System.OsPath.Windows

Types

data WindowsString

Commonly used windows string as wide character bytes.

Instances

Monoid WindowsString

Defined in System.OsString.Internal.Types

Methods

mempty :: WindowsString

mappend :: WindowsString -> WindowsString -> WindowsString

mconcat :: [WindowsString] -> WindowsString

Semigroup WindowsString

Defined in System.OsString.Internal.Types

Methods

(<>) :: WindowsString -> WindowsString -> WindowsString

sconcat :: NonEmpty WindowsString -> WindowsString

stimes :: Integral b => b -> WindowsString -> WindowsString

Generic WindowsString

Defined in System.OsString.Internal.Types

Associated Types

type Rep WindowsString :: Type -> Type

Methods

from :: WindowsString -> Rep WindowsString x

to :: Rep WindowsString x -> WindowsString

Show WindowsString

Decodes as UCS-2.

Defined in System.OsString.Internal.Types

Methods

showsPrec :: Int -> WindowsString -> ShowS

show :: WindowsString -> String

showList :: [WindowsString] -> ShowS

NFData WindowsString

Defined in System.OsString.Internal.Types

Methods

rnf :: WindowsString -> ()

Eq WindowsString

Defined in System.OsString.Internal.Types

Methods

(==) :: WindowsString -> WindowsString -> Bool

(/=) :: WindowsString -> WindowsString -> Bool

Ord WindowsString

Defined in System.OsString.Internal.Types

Methods

compare :: WindowsString -> WindowsString -> Ordering

(<) :: WindowsString -> WindowsString -> Bool

(<=) :: WindowsString -> WindowsString -> Bool

(>) :: WindowsString -> WindowsString -> Bool

(>=) :: WindowsString -> WindowsString -> Bool

max :: WindowsString -> WindowsString -> WindowsString

min :: WindowsString -> WindowsString -> WindowsString

Lift WindowsString

Defined in System.OsString.Internal.Types

Methods

lift :: Quote m => WindowsString -> m Exp

liftTyped :: forall (m :: Type -> Type). Quote m => WindowsString -> Code m WindowsString

type Rep WindowsString

Defined in System.OsString.Internal.Types

type Rep WindowsString = D1 ('MetaData "WindowsString" "System.OsString.Internal.Types" "filepath-1.4.101.0-inplace" 'True) (C1 ('MetaCons "WindowsString" 'PrefixI 'True) (S1 ('MetaSel ('Just "getWindowsString") 'NoSourceUnpackedness 'NoSourceStrictness 'DecidedLazy) (Rec0 ShortByteString)))

data WindowsChar

Instances

Generic WindowsChar

Defined in System.OsString.Internal.Types

Associated Types

type Rep WindowsChar :: Type -> Type

Methods

from :: WindowsChar -> Rep WindowsChar x

to :: Rep WindowsChar x -> WindowsChar

Show WindowsChar

Defined in System.OsString.Internal.Types

Methods

showsPrec :: Int -> WindowsChar -> ShowS

show :: WindowsChar -> String

showList :: [WindowsChar] -> ShowS

NFData WindowsChar

Defined in System.OsString.Internal.Types

Methods

rnf :: WindowsChar -> ()

Eq WindowsChar

Defined in System.OsString.Internal.Types

Methods

(==) :: WindowsChar -> WindowsChar -> Bool

(/=) :: WindowsChar -> WindowsChar -> Bool

Ord WindowsChar

Defined in System.OsString.Internal.Types

Methods

compare :: WindowsChar -> WindowsChar -> Ordering

(<) :: WindowsChar -> WindowsChar -> Bool

(<=) :: WindowsChar -> WindowsChar -> Bool

(>) :: WindowsChar -> WindowsChar -> Bool

(>=) :: WindowsChar -> WindowsChar -> Bool

max :: WindowsChar -> WindowsChar -> WindowsChar

min :: WindowsChar -> WindowsChar -> WindowsChar

type Rep WindowsChar

Defined in System.OsString.Internal.Types

type Rep WindowsChar = D1 ('MetaData "WindowsChar" "System.OsString.Internal.Types" "filepath-1.4.101.0-inplace" 'True) (C1 ('MetaCons "WindowsChar" 'PrefixI 'True) (S1 ('MetaSel ('Just "getWindowsChar") 'NoSourceUnpackedness 'NoSourceStrictness 'DecidedLazy) (Rec0 Word16)))

type WindowsPath = WindowsString

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

Filepath construction

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

Partial unicode friendly encoding.

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

Throws an EncodingException if encoding fails.

encodeWith :: TextEncoding -> String -> Either EncodingException WindowsString

Encode a String with the specified encoding.

encodeFS :: String -> IO WindowsString

This mimics the behavior of the base library when doing filesystem operations, which does permissive UTF-16 encoding, where coding errors generate Chars in the surrogate range.

The reason this is in IO is because it unifies with the Posix counterpart, which does require IO. This is safe to unsafePerformIO/unsafeDupablePerformIO.

pstr :: QuasiQuoter

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

pack :: [WindowsChar] -> WindowsString

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

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

Decode a WindowsString with the specified encoding.

The String is forced into memory to catch all exceptions.

decodeFS :: WindowsString -> IO String

Like decodeUtf, except this mimics the behavior of the base library when doing filesystem operations, which does permissive UTF-16 encoding, where coding errors generate Chars in the surrogate range.

The reason this is in IO is because it unifies with the Posix counterpart, which does require IO. unsafePerformIO/unsafeDupablePerformIO are safe, however.

unpack :: WindowsString -> [WindowsChar]

Unpack a platform string to a list of platform words.

Word construction

unsafeFromChar :: Char -> WindowsChar

Truncates to 2 octets.

Word deconstruction

toChar :: WindowsChar -> Char

Converts back to a unicode codepoint (total).

Separator predicates

pathSeparator :: WindowsChar

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

pathSeparator == '\\'S

pathSeparators :: [WindowsChar]

The list of all possible separators.

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

isPathSeparator :: WindowsChar -> Bool

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

isPathSeparator a == (a `elem` pathSeparators)

searchPathSeparator :: WindowsChar

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

searchPathSeparator == ';'

isSearchPathSeparator :: WindowsChar -> Bool

Is the character a file separator?

isSearchPathSeparator a == (a == searchPathSeparator)

extSeparator :: WindowsChar

File extension character

extSeparator == '.'

isExtSeparator :: WindowsChar -> Bool

Is the character an extension character?

isExtSeparator a == (a == extSeparator)

$PATH methods

splitSearchPath :: WindowsString -> [WindowsPath]

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)

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

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

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

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

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

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

addExtension :: WindowsPath -> WindowsString -> WindowsPath

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

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

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)

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

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

Get all extensions.

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

replaceExtensions :: WindowsPath -> WindowsString -> WindowsPath

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

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

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)

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

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

Set the filename.

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

dropFileName :: WindowsPath -> WindowsPath

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

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

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

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

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

An alias for </>.

(</>) :: WindowsPath -> WindowsPath -> WindowsPath

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]

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

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]

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)

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

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

Get the drive from a filepath.

takeDrive x == fst (splitDrive x)

hasDrive :: WindowsPath -> Bool

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

Delete the drive, if it exists.

dropDrive x == snd (splitDrive x)

isDrive :: WindowsPath -> Bool

Is an element a drive

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

Trailing slash functions

hasTrailingPathSeparator :: WindowsPath -> Bool

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

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

addTrailingPathSeparator :: WindowsPath -> WindowsPath

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

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

dropTrailingPathSeparator :: WindowsPath -> WindowsPath

Remove any trailing path separators

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

File name manipulations

normalise :: WindowsPath -> WindowsPath

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

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

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

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

not . isRelative

isAbsolute x == not (isRelative x)

isValid :: WindowsPath -> Bool

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

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"