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
- Transforming ByteStrings
- Reducing
ByteString
s (folds) - Building ByteStrings
- Substrings
- Predicates
- Searching ByteStrings
- Indexing ByteStrings
- Zipping and unzipping ByteStrings
- Ordered ByteStrings
- Low level conversions
- Reading from ByteStrings
- I/O with
ByteString
s
Manipulate lazy 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.Lazy.
This module is intended to be imported qualified
, to avoid name
clashes with Prelude functions. eg.
import qualified Data.ByteString.Lazy.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.
Synopsis
- data ByteString
- empty :: ByteString
- singleton :: Char -> ByteString
- pack :: [Char] -> ByteString
- unpack :: ByteString -> [Char]
- fromChunks :: [ByteString] -> ByteString
- toChunks :: ByteString -> [ByteString]
- fromStrict :: ByteString -> ByteString
- toStrict :: ByteString -> ByteString
- cons :: Char -> ByteString -> ByteString
- cons' :: Char -> ByteString -> ByteString
- snoc :: ByteString -> Char -> ByteString
- append :: ByteString -> ByteString -> ByteString
- head :: ByteString -> Char
- uncons :: ByteString -> Maybe (Char, ByteString)
- last :: ByteString -> Char
- tail :: ByteString -> ByteString
- unsnoc :: ByteString -> Maybe (ByteString, Char)
- init :: ByteString -> ByteString
- null :: ByteString -> Bool
- length :: ByteString -> Int64
- 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
- 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
- mapAccumL :: (acc -> Char -> (acc, Char)) -> acc -> ByteString -> (acc, ByteString)
- mapAccumR :: (acc -> Char -> (acc, Char)) -> acc -> ByteString -> (acc, ByteString)
- repeat :: Char -> ByteString
- replicate :: Int64 -> Char -> ByteString
- cycle :: ByteString -> ByteString
- iterate :: (Char -> Char) -> Char -> ByteString
- unfoldr :: (a -> Maybe (Char, a)) -> a -> ByteString
- take :: Int64 -> ByteString -> ByteString
- drop :: Int64 -> ByteString -> ByteString
- splitAt :: Int64 -> ByteString -> (ByteString, ByteString)
- takeWhile :: (Char -> Bool) -> ByteString -> ByteString
- dropWhile :: (Char -> Bool) -> ByteString -> ByteString
- span :: (Char -> Bool) -> ByteString -> (ByteString, ByteString)
- break :: (Char -> Bool) -> ByteString -> (ByteString, ByteString)
- group :: ByteString -> [ByteString]
- groupBy :: (Char -> Char -> Bool) -> ByteString -> [ByteString]
- inits :: ByteString -> [ByteString]
- tails :: ByteString -> [ByteString]
- stripPrefix :: ByteString -> ByteString -> Maybe ByteString
- stripSuffix :: ByteString -> ByteString -> Maybe 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
- elem :: Char -> ByteString -> Bool
- notElem :: Char -> ByteString -> Bool
- find :: (Char -> Bool) -> ByteString -> Maybe Char
- filter :: (Char -> Bool) -> ByteString -> ByteString
- index :: ByteString -> Int64 -> Char
- elemIndex :: Char -> ByteString -> Maybe Int64
- elemIndices :: Char -> ByteString -> [Int64]
- findIndex :: (Char -> Bool) -> ByteString -> Maybe Int64
- findIndices :: (Char -> Bool) -> ByteString -> [Int64]
- count :: Char -> ByteString -> Int64
- zip :: ByteString -> ByteString -> [(Char, Char)]
- zipWith :: (Char -> Char -> a) -> ByteString -> ByteString -> [a]
- copy :: ByteString -> ByteString
- readInt :: ByteString -> Maybe (Int, ByteString)
- readInteger :: ByteString -> Maybe (Integer, 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 ()
- hGetContents :: Handle -> IO ByteString
- hGet :: 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 lazy ByteString
contains 8-bit bytes, or by using the operations
from Data.ByteString.Lazy.Char8 it can be interpreted as containing
8-bit characters.
Instances
Introducing and eliminating
ByteString
s
empty :: ByteString Source #
O(1) The empty ByteString
singleton :: Char -> ByteString Source #
O(1) Convert a Char
into a ByteString
pack :: [Char] -> ByteString Source #
O(n) Convert a String
into a ByteString
.
unpack :: ByteString -> [Char] Source #
O(n) Converts a ByteString
to a String
.
fromChunks :: [ByteString] -> ByteString Source #
O(c) Convert a list of strict ByteString
into a lazy ByteString
toChunks :: ByteString -> [ByteString] Source #
O(c) Convert a lazy ByteString
into a list of strict ByteString
fromStrict :: ByteString -> ByteString Source #
O(1) Convert a strict ByteString
into a lazy ByteString
.
toStrict :: ByteString -> ByteString Source #
O(n) Convert a lazy ByteString
into a strict ByteString
.
Note that this is an expensive operation that forces the whole lazy ByteString into memory and then copies all the data. If possible, try to avoid converting back and forth between strict and lazy bytestrings.
Basic interface
cons :: Char -> ByteString -> ByteString infixr 5 Source #
O(1) cons
is analogous to '(:)' for lists.
cons' :: Char -> ByteString -> ByteString infixr 5 Source #
O(1) Unlike cons
, 'cons\'' is
strict in the ByteString that we are consing onto. More precisely, it forces
the head and the first chunk. It does this because, for space efficiency, it
may coalesce the new byte onto the first 'chunk' rather than starting a
new 'chunk'.
So that means you can't use a lazy recursive contruction like this:
let xs = cons\' c xs in xs
You can however use cons
, as well as repeat
and cycle
, to build
infinite lazy ByteStrings.
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/c) 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.
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.
unsnoc :: ByteString -> Maybe (ByteString, Char) Source #
init :: ByteString -> ByteString Source #
O(n/c) Return all the elements of a ByteString
except the last one.
null :: ByteString -> Bool Source #
O(1) Test whether a ByteString is empty.
Transforming 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
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.
foldl1' :: (Char -> Char -> Char) -> ByteString -> Char Source #
'foldl1\'' is like foldl1
, 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.
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 #
Accumulating maps
mapAccumL :: (acc -> Char -> (acc, Char)) -> acc -> ByteString -> (acc, ByteString) Source #
mapAccumR :: (acc -> Char -> (acc, Char)) -> acc -> ByteString -> (acc, ByteString) Source #
Infinite ByteStrings
repeat :: Char -> ByteString Source #
is an infinite ByteString, with repeat
xx
the value of every
element.
replicate :: Int64 -> Char -> ByteString Source #
O(n)
is a ByteString of length replicate
n xn
with x
the value of every element.
cycle :: ByteString -> ByteString Source #
cycle
ties a finite ByteString into a circular one, or equivalently,
the infinite repetition of the original ByteString.
iterate :: (Char -> Char) -> Char -> ByteString Source #
returns an infinite ByteString of repeated applications
of iterate
f xf
to x
:
iterate f x == [x, f x, f (f x), ...]
Unfolding ByteStrings
unfoldr :: (a -> Maybe (Char, a)) -> a -> ByteString Source #
O(n) 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 a
prepending to the ByteString and b
is used as the next element in a
recursive call.
Substrings
Breaking strings
take :: Int64 -> ByteString -> ByteString Source #
drop :: Int64 -> ByteString -> ByteString Source #
splitAt :: Int64 -> 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 #
break :: (Char -> Bool) -> ByteString -> (ByteString, ByteString) Source #
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.
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.
stripPrefix :: ByteString -> ByteString -> Maybe ByteString Source #
O(n) The stripPrefix
function takes two ByteStrings and returns Just
the remainder of the second iff the first is its prefix, and otherwise
Nothing
.
Since: bytestring-0.10.8.0
stripSuffix :: ByteString -> ByteString -> Maybe ByteString Source #
O(n) The stripSuffix
function takes two ByteStrings and returns Just
the remainder of the second iff the first is its suffix, and otherwise
Nothing
.
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.
As of bytestring 0.9.0.3, this function is stricter than its list cousin.
words :: ByteString -> [ByteString] Source #
words
breaks a ByteString up into a list of words, which
were delimited by Chars representing white space. And
tokens isSpace = words
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
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 -> Int64 -> Char Source #
O(1) ByteString
index (subscript) operator, starting from 0.
elemIndex :: Char -> ByteString -> Maybe Int64 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 -> [Int64] Source #
O(n) The elemIndices
function extends elemIndex
, by returning
the indices of all elements equal to the query element, in ascending order.
findIndex :: (Char -> Bool) -> ByteString -> Maybe Int64 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 -> [Int64] Source #
The findIndices
function extends findIndex
, by returning the
indices of all elements satisfying the predicate, in ascending order.
count :: Char -> ByteString -> Int64 Source #
count returns the number of times its argument appears in the ByteString
count == length . elemIndices 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 #
Ordered ByteStrings
Low level 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.
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.
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
getContents :: IO ByteString Source #
getContents. Equivalent to hGetContents stdin. Will read lazily
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 lazily into a ByteString
.
The Handle will be held open until EOF is encountered.
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
hGetContents :: Handle -> IO ByteString Source #
Read entire handle contents lazily into a ByteString
. Chunks
are read on demand, using the default chunk size.
Once EOF is encountered, the Handle is closed.
Note: the Handle
should be placed in binary mode with
hSetBinaryMode
for hGetContents
to
work correctly.
hGet :: Handle -> Int -> IO ByteString Source #
Read n
bytes into a ByteString
, directly from the specified Handle
.
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
. The chunks will be
written one at a time. Other threads might write to the Handle
between the
writes, and hence hPut
alone might not be suitable for concurrent writes.
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
.