Safe Haskell | None |
---|---|
Language | Haskell2010 |
Wrap Data.Text
We plan to replace it with Haskus.Text in the future
Synopsis
- data Text
- copy :: Text -> Text
- stripSuffix :: Text -> Text -> Maybe Text
- commonPrefixes :: Text -> Text -> Maybe (Text, Text, Text)
- stripPrefix :: Text -> Text -> Maybe Text
- isInfixOf :: Text -> Text -> Bool
- isSuffixOf :: Text -> Text -> Bool
- isPrefixOf :: Text -> Text -> Bool
- unwords :: [Text] -> Text
- unlines :: [Text] -> Text
- lines :: Text -> [Text]
- words :: Text -> [Text]
- zipWith :: (Char -> Char -> Char) -> Text -> Text -> Text
- zip :: Text -> Text -> [(Char, Char)]
- count :: Text -> Text -> Int
- findIndex :: (Char -> Bool) -> Text -> Maybe Int
- index :: Text -> Int -> Char
- breakOnAll :: Text -> Text -> [(Text, Text)]
- breakOnEnd :: Text -> Text -> (Text, Text)
- breakOn :: Text -> Text -> (Text, Text)
- filter :: (Char -> Bool) -> Text -> Text
- partition :: (Char -> Bool) -> Text -> (Text, Text)
- find :: (Char -> Bool) -> Text -> Maybe Char
- chunksOf :: Int -> Text -> [Text]
- split :: (Char -> Bool) -> Text -> [Text]
- splitOn :: Text -> Text -> [Text]
- tails :: Text -> [Text]
- inits :: Text -> [Text]
- group :: Text -> [Text]
- groupBy :: (Char -> Char -> Bool) -> Text -> [Text]
- break :: (Char -> Bool) -> Text -> (Text, Text)
- span :: (Char -> Bool) -> Text -> (Text, Text)
- splitAt :: Int -> Text -> (Text, Text)
- strip :: Text -> Text
- stripEnd :: Text -> Text
- stripStart :: Text -> Text
- dropAround :: (Char -> Bool) -> Text -> Text
- dropWhileEnd :: (Char -> Bool) -> Text -> Text
- dropWhile :: (Char -> Bool) -> Text -> Text
- takeWhileEnd :: (Char -> Bool) -> Text -> Text
- takeWhile :: (Char -> Bool) -> Text -> Text
- dropEnd :: Int -> Text -> Text
- drop :: Int -> Text -> Text
- takeEnd :: Int -> Text -> Text
- take :: Int -> Text -> Text
- unfoldrN :: Int -> (a -> Maybe (Char, a)) -> a -> Text
- unfoldr :: (a -> Maybe (Char, a)) -> a -> Text
- replicate :: Int -> Text -> Text
- mapAccumR :: (a -> Char -> (a, Char)) -> a -> Text -> (a, Text)
- mapAccumL :: (a -> Char -> (a, Char)) -> a -> Text -> (a, Text)
- scanr1 :: (Char -> Char -> Char) -> Text -> Text
- scanr :: (Char -> Char -> Char) -> Char -> Text -> Text
- scanl1 :: (Char -> Char -> Char) -> Text -> Text
- scanl :: (Char -> Char -> Char) -> Char -> Text -> Text
- minimum :: Text -> Char
- maximum :: Text -> Char
- all :: (Char -> Bool) -> Text -> Bool
- any :: (Char -> Bool) -> Text -> Bool
- concatMap :: (Char -> Text) -> Text -> Text
- concat :: [Text] -> Text
- foldr1 :: (Char -> Char -> Char) -> Text -> Char
- foldr :: (Char -> a -> a) -> a -> Text -> a
- foldl1' :: (Char -> Char -> Char) -> Text -> Char
- foldl1 :: (Char -> Char -> Char) -> Text -> Char
- foldl' :: (a -> Char -> a) -> a -> Text -> a
- foldl :: (a -> Char -> a) -> a -> Text -> a
- transpose :: [Text] -> [Text]
- justifyRight :: Int -> Char -> Text -> Text
- justifyLeft :: Int -> Char -> Text -> Text
- toTitle :: Text -> Text
- toUpper :: Text -> Text
- toLower :: Text -> Text
- toCaseFold :: Text -> Text
- replace :: Text -> Text -> Text -> Text
- reverse :: Text -> Text
- intersperse :: Char -> Text -> Text
- intercalate :: Text -> [Text] -> Text
- map :: (Char -> Char) -> Text -> Text
- compareLength :: Text -> Int -> Ordering
- length :: Text -> Int
- null :: Text -> Bool
- unsnoc :: Text -> Maybe (Text, Char)
- init :: Text -> Text
- tail :: Text -> Text
- last :: Text -> Char
- uncons :: Text -> Maybe (Char, Text)
- head :: Text -> Char
- append :: Text -> Text -> Text
- snoc :: Text -> Char -> Text
- cons :: Char -> Text -> Text
- pack :: String -> Text
- singleton :: Char -> Text
- unpackCString# :: Addr# -> Text
- unpack :: Text -> String
- empty :: Text
- bufferDecodeUtf8 :: Buffer -> Text
- textEncodeUtf8 :: Text -> Buffer
- stringEncodeUtf8 :: String -> Buffer
- textFormat :: Format Text a -> a
- data Format r a
- (%) :: Format r a -> Format r' r -> Format r' a
- (%.) :: Format r (Builder -> r') -> Format r' a -> Format r a
- module Formatting.Formatters
- textParseHexadecimal :: Integral a => Text -> Either String a
- putTextUtf8 :: Text -> Put
- getTextUtf8 :: Word -> Get Text
- getTextUtf8Nul :: Get Text
- tshow :: Show a => a -> Text
- putStrLn :: Text -> IO ()
Documentation
A space efficient, packed, unboxed Unicode text type.
O(n) Make a distinct copy of the given string, sharing no storage with the original string.
As an example, suppose you read a large string, of which you need
only a small portion. If you do not use copy
, the entire original
array will be kept alive in memory by the smaller string. Making a
copy "breaks the link" to the original array, allowing it to be
garbage collected if there are no other live references to it.
stripSuffix :: Text -> Text -> Maybe Text #
O(n) Return the prefix of the second string if its suffix matches the entire first string.
Examples:
>>>
stripSuffix "bar" "foobar"
Just "foo"
>>>
stripSuffix "" "baz"
Just "baz"
>>>
stripSuffix "foo" "quux"
Nothing
This is particularly useful with the ViewPatterns
extension to
GHC, as follows:
{-# LANGUAGE ViewPatterns #-} import Data.Text as T quuxLength :: Text -> Int quuxLength (stripSuffix "quux" -> Just pre) = T.length pre quuxLength _ = -1
commonPrefixes :: Text -> Text -> Maybe (Text, Text, Text) #
O(n) Find the longest non-empty common prefix of two strings and return it, along with the suffixes of each string at which they no longer match.
If the strings do not have a common prefix or either one is empty,
this function returns Nothing
.
Examples:
>>>
commonPrefixes "foobar" "fooquux"
Just ("foo","bar","quux")
>>>
commonPrefixes "veeble" "fetzer"
Nothing
>>>
commonPrefixes "" "baz"
Nothing
stripPrefix :: Text -> Text -> Maybe Text #
O(n) Return the suffix of the second string if its prefix matches the entire first string.
Examples:
>>>
stripPrefix "foo" "foobar"
Just "bar"
>>>
stripPrefix "" "baz"
Just "baz"
>>>
stripPrefix "foo" "quux"
Nothing
This is particularly useful with the ViewPatterns
extension to
GHC, as follows:
{-# LANGUAGE ViewPatterns #-} import Data.Text as T fnordLength :: Text -> Int fnordLength (stripPrefix "fnord" -> Just suf) = T.length suf fnordLength _ = -1
isSuffixOf :: Text -> Text -> Bool #
O(n) The isSuffixOf
function takes two Text
s and returns
True
iff the first is a suffix of the second.
isPrefixOf :: Text -> Text -> Bool #
O(n) The isPrefixOf
function takes two Text
s and returns
True
iff the first is a prefix of the second. Subject to fusion.
O(n+m) Find all non-overlapping instances of needle
in
haystack
. Each element of the returned list consists of a pair:
- The entire string prior to the kth match (i.e. the prefix)
- The kth match, followed by the remainder of the string
Examples:
>>>
breakOnAll "::" ""
[]
>>>
breakOnAll "/" "a/b/c/"
[("a","/b/c/"),("a/b","/c/"),("a/b/c","/")]
In (unlikely) bad cases, this function's time complexity degrades towards O(n*m).
The needle
parameter may not be empty.
breakOnEnd :: Text -> Text -> (Text, Text) #
O(n+m) Similar to breakOn
, but searches from the end of the
string.
The first element of the returned tuple is the prefix of haystack
up to and including the last match of needle
. The second is the
remainder of haystack
, following the match.
>>>
breakOnEnd "::" "a::b::c"
("a::b::","c")
breakOn :: Text -> Text -> (Text, Text) #
O(n+m) Find the first instance of needle
(which must be
non-null
) in haystack
. The first element of the returned tuple
is the prefix of haystack
before needle
is matched. The second
is the remainder of haystack
, starting with the match.
Examples:
>>>
breakOn "::" "a::b::c"
("a","::b::c")
>>>
breakOn "/" "foobar"
("foobar","")
Laws:
append prefix match == haystack where (prefix, match) = breakOn needle haystack
If you need to break a string by a substring repeatedly (e.g. you
want to break on every instance of a substring), use breakOnAll
instead, as it has lower startup overhead.
In (unlikely) bad cases, this function's time complexity degrades towards O(n*m).
chunksOf :: Int -> Text -> [Text] #
O(n) Splits a Text
into components of length k
. The last
element may be shorter than the other chunks, depending on the
length of the input. Examples:
>>>
chunksOf 3 "foobarbaz"
["foo","bar","baz"]
>>>
chunksOf 4 "haskell.org"
["hask","ell.","org"]
split :: (Char -> Bool) -> Text -> [Text] #
O(n) Splits a Text
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.
>>>
split (=='a') "aabbaca"
["","","bb","c",""]
>>>
split (=='a') ""
[""]
O(m+n) Break a Text
into pieces separated by the first Text
argument (which cannot be empty), consuming the delimiter. An empty
delimiter is invalid, and will cause an error to be raised.
Examples:
>>>
splitOn "\r\n" "a\r\nb\r\nd\r\ne"
["a","b","d","e"]
>>>
splitOn "aaa" "aaaXaaaXaaaXaaa"
["","X","X","X",""]
>>>
splitOn "x" "x"
["",""]
and
intercalate s . splitOn s == id splitOn (singleton c) == split (==c)
(Note: the string s
to split on above cannot be empty.)
In (unlikely) bad cases, this function's time complexity degrades towards O(n*m).
groupBy :: (Char -> Char -> Bool) -> Text -> [Text] #
O(n) Group characters in a string according to a predicate.
span :: (Char -> Bool) -> Text -> (Text, Text) #
O(n) span
, applied to a predicate p
and text t
, returns
a pair whose first element is the longest prefix (possibly empty)
of t
of elements that satisfy p
, and whose second is the
remainder of the list.
O(n) Remove leading and trailing white space from a string. Equivalent to:
dropAround isSpace
O(n) Remove trailing white space from a string. Equivalent to:
dropWhileEnd isSpace
stripStart :: Text -> Text #
O(n) Remove leading white space from a string. Equivalent to:
dropWhile isSpace
dropAround :: (Char -> Bool) -> Text -> Text #
O(n) dropAround
p
t
returns the substring remaining after
dropping characters that satisfy the predicate p
from both the
beginning and end of t
. Subject to fusion.
dropWhileEnd :: (Char -> Bool) -> Text -> Text #
O(n) dropWhileEnd
p
t
returns the prefix remaining after
dropping characters that satisfy the predicate p
from the end of
t
. Subject to fusion.
Examples:
>>>
dropWhileEnd (=='.') "foo..."
"foo"
takeWhileEnd :: (Char -> Bool) -> Text -> Text #
O(n) takeWhileEnd
, applied to a predicate p
and a Text
,
returns the longest suffix (possibly empty) of elements that
satisfy p
. Subject to fusion.
Examples:
>>>
takeWhileEnd (=='o') "foo"
"oo"
Since: text-1.2.2.0
dropEnd :: Int -> Text -> Text #
O(n) dropEnd
n
t
returns the prefix remaining after
dropping n
characters from the end of t
.
Examples:
>>>
dropEnd 3 "foobar"
"foo"
Since: text-1.1.1.0
takeEnd :: Int -> Text -> Text #
O(n) takeEnd
n
t
returns the suffix remaining after
taking n
characters from the end of t
.
Examples:
>>>
takeEnd 3 "foobar"
"bar"
Since: text-1.1.1.0
unfoldrN :: Int -> (a -> Maybe (Char, a)) -> a -> Text #
O(n) Like unfoldr
, unfoldrN
builds a Text
from a seed
value. However, the length of the result should be limited by the
first argument to unfoldrN
. This function is more efficient than
unfoldr
when the maximum length of the result is known and
correct, otherwise its performance is similar to unfoldr
. Subject
to fusion. Performs replacement on invalid scalar values.
unfoldr :: (a -> Maybe (Char, a)) -> a -> Text #
O(n), where n
is the length of the result. The unfoldr
function is analogous to the List unfoldr
. unfoldr
builds a
Text
from a seed value. The function takes the element and
returns Nothing
if it is done producing the Text
, otherwise
Just
(a,b)
. In this case, a
is the next Char
in the
string, and b
is the seed value for further production. Subject
to fusion. Performs replacement on invalid scalar values.
mapAccumR :: (a -> Char -> (a, Char)) -> a -> Text -> (a, Text) #
The mapAccumR
function behaves like a combination of map
and
a strict foldr
; it applies a function to each element of a
Text
, passing an accumulating parameter from right to left, and
returning a final value of this accumulator together with the new
Text
.
Performs replacement on invalid scalar values.
foldl1' :: (Char -> Char -> Char) -> Text -> Char #
O(n) A strict version of foldl1
. Subject to fusion.
transpose :: [Text] -> [Text] #
O(n) The transpose
function transposes the rows and columns
of its Text
argument. Note that this function uses pack
,
unpack
, and the list version of transpose, and is thus not very
efficient.
Examples:
>>>
transpose ["green","orange"]
["go","rr","ea","en","ng","e"]
>>>
transpose ["blue","red"]
["br","le","ud","e"]
justifyRight :: Int -> Char -> Text -> Text #
O(n) Right-justify a string to the given length, using the specified fill character on the left. Performs replacement on invalid scalar values.
Examples:
>>>
justifyRight 7 'x' "bar"
"xxxxbar"
>>>
justifyRight 3 'x' "foobar"
"foobar"
justifyLeft :: Int -> Char -> Text -> Text #
O(n) Left-justify a string to the given length, using the specified fill character on the right. Subject to fusion. Performs replacement on invalid scalar values.
Examples:
>>>
justifyLeft 7 'x' "foo"
"fooxxxx"
>>>
justifyLeft 3 'x' "foobar"
"foobar"
O(n) Convert a string to title case, using simple case conversion. Subject to fusion.
The first letter of the input is converted to title case, as is every subsequent letter that immediately follows a non-letter. Every letter that immediately follows another letter is converted to lower case.
The result string may be longer than the input string. For example, the Latin small ligature fl (U+FB02) is converted to the sequence Latin capital letter F (U+0046) followed by Latin small letter l (U+006C).
Note: this function does not take language or culture specific rules into account. For instance, in English, different style guides disagree on whether the book name "The Hill of the Red Fox" is correctly title cased—but this function will capitalize every word.
Since: text-1.0.0.0
O(n) Convert a string to upper case, using simple case conversion. Subject to fusion.
The result string may be longer than the input string. For instance, the German "ß" (eszett, U+00DF) maps to the two-letter sequence "SS".
O(n) Convert a string to lower case, using simple case conversion. Subject to fusion.
The result string may be longer than the input string. For instance, "İ" (Latin capital letter I with dot above, U+0130) maps to the sequence "i" (Latin small letter i, U+0069) followed by " ̇" (combining dot above, U+0307).
toCaseFold :: Text -> Text #
O(n) Convert a string to folded case. Subject to fusion.
This function is mainly useful for performing caseless (also known as case insensitive) string comparisons.
A string x
is a caseless match for a string y
if and only if:
toCaseFold x == toCaseFold y
The result string may be longer than the input string, and may
differ from applying toLower
to the input string. For instance,
the Armenian small ligature "ﬓ" (men now, U+FB13) is case
folded to the sequence "մ" (men, U+0574) followed by
"ն" (now, U+0576), while the Greek "µ" (micro sign,
U+00B5) is case folded to "μ" (small letter mu, U+03BC)
instead of itself.
:: Text |
|
-> Text |
|
-> Text |
|
-> Text |
O(m+n) Replace every non-overlapping occurrence of needle
in
haystack
with replacement
.
This function behaves as though it was defined as follows:
replace needle replacement haystack =intercalate
replacement (splitOn
needle haystack)
As this suggests, each occurrence is replaced exactly once. So if
needle
occurs in replacement
, that occurrence will not itself
be replaced recursively:
>>>
replace "oo" "foo" "oo"
"foo"
In cases where several instances of needle
overlap, only the
first one will be replaced:
>>>
replace "ofo" "bar" "ofofo"
"barfo"
In (unlikely) bad cases, this function's time complexity degrades towards O(n*m).
O(n) Reverse the characters of a string.
Example:
>>>
T.reverse "desrever"
"reversed"
Subject to fusion.
intersperse :: Char -> Text -> Text #
O(n) The intersperse
function takes a character and places it
between the characters of a Text
.
Example:
>>>
T.intersperse '.' "SHIELD"
"S.H.I.E.L.D"
Subject to fusion. Performs replacement on invalid scalar values.
intercalate :: Text -> [Text] -> Text #
O(n) The intercalate
function takes a Text
and a list of
Text
s and concatenates the list after interspersing the first
argument between each element of the list.
Example:
>>>
T.intercalate "NI!" ["We", "seek", "the", "Holy", "Grail"]
"WeNI!seekNI!theNI!HolyNI!Grail"
compareLength :: Text -> Int -> Ordering #
O(1) Returns all but the last character of a Text
, which must
be non-empty. Subject to fusion.
O(1) Returns all characters after the head of a Text
, which
must be non-empty. Subject to fusion.
O(1) Returns the last character of a Text
, which must be
non-empty. Subject to fusion.
O(1) Returns the first character of a Text
, which must be
non-empty. Subject to fusion.
snoc :: Text -> Char -> Text #
O(n) Adds a character to the end of a Text
. This copies the
entire array in the process, unless fused. Subject to fusion.
Performs replacement on invalid scalar values.
cons :: Char -> Text -> Text infixr 5 #
O(n) Adds a character to the front of a Text
. This function
is more costly than its List
counterpart because it requires
copying a new array. Subject to fusion. Performs replacement on
invalid scalar values.
O(1) Convert a character into a Text. Subject to fusion. Performs replacement on invalid scalar values.
unpackCString# :: Addr# -> Text #
O(n) Convert a literal string into a Text
. Subject to
fusion.
This is exposed solely for people writing GHC rewrite rules.
Since: text-1.2.1.1
Conversions
bufferDecodeUtf8 :: Buffer -> Text Source #
Decode Utf8
textEncodeUtf8 :: Text -> Buffer Source #
Encode Text into Utf8
stringEncodeUtf8 :: String -> Buffer Source #
Encode String into Utf8
Formatting
textFormat :: Format Text a -> a Source #
Format a text (strict)
A formatter. When you construct formatters the first type
parameter, r
, will remain polymorphic. The second type
parameter, a
, will change to reflect the types of the data that
will be formatted. For example, in
myFormat :: Formatter r (Text -> Int -> r) myFormat = "Person's name is " % text % ", age is " % hex
the first type parameter remains polymorphic, and the second type
parameter is Text -> Int -> r
, which indicates that it formats a
Text
and an Int
.
When you run the Format
, for example with format
, you provide
the arguments and they will be formatted into a string.
> format ("Person's name is " % text % ", age is " % hex) "Dave" 54 "Person's name is Dave, age is 36"
Instances
Functor (Format r) | Not particularly useful, but could be. |
Category Format | The same as (%). At present using |
a ~ r => IsString (Format r a) | Useful instance for writing format string. With this you can
write |
Defined in Formatting.Internal fromString :: String -> Format r a # | |
Semigroup (Format r (a -> r)) | |
Monoid (Format r (a -> r)) | Useful instance for applying two formatters to the same input
argument. For example: |
(%) :: Format r a -> Format r' r -> Format r' a infixr 9 #
Concatenate two formatters.
formatter1 % formatter2
is a formatter that accepts arguments for
formatter1
and formatter2
and concatenates their results. For example
format1 :: Format r (Text -> r) format1 = "Person's name is " % text
format2 :: Format r r format2 = ", "
format3 :: Format r (Int -> r) format3 = "age is " % hex
myFormat :: Formatter r (Text -> Int -> r) myFormat = format1 % format2 % format3
Notice how the argument types of format1
and format3
are
gathered into the type of myFormat
.
(This is actually the composition operator for Format'
s
Category
instance, but that is (at present) inconvenient to use
with regular Prelude. So this function is provided as a
convenience.)
(%.) :: Format r (Builder -> r') -> Format r' a -> Format r a infixr 8 #
Function compose two formatters. Will feed the result of one formatter into another.
module Formatting.Formatters
Parsing
textParseHexadecimal :: Integral a => Text -> Either String a Source #
Parse an hexadecimal number FIXME: use a real parser (MegaParsec, etc.)
Get/Put
putTextUtf8 :: Text -> Put Source #
Put an UTF8 encoded text
getTextUtf8Nul :: Get Text Source #
Pull 0 terminal text