Portability | portable |
---|---|
Stability | experimental |
Maintainer | dons@cse.unsw.edu.au |
Safe Haskell | Trustworthy |
- The
ByteString
type - Introducing and eliminating
ByteString
s - Basic interface
- Transforming ByteStrings
- Reducing
ByteString
s (folds) - Building ByteStrings
- Substrings
- Predicates
- Searching ByteStrings
- Indexing ByteStrings
- Zipping and unzipping ByteStrings
- Ordered ByteStrings
- Low level conversions
- I/O with
ByteString
s
A time and space-efficient implementation of byte vectors using
packed Word8 arrays, suitable for high performance use, both in terms
of large data quantities, or high speed requirements. Byte vectors
are encoded as strict Word8
arrays of bytes, held in a ForeignPtr
,
and can be passed between C and Haskell with little effort.
This module is intended to be imported qualified
, to avoid name
clashes with Prelude functions. eg.
import qualified Data.ByteString as B
Original GHC implementation by Bryan O'Sullivan.
Rewritten to use UArray
by Simon Marlow.
Rewritten to support slices and use ForeignPtr
by David Roundy.
Polished and extended by Don Stewart.
- data ByteString
- empty :: ByteString
- singleton :: Word8 -> ByteString
- pack :: [Word8] -> ByteString
- unpack :: ByteString -> [Word8]
- cons :: Word8 -> ByteString -> ByteString
- snoc :: ByteString -> Word8 -> ByteString
- append :: ByteString -> ByteString -> ByteString
- head :: ByteString -> Word8
- uncons :: ByteString -> Maybe (Word8, ByteString)
- last :: ByteString -> Word8
- tail :: ByteString -> ByteString
- init :: ByteString -> ByteString
- null :: ByteString -> Bool
- length :: ByteString -> Int
- map :: (Word8 -> Word8) -> ByteString -> ByteString
- reverse :: ByteString -> ByteString
- intersperse :: Word8 -> ByteString -> ByteString
- intercalate :: ByteString -> [ByteString] -> ByteString
- transpose :: [ByteString] -> [ByteString]
- foldl :: (a -> Word8 -> a) -> a -> ByteString -> a
- foldl' :: (a -> Word8 -> a) -> a -> ByteString -> a
- foldl1 :: (Word8 -> Word8 -> Word8) -> ByteString -> Word8
- foldl1' :: (Word8 -> Word8 -> Word8) -> ByteString -> Word8
- foldr :: (Word8 -> a -> a) -> a -> ByteString -> a
- foldr' :: (Word8 -> a -> a) -> a -> ByteString -> a
- foldr1 :: (Word8 -> Word8 -> Word8) -> ByteString -> Word8
- foldr1' :: (Word8 -> Word8 -> Word8) -> ByteString -> Word8
- concat :: [ByteString] -> ByteString
- concatMap :: (Word8 -> ByteString) -> ByteString -> ByteString
- any :: (Word8 -> Bool) -> ByteString -> Bool
- all :: (Word8 -> Bool) -> ByteString -> Bool
- maximum :: ByteString -> Word8
- minimum :: ByteString -> Word8
- scanl :: (Word8 -> Word8 -> Word8) -> Word8 -> ByteString -> ByteString
- scanl1 :: (Word8 -> Word8 -> Word8) -> ByteString -> ByteString
- scanr :: (Word8 -> Word8 -> Word8) -> Word8 -> ByteString -> ByteString
- scanr1 :: (Word8 -> Word8 -> Word8) -> ByteString -> ByteString
- mapAccumL :: (acc -> Word8 -> (acc, Word8)) -> acc -> ByteString -> (acc, ByteString)
- mapAccumR :: (acc -> Word8 -> (acc, Word8)) -> acc -> ByteString -> (acc, ByteString)
- replicate :: Int -> Word8 -> ByteString
- unfoldr :: (a -> Maybe (Word8, a)) -> a -> ByteString
- unfoldrN :: Int -> (a -> Maybe (Word8, a)) -> a -> (ByteString, Maybe a)
- take :: Int -> ByteString -> ByteString
- drop :: Int -> ByteString -> ByteString
- splitAt :: Int -> ByteString -> (ByteString, ByteString)
- takeWhile :: (Word8 -> Bool) -> ByteString -> ByteString
- dropWhile :: (Word8 -> Bool) -> ByteString -> ByteString
- span :: (Word8 -> Bool) -> ByteString -> (ByteString, ByteString)
- spanEnd :: (Word8 -> Bool) -> ByteString -> (ByteString, ByteString)
- break :: (Word8 -> Bool) -> ByteString -> (ByteString, ByteString)
- breakEnd :: (Word8 -> Bool) -> ByteString -> (ByteString, ByteString)
- group :: ByteString -> [ByteString]
- groupBy :: (Word8 -> Word8 -> Bool) -> ByteString -> [ByteString]
- inits :: ByteString -> [ByteString]
- tails :: ByteString -> [ByteString]
- split :: Word8 -> ByteString -> [ByteString]
- splitWith :: (Word8 -> Bool) -> ByteString -> [ByteString]
- isPrefixOf :: ByteString -> ByteString -> Bool
- isSuffixOf :: ByteString -> ByteString -> Bool
- isInfixOf :: ByteString -> ByteString -> Bool
- breakSubstring :: ByteString -> ByteString -> (ByteString, ByteString)
- findSubstring :: ByteString -> ByteString -> Maybe Int
- findSubstrings :: ByteString -> ByteString -> [Int]
- elem :: Word8 -> ByteString -> Bool
- notElem :: Word8 -> ByteString -> Bool
- find :: (Word8 -> Bool) -> ByteString -> Maybe Word8
- filter :: (Word8 -> Bool) -> ByteString -> ByteString
- partition :: (Word8 -> Bool) -> ByteString -> (ByteString, ByteString)
- index :: ByteString -> Int -> Word8
- elemIndex :: Word8 -> ByteString -> Maybe Int
- elemIndices :: Word8 -> ByteString -> [Int]
- elemIndexEnd :: Word8 -> ByteString -> Maybe Int
- findIndex :: (Word8 -> Bool) -> ByteString -> Maybe Int
- findIndices :: (Word8 -> Bool) -> ByteString -> [Int]
- count :: Word8 -> ByteString -> Int
- zip :: ByteString -> ByteString -> [(Word8, Word8)]
- zipWith :: (Word8 -> Word8 -> a) -> ByteString -> ByteString -> [a]
- unzip :: [(Word8, Word8)] -> (ByteString, ByteString)
- sort :: ByteString -> ByteString
- copy :: ByteString -> ByteString
- packCString :: CString -> IO ByteString
- packCStringLen :: CStringLen -> IO ByteString
- useAsCString :: ByteString -> (CString -> IO a) -> IO a
- useAsCStringLen :: ByteString -> (CStringLen -> IO a) -> IO a
- getLine :: IO ByteString
- getContents :: IO ByteString
- putStr :: ByteString -> IO ()
- putStrLn :: ByteString -> IO ()
- interact :: (ByteString -> ByteString) -> IO ()
- readFile :: FilePath -> IO ByteString
- writeFile :: FilePath -> ByteString -> IO ()
- appendFile :: FilePath -> ByteString -> IO ()
- hGetLine :: Handle -> IO ByteString
- hGetContents :: Handle -> IO ByteString
- hGet :: Handle -> Int -> IO ByteString
- hGetSome :: Handle -> Int -> IO ByteString
- hGetNonBlocking :: Handle -> Int -> IO ByteString
- hPut :: Handle -> ByteString -> IO ()
- hPutNonBlocking :: Handle -> ByteString -> IO ByteString
- hPutStr :: Handle -> ByteString -> IO ()
- hPutStrLn :: Handle -> ByteString -> IO ()
- breakByte :: Word8 -> ByteString -> (ByteString, ByteString)
The ByteString
type
data ByteString Source
A space-efficient representation of a Word8 vector, supporting many
efficient operations. A ByteString
contains 8-bit characters only.
Instances of Eq, Ord, Read, Show, Data, Typeable
Introducing and eliminating ByteString
s
O(1) The empty ByteString
singleton :: Word8 -> ByteStringSource
O(1) Convert a Word8
into a ByteString
pack :: [Word8] -> ByteStringSource
O(n) Convert a '[Word8]' into a ByteString
.
For applications with large numbers of string literals, pack can be a bottleneck. In such cases, consider using packAddress (GHC only).
unpack :: ByteString -> [Word8]Source
O(n) Converts a ByteString
to a '[Word8]'.
Basic interface
cons :: Word8 -> ByteString -> ByteStringSource
O(n) cons
is analogous to (:) for lists, but of different
complexity, as it requires a memcpy.
snoc :: ByteString -> Word8 -> ByteStringSource
O(n) Append a byte to the end of a ByteString
append :: ByteString -> ByteString -> ByteStringSource
O(n) Append two ByteStrings
head :: ByteString -> Word8Source
O(1) Extract the first element of a ByteString, which must be non-empty. An exception will be thrown in the case of an empty ByteString.
uncons :: ByteString -> Maybe (Word8, ByteString)Source
O(1) Extract the head and tail of a ByteString, returning Nothing if it is empty.
last :: ByteString -> Word8Source
O(1) Extract the last element of a ByteString, which must be finite and non-empty. An exception will be thrown in the case of an empty ByteString.
tail :: ByteString -> ByteStringSource
O(1) Extract the elements after the head of a ByteString, which must be non-empty. An exception will be thrown in the case of an empty ByteString.
init :: ByteString -> ByteStringSource
O(1) Return all the elements of a ByteString
except the last one.
An exception will be thrown in the case of an empty ByteString.
null :: ByteString -> BoolSource
O(1) Test whether a ByteString is empty.
Transforming ByteStrings
map :: (Word8 -> Word8) -> ByteString -> ByteStringSource
O(n) map
f xs
is the ByteString obtained by applying f
to each
element of xs
. This function is subject to array fusion.
reverse :: ByteString -> ByteStringSource
O(n) reverse
xs
efficiently returns the elements of xs
in reverse order.
intersperse :: Word8 -> ByteString -> ByteStringSource
O(n) The intersperse
function takes a Word8
and a
ByteString
and `intersperses' that byte between the elements of
the ByteString
. It is analogous to the intersperse function on
Lists.
intercalate :: ByteString -> [ByteString] -> ByteStringSource
O(n) The intercalate
function takes a ByteString
and a list of
ByteString
s and concatenates the list after interspersing the first
argument between each element of the list.
transpose :: [ByteString] -> [ByteString]Source
The transpose
function transposes the rows and columns of its
ByteString
argument.
Reducing ByteString
s (folds)
foldl :: (a -> Word8 -> a) -> a -> ByteString -> aSource
foldl
, applied to a binary operator, a starting value (typically
the left-identity of the operator), and a ByteString, reduces the
ByteString using the binary operator, from left to right.
This function is subject to array fusion.
foldl' :: (a -> Word8 -> a) -> a -> ByteString -> aSource
'foldl\'' is like foldl
, but strict in the accumulator.
However, for ByteStrings, all left folds are strict in the accumulator.
foldl1' :: (Word8 -> Word8 -> Word8) -> ByteString -> Word8Source
'foldl1\'' is like foldl1
, but strict in the accumulator.
An exception will be thrown in the case of an empty ByteString.
foldr :: (Word8 -> a -> a) -> a -> ByteString -> aSource
foldr
, applied to a binary operator, a starting value
(typically the right-identity of the operator), and a ByteString,
reduces the ByteString using the binary operator, from right to left.
foldr' :: (Word8 -> a -> a) -> a -> ByteString -> aSource
'foldr\'' is like foldr
, but strict in the accumulator.
foldr1 :: (Word8 -> Word8 -> Word8) -> ByteString -> Word8Source
foldr1
is a variant of foldr
that has no starting value argument,
and thus must be applied to non-empty ByteString
s
An exception will be thrown in the case of an empty ByteString.
foldr1' :: (Word8 -> Word8 -> Word8) -> ByteString -> Word8Source
'foldr1\'' is a variant of foldr1
, but is strict in the
accumulator.
Special folds
concat :: [ByteString] -> ByteStringSource
O(n) Concatenate a list of ByteStrings.
concatMap :: (Word8 -> ByteString) -> ByteString -> ByteStringSource
Map a function over a ByteString
and concatenate the results
any :: (Word8 -> Bool) -> ByteString -> BoolSource
O(n) Applied to a predicate and a ByteString, any
determines if
any element of the ByteString
satisfies the predicate.
all :: (Word8 -> Bool) -> ByteString -> BoolSource
O(n) Applied to a predicate and a ByteString
, all
determines
if all elements of the ByteString
satisfy the predicate.
maximum :: ByteString -> Word8Source
O(n) maximum
returns the maximum value from a ByteString
This function will fuse.
An exception will be thrown in the case of an empty ByteString.
minimum :: ByteString -> Word8Source
O(n) minimum
returns the minimum value from a ByteString
This function will fuse.
An exception will be thrown in the case of an empty ByteString.
Building ByteStrings
Scans
scanl :: (Word8 -> Word8 -> Word8) -> Word8 -> ByteString -> ByteStringSource
scanl1 :: (Word8 -> Word8 -> Word8) -> ByteString -> ByteStringSource
scanr :: (Word8 -> Word8 -> Word8) -> Word8 -> ByteString -> ByteStringSource
scanr is the right-to-left dual of scanl.
scanr1 :: (Word8 -> Word8 -> Word8) -> ByteString -> ByteStringSource
Accumulating maps
mapAccumL :: (acc -> Word8 -> (acc, Word8)) -> acc -> ByteString -> (acc, ByteString)Source
mapAccumR :: (acc -> Word8 -> (acc, Word8)) -> acc -> ByteString -> (acc, ByteString)Source
Generating and unfolding ByteStrings
replicate :: Int -> Word8 -> ByteStringSource
O(n) replicate
n x
is a ByteString of length n
with x
the value of every element. The following holds:
replicate w c = unfoldr w (\u -> Just (u,u)) c
This implemenation uses memset(3)
unfoldr :: (a -> Maybe (Word8, a)) -> a -> ByteStringSource
O(n), where n is the length of the result. The unfoldr
function is analogous to the List 'unfoldr'. unfoldr
builds a
ByteString from a seed value. The function takes the element and
returns Nothing
if it is done producing the ByteString or returns
Just
(a,b)
, in which case, a
is the next byte in the string,
and b
is the seed value for further production.
Examples:
unfoldr (\x -> if x <= 5 then Just (x, x + 1) else Nothing) 0 == pack [0, 1, 2, 3, 4, 5]
unfoldrN :: Int -> (a -> Maybe (Word8, a)) -> a -> (ByteString, Maybe a)Source
O(n) Like unfoldr
, unfoldrN
builds a ByteString from a seed
value. However, the length of the result is limited by the first
argument to unfoldrN
. This function is more efficient than unfoldr
when the maximum length of the result is known.
The following equation relates unfoldrN
and unfoldr
:
snd (unfoldrN n f s) == take n (unfoldr f s)
Substrings
Breaking strings
take :: Int -> ByteString -> ByteStringSource
drop :: Int -> ByteString -> ByteStringSource
splitAt :: Int -> ByteString -> (ByteString, ByteString)Source
takeWhile :: (Word8 -> Bool) -> ByteString -> ByteStringSource
takeWhile
, applied to a predicate p
and a ByteString xs
,
returns the longest prefix (possibly empty) of xs
of elements that
satisfy p
.
dropWhile :: (Word8 -> Bool) -> ByteString -> ByteStringSource
span :: (Word8 -> Bool) -> ByteString -> (ByteString, ByteString)Source
spanEnd :: (Word8 -> Bool) -> ByteString -> (ByteString, ByteString)Source
spanEnd
behaves like span
but from the end of the ByteString
.
We have
spanEnd (not.isSpace) "x y z" == ("x y ","z")
and
spanEnd (not . isSpace) ps == let (x,y) = span (not.isSpace) (reverse ps) in (reverse y, reverse x)
break :: (Word8 -> Bool) -> ByteString -> (ByteString, ByteString)Source
breakEnd :: (Word8 -> Bool) -> ByteString -> (ByteString, ByteString)Source
breakEnd
behaves like break
but from the end of the ByteString
breakEnd p == spanEnd (not.p)
group :: ByteString -> [ByteString]Source
The group
function takes a ByteString and returns a list of
ByteStrings such that the concatenation of the result is equal to the
argument. Moreover, each sublist in the result contains only equal
elements. For example,
group "Mississippi" = ["M","i","ss","i","ss","i","pp","i"]
It is a special case of groupBy
, which allows the programmer to
supply their own equality test. It is about 40% faster than
groupBy (==)
groupBy :: (Word8 -> Word8 -> Bool) -> ByteString -> [ByteString]Source
inits :: ByteString -> [ByteString]Source
O(n) Return all initial segments of the given ByteString
, shortest first.
tails :: ByteString -> [ByteString]Source
O(n) Return all final segments of the given ByteString
, longest first.
Breaking into many substrings
split :: Word8 -> ByteString -> [ByteString]Source
O(n) Break a ByteString
into pieces separated by the byte
argument, consuming the delimiter. I.e.
split '\n' "a\nb\nd\ne" == ["a","b","d","e"] split 'a' "aXaXaXa" == ["","X","X","X",""] split 'x' "x" == ["",""]
and
intercalate [c] . split c == id split == splitWith . (==)
As for all splitting functions in this library, this function does
not copy the substrings, it just constructs new ByteStrings
that
are slices of the original.
splitWith :: (Word8 -> Bool) -> ByteString -> [ByteString]Source
O(n) Splits a ByteString
into components delimited by
separators, where the predicate returns True for a separator element.
The resulting components do not contain the separators. Two adjacent
separators result in an empty component in the output. eg.
splitWith (=='a') "aabbaca" == ["","","bb","c",""] splitWith (=='a') [] == []
Predicates
isPrefixOf :: ByteString -> ByteString -> BoolSource
O(n) The isPrefixOf
function takes two ByteStrings and returns True
iff the first is a prefix of the second.
isSuffixOf :: ByteString -> ByteString -> BoolSource
O(n) The isSuffixOf
function takes two ByteStrings and returns True
iff the first is a suffix of the second.
The following holds:
isSuffixOf x y == reverse x `isPrefixOf` reverse y
However, the real implemenation uses memcmp to compare the end of the string only, with no reverse required..
isInfixOf :: ByteString -> ByteString -> BoolSource
Check whether one string is a substring of another. isInfixOf
p s
is equivalent to not (null (findSubstrings p s))
.
Search for arbitrary substrings
:: ByteString | String to search for |
-> ByteString | String to search in |
-> (ByteString, ByteString) | Head and tail of string broken at substring |
Break a string on a substring, returning a pair of the part of the string prior to the match, and the rest of the string.
The following relationships hold:
break (== c) l == breakSubstring (singleton c) l
and:
findSubstring s l == if null s then Just 0 else case breakSubstring s l of (x,y) | null y -> Nothing | otherwise -> Just (length x)
For example, to tokenise a string, dropping delimiters:
tokenise x y = h : if null t then [] else tokenise x (drop (length x) t) where (h,t) = breakSubstring x y
To skip to the first occurence of a string:
snd (breakSubstring x y)
To take the parts of a string before a delimiter:
fst (breakSubstring x y)
:: ByteString | String to search for. |
-> ByteString | String to seach in. |
-> Maybe Int |
Get the first index of a substring in another string,
or Nothing
if the string is not found.
findSubstring p s
is equivalent to listToMaybe (findSubstrings p s)
.
:: ByteString | String to search for. |
-> ByteString | String to seach in. |
-> [Int] |
Find the indexes of all (possibly overlapping) occurances of a substring in a string.
Searching ByteStrings
Searching by equality
elem :: Word8 -> ByteString -> BoolSource
O(n) elem
is the ByteString
membership predicate.
Searching with a predicate
filter :: (Word8 -> Bool) -> ByteString -> ByteStringSource
O(n) filter
, applied to a predicate and a ByteString,
returns a ByteString containing those characters that satisfy the
predicate. This function is subject to array fusion.
partition :: (Word8 -> Bool) -> ByteString -> (ByteString, ByteString)Source
O(n) The partition
function takes a predicate a ByteString and returns
the pair of ByteStrings with elements which do and do not satisfy the
predicate, respectively; i.e.,
partition p bs == (filter p xs, filter (not . p) xs)
Indexing ByteStrings
index :: ByteString -> Int -> Word8Source
O(1) ByteString
index (subscript) operator, starting from 0.
elemIndex :: Word8 -> ByteString -> Maybe IntSource
O(n) The elemIndex
function returns the index of the first
element in the given ByteString
which is equal to the query
element, or Nothing
if there is no such element.
This implementation uses memchr(3).
elemIndices :: Word8 -> ByteString -> [Int]Source
O(n) The elemIndices
function extends elemIndex
, by returning
the indices of all elements equal to the query element, in ascending order.
This implementation uses memchr(3).
elemIndexEnd :: Word8 -> ByteString -> Maybe IntSource
O(n) The elemIndexEnd
function returns the last index of the
element in the given ByteString
which is equal to the query
element, or Nothing
if there is no such element. The following
holds:
elemIndexEnd c xs == (-) (length xs - 1) `fmap` elemIndex c (reverse xs)
findIndex :: (Word8 -> Bool) -> ByteString -> Maybe IntSource
The findIndex
function takes a predicate and a ByteString
and
returns the index of the first element in the ByteString
satisfying the predicate.
findIndices :: (Word8 -> Bool) -> ByteString -> [Int]Source
The findIndices
function extends findIndex
, by returning the
indices of all elements satisfying the predicate, in ascending order.
count :: Word8 -> ByteString -> IntSource
count returns the number of times its argument appears in the ByteString
count = length . elemIndices
But more efficiently than using length on the intermediate list.
Zipping and unzipping ByteStrings
zip :: ByteString -> ByteString -> [(Word8, Word8)]Source
zipWith :: (Word8 -> Word8 -> a) -> ByteString -> ByteString -> [a]Source
unzip :: [(Word8, Word8)] -> (ByteString, ByteString)Source
Ordered ByteStrings
sort :: ByteString -> ByteStringSource
O(n) Sort a ByteString efficiently, using counting sort.
Low level conversions
Copying ByteStrings
copy :: ByteString -> ByteStringSource
O(n) Make a copy of the ByteString
with its own storage.
This is mainly useful to allow the rest of the data pointed
to by the ByteString
to be garbage collected, for example
if a large string has been read in, and only a small part of it
is needed in the rest of the program.
Packing CString
s and pointers
packCString :: CString -> IO ByteStringSource
O(n). Construct a new ByteString
from a CString
. The
resulting ByteString
is an immutable copy of the original
CString
, and is managed on the Haskell heap. The original
CString
must be null terminated.
packCStringLen :: CStringLen -> IO ByteStringSource
O(n). Construct a new ByteString
from a CStringLen
. The
resulting ByteString
is an immutable copy of the original CStringLen
.
The ByteString
is a normal Haskell value and will be managed on the
Haskell heap.
Using ByteStrings as CString
s
useAsCString :: ByteString -> (CString -> IO a) -> IO aSource
O(n) construction Use a ByteString
with a function requiring a
null-terminated CString
. The CString
will be freed
automatically. This is a memcpy(3).
useAsCStringLen :: ByteString -> (CStringLen -> IO a) -> IO aSource
O(n) construction Use a ByteString
with a function requiring a CStringLen
.
As for useAsCString
this function makes a copy of the original ByteString
.
I/O with ByteString
s
Standard input and output
getLine :: IO ByteStringSource
Read a line from stdin.
getContents :: IO ByteStringSource
getContents. Read stdin strictly. Equivalent to hGetContents stdin
The Handle
is closed after the contents have been read.
putStr :: ByteString -> IO ()Source
Write a ByteString to stdout
putStrLn :: ByteString -> IO ()Source
Write a ByteString to stdout, appending a newline byte
interact :: (ByteString -> ByteString) -> IO ()Source
The interact function takes a function of type ByteString -> ByteString
as its argument. The entire input from the standard input device is passed
to this function as its argument, and the resulting string is output on the
standard output device.
Files
readFile :: FilePath -> IO ByteStringSource
Read an entire file strictly into a ByteString
. This is far more
efficient than reading the characters into a String
and then using
pack
. It also may be more efficient than opening the file and
reading it using hGet. Files are read using 'binary mode' on Windows,
for 'text mode' use the Char8 version of this function.
writeFile :: FilePath -> ByteString -> IO ()Source
Write a ByteString
to a file.
appendFile :: FilePath -> ByteString -> IO ()Source
Append a ByteString
to a file.
I/O with Handles
hGetLine :: Handle -> IO ByteStringSource
Read a line from a handle
hGetContents :: Handle -> IO ByteStringSource
Read entire handle contents strictly into a ByteString
.
This function reads chunks at a time, doubling the chunksize on each
read. The final buffer is then realloced to the appropriate size. For
files > half of available memory, this may lead to memory exhaustion.
Consider using readFile
in this case.
As with hGet
, the string representation in the file is assumed to
be ISO-8859-1.
The Handle is closed once the contents have been read, or if an exception is thrown.
hGet :: Handle -> Int -> IO ByteStringSource
Read a ByteString
directly from the specified Handle
. This
is far more efficient than reading the characters into a String
and then using pack
. First argument is the Handle to read from,
and the second is the number of bytes to read. It returns the bytes
read, up to n, or null
if EOF has been reached.
hGet
is implemented in terms of hGetBuf
.
If the handle is a pipe or socket, and the writing end
is closed, hGet
will behave as if EOF was reached.
hGetSome :: Handle -> Int -> IO ByteStringSource
Like hGet
, except that a shorter ByteString
may be returned
if there are not enough bytes immediately available to satisfy the
whole request. hGetSome
only blocks if there is no data
available, and EOF has not yet been reached.
hGetNonBlocking :: Handle -> Int -> IO ByteStringSource
hGetNonBlocking is similar to hGet
, except that it will never block
waiting for data to become available, instead it returns only whatever data
is available. If there is no data available to be read, hGetNonBlocking
returns empty
.
Note: on Windows and with Haskell implementation other than GHC, this
function does not work correctly; it behaves identically to hGet
.
hPut :: Handle -> ByteString -> IO ()Source
Outputs a ByteString
to the specified Handle
.
hPutNonBlocking :: Handle -> ByteString -> IO ByteStringSource
Similar to hPut
except that it will never block. Instead it returns
any tail that did not get written. This tail may be empty
in the case that
the whole string was written, or the whole original string if nothing was
written. Partial writes are also possible.
Note: on Windows and with Haskell implementation other than GHC, this
function does not work correctly; it behaves identically to hPut
.
hPutStrLn :: Handle -> ByteString -> IO ()Source
Write a ByteString to a handle, appending a newline byte
breakByte :: Word8 -> ByteString -> (ByteString, ByteString)Source