x)
     splitFileName "file/bob.txt" == ("file/", "bob.txt")
     splitFileName "file/" == ("file/", "")
     splitFileName "bob" == ("", "bob")
     Posix:   splitFileName "/" == ("/","")
     Windows: splitFileName "c:" == ("c:","")

takeFileName :: FilePath -> FilePath

Get the file name.

     takeFileName "test/" == ""
     takeFileName x == snd (splitFileName x)
     takeFileName (replaceFileName x "fred") == "fred"
     takeFileName (combine x "fred") == "fred"
     isRelative (takeFileName (makeValid x))

replaceFileName :: FilePath -> String -> FilePath

Set the filename.

     replaceFileName (makeValid x) (takeFileName (makeValid x)) == makeValid x

dropFileName :: FilePath -> FilePath

Drop the filename.

     dropFileName x == fst (splitFileName x)

takeBaseName :: FilePath -> String

Get the base name, without an extension or path.

     takeBaseName "file/test.txt" == "test"
     takeBaseName "dave.ext" == "dave"
     takeBaseName "" == ""
     takeBaseName "test" == "test"
     takeBaseName (addTrailingPathSeparator x) == ""
     takeBaseName "file/file.tar.gz" == "file.tar"

replaceBaseName :: FilePath -> String -> FilePath

Set the base name.

     replaceBaseName "file/test.txt" "bob" == "file/bob.txt"
     replaceBaseName "fred" "bill" == "bill"
     replaceBaseName "/dave/fred/bob.gz.tar" "new" == "/dave/fred/new.tar"
     replaceBaseName x (takeBaseName x) == x

takeDirectory :: FilePath -> FilePath

Get the directory name, move up one level.

     Posix:    takeDirectory "/foo/bar/baz" == "/foo/bar"
     Posix:    takeDirectory "/foo/bar/baz/" == "/foo/bar/baz"
     Windows:  takeDirectory "foo\\bar" == "foo"
     Windows:  takeDirectory "foo\\bar\\\\" == "foo\\bar"
     Windows:  takeDirectory "C:\\" == "C:\\"

replaceDirectory :: FilePath -> String -> FilePath

Set the directory, keeping the filename the same.

     replaceDirectory x (takeDirectory x) `equalFilePath` x

combine :: FilePath -> FilePath -> FilePath

Combine two paths, if the second path `isAbsolute`, then it returns the second.

     combine (takeDirectory (makeValid x)) (takeFileName (makeValid x)) `equalFilePath` makeValid x
     Posix:   combine "/" "test" == "/test"
     Posix:   combine "home" "bob" == "home/bob"
     Windows: combine "home" "bob" == "home\\bob"

(</>) :: FilePath -> FilePath -> FilePath
A nice alias for `combine`.
splitPath :: FilePath -> [FilePath]

Split a path by the directory separator.

     concat (splitPath x) == x
     splitPath "test//item/" == ["test//","item/"]
     splitPath "test/item/file" == ["test/","item/","file"]
     splitPath "" == []
     Windows: splitPath "c:\\test\\path" == ["c:\\","test\\","path"]
     Posix:   splitPath "/file/test" == ["/","file/","test"]

joinPath :: [FilePath] -> FilePath

Join path elements back together.

     joinPath (splitPath (makeValid x)) == makeValid x

splitDirectories :: FilePath -> [FilePath]

Just as `splitPath`, but don't add the trailing slashes to each element.

     splitDirectories "test/file" == ["test","file"]
     splitDirectories "/test/file" == ["/","test","file"]
     joinPath (splitDirectories (makeValid x)) `equalFilePath` makeValid x
     splitDirectories "" == []

Low level FilePath operators
hasTrailingPathSeparator :: FilePath -> Bool

Is an item either a directory or the last character a path separator?

     hasTrailingPathSeparator "test" == False
     hasTrailingPathSeparator "test/" == True

addTrailingPathSeparator :: FilePath -> FilePath

Add a trailing file path separator if one is not already present.

     hasTrailingPathSeparator (addTrailingPathSeparator x)
     if hasTrailingPathSeparator x then addTrailingPathSeparator x == x else True
     Posix:    addTrailingPathSeparator "test/rest" == "test/rest/"

dropTrailingPathSeparator :: FilePath -> FilePath

Remove any trailing path separators

     dropTrailingPathSeparator "file/test/" == "file/test"
     not (hasTrailingPathSeparator (dropTrailingPathSeparator x)) || isDrive x
     Posix:    dropTrailingPathSeparator "/" == "/"

File name manipulators
normalise :: FilePath -> FilePath

Normalise a file

- // outside of the drive can be made blank
- / -> `pathSeparator`
- ./ -> ""

     Posix:   normalise "/file/\\test////" == "/file/\\test/"
     Posix:   normalise "/file/./test" == "/file/test"
     Posix:   normalise "/test/file/../bob/fred/" == "/test/file/../bob/fred/"
     Posix:   normalise "../bob/fred/" == "../bob/fred/"
     Posix:   normalise "./bob/fred/" == "bob/fred/"
     Windows: normalise "c:\\file/bob\\" == "C:\\file\\bob\\"
     Windows: normalise "\\\\server\\test" == "\\\\server\\test"
     Windows: normalise "c:/file" == "C:\\file"

equalFilePath :: FilePath -> FilePath -> Bool
Equality of two `FilePath`s. If you call `System.Directory.canonicalizePath` first this has a much better chance of working. Note that this doesn't follow symlinks or DOSNAM~1s.
makeRelativeToCurrentDirectory :: FilePath -> IO FilePath
`makeRelative` the current directory.
makeRelative :: FilePath -> FilePath -> FilePath

Contract a filename, based on a relative path.

     Windows: makeRelative x (x `combine` y) == y || takeDrive x == x
     Posix:   makeRelative x (x `combine` y) == y
     (isRelative x && makeRelative y x == x) || y `combine` makeRelative y x == x
     Windows: makeRelative "C:\\Home" "c:\\home\\bob" == "bob"
     Posix:   makeRelative "/Home" "/home/bob" == "/home/bob"
     Posix:   makeRelative "/home/" "/home/bob/foo/bar" == "bob/foo/bar"
     Posix:   makeRelative "/fred" "bob" == "bob"
     Posix:   makeRelative "/file/test" "/file/test/fred" == "fred"
     Posix:   makeRelative "/file/test" "/file/test/fred/" == "fred/"
     Posix:   makeRelative "some/path" "some/path/a/b/c" == "a/b/c"

isRelative :: FilePath -> Bool

Is a path relative, or is it fixed to the root?

     Windows: isRelative "path\\test" == True
     Windows: isRelative "c:\\test" == False
     Posix:   isRelative "test/path" == True
     Posix:   isRelative "/test" == False

isAbsolute :: FilePath -> Bool

    not . isRelative

     isAbsolute x == not (isRelative x)

isValid :: FilePath -> Bool

Is a FilePath valid, i.e. could you create a file like it?

     Posix:   isValid "/random_ path:*" == True
     Posix:   isValid x == True
     Windows: isValid "c:\\test" == True
     Windows: isValid "c:\\test:of_test" == False
     Windows: isValid "test*" == False
     Windows: isValid "c:\\test\\nul" == False
     Windows: isValid "c:\\test\\prn.txt" == False
     Windows: isValid "c:\\nul\\file" == False

makeValid :: FilePath -> FilePath

Take a FilePath and make it valid; does not change already valid FilePaths.

     isValid (makeValid x)
     if isValid x then makeValid x == x else True
     Windows: makeValid "c:\\test:of_test" == "c:\\test_of_test"
     Windows: makeValid "test*" == "test_"
     Windows: makeValid "c:\\test\\nul" == "c:\\test\\nul_"
     Windows: makeValid "c:\\test\\prn.txt" == "c:\\test\\prn_.txt"
     Windows: makeValid "c:\\test/prn.txt" == "c:\\test/prn_.txt"
     Windows: makeValid "c:\\nul\\file" == "c:\\nul_\\file"

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