Safe Haskell | Safe-Inferred |
---|---|
Language | Haskell2010 |
HaskellWorks.Polysemy.Data.Text.Strict
Synopsis
- data Text
- pack :: String -> Text
- unpack :: Text -> String
- singleton :: Char -> Text
- empty :: Text
- length :: Text -> Int
- compareLength :: Text -> Int -> Ordering
- null :: Text -> Bool
- map :: (Char -> Char) -> Text -> Text
- intercalate :: Text -> [Text] -> Text
- intersperse :: Char -> Text -> Text
- transpose :: [Text] -> [Text]
- reverse :: Text -> Text
- replace :: HasCallStack => Text -> Text -> Text -> Text
- toCaseFold :: Text -> Text
- toLower :: Text -> Text
- toUpper :: Text -> Text
- toTitle :: Text -> Text
- justifyLeft :: Int -> Char -> Text -> Text
- justifyRight :: Int -> Char -> Text -> Text
- center :: Int -> Char -> Text -> Text
- foldl :: (a -> Char -> a) -> a -> Text -> a
- foldl' :: (a -> Char -> a) -> a -> Text -> a
- foldl1 :: HasCallStack => (Char -> Char -> Char) -> Text -> Char
- foldl1' :: HasCallStack => (Char -> Char -> Char) -> Text -> Char
- foldr :: (Char -> a -> a) -> a -> Text -> a
- foldr' :: (Char -> a -> a) -> a -> Text -> a
- foldr1 :: HasCallStack => (Char -> Char -> Char) -> Text -> Char
- concat :: [Text] -> Text
- concatMap :: (Char -> Text) -> Text -> Text
- any :: (Char -> Bool) -> Text -> Bool
- all :: (Char -> Bool) -> Text -> Bool
- maximum :: HasCallStack => Text -> Char
- minimum :: HasCallStack => Text -> Char
- isAscii :: Text -> Bool
- scanl :: (Char -> Char -> Char) -> Char -> Text -> Text
- scanl1 :: (Char -> Char -> Char) -> Text -> Text
- scanr :: (Char -> Char -> Char) -> Char -> Text -> Text
- scanr1 :: (Char -> Char -> Char) -> Text -> Text
- mapAccumL :: (a -> Char -> (a, Char)) -> a -> Text -> (a, Text)
- mapAccumR :: (a -> Char -> (a, Char)) -> a -> Text -> (a, Text)
- replicate :: Int -> Text -> Text
- unfoldr :: (a -> Maybe (Char, a)) -> a -> Text
- unfoldrN :: Int -> (a -> Maybe (Char, a)) -> a -> Text
- take :: Int -> Text -> Text
- takeEnd :: Int -> Text -> Text
- drop :: Int -> Text -> Text
- dropEnd :: Int -> Text -> Text
- takeWhile :: (Char -> Bool) -> Text -> Text
- takeWhileEnd :: (Char -> Bool) -> Text -> Text
- dropWhile :: (Char -> Bool) -> Text -> Text
- dropWhileEnd :: (Char -> Bool) -> Text -> Text
- dropAround :: (Char -> Bool) -> Text -> Text
- strip :: Text -> Text
- stripStart :: Text -> Text
- stripEnd :: Text -> Text
- splitAt :: Int -> Text -> (Text, Text)
- breakOn :: HasCallStack => Text -> Text -> (Text, Text)
- breakOnEnd :: HasCallStack => Text -> Text -> (Text, Text)
- break :: (Char -> Bool) -> Text -> (Text, Text)
- span :: (Char -> Bool) -> Text -> (Text, Text)
- spanM :: Monad m => (Char -> m Bool) -> Text -> m (Text, Text)
- spanEndM :: Monad m => (Char -> m Bool) -> Text -> m (Text, Text)
- group :: Text -> [Text]
- groupBy :: (Char -> Char -> Bool) -> Text -> [Text]
- inits :: Text -> [Text]
- tails :: Text -> [Text]
- splitOn :: HasCallStack => Text -> Text -> [Text]
- split :: (Char -> Bool) -> Text -> [Text]
- chunksOf :: Int -> Text -> [Text]
- lines :: Text -> [Text]
- words :: Text -> [Text]
- unlines :: [Text] -> Text
- unwords :: [Text] -> Text
- isPrefixOf :: Text -> Text -> Bool
- isSuffixOf :: Text -> Text -> Bool
- isInfixOf :: Text -> Text -> Bool
- stripPrefix :: Text -> Text -> Maybe Text
- stripSuffix :: Text -> Text -> Maybe Text
- commonPrefixes :: Text -> Text -> Maybe (Text, Text, Text)
- filter :: (Char -> Bool) -> Text -> Text
- breakOnAll :: HasCallStack => Text -> Text -> [(Text, Text)]
- find :: (Char -> Bool) -> Text -> Maybe Char
- elem :: Char -> Text -> Bool
- partition :: (Char -> Bool) -> Text -> (Text, Text)
- index :: HasCallStack => Text -> Int -> Char
- findIndex :: (Char -> Bool) -> Text -> Maybe Int
- count :: HasCallStack => Text -> Text -> Int
- zip :: Text -> Text -> [(Char, Char)]
- zipWith :: (Char -> Char -> Char) -> Text -> Text -> Text
- readFile :: HasCallStack => Member (Error IOException) r => Member (Embed IO) r => Member Log r => FilePath -> Sem r Text
Documentation
A space efficient, packed, unboxed Unicode text type.
Instances
FromJSON Text | |
Defined in Data.Aeson.Types.FromJSON | |
FromJSONKey Text | |
Defined in Data.Aeson.Types.FromJSON | |
ToJSON Text | |
ToJSONKey Text | |
Defined in Data.Aeson.Types.ToJSON | |
Chunk Text | |
Defined in Data.Attoparsec.Internal.Types | |
Hashable Text | |
Defined in Data.Hashable.Class | |
ToString Text Source # | |
type ChunkElem Text | |
Defined in Data.Attoparsec.Internal.Types | |
type State Text | |
Defined in Data.Attoparsec.Internal.Types | |
type Item Text | |
Creation and elimination
O(1) Convert a character into a Text. Performs replacement on invalid scalar values.
Basic interface
compareLength :: Text -> Int -> Ordering #
O(min(n,c)) Compare the count of characters in a Text
to a number.
compareLength
t c =compare
(length
t) c
This function gives the same answer as comparing against the result
of length
, but can short circuit if the count of characters is
greater than the number, and hence be more efficient.
Transformations
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"
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"
Performs replacement on invalid scalar values.
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"]
O(n) Reverse the characters of a string.
Example:
>>>
T.reverse "desrever"
"reversed"
Arguments
:: HasCallStack | |
=> 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).
Case conversion
toCaseFold :: Text -> Text #
O(n) Convert a string to folded case.
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.
O(n) Convert a string to lower case, using simple case conversion.
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).
O(n) Convert a string to upper case, using simple case conversion.
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 title case, using simple case conversion.
The first letter (as determined by isLetter
)
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.
This function is not idempotent.
Consider lower-case letter ʼn
(U+0149 LATIN SMALL LETTER N PRECEDED BY APOSTROPHE).
Then toTitle
"ʼn"
= "ʼN"
: the first (and the only) letter of the input
is converted to title case, becoming two letters.
Now ʼ
(U+02BC MODIFIER LETTER APOSTROPHE) is a modifier letter
and as such is recognised as a letter by isLetter
,
so toTitle
"ʼN"
= "'n"
.
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
Justification
justifyLeft :: Int -> Char -> Text -> Text #
O(n) Left-justify a string to the given length, using the specified fill character on the right. Performs replacement on invalid scalar values.
Examples:
>>>
justifyLeft 7 'x' "foo"
"fooxxxx"
>>>
justifyLeft 3 'x' "foobar"
"foobar"
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"
center :: Int -> Char -> Text -> Text #
O(n) Center a string to the given length, using the specified fill character on either side. Performs replacement on invalid scalar values.
Examples:
>>>
center 8 'x' "HS"
"xxxHSxxx"
Folds
foldr :: (Char -> a -> a) -> a -> Text -> a #
O(n) foldr
, applied to a binary operator, a starting value
(typically the right-identity of the operator), and a Text
,
reduces the Text
using the binary operator, from right to left.
If the binary operator is strict in its second argument, use foldr'
instead.
foldr
is lazy like foldr
for lists: evaluation actually
traverses the Text
from left to right, only as far as it needs to.
For example, head
can be defined with O(1) complexity using foldr
:
head :: Text -> Char head = foldr const (error "head empty")
Searches from left to right with short-circuiting behavior can
also be defined using foldr
(e.g., any
, all
, find
, elem
).
Special folds
maximum :: HasCallStack => Text -> Char #
minimum :: HasCallStack => Text -> Char #
Construction
Scans
Accumulating maps
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.
Generation and unfolding
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.
Performs replacement on invalid scalar values.
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
.
Performs replacement on invalid scalar values.
Substrings
Breaking strings
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
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
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
.
Examples:
>>>
takeWhileEnd (=='o') "foo"
"oo"
Since: text-1.2.2.0
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
.
Examples:
>>>
dropWhileEnd (=='.') "foo..."
"foo"
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
.
O(n) Remove leading and trailing white space from a string. Equivalent to:
dropAround isSpace
stripStart :: Text -> Text #
O(n) Remove leading white space from a string. Equivalent to:
dropWhile isSpace
O(n) Remove trailing white space from a string. Equivalent to:
dropWhileEnd isSpace
breakOn :: HasCallStack => 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).
breakOnEnd :: HasCallStack => 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")
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 text.
>>>
T.span (=='0') "000AB"
("000","AB")
spanM :: Monad m => (Char -> m Bool) -> Text -> m (Text, Text) #
O(length of prefix) spanM
, applied to a monadic predicate p
,
a text t
, returns a pair (t1, t2)
where t1
is the longest prefix of
t
whose elements satisfy p
, and t2
is the remainder of the text.
>>>
T.spanM (\c -> state $ \i -> (fromEnum c == i, i+1)) "abcefg" `runState` 97
(("abc","efg"),101)
span
is spanM
specialized to Identity
:
-- for all p :: Char -> Boolspan
p =runIdentity
.spanM
(pure
. p)
Since: text-2.0.1
spanEndM :: Monad m => (Char -> m Bool) -> Text -> m (Text, Text) #
O(length of suffix) spanEndM
, applied to a monadic predicate p
,
a text t
, returns a pair (t1, t2)
where t2
is the longest suffix of
t
whose elements satisfy p
, and t1
is the remainder of the text.
>>>
T.spanEndM (\c -> state $ \i -> (fromEnum c == i, i-1)) "tuvxyz" `runState` 122
(("tuv","xyz"),118)
spanEndM
p .reverse
= fmap (bimap
reverse
reverse
) .spanM
p
Since: text-2.0.1
groupBy :: (Char -> Char -> Bool) -> Text -> [Text] #
O(n) Group characters in a string according to a predicate.
Breaking into many substrings
Arguments
:: HasCallStack | |
=> Text | String to split on. If this string is empty, an error will occur. |
-> Text | Input text. |
-> [Text] |
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).
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') ""
[""]
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"]
Breaking into lines and words
Predicates
isPrefixOf :: Text -> Text -> Bool #
O(n) The isPrefixOf
function takes two Text
s and returns
True
if and only if the first is a prefix of the second.
isSuffixOf :: Text -> Text -> Bool #
O(n) The isSuffixOf
function takes two Text
s and returns
True
if and only if the first is a suffix of the second.
View patterns
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
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
Searching
Arguments
:: HasCallStack | |
=> Text |
|
-> Text |
|
-> [(Text, Text)] |
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.
Indexing
index :: HasCallStack => Text -> Int -> Char #
O(n) Text
index (subscript) operator, starting from 0.