Safe Haskell	None
Language	Haskell2010

Types

data PosixString Source

Commonly used Posix string as uninterpreted char[] array.

data PosixChar Source

type PosixPath = PosixString Source

Filepaths are char[] data on unix as passed to syscalls.

Filepath construction

encodeUtf :: MonadThrow m => String -> m PosixString Source

Partial unicode friendly encoding.

This encodes as UTF8 (strictly), which is a good guess.

Throws an EncodingException if encoding fails. If the input does not contain surrogate chars, you can use unsafeEncodeUtf.

unsafeEncodeUtf :: HasCallStack => String -> PosixString Source

Unsafe unicode friendly encoding.

Like encodeUtf, except it crashes when the input contains surrogate chars. For sanitized input, this can be useful.

encodeWith :: TextEncoding -> String -> Either EncodingException PosixString Source

Encode a String with the specified encoding.

encodeFS :: String -> IO PosixPath Source

pstr :: QuasiQuoter Source

QuasiQuote a PosixPath. This accepts Unicode characters and encodes as UTF-8. Runs isValid on the input.

pack :: [PosixChar] -> PosixString Source

Pack a list of platform words to a platform string.

Note that using this in conjunction with unsafeFromChar to convert from [Char] to platform string is probably not what you want, because it will truncate unicode code points.

Filepath deconstruction

decodeUtf :: MonadThrow m => PosixString -> m String Source

Partial unicode friendly decoding.

This decodes as UTF8 (strictly), which is a good guess. Note that filenames on unix are encoding agnostic char arrays.

Throws a EncodingException if decoding fails.

decodeWith :: TextEncoding -> PosixString -> Either EncodingException String Source

Decode a PosixString with the specified encoding.

The String is forced into memory to catch all exceptions.

decodeFS :: PosixPath -> IO String Source

unpack :: PosixString -> [PosixChar] Source

Unpack a platform string to a list of platform words.

Word construction

unsafeFromChar :: Char -> PosixChar Source

Truncates to 1 octet.

Word deconstruction

toChar :: PosixChar -> Char Source

Converts back to a unicode codepoint (total).

Separator predicates

pathSeparator :: PosixChar Source

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

pathSeparator ==  '/'

pathSeparators :: [PosixChar] Source

The list of all possible separators.

pathSeparators == ['/']
pathSeparator `elem` pathSeparators

isPathSeparator :: PosixChar -> Bool Source

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

isPathSeparator a == (a `elem` pathSeparators)

searchPathSeparator :: PosixChar Source

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

searchPathSeparator == ':'

isSearchPathSeparator :: PosixChar -> Bool Source

Is the character a file separator?

isSearchPathSeparator a == (a == searchPathSeparator)

extSeparator :: PosixChar Source

File extension character

extSeparator == '.'

isExtSeparator :: PosixChar -> Bool Source

Is the character an extension character?

isExtSeparator a == (a == extSeparator)

$PATH methods

splitSearchPath :: PosixString -> [PosixPath] Source

Take a string, split it on the searchPathSeparator character.

Blank items are converted to . on , and quotes are not treated specially.

Follows the recommendations in http://www.opengroup.org/onlinepubs/009695399/basedefs/xbd_chap08.html

splitSearchPath "File1:File2:File3"  == ["File1","File2","File3"]
splitSearchPath "File1::File2:File3" == ["File1",".","File2","File3"]

Extension functions

splitExtension :: PosixPath -> (PosixPath, PosixString) Source

Split on the extension. addExtension is the inverse.

splitExtension "/directory/path.ext" == ("/directory/path",".ext")
uncurry (<>) (splitExtension x) == x
Valid 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 :: PosixPath -> PosixString Source

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

takeExtension "/directory/path.ext" == ".ext"
takeExtension x == snd (splitExtension x)
Valid x => takeExtension (addExtension x "ext") == ".ext"
Valid x => takeExtension (replaceExtension x "ext") == ".ext"

replaceExtension :: PosixPath -> PosixString -> PosixPath Source

Set the extension of a file, overwriting one if already present, equivalent to -<.>.

replaceExtension "/directory/path.txt" "ext" == "/directory/path.ext"
replaceExtension "/directory/path.txt" ".ext" == "/directory/path.ext"
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"
replaceExtension x y == addExtension (dropExtension x) y

(-<.>) :: PosixPath -> PosixString -> PosixPath Source

Remove the current extension and add another, equivalent to replaceExtension.

"/directory/path.txt" -<.> "ext" == "/directory/path.ext"
"/directory/path.txt" -<.> ".ext" == "/directory/path.ext"
"foo.o" -<.> "c" == "foo.c"

dropExtension :: PosixPath -> PosixPath Source

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

dropExtension "/directory/path.ext" == "/directory/path"
dropExtension x == fst (splitExtension x)

addExtension :: PosixPath -> PosixString -> PosixPath Source

Add an extension, even if there is already one there, equivalent to <.>.

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

Add an extension, even if there is already one there, equivalent to <.>.

addExtension "/directory/path" "ext" == "/directory/path.ext"
addExtension "file.txt" "bib" == "file.txt.bib"
addExtension "file." ".bib" == "file..bib"
addExtension "file" ".bib" == "file.bib"
addExtension "/" "x" == "/.x"
addExtension x "" == x
Valid x => takeFileName (addExtension (addTrailingPathSeparator x) "ext") == ".ext"

hasExtension :: PosixPath -> Bool Source

Does the given filename have an extension?

hasExtension "/directory/path.ext" == True
hasExtension "/directory/path" == False
null (takeExtension x) == not (hasExtension x)

(<.>) :: PosixPath -> PosixString -> PosixPath Source

Add an extension, even if there is already one there, equivalent to addExtension.

"/directory/path" <.> "ext" == "/directory/path.ext"
"/directory/path" <.> ".ext" == "/directory/path.ext"

splitExtensions :: PosixPath -> (PosixPath, PosixString) Source

Split on all extensions.

splitExtensions "/directory/path.ext" == ("/directory/path",".ext")
splitExtensions "file.tar.gz" == ("file",".tar.gz")
uncurry (<>) (splitExtensions x) == x
Valid x => uncurry addExtension (splitExtensions x) == x
splitExtensions "file.tar.gz" == ("file",".tar.gz")

dropExtensions :: PosixPath -> PosixPath Source

Drop all extensions.

dropExtensions "/directory/path.ext" == "/directory/path"
dropExtensions "file.tar.gz" == "file"
not $ hasExtension $ dropExtensions x
not $ any isExtSeparator $ takeFileName $ dropExtensions x

takeExtensions :: PosixPath -> PosixString Source

Get all extensions.

takeExtensions "/directory/path.ext" == ".ext"
takeExtensions "file.tar.gz" == ".tar.gz"

replaceExtensions :: PosixPath -> PosixString -> PosixPath Source

Replace all extensions of a file with a new extension. Note that replaceExtension and addExtension both work for adding multiple extensions, so only required when you need to drop all extensions first.

replaceExtensions "file.fred.bob" "txt" == "file.txt"
replaceExtensions "file.fred.bob" "tar.gz" == "file.tar.gz"

isExtensionOf :: PosixString -> PosixPath -> Bool Source

Does the given filename have the specified extension?

"png" `isExtensionOf` "/directory/file.png" == True
".png" `isExtensionOf` "/directory/file.png" == True
".tar.gz" `isExtensionOf` "bar/foo.tar.gz" == True
"ar.gz" `isExtensionOf` "bar/foo.tar.gz" == False
"png" `isExtensionOf` "/directory/file.png.jpg" == False
"csv/table.csv" `isExtensionOf` "/data/csv/table.csv" == False

stripExtension :: PosixString -> PosixPath -> Maybe PosixPath Source

Drop the given extension from a filepath, and the "." preceding it. Returns Nothing if the filepath does not have the given extension, or Just and the part before the extension if it does.

This function can be more predictable than dropExtensions, especially if the filename might itself contain . characters.

stripExtension "hs.o" "foo.x.hs.o" == Just "foo.x"
stripExtension "hi.o" "foo.x.hs.o" == Nothing
dropExtension x == fromJust (stripExtension (takeExtension x) x)
dropExtensions x == fromJust (stripExtension (takeExtensions x) x)
stripExtension ".c.d" "a.b.c.d"  == Just "a.b"
stripExtension ".c.d" "a.b..c.d" == Just "a.b."
stripExtension "baz"  "foo.bar"  == Nothing
stripExtension "bar"  "foobar"   == Nothing
stripExtension ""     x          == Just x

Filename/directory functions

splitFileName :: PosixPath -> (PosixPath, PosixPath) Source

Split a filename into directory and file. </> is the inverse. The first component will often end with a trailing slash.

splitFileName "/directory/file.ext" == ("/directory/","file.ext")
Valid x => uncurry (</>) (splitFileName x) == x || fst (splitFileName x) == "./"
Valid x => isValid (fst (splitFileName x))
splitFileName "file/bob.txt" == ("file/", "bob.txt")
splitFileName "file/" == ("file/", "")
splitFileName "bob" == ("./", "bob")
splitFileName "/" == ("/","")

takeFileName :: PosixPath -> PosixPath Source

Get the file name.

takeFileName "/directory/file.ext" == "file.ext"
takeFileName "test/" == ""
takeFileName x `isSuffixOf` x
takeFileName x == snd (splitFileName x)
Valid x => takeFileName (replaceFileName x "fred") == "fred"
Valid x => takeFileName (x </> "fred") == "fred"
Valid x => isRelative (takeFileName x)

replaceFileName :: PosixPath -> PosixString -> PosixPath Source

Set the filename.

replaceFileName "/directory/other.txt" "file.ext" == "/directory/file.ext"
Valid x => replaceFileName x (takeFileName x) == x

dropFileName :: PosixPath -> PosixPath Source

Drop the filename. Unlike takeDirectory, this function will leave a trailing path separator on the directory.

dropFileName "/directory/file.ext" == "/directory/"
dropFileName x == fst (splitFileName x)

takeBaseName :: PosixPath -> PosixPath Source

Get the base name, without an extension or path.

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

replaceBaseName :: PosixPath -> PosixString -> PosixPath Source

Set the base name.

replaceBaseName "/directory/other.ext" "file" == "/directory/file.ext"
replaceBaseName "file/test.txt" "bob" == "file/bob.txt"
replaceBaseName "fred" "bill" == "bill"
replaceBaseName "/dave/fred/bob.gz.tar" "new" == "/dave/fred/new.tar"
Valid x => replaceBaseName x (takeBaseName x) == x

takeDirectory :: PosixPath -> PosixPath Source

Get the directory name, move up one level.

          takeDirectory "/directory/other.ext" == "/directory"
          takeDirectory x `isPrefixOf` x || takeDirectory x == "."
          takeDirectory "foo" == "."
          takeDirectory "/" == "/"
          takeDirectory "/foo" == "/"
          takeDirectory "/foo/bar/baz" == "/foo/bar"
          takeDirectory "/foo/bar/baz/" == "/foo/bar/baz"
          takeDirectory "foo/bar/baz" == "foo/bar"

replaceDirectory :: PosixPath -> PosixPath -> PosixPath Source

Set the directory, keeping the filename the same.

replaceDirectory "root/file.ext" "/directory/" == "/directory/file.ext"
Valid x => replaceDirectory x (takeDirectory x) `equalFilePath` x

combine :: PosixPath -> PosixPath -> PosixPath Source

An alias for </>.

(</>) :: PosixPath -> PosixPath -> PosixPath Source

Combine two paths with a path separator. If the second path starts with a path separator or a drive letter, then it returns the second. The intention is that readFile (dir </> file) will access the same file as setCurrentDirectory dir; readFile file.

"/directory" </> "file.ext" == "/directory/file.ext"
Valid x => (takeDirectory x </> takeFileName x) `equalFilePath` x

Combined:

"/" </> "test" == "/test"
"home" </> "bob" == "home/bob"
"x:" </> "foo" == "x:/foo"

Not combined:

"home" </> "/bob" == "/bob"

splitPath :: PosixPath -> [PosixPath] Source

Split a path by the directory separator.

splitPath "/directory/file.ext" == ["/","directory/","file.ext"]
concat (splitPath x) == x
splitPath "test//item/" == ["test//","item/"]
splitPath "test/item/file" == ["test/","item/","file"]
splitPath "" == []
splitPath "/file/test" == ["/","file/","test"]

joinPath :: [PosixPath] -> PosixPath Source

Join path elements back together.

joinPath z == foldr (</>) "" z
joinPath ["/","directory/","file.ext"] == "/directory/file.ext"
Valid x => joinPath (splitPath x) == x
joinPath [] == ""
joinPath ["test","file","path"] == "test/file/path"

splitDirectories :: PosixPath -> [PosixPath] Source

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

splitDirectories "/directory/file.ext" == ["/","directory","file.ext"]
splitDirectories "test/file" == ["test","file"]
splitDirectories "/test/file" == ["/","test","file"]
Valid x => joinPath (splitDirectories x) `equalFilePath` x
splitDirectories "" == []
splitDirectories "/test///file" == ["/","test","file"]

Drive functions

splitDrive :: PosixPath -> (PosixPath, PosixPath) Source

Split a path into a drive and a path. / is a Drive.

uncurry (<>) (splitDrive x) == x
splitDrive "/test" == ("/","test")
splitDrive "//test" == ("//","test")
splitDrive "test/file" == ("","test/file")
splitDrive "file" == ("","file")

joinDrive :: PosixPath -> PosixPath -> PosixPath Source

Join a drive and the rest of the path.

Valid x => uncurry joinDrive (splitDrive x) == x
Windows: joinDrive "C:" "foo" == "C:foo"
Windows: joinDrive "C:\\" "bar" == "C:\\bar"
Windows: joinDrive "\\\\share" "foo" == "\\\\share\\foo"
Windows: joinDrive "/:" "foo" == "/:\\foo"

Join a drive and the rest of the path.

Valid x => uncurry joinDrive (splitDrive x) == x

takeDrive :: PosixPath -> PosixPath Source

Get the drive from a filepath.

takeDrive x == fst (splitDrive x)

hasDrive :: PosixPath -> Bool Source

Does a path have a drive.

not (hasDrive x) == null (takeDrive x)
hasDrive "/foo" == True
hasDrive "foo" == False
hasDrive "" == False

dropDrive :: PosixPath -> PosixPath Source

Delete the drive, if it exists.

dropDrive x == snd (splitDrive x)

isDrive :: PosixPath -> Bool Source

Is an element a drive

isDrive "/" == True
isDrive "/foo" == False
isDrive "" == False

Trailing slash functions

hasTrailingPathSeparator :: PosixPath -> Bool Source

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

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

addTrailingPathSeparator :: PosixPath -> PosixPath Source

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

hasTrailingPathSeparator (addTrailingPathSeparator x)
hasTrailingPathSeparator x ==> addTrailingPathSeparator x == x
addTrailingPathSeparator "test/rest" == "test/rest/"

dropTrailingPathSeparator :: PosixPath -> PosixPath Source

Remove any trailing path separators

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

File name manipulations

normalise :: PosixPath -> PosixPath Source

Normalise a file

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

Does not remove "..", because of symlinks.

normalise "/file/\\test////" == "/file/\\test/"
normalise "/file/./test" == "/file/test"
normalise "/test/file/../bob/fred/" == "/test/file/../bob/fred/"
normalise "../bob/fred/" == "../bob/fred/"
normalise "/a/../c" == "/a/../c"
normalise "./bob/fred/" == "bob/fred/"
normalise "." == "."
normalise "./" == "./"
normalise "./." == "./"
normalise "/./" == "/"
normalise "/" == "/"
normalise "bob/fred/." == "bob/fred/"
normalise "//home" == "/home"

equalFilePath :: PosixPath -> PosixPath -> Bool Source

Equality of two filepaths. 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.

Similar to normalise, this does not expand "..", because of symlinks.

x == y ==> equalFilePath x y
normalise x == normalise y ==> equalFilePath x y
equalFilePath "foo" "foo/"
not (equalFilePath "/a/../c" "/c")
not (equalFilePath "foo" "/foo")
not (equalFilePath "foo" "FOO")

makeRelative :: PosixPath -> PosixPath -> PosixPath Source

Contract a filename, based on a relative path. Note that the resulting path will never introduce .. paths, as the presence of symlinks means ../b may not reach a/b if it starts from a/c. For a worked example see this blog post.

The corresponding makeAbsolute function can be found in System.Directory.

makeRelative "/directory" "/directory/file.ext" == "file.ext"
Valid x => makeRelative (takeDirectory x) x `equalFilePath` takeFileName x
makeRelative x x == "."
Valid x y => equalFilePath x y || (isRelative x && makeRelative y x == x) || equalFilePath (y </> makeRelative y x) x
makeRelative "/Home" "/home/bob" == "/home/bob"
makeRelative "/home/" "/home/bob/foo/bar" == "bob/foo/bar"
makeRelative "/fred" "bob" == "bob"
makeRelative "/file/test" "/file/test/fred" == "fred"
makeRelative "/file/test" "/file/test/fred/" == "fred/"
makeRelative "some/path" "some/path/a/b/c" == "a/b/c"

isRelative :: PosixPath -> Bool Source

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

isRelative "test/path" == True
isRelative "/test" == False
isRelative "/" == False

isAbsolute :: PosixPath -> Bool Source

not . isRelative

isAbsolute x == not (isRelative x)

isValid :: PosixPath -> Bool Source

Is a filepath valid, i.e. could you create a file like it? This function checks for invalid names, and invalid characters, but does not check if length limits are exceeded, as these are typically filesystem dependent.

isValid "" == False
isValid "\0" == False
isValid "/random_ path:*" == True
isValid x == not (null x)

makeValid :: PosixPath -> PosixPath Source

Take a filepath and make it valid; does not change already valid filepaths.

isValid (makeValid x)
isValid x ==> makeValid x == x
makeValid "" == "_"
makeValid "file\0name" == "file_name"