Copyright | (c) Don Stewart 2006-2008 (c) Duncan Coutts 2006-2011 |
---|---|
License | BSD-style |
Maintainer | dons00@gmail.com, duncan@community.haskell.org |
Stability | stable |
Portability | portable |
Safe Haskell | Trustworthy |
Language | Haskell98 |
- The
ByteString
type - Introducing and eliminating
ByteString
s - Basic interface
- Transformating ByteStrings
- Reducing
ByteString
s (folds) - Building ByteStrings
- Substrings
- Predicates
- Searching ByteStrings
- Indexing ByteStrings
- Zipping and unzipping ByteStrings
- Ordered ByteStrings
- Reading from ByteStrings
- Low level CString conversions
- I/O with
ByteString
s
Manipulate ByteString
s using Char
operations. All Chars will be
truncated to 8 bits. It can be expected that these functions will run
at identical speeds to their Word8
equivalents in Data.ByteString.
More specifically these byte strings are taken to be in the subset of Unicode covered by code points 0-255. This covers Unicode Basic Latin, Latin-1 Supplement and C0+C1 Controls.
See:
- http://www.unicode.org/charts/
- http://www.unicode.org/charts/PDF/U0000.pdf
- http://www.unicode.org/charts/PDF/U0080.pdf
This module is intended to be imported qualified
, to avoid name
clashes with Prelude functions. eg.
import qualified Data.ByteString.Char8 as C
The Char8 interface to bytestrings provides an instance of IsString
for the ByteString type, enabling you to use string literals, and
have them implicitly packed to ByteStrings.
Use {-# LANGUAGE OverloadedStrings #-}
to enable this.
- data ByteString
- empty :: ByteString
- singleton :: Char -> ByteString
- pack :: String -> ByteString
- unpack :: ByteString -> [Char]
- cons :: Char -> ByteString -> ByteString
- snoc :: ByteString -> Char -> ByteString
- append :: ByteString -> ByteString -> ByteString
- head :: ByteString -> Char
- uncons :: ByteString -> Maybe (Char, ByteString)
- unsnoc :: ByteString -> Maybe (ByteString, Char)
- last :: ByteString -> Char
- tail :: ByteString -> ByteString
- init :: ByteString -> ByteString
- null :: ByteString -> Bool
- length :: ByteString -> Int
- map :: (Char -> Char) -> ByteString -> ByteString
- reverse :: ByteString -> ByteString
- intersperse :: Char -> ByteString -> ByteString
- intercalate :: ByteString -> [ByteString] -> ByteString
- transpose :: [ByteString] -> [ByteString]
- foldl :: (a -> Char -> a) -> a -> ByteString -> a
- foldl' :: (a -> Char -> a) -> a -> ByteString -> a
- foldl1 :: (Char -> Char -> Char) -> ByteString -> Char
- foldl1' :: (Char -> Char -> Char) -> ByteString -> Char
- foldr :: (Char -> a -> a) -> a -> ByteString -> a
- foldr' :: (Char -> a -> a) -> a -> ByteString -> a
- foldr1 :: (Char -> Char -> Char) -> ByteString -> Char
- foldr1' :: (Char -> Char -> Char) -> ByteString -> Char
- concat :: [ByteString] -> ByteString
- concatMap :: (Char -> ByteString) -> ByteString -> ByteString
- any :: (Char -> Bool) -> ByteString -> Bool
- all :: (Char -> Bool) -> ByteString -> Bool
- maximum :: ByteString -> Char
- minimum :: ByteString -> Char
- scanl :: (Char -> Char -> Char) -> Char -> ByteString -> ByteString
- scanl1 :: (Char -> Char -> Char) -> ByteString -> ByteString
- scanr :: (Char -> Char -> Char) -> Char -> ByteString -> ByteString
- scanr1 :: (Char -> Char -> Char) -> ByteString -> ByteString
- mapAccumL :: (acc -> Char -> (acc, Char)) -> acc -> ByteString -> (acc, ByteString)
- mapAccumR :: (acc -> Char -> (acc, Char)) -> acc -> ByteString -> (acc, ByteString)
- replicate :: Int -> Char -> ByteString
- unfoldr :: (a -> Maybe (Char, a)) -> a -> ByteString
- unfoldrN :: Int -> (a -> Maybe (Char, a)) -> a -> (ByteString, Maybe a)
- take :: Int -> ByteString -> ByteString
- drop :: Int -> ByteString -> ByteString
- splitAt :: Int -> ByteString -> (ByteString, ByteString)
- takeWhile :: (Char -> Bool) -> ByteString -> ByteString
- dropWhile :: (Char -> Bool) -> ByteString -> ByteString
- span :: (Char -> Bool) -> ByteString -> (ByteString, ByteString)
- spanEnd :: (Char -> Bool) -> ByteString -> (ByteString, ByteString)
- break :: (Char -> Bool) -> ByteString -> (ByteString, ByteString)
- breakEnd :: (Char -> Bool) -> ByteString -> (ByteString, ByteString)
- group :: ByteString -> [ByteString]
- groupBy :: (Char -> Char -> Bool) -> ByteString -> [ByteString]
- inits :: ByteString -> [ByteString]
- tails :: ByteString -> [ByteString]
- split :: Char -> ByteString -> [ByteString]
- splitWith :: (Char -> Bool) -> ByteString -> [ByteString]
- lines :: ByteString -> [ByteString]
- words :: ByteString -> [ByteString]
- unlines :: [ByteString] -> ByteString
- unwords :: [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 :: Char -> ByteString -> Bool
- notElem :: Char -> ByteString -> Bool
- find :: (Char -> Bool) -> ByteString -> Maybe Char
- filter :: (Char -> Bool) -> ByteString -> ByteString
- index :: ByteString -> Int -> Char
- elemIndex :: Char -> ByteString -> Maybe Int
- elemIndices :: Char -> ByteString -> [Int]
- elemIndexEnd :: Char -> ByteString -> Maybe Int
- findIndex :: (Char -> Bool) -> ByteString -> Maybe Int
- findIndices :: (Char -> Bool) -> ByteString -> [Int]
- count :: Char -> ByteString -> Int
- zip :: ByteString -> ByteString -> [(Char, Char)]
- zipWith :: (Char -> Char -> a) -> ByteString -> ByteString -> [a]
- unzip :: [(Char, Char)] -> (ByteString, ByteString)
- sort :: ByteString -> ByteString
- readInt :: ByteString -> Maybe (Int, ByteString)
- readInteger :: ByteString -> Maybe (Integer, 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 ()
The ByteString
type
data ByteString Source
A space-efficient representation of a Word8
vector, supporting many
efficient operations.
A ByteString
contains 8-bit bytes, or by using the operations from
Data.ByteString.Char8 it can be interpreted as containing 8-bit
characters.
Introducing and eliminating ByteString
s
O(1) The empty ByteString
singleton :: Char -> ByteString Source
O(1) Convert a Char
into a ByteString
pack :: String -> ByteString Source
O(n) Convert a String
into a ByteString
For applications with large numbers of string literals, pack can be a bottleneck.
unpack :: ByteString -> [Char] Source
O(n) Converts a ByteString
to a String
.
Basic interface
cons :: Char -> ByteString -> ByteString infixr 5 Source
O(n) cons
is analogous to (:) for lists, but of different
complexity, as it requires a memcpy.
snoc :: ByteString -> Char -> ByteString infixl 5 Source
O(n) Append a Char to the end of a ByteString
. Similar to
cons
, this function performs a memcpy.
append :: ByteString -> ByteString -> ByteString Source
O(n) Append two ByteStrings
head :: ByteString -> Char Source
O(1) Extract the first element of a ByteString, which must be non-empty.
uncons :: ByteString -> Maybe (Char, ByteString) Source
O(1) Extract the head and tail of a ByteString, returning Nothing if it is empty.
unsnoc :: ByteString -> Maybe (ByteString, Char) Source
last :: ByteString -> Char Source
O(1) Extract the last element of a packed string, which must be non-empty.
tail :: ByteString -> ByteString Source
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 -> ByteString Source
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 -> Bool Source
O(1) Test whether a ByteString is empty.
Transformating ByteStrings
map :: (Char -> Char) -> ByteString -> ByteString Source
O(n) map
f xs
is the ByteString obtained by applying f
to each element of xs
reverse :: ByteString -> ByteString Source
O(n) reverse
xs
efficiently returns the elements of xs
in reverse order.
intersperse :: Char -> ByteString -> ByteString Source
O(n) The intersperse
function takes a Char and a ByteString
and `intersperses' that Char between the elements of the
ByteString
. It is analogous to the intersperse function on Lists.
intercalate :: ByteString -> [ByteString] -> ByteString Source
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 -> Char -> a) -> a -> ByteString -> a Source
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.
foldl' :: (a -> Char -> a) -> a -> ByteString -> a Source
'foldl\'' is like foldl, but strict in the accumulator.
foldr :: (Char -> a -> a) -> a -> ByteString -> a Source
foldr
, applied to a binary operator, a starting value
(typically the right-identity of the operator), and a packed string,
reduces the packed string using the binary operator, from right to left.
foldr' :: (Char -> a -> a) -> a -> ByteString -> a Source
'foldr\'' is a strict variant of foldr
foldr1 :: (Char -> Char -> Char) -> ByteString -> Char Source
foldr1
is a variant of foldr
that has no starting value argument,
and thus must be applied to non-empty ByteString
s
Special folds
concat :: [ByteString] -> ByteString Source
O(n) Concatenate a list of ByteStrings.
concatMap :: (Char -> ByteString) -> ByteString -> ByteString Source
Map a function over a ByteString
and concatenate the results
any :: (Char -> Bool) -> ByteString -> Bool Source
Applied to a predicate and a ByteString, any
determines if
any element of the ByteString
satisfies the predicate.
all :: (Char -> Bool) -> ByteString -> Bool Source
Applied to a predicate and a ByteString
, all
determines if
all elements of the ByteString
satisfy the predicate.
maximum :: ByteString -> Char Source
maximum
returns the maximum value from a ByteString
minimum :: ByteString -> Char Source
minimum
returns the minimum value from a ByteString
Building ByteStrings
Scans
scanl :: (Char -> Char -> Char) -> Char -> ByteString -> ByteString Source
scanl1 :: (Char -> Char -> Char) -> ByteString -> ByteString Source
scanr :: (Char -> Char -> Char) -> Char -> ByteString -> ByteString Source
scanr is the right-to-left dual of scanl.
scanr1 :: (Char -> Char -> Char) -> ByteString -> ByteString Source
Accumulating maps
mapAccumL :: (acc -> Char -> (acc, Char)) -> acc -> ByteString -> (acc, ByteString) Source
mapAccumR :: (acc -> Char -> (acc, Char)) -> acc -> ByteString -> (acc, ByteString) Source
Generating and unfolding ByteStrings
replicate :: Int -> Char -> ByteString Source
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 (Char, a)) -> a -> ByteString Source
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 character in the string,
and b
is the seed value for further production.
Examples:
unfoldr (\x -> if x <= '9' then Just (x, succ x) else Nothing) '0' == "0123456789"
unfoldrN :: Int -> (a -> Maybe (Char, 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
:
unfoldrN n f s == take n (unfoldr f s)
Substrings
Breaking strings
take :: Int -> ByteString -> ByteString Source
drop :: Int -> ByteString -> ByteString Source
splitAt :: Int -> ByteString -> (ByteString, ByteString) Source
takeWhile :: (Char -> Bool) -> ByteString -> ByteString Source
takeWhile
, applied to a predicate p
and a ByteString xs
,
returns the longest prefix (possibly empty) of xs
of elements that
satisfy p
.
dropWhile :: (Char -> Bool) -> ByteString -> ByteString Source
span :: (Char -> Bool) -> ByteString -> (ByteString, ByteString) Source
spanEnd :: (Char -> 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 :: (Char -> Bool) -> ByteString -> (ByteString, ByteString) Source
breakEnd :: (Char -> 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 :: (Char -> Char -> 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 :: Char -> 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 :: (Char -> 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",""]
Breaking into lines and words
lines :: ByteString -> [ByteString] Source
lines
breaks a ByteString up into a list of ByteStrings at
newline Chars. The resulting strings do not contain newlines.
words :: ByteString -> [ByteString] Source
words
breaks a ByteString up into a list of words, which
were delimited by Chars representing white space.
unlines :: [ByteString] -> ByteString Source
unwords :: [ByteString] -> ByteString Source
Predicates
isPrefixOf :: ByteString -> ByteString -> Bool Source
O(n) The isPrefixOf
function takes two ByteStrings and returns True
iff the first is a prefix of the second.
isSuffixOf :: ByteString -> ByteString -> Bool Source
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 -> Bool Source
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 |
Deprecated: findSubstring is deprecated in favour of breakSubstring.
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] |
Deprecated: findSubstrings is deprecated in favour of breakSubstring.
Find the indexes of all (possibly overlapping) occurances of a substring in a string.
Searching ByteStrings
Searching by equality
elem :: Char -> ByteString -> Bool Source
O(n) elem
is the ByteString
membership predicate. This
implementation uses memchr(3)
.
Searching with a predicate
filter :: (Char -> Bool) -> ByteString -> ByteString Source
O(n) filter
, applied to a predicate and a ByteString,
returns a ByteString containing those characters that satisfy the
predicate.
Indexing ByteStrings
index :: ByteString -> Int -> Char Source
O(1) ByteString
index (subscript) operator, starting from 0.
elemIndex :: Char -> ByteString -> Maybe Int Source
O(n) The elemIndex
function returns the index of the first
element in the given ByteString
which is equal (by memchr) to the
query element, or Nothing
if there is no such element.
elemIndices :: Char -> 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.
elemIndexEnd :: Char -> ByteString -> Maybe Int Source
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 :: (Char -> Bool) -> ByteString -> Maybe Int Source
The findIndex
function takes a predicate and a ByteString
and
returns the index of the first element in the ByteString satisfying the predicate.
findIndices :: (Char -> Bool) -> ByteString -> [Int] Source
The findIndices
function extends findIndex
, by returning the
indices of all elements satisfying the predicate, in ascending order.
count :: Char -> ByteString -> Int Source
count returns the number of times its argument appears in the ByteString
count = length . elemIndices
Also
count '\n' == length . lines
But more efficiently than using length on the intermediate list.
Zipping and unzipping ByteStrings
zip :: ByteString -> ByteString -> [(Char, Char)] Source
zipWith :: (Char -> Char -> a) -> ByteString -> ByteString -> [a] Source
unzip :: [(Char, Char)] -> (ByteString, ByteString) Source
Ordered ByteStrings
sort :: ByteString -> ByteString Source
O(n) Sort a ByteString efficiently, using counting sort.
Reading from ByteStrings
readInt :: ByteString -> Maybe (Int, ByteString) Source
readInt reads an Int from the beginning of the ByteString. If there is no integer at the beginning of the string, it returns Nothing, otherwise it just returns the int read, and the rest of the string.
readInteger :: ByteString -> Maybe (Integer, ByteString) Source
readInteger reads an Integer from the beginning of the ByteString. If there is no integer at the beginning of the string, it returns Nothing, otherwise it just returns the int read, and the rest of the string.
Low level CString conversions
Copying ByteStrings
copy :: ByteString -> ByteString Source
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 CStrings and pointers
packCString :: CString -> IO ByteString Source
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 ByteString Source
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 CStrings
useAsCString :: ByteString -> (CString -> IO a) -> IO a Source
O(n) construction Use a ByteString
with a function requiring a
null-terminated CString
. The CString
is a copy and will be freed
automatically.
useAsCStringLen :: ByteString -> (CStringLen -> IO a) -> IO a Source
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
ByteString I/O uses binary mode, without any character decoding or newline conversion. The fact that it does not respect the Handle newline mode is considered a flaw and may be changed in a future version.
Standard input and output
getLine :: IO ByteString Source
Read a line from stdin.
getContents :: IO ByteString Source
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 ByteString Source
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.
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 ByteString Source
Read a line from a handle
hGetContents :: Handle -> IO ByteString Source
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 ByteString Source
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 ByteString Source
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 ByteString Source
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 ByteString Source
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
.
hPutStr :: Handle -> ByteString -> IO () Source
A synonym for hPut
, for compatibility
hPutStrLn :: Handle -> ByteString -> IO () Source
Write a ByteString to a handle, appending a newline byte