HPath

Support for well-typed paths.

Types

data Abs

An absolute path.

data Path b

Path of some base and type.

Internally is a string. The string can be of two formats only:

1. without trailing path separator: file.txt, foo/bar.txt, /foo/bar.txt
2. with trailing path separator: foo/, /foo/bar/

There are no duplicate path separators //, no .., no ./, no ~/, etc.

Instances

Eq (Path b)

String equality.

The following property holds:

show x == show y ≡ x == y

Ord (Path b)

String ordering.

The following property holds:

show x `compare` show y ≡ x `compare` y

Show (Path b)

Same as toFilePath.

The following property holds:

x == y ≡ show x == show y

NFData (Path b)

data Rel

A relative path; one without a root.

Instances

RelC Rel

data Fn

A filename, without any /.

Instances

RelC Fn

data PathParseException

Exception when parsing a location.

Instances

Show PathParseException

Exception PathParseException

data PathException

Instances

Show PathException

Exception PathException

PatternSynonyms/ViewPatterns

pattern Path :: ByteString -> Path t

Path Parsing

parseAbs :: MonadThrow m => ByteString -> m (Path Abs)

Get a location for an absolute path. Produces a normalised path.

Throws: PathParseException

>>> parseAbs "/abc" :: Maybe (Path Abs)
Just "/abc"
>>> parseAbs "/" :: Maybe (Path Abs)
Just "/"
>>> parseAbs "/abc/def" :: Maybe (Path Abs)
Just "/abc/def"
>>> parseAbs "/abc/def/.///" :: Maybe (Path Abs)
Just "/abc/def/"
>>> parseAbs "abc" :: Maybe (Path Abs)
Nothing
>>> parseAbs "" :: Maybe (Path Abs)
Nothing
>>> parseAbs "/abc/../foo" :: Maybe (Path Abs)
Nothing

parseFn :: MonadThrow m => ByteString -> m (Path Fn)

Parses a filename. Filenames must not contain slashes. Excludes . and '..'.

Throws: PathParseException

>>> parseFn "abc" :: Maybe (Path Fn)
Just "abc"
>>> parseFn "..." :: Maybe (Path Fn)
Just "..."
>>> parseFn "def/" :: Maybe (Path Fn)
Nothing
>>> parseFn "abc/def" :: Maybe (Path Fn)
Nothing
>>> parseFn "abc/def/." :: Maybe (Path Fn)
Nothing
>>> parseFn "/abc" :: Maybe (Path Fn)
Nothing
>>> parseFn "" :: Maybe (Path Fn)
Nothing
>>> parseFn "abc/../foo" :: Maybe (Path Fn)
Nothing
>>> parseFn "." :: Maybe (Path Fn)
Nothing
>>> parseFn ".." :: Maybe (Path Fn)
Nothing

parseRel :: MonadThrow m => ByteString -> m (Path Rel)

Get a location for a relative path. Produces a normalised path.

Note that filepath may contain any number of ./ but may not consist solely of ./. It also may not contain a single .. anywhere.

Throws: PathParseException

>>> parseRel "abc" :: Maybe (Path Rel)
Just "abc"
>>> parseRel "def/" :: Maybe (Path Rel)
Just "def/"
>>> parseRel "abc/def" :: Maybe (Path Rel)
Just "abc/def"
>>> parseRel "abc/def/." :: Maybe (Path Rel)
Just "abc/def/"
>>> parseRel "/abc" :: Maybe (Path Rel)
Nothing
>>> parseRel "" :: Maybe (Path Rel)
Nothing
>>> parseRel "abc/../foo" :: Maybe (Path Rel)
Nothing
>>> parseRel "." :: Maybe (Path Rel)
Nothing
>>> parseRel ".." :: Maybe (Path Rel)
Nothing

Path Conversion

fromAbs :: Path Abs -> ByteString

Convert an absolute Path to a ByteString type.

fromRel :: RelC r => Path r -> ByteString

Convert a relative Path to a ByteString type.

toFilePath :: Path b -> ByteString

Convert any Path to a ByteString type.

Path Operations

(</>) :: RelC r => Path b -> Path r -> Path b

Append two paths.

The second argument must always be a relative path, which ensures that undefinable things like `"abc" <> "/def"` cannot happen.

Technically, the first argument can be a path that points to a non-directory, because this library is IO-agnostic and makes no assumptions about file types.

>>> (MkPath "/") </> (MkPath "file" :: Path Rel)
"/file"
>>> (MkPath "/path/to") </> (MkPath "file" :: Path Rel)
"/path/to/file"
>>> (MkPath "/") </> (MkPath "file/lal" :: Path Rel)
"/file/lal"
>>> (MkPath "/") </> (MkPath "file/" :: Path Rel)
"/file/"

basename :: MonadThrow m => Path b -> m (Path Fn)

Extract the file part of a path.

The following properties hold:

basename (p </> a) == basename a

Throws: PathException if given the root path "/"

>>> basename (MkPath "/abc/def/dod") :: Maybe (Path Fn)
Just "dod"
>>> basename (MkPath "/") :: Maybe (Path Fn)
Nothing

dirname :: Path Abs -> Path Abs

Extract the directory name of a path.

The following properties hold:

dirname (p </> a) == dirname p

>>> dirname (MkPath "/abc/def/dod")
"/abc/def"
>>> dirname (MkPath "/")
"/"

isParentOf :: Path b -> Path b -> Bool

Is p a parent of the given location? Implemented in terms of stripDir. The bases must match.

>>> (MkPath "/lal/lad") `isParentOf` (MkPath "/lal/lad/fad")
True
>>> (MkPath "lal/lad") `isParentOf` (MkPath "lal/lad/fad")
True
>>> (MkPath "/") `isParentOf` (MkPath "/")
False
>>> (MkPath "/lal/lad/fad") `isParentOf` (MkPath "/lal/lad")
False
>>> (MkPath "fad") `isParentOf` (MkPath "fad")
False

getAllParents :: Path Abs -> [Path Abs]

Get all parents of a path.

>>> getAllParents (MkPath "/abs/def/dod")
["/abs/def","/abs","/"]
>>> getAllParents (MkPath "/")
[]

stripDir :: MonadThrow m => Path b -> Path b -> m (Path Rel)

Strip directory from path, making it relative to that directory. Throws Couldn'tStripPrefixDir if directory is not a parent of the path.

The bases must match.

>>> (MkPath "/lal/lad") `stripDir` (MkPath "/lal/lad/fad") :: Maybe (Path Rel)
Just "fad"
>>> (MkPath "lal/lad") `stripDir` (MkPath "lal/lad/fad") :: Maybe (Path Rel)
Just "fad"
>>> (MkPath "/") `stripDir` (MkPath "/") :: Maybe (Path Rel)
Nothing
>>> (MkPath "/lal/lad/fad") `stripDir` (MkPath "/lal/lad") :: Maybe (Path Rel)
Nothing
>>> (MkPath "fad") `stripDir` (MkPath "fad") :: Maybe (Path Rel)
Nothing

Path IO helpers

withAbsPath :: Path Abs -> (ByteString -> IO a) -> IO a

withRelPath :: Path Rel -> (ByteString -> IO a) -> IO a

withFnPath :: Path Fn -> (ByteString -> IO a) -> IO a

ByteString operations

fpToString :: ByteString -> String

Uses UTF-8 decoding to convert the bytestring into a String.

userStringToFP :: String -> ByteString

Uses UTF-8 encoding to convert a user provided String into a ByteString, which represents a filepath.