rio-0.1.22.0: A standard library for Haskell

Safe Haskell | Safe-Inferred
Language | Haskell2010

RIO.Text

Contents

- Types
- Creation and elimination
- Basic interface
- Transformations
  - Case conversion
  - Justification
- Folds
  - Special folds
- Construction
  - Scans
  - Accumulating maps
  - Generation and unfolding
- Substrings
  - Breaking strings
  - Breaking into many substrings
  - Breaking into lines and words
- Predicates
  - View patterns
- Searching
- Indexing
- Zipping
- Low level operations
- Encoding

Description

Strict `Text`. Import as:

    import qualified RIO.Text as T

This module does not export any partial functions. For those, see RIO.Text.Partial

Synopsis

- data Text
- pack :: String -> Text
- unpack :: Text -> String
- singleton :: Char -> Text
- empty :: Text
- cons :: Char -> Text -> Text
- snoc :: Text -> Char -> Text
- append :: Text -> Text -> Text
- uncons :: Text -> Maybe (Char, Text)
- null :: Text -> Bool
- length :: Text -> Int
- compareLength :: Text -> Int -> Ordering
- map :: (Char -> Char) -> Text -> Text
- intercalate :: Text -> [Text] -> Text
- intersperse :: Char -> Text -> Text
- transpose :: [Text] -> [Text]
- reverse :: 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
- foldr :: (Char -> a -> a) -> a -> Text -> a
- concat :: [Text] -> Text
- concatMap :: (Char -> Text) -> Text -> Text
- any :: (Char -> Bool) -> Text -> Bool
- all :: (Char -> Bool) -> 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)
- break :: (Char -> Bool) -> Text -> (Text, Text)
- span :: (Char -> Bool) -> Text -> (Text, Text)
- group :: Text -> [Text]
- groupBy :: (Char -> Char -> Bool) -> Text -> [Text]
- inits :: Text -> [Text]
- tails :: Text -> [Text]
- split :: (Char -> Bool) -> Text -> [Text]
- chunksOf :: Int -> Text -> [Text]
- lines :: Text -> [Text]
- linesCR :: 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
- dropPrefix :: Text -> Text -> Text
- dropSuffix :: Text -> Text -> Text
- commonPrefixes :: Text -> Text -> Maybe (Text, Text, Text)
- filter :: (Char -> Bool) -> Text -> Text
- find :: (Char -> Bool) -> Text -> Maybe Char
- partition :: (Char -> Bool) -> Text -> (Text, Text)
- index :: HasCallStack => Text -> Int -> Char
- findIndex :: (Char -> Bool) -> Text -> Maybe Int
- zip :: Text -> Text -> [(Char, Char)]
- zipWith :: (Char -> Char -> Char) -> Text -> Text -> Text
- copy :: Text -> Text
- unpackCString# :: Addr# -> Text
- encodeUtf8 :: Text -> ByteString
- decodeUtf8With :: OnDecodeError -> ByteString -> Text
- decodeUtf8' :: ByteString -> Either UnicodeException Text
- lenientDecode :: OnDecodeError

# Types

data Text Source #

A space efficient, packed, unboxed Unicode text type.

#### Instances

Instances details

Hashable Text |
Instance details Defined in Data.Hashable.Class Methods hashWithSalt :: Int -> Text -> Int Source # hash :: Text -> Int Source #
Display Text Source # | Since: 0.1.0.0
Instance details Defined in RIO.Prelude.Display Methods display :: Text -> Utf8Builder Source # textDisplay :: Text -> Text Source #
type Item Text |
Instance details Defined in Data.Text type Item Text = Char

# Creation and elimination

pack :: String -> Text Source #

O(n) Convert a `String` into a `Text`. Performs replacement on invalid scalar values, so ``unpack` . `pack`` is not `id`:

    >>> Data.Text.unpack (pack "\55555")
    "\65533"

unpack :: Text -> String Source #

O(n) Convert a `Text` into a `String`.

singleton :: Char -> Text Source #

O(1) Convert a character into a Text. Performs replacement on invalid scalar values.

empty :: Text Source #

O(1) The empty `Text`.

# Basic interface

cons :: Char -> Text -> Text infixr 5 Source #

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. Performs replacement on invalid scalar values.

snoc :: Text -> Char -> Text Source #

O(n) Adds a character to the end of a `Text`. This copies the entire array in the process. Performs replacement on invalid scalar values.

append :: Text -> Text -> Text Source #

O(n) Appends one `Text` to the other by copying both of them into a new `Text`.

uncons :: Text -> Maybe (Char, Text) Source #

O(1) Returns the first character and rest of a `Text`, or `Nothing` if empty.

null :: Text -> Bool Source #

O(1) Tests whether a `Text` is empty or not.

length :: Text -> Int Source #

O(n) Returns the number of characters in a `Text`.

compareLength :: Text -> Int -> Ordering Source #

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

map :: (Char -> Char) -> Text -> Text Source #

O(n) `map` `f` `t` is the `Text` obtained by applying `f` to each element of `t`.

Example:

    >>> let message = pack "I am not angry. Not at all."
    >>> T.map (\c -> if c == '.' then '!' else c) message
    "I am not angry! Not at all!"

Performs replacement on invalid scalar values.

intercalate :: Text -> [Text] -> Text Source #

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 Source #

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] Source #

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"]

reverse :: Text -> Text Source #

O(n) Reverse the characters of a string.

Example:

    >>> T.reverse "desrever"
    "reversed"

## Case conversion

toCaseFold :: Text -> Text Source #

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.

toLower :: Text -> Text Source #

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).

toUpper :: Text -> Text Source #

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".

toTitle :: Text -> Text Source #

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 Source #

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 Source #

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 Source #

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

foldl :: (a -> Char -> a) -> a -> Text -> a Source #

O(n) `foldl`, applied to a binary operator, a starting value (typically the left-identity of the operator), and a `Text`, reduces the `Text` using the binary operator, from left to right.

foldl' :: (a -> Char -> a) -> a -> Text -> a Source #

O(n) A strict version of `foldl`.

foldr :: (Char -> a -> a) -> a -> Text -> a Source #

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

concat :: [Text] -> Text Source #

O(n) Concatenate a list of `Text`s.

concatMap :: (Char -> Text) -> Text -> Text Source #

O(n) Map a function over a `Text` that results in a `Text`, and concatenate the results.

any :: (Char -> Bool) -> Text -> Bool Source #

O(n) `any` `p` `t` determines whether any character in the `Text` `t` satisfies the predicate `p`.

all :: (Char -> Bool) -> Text -> Bool Source #

O(n) `all` `p` `t` determines whether all characters in the `Text` `t` satisfy the predicate `p`.

# Construction

## Scans

scanl :: (Char -> Char -> Char) -> Char -> Text -> Text Source #

O(n) `scanl` is similar to `foldl`, but returns a list of successive reduced values from the left. Performs replacement on invalid scalar values.

    scanl f z [x1, x2, ...] == [z, z `f` x1, (z `f` x1) `f` x2, ...]

Properties

    head (scanl f z xs) = z

    last (scanl f z xs) = foldl f z xs

scanl1 :: (Char -> Char -> Char) -> Text -> Text Source #

O(n) `scanl1` is a variant of `scanl` that has no starting value argument. Performs replacement on invalid scalar values.

    scanl1 f [x1, x2, ...] == [x1, x1 `f` x2, ...]

scanr :: (Char -> Char -> Char) -> Char -> Text -> Text Source #

O(n) `scanr` is the right-to-left dual of `scanl`. Performs replacement on invalid scalar values.

    scanr f v == reverse . scanl (flip f) v . reverse

scanr1 :: (Char -> Char -> Char) -> Text -> Text Source #

O(n) `scanr1` is a variant of `scanr` that has no starting value argument. Performs replacement on invalid scalar values.

## Accumulating maps

mapAccumL :: (a -> Char -> (a, Char)) -> a -> Text -> (a, Text) Source #

O(n) Like a combination of `map` and `foldl'`. Applies a function to each element of a `Text`, passing an accumulating parameter from left to right, and returns a final `Text`. Performs replacement on invalid scalar values.

mapAccumR :: (a -> Char -> (a, Char)) -> a -> Text -> (a, Text) Source #

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

replicate :: Int -> Text -> Text Source #

O(n*m) `replicate` `n` `t` is a `Text` consisting of the input `t` repeated `n` times.

unfoldr :: (a -> Maybe (Char, a)) -> a -> Text Source #

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 Source #

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

take :: Int -> Text -> Text Source #

O(n) `take` `n`, applied to a `Text`, returns the prefix of the `Text` of length `n`, or the `Text` itself if `n` is greater than the length of the Text.

takeEnd :: Int -> Text -> Text Source #

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

drop :: Int -> Text -> Text Source #

O(n) `drop` `n`, applied to a `Text`, returns the suffix of the `Text` after the first `n` characters, or the empty `Text` if `n` is greater than the length of the `Text`.

dropEnd :: Int -> Text -> Text Source #

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

takeWhile :: (Char -> Bool) -> Text -> Text Source #

O(n) `takeWhile`, applied to a predicate `p` and a `Text`, returns the longest prefix (possibly empty) of elements that satisfy `p`.

takeWhileEnd :: (Char -> Bool) -> Text -> Text Source #

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

dropWhile :: (Char -> Bool) -> Text -> Text Source #

O(n) `dropWhile` `p` `t` returns the suffix remaining after `takeWhile` `p` `t`.

dropWhileEnd :: (Char -> Bool) -> Text -> Text Source #

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 Source #

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`.

strip :: Text -> Text Source #

O(n) Remove leading and trailing white space from a string. Equivalent to:

    dropAround isSpace

stripStart :: Text -> Text Source #

O(n) Remove leading white space from a string. Equivalent to:

    dropWhile isSpace

stripEnd :: Text -> Text Source #

O(n) Remove trailing white space from a string. Equivalent to:

    dropWhileEnd isSpace

splitAt :: Int -> Text -> (Text, Text) Source #

O(n) `splitAt` `n t` returns a pair whose first element is a prefix of `t` of length `n`, and whose second is the remainder of the string. It is equivalent to `(`take` n t, `drop` n t)`.

break :: (Char -> Bool) -> Text -> (Text, Text) Source #

O(n) `break` is like `span`, but the prefix returned is over elements that fail the predicate `p`.

    >>> T.break (=='c') "180cm"
    ("180","cm")

span :: (Char -> Bool) -> Text -> (Text, Text) Source #

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")

group :: Text -> [Text] Source #

O(n) Group characters in a string by equality.

groupBy :: (Char -> Char -> Bool) -> Text -> [Text] Source #

O(n) Group characters in a string according to a predicate.

inits :: Text -> [Text] Source #

O(n) Return all initial segments of the given `Text`, shortest first.

tails :: Text -> [Text] Source #

O(n) Return all final segments of the given `Text`, longest first.

## Breaking into many substrings

split :: (Char -> Bool) -> Text -> [Text] Source #

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] Source #

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

lines :: Text -> [Text] Source #

O(n) Breaks a `Text` up into a list of `Text`s at newline characters `'\n'` (LF, line feed). The resulting strings do not contain newlines.

`lines` does not treat `'\r'` (CR, carriage return) as a newline character.

linesCR :: Text -> [Text] Source #

`linesCR` breaks a `Text` up into a list of `Text`s at newline `Char`s. It is very similar to `lines`, but it also removes any trailing `'r'` characters. The resulting `Text` values do not contain newlines or trailing `'r'` characters.

Since: 0.1.0.0

words :: Text -> [Text] Source #

O(n) Breaks a `Text` up into a list of words, delimited by `Char`s representing white space.

unlines :: [Text] -> Text Source #

O(n) Joins lines, after appending a terminating newline to each.

unwords :: [Text] -> Text Source #

O(n) Joins words using single space characters.

# Predicates

isPrefixOf :: Text -> Text -> Bool Source #

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 Source #

O(n) The `isSuffixOf` function takes two `Text`s and returns `True` if and only if the first is a suffix of the second.

isInfixOf :: Text -> Text -> Bool Source #

O(n+m) The `isInfixOf` function takes two `Text`s and returns `True` if and only if the first is contained, wholly and intact, anywhere within the second.

In (unlikely) bad cases, this function's time complexity degrades towards O(n*m).

## View patterns

stripPrefix :: Text -> Text -> Maybe Text Source #

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 Source #

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

dropPrefix Source #

Arguments

:: Text | prefix
-> Text |
-> Text |

Drop prefix if present, otherwise return original `Text`.

Since: 0.0.0.0

dropSuffix Source #

Arguments

:: Text | suffix
-> Text |
-> Text |

Drop prefix if present, otherwise return original `Text`.

Since: 0.0.0.0

commonPrefixes :: Text -> Text -> Maybe (Text, Text, Text) Source #

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

filter :: (Char -> Bool) -> Text -> Text Source #

O(n) `filter`, applied to a predicate and a `Text`, returns a `Text` containing those characters that satisfy the predicate.

find :: (Char -> Bool) -> Text -> Maybe Char Source #

O(n) The `find` function takes a predicate and a `Text`, and returns the first element matching the predicate, or `Nothing` if there is no such element.

partition :: (Char -> Bool) -> Text -> (Text, Text) Source #

O(n) The `partition` function takes a predicate and a `Text`, and returns the pair of `Text`s with elements which do and do not satisfy the predicate, respectively; i.e.

    partition p t == (filter p t, filter (not . p) t)

# Indexing

index :: HasCallStack => Text -> Int -> Char Source #

O(n) `Text` index (subscript) operator, starting from 0.

findIndex :: (Char -> Bool) -> Text -> Maybe Int Source #

O(n) The `findIndex` function takes a predicate and a `Text` and returns the index of the first element in the `Text` satisfying the predicate.

# Zipping

zip :: Text -> Text -> [(Char, Char)] Source #

O(n) `zip` takes two `Text`s and returns a list of corresponding pairs of bytes. If one input `Text` is short, excess elements of the longer `Text` are discarded. This is equivalent to a pair of `unpack` operations.

zipWith :: (Char -> Char -> Char) -> Text -> Text -> Text Source #

O(n) `zipWith` generalises `zip` by zipping with the function given as the first argument, instead of a tupling function. Performs replacement on invalid scalar values.

# Low level operations

copy :: Text -> Text Source #

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.

unpackCString# :: Addr# -> Text Source #

O(n) Convert a null-terminated modified UTF-8 (but with a standard UTF-8 representation of characters from supplementary planes) string to a `Text`. Counterpart to `unpackCStringUtf8#`. No validation is performed, malformed input can lead to memory access violation.

Since: text-1.2.1.1

# Encoding

encodeUtf8 :: Text -> ByteString Source #

Encode text using UTF-8 encoding.

decodeUtf8With :: OnDecodeError -> ByteString -> Text Source #

Decode a `ByteString` containing UTF-8 encoded text.

Surrogate code points in replacement character returned by `OnDecodeError` will be automatically remapped to the replacement char `U+FFFD`.

decodeUtf8' :: ByteString -> Either UnicodeException Text Source #

Decode a `ByteString` containing UTF-8 encoded text.

If the input contains any invalid UTF-8 data, the relevant exception will be returned, otherwise the decoded text.

lenientDecode :: OnDecodeError Source #

Replace an invalid input byte with the Unicode replacement character U+FFFD.