Safe Haskell	None
Language	Haskell2010

Types

data WindowsString Source

Commonly used windows string as wide character bytes.

data WindowsChar Source

type WindowsPath = WindowsString Source

Filepaths are wchar_t* data on windows as passed to syscalls.

Filepath construction

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

Partial unicode friendly encoding.

This encodes as UTF16-LE (strictly), which is a pretty good guess.

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

unsafeEncodeUtf :: HasCallStack => String -> WindowsString Source

Unsafe unicode friendly encoding.

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

encodeWith Source

Encode a String with the specified encoding.

Note: We expect a "wide char" encoding (e.g. UCS-2 or UTF-16). Anything that works with Word16 boundaries. Picking an incompatible encoding may crash filepath operations.

encodeFS :: String -> IO WindowsPath Source

pstr :: QuasiQuoter Source

QuasiQuote a WindowsPath. This accepts Unicode characters and encodes as UTF-16LE. Runs isValid on the input.

pack :: [WindowsChar] -> WindowsString 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 => WindowsString -> m String Source

Partial unicode friendly decoding.

This decodes as UTF16-LE (strictly), which is a pretty good.

Throws a EncodingException if decoding fails.

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

Decode a WindowsString with the specified encoding.

The String is forced into memory to catch all exceptions.

decodeFS :: WindowsPath -> IO String Source

unpack :: WindowsString -> [WindowsChar] Source

Unpack a platform string to a list of platform words.

Word construction

unsafeFromChar :: Char -> WindowsChar Source

Truncates to 2 octets.

Word deconstruction

toChar :: WindowsChar -> Char Source

Converts back to a unicode codepoint (total).

Separator predicates

pathSeparator :: WindowsChar Source

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

pathSeparator == '\\'S

pathSeparators :: [WindowsChar] Source

The list of all possible separators.

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

isPathSeparator :: WindowsChar -> Bool Source

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

isPathSeparator a == (a `elem` pathSeparators)

searchPathSeparator :: WindowsChar Source

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

searchPathSeparator == ';'

isSearchPathSeparator :: WindowsChar -> Bool Source

Is the character a file separator?

isSearchPathSeparator a == (a == searchPathSeparator)

extSeparator :: WindowsChar Source

File extension character

extSeparator == '.'

isExtSeparator :: WindowsChar -> Bool Source

Is the character an extension character?

isExtSeparator a == (a == extSeparator)

$PATH methods

splitSearchPath :: WindowsString -> [WindowsPath] Source

Take a string, split it on the searchPathSeparator character.

Blank items are ignored and path elements are stripped of quotes.

splitSearchPath "File1;File2;File3"  == ["File1","File2","File3"]
splitSearchPath "File1;;File2;File3" == ["File1","File2","File3"]
splitSearchPath "File1;\"File2\";File3" == ["File1","File2","File3"]

Extension functions

splitExtension :: WindowsPath -> (WindowsPath, WindowsString) 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 :: WindowsPath -> WindowsString 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 :: WindowsPath -> WindowsString -> WindowsPath 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

(-<.>) :: WindowsPath -> WindowsString -> WindowsPath 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 :: WindowsPath -> WindowsPath Source

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

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

addExtension :: WindowsPath -> WindowsString -> WindowsPath 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"
addExtension "\\\\share" ".txt" == "\\\\share\\.txt"

hasExtension :: WindowsPath -> Bool Source

Does the given filename have an extension?

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

(<.>) :: WindowsPath -> WindowsString -> WindowsPath 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 :: WindowsPath -> (WindowsPath, WindowsString) 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 :: WindowsPath -> WindowsPath 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 :: WindowsPath -> WindowsString Source

Get all extensions.

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

replaceExtensions :: WindowsPath -> WindowsString -> WindowsPath 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 :: WindowsString -> WindowsPath -> 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 :: WindowsString -> WindowsPath -> Maybe WindowsPath 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 :: WindowsPath -> (WindowsPath, WindowsPath) 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 "c:" == ("c:","")

takeFileName :: WindowsPath -> WindowsPath 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 :: WindowsPath -> WindowsString -> WindowsPath Source

Set the filename.

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

dropFileName :: WindowsPath -> WindowsPath 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 :: WindowsPath -> WindowsPath 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 :: WindowsPath -> WindowsString -> WindowsPath 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 :: WindowsPath -> WindowsPath 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"
takeDirectory "foo\\bar" == "foo"
takeDirectory "foo\\bar\\\\" == "foo\\bar"
takeDirectory "C:\\" == "C:\\"

replaceDirectory :: WindowsPath -> WindowsPath -> WindowsPath 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 :: WindowsPath -> WindowsPath -> WindowsPath Source

An alias for </>.

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

Combined:

"C:\\foo" </> "bar" == "C:\\foo\\bar"
"home" </> "bob" == "home\\bob"

Not combined:

"home" </> "C:\\bob" == "C:\\bob"

Not combined (tricky):

If a filepath starts with a single slash, it is relative to the root of the current drive. In [1], this is (confusingly) referred to as an absolute path. The current behavior of </> is to never combine these forms.

"home" </> "/bob" == "/bob"
"home" </> "\\bob" == "\\bob"
"C:\\home" </> "\\bob" == "\\bob"

From [1]: "If a file name begins with only a disk designator but not the backslash after the colon, it is interpreted as a relative path to the current directory on the drive with the specified letter." The current behavior of </> is to never combine these forms.

"D:\\foo" </> "C:bar" == "C:bar"
"C:\\foo" </> "C:bar" == "C:bar"

splitPath :: WindowsPath -> [WindowsPath] 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 "c:\\test\\path" == ["c:\\","test\\","path"]

joinPath :: [WindowsPath] -> WindowsPath Source

Join path elements back together.

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

splitDirectories :: WindowsPath -> [WindowsPath] 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"]
splitDirectories "C:\\test\\file" == ["C:\\", "test", "file"]
Valid x => joinPath (splitDirectories x) `equalFilePath` x
splitDirectories "" == []
splitDirectories "C:\\test\\\\\\file" == ["C:\\", "test", "file"]
splitDirectories "/test///file" == ["/","test","file"]

Drive functions

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

Split a path into a drive and a path.

uncurry (<>) (splitDrive x) == x
splitDrive "file" == ("","file")
splitDrive "c:/file" == ("c:/","file")
splitDrive "c:\\file" == ("c:\\","file")
splitDrive "\\\\shared\\test" == ("\\\\shared\\","test")
splitDrive "\\\\shared" == ("\\\\shared","")
splitDrive "\\\\?\\UNC\\shared\\file" == ("\\\\?\\UNC\\shared\\","file")
splitDrive "\\\\?\\UNCshared\\file" == ("\\\\?\\","UNCshared\\file")
splitDrive "\\\\?\\d:\\file" == ("\\\\?\\d:\\","file")
splitDrive "/d" == ("","/d")

joinDrive :: WindowsPath -> WindowsPath -> WindowsPath 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
joinDrive "C:" "foo" == "C:foo"
joinDrive "C:\\" "bar" == "C:\\bar"
joinDrive "\\\\share" "foo" == "\\\\share\\foo"
joinDrive "/:" "foo" == "/:\\foo"

takeDrive :: WindowsPath -> WindowsPath Source

Get the drive from a filepath.

takeDrive x == fst (splitDrive x)

hasDrive :: WindowsPath -> Bool Source

Does a path have a drive.

not (hasDrive x) == null (takeDrive x)
hasDrive "C:\\foo" == True
hasDrive "C:foo" == True
hasDrive "foo" == False
hasDrive "" == False

dropDrive :: WindowsPath -> WindowsPath Source

Delete the drive, if it exists.

dropDrive x == snd (splitDrive x)

isDrive :: WindowsPath -> Bool Source

Is an element a drive

isDrive "C:\\" == True
isDrive "C:\\foo" == False
isDrive "" == False

Trailing slash functions

hasTrailingPathSeparator :: WindowsPath -> Bool Source

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

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

addTrailingPathSeparator :: WindowsPath -> WindowsPath Source

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

hasTrailingPathSeparator (addTrailingPathSeparator x)
hasTrailingPathSeparator x ==> addTrailingPathSeparator x == x

dropTrailingPathSeparator :: WindowsPath -> WindowsPath Source

Remove any trailing path separators

dropTrailingPathSeparator "file/test/" == "file/test"
dropTrailingPathSeparator "/" == "/"
dropTrailingPathSeparator "\\" == "\\"

File name manipulations

normalise :: WindowsPath -> WindowsPath Source

Normalise a file

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

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

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

equalFilePath :: WindowsPath -> WindowsPath -> 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")
equalFilePath "foo" "FOO"
not (equalFilePath "C:" "C:/")

makeRelative :: WindowsPath -> WindowsPath -> WindowsPath 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 "C:\\Home" "c:\\home\\bob" == "bob"
makeRelative "C:\\Home" "c:/home/bob" == "bob"
makeRelative "C:\\Home" "D:\\Home\\Bob" == "D:\\Home\\Bob"
makeRelative "C:\\Home" "C:Home\\Bob" == "C:Home\\Bob"
makeRelative "/Home" "/home/bob" == "bob"
makeRelative "/" "//" == "//"

isRelative :: WindowsPath -> Bool Source

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

isRelative "path\\test" == True
isRelative "c:\\test" == False
isRelative "c:test" == True
isRelative "c:\\" == False
isRelative "c:/" == False
isRelative "c:" == True
isRelative "\\\\foo" == False
isRelative "\\\\?\\foo" == False
isRelative "\\\\?\\UNC\\foo" == False
isRelative "/foo" == True
isRelative "\\foo" == True

According to [1]:

• "A UNC name of any format [is never relative]."
• "You cannot use the "\?" prefix with a relative path."

isAbsolute :: WindowsPath -> Bool Source

not . isRelative

isAbsolute x == not (isRelative x)

isValid :: WindowsPath -> 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 "c:\\test" == True
isValid "c:\\test:of_test" == False
isValid "test*" == False
isValid "c:\\test\\nul" == False
isValid "c:\\test\\prn.txt" == False
isValid "c:\\nul\\file" == False
isValid "\\\\" == False
isValid "\\\\\\foo" == False
isValid "\\\\?\\D:file" == False
isValid "foo\tbar" == False
isValid "nul .txt" == False
isValid " nul.txt" == True

makeValid :: WindowsPath -> WindowsPath 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"
makeValid "c:\\already\\/valid" == "c:\\already\\/valid"
makeValid "c:\\test:of_test" == "c:\\test_of_test"
makeValid "test*" == "test_"
makeValid "c:\\test\\nul" == "c:\\test\\nul_"
makeValid "c:\\test\\prn.txt" == "c:\\test\\prn_.txt"
makeValid "c:\\test/prn.txt" == "c:\\test/prn_.txt"
makeValid "c:\\nul\\file" == "c:\\nul_\\file"
makeValid "\\\\\\foo" == "\\\\drive"
makeValid "\\\\?\\D:file" == "\\\\?\\D:\\file"
makeValid "nul .txt" == "nul _.txt"