Data.Text.Lazy.Sized

Sized wrappers around Lazy

This module is intended to be imported qualified, to avoid name clashes with Prelude functions. eg.

import qualified Data.Text.Lazy.Sized as NEL

Types

type SizedText s = SizedLazyText s

type SizedLazyText s = Sized s Text

Creation and elimination

pack :: Sized s String -> SizedLazyText s

O(n) Convert a 'Sized String' into a SizedLazyText. Performs replacement on invalid scalar values.

unpack :: HasCallStack => SizedLazyText s -> Sized s String

O(n) Convert a 'SizedLazyText s' into a 'Sized s String'.

singleton :: SizedSingleton a => Proxy a -> SizedSingletonElement a -> Sized (Exactly 1) a

Build a Sized value from a singleton value

fromChunks :: Sized s [SizedStrictText s'] -> SizedLazyText (s <*> s')

O(c) Convert a list of strict SizedStrictTexts into a lazy SizedLazyText.

toChunks :: SizedLazyText s -> Sized (RestrictAtMost s) [SizedStrictText (RestrictAtMost s)]

O(n) Convert a lazy SizedLazyText into a list of strict SizedStrictTexts.

toStrict :: SizedLazyText s -> SizedStrictText s

O(n) Convert a lazy SizedLazyText into a strict SizedStrictText.

fromStrict :: SizedStrictText s -> SizedLazyText s

O(c) Convert a strict SizedStrictText into a lazy SizedLazyText.

Basic interface

cons :: Char -> SizedLazyText s -> SizedLazyText (Exactly 1 <+> s) infixr 5

O(n) Adds a character to the front of a SizedLazyText. This function is more costly than its List counterpart because it requires copying a new array. Performs replacement on invalid scalar values.

snoc :: SizedLazyText s -> Char -> SizedLazyText (s <+> Exactly 1)

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

uncons :: (IsNotEmpty s, (Exactly 1 <+> s) ~ s') => SizedLazyText s -> (Char, SizedLazyText s')

O(1) Returns the first character and rest of a SizedLazyText.

unsnoc :: (IsNotEmpty s, (s <+> Exactly 1) ~ s') => SizedLazyText s -> (SizedLazyText s', Char)

O(1) Returns all but the last character and the last character of a SizedLazyText.

head :: IsNotEmpty s => SizedLazyText s -> Char

O(1) Returns the first character of a SizedLazyText.

last :: (IsNotEmpty s, (Exactly 1 <+> s) ~ s') => SizedLazyText s -> Char

O(1) Returns the last character of a SizedLazyText.

tail :: (IsNotEmpty s, (Exactly 1 <+> s) ~ s') => SizedLazyText s -> SizedLazyText s'

O(1) Returns all characters after the head of a SizedLazyText.

init :: (IsNotEmpty s, (s <+> Exactly 1) ~ s') => SizedLazyText s -> SizedLazyText s'

O(1) Returns all but the last character of a SizedLazyText.

length :: SizedLazyText s -> Int64

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

compareLength :: (KnownNat n, Includes s n) => SizedLazyText s -> Proxy n -> Ordering

O(min(n,c)) Compare the count of characters in a SizedLazyText 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) -> SizedLazyText s -> SizedLazyText s

O(n) map f t is the SizedLazyText 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 -> Sized s [SizedLazyText s'] -> SizedLazyText (s <*> s')

O(n) The intercalate function takes a SizedLazyText and a list of SizedLazyTexts 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 -> SizedLazyText s -> SizedLazyText ((s <*> Exactly 2) <-> Exactly 1)

O(n) The intersperse function takes a character and places it between the characters of a SizedLazyText.

Example:

>>> T.intersperse '.' "SHIELD"
"S.H.I.E.L.D"

Performs replacement on invalid scalar values.

transpose :: Sized s [SizedLazyText s'] -> Sized s' [SizedLazyText s]

O(n) The transpose function transposes the rows and columns of its SizedLazyText 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 :: HasCallStack => SizedLazyText s -> SizedLazyText s

O(n) Reverse the characters of a string.

Example:

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

replace

Arguments

:: SizedLazyText s0

needle to search for. If this string is empty, an error will occur.

-> SizedLazyText s1

replacement to replace needle with.

-> SizedLazyText s2

haystack in which to search.

-> SizedLazyText Unknown

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

When case converting SizedLazyText values, do not use combinators like map toUpper to case convert each character of a string individually, as this gives incorrect results according to the rules of some writing systems. The whole-string case conversion functions from this module, such as toUpper, obey the correct case conversion rules. As a result, these functions may map one input character to two or three output characters. For examples, see the documentation of each function.

Note: In some languages, case conversion is a locale- and context-dependent operation. The case conversion functions in this module are not locale sensitive. Programs that require locale sensitivity should use appropriate versions of the case mapping functions from the text-icu package.

toCaseFold :: SizedLazyText s -> SizedLazyText s

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 :: SizedLazyText s -> SizedLazyText s

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 :: SizedLazyText s -> SizedLazyText s

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 :: SizedLazyText s -> SizedLazyText s

O(n) Convert a string to title case, using simple case conversion.

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.

Justification

justifyLeft :: KnownNat n => Proxy n -> Char -> SizedLazyText s -> SizedLazyText (AtLeast n)

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 :: KnownNat n => Proxy n -> Char -> SizedLazyText s -> SizedLazyText (AtLeast n)

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 :: KnownNat n => Proxy n -> Char -> SizedLazyText s -> SizedLazyText (AtLeast n)

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 -> SizedLazyText s -> a

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

foldl' :: (a -> Char -> a) -> a -> SizedLazyText s -> a

O(n) A strict version of foldl.

foldl1 :: IsNotEmpty s => (Char -> Char -> Char) -> SizedLazyText s -> Char

O(n) A variant of foldl that has no starting value argument.

foldl1' :: IsNotEmpty s => (Char -> Char -> Char) -> SizedLazyText s -> Char

O(n) A strict version of foldl1.

foldr :: (Char -> a -> a) -> a -> SizedLazyText s -> a

O(n) foldr, applied to a binary operator, a starting value (typically the right-identity of the operator), and a SizedLazyText, reduces the SizedLazyText 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 SizedLazyText from left to right, only as far as it needs to. @

Searches from left to right with short-circuiting behavior can also be defined using foldr (e.g., any, all, find, elem).

foldr1 :: IsNotEmpty s => (Char -> Char -> Char) -> SizedLazyText s -> Char

O(n) A variant of foldr that has no starting value argument.

Special folds

concat :: Sized s [SizedLazyText s'] -> SizedLazyText (s <*> s')

O(n) Concatenate a list of SizedLazyTexts.

concatMap :: (Char -> SizedLazyText s') -> SizedLazyText s -> SizedLazyText (s <*> s')

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

any :: (Char -> Bool) -> SizedLazyText s -> Bool

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

all :: (Char -> Bool) -> SizedLazyText s -> Bool

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

maximum :: IsNotEmpty s => SizedLazyText s -> Char

O(n) maximum returns the maximum value from a SizedLazyText.

minimum :: IsNotEmpty s => SizedLazyText s -> Char

O(n) minimum returns the minimum value from a SizedLazyText.

Construction

Scans

scanl :: (Char -> Char -> Char) -> Char -> SizedLazyText s -> SizedLazyText s

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 :: IsNotEmpty s => (Char -> Char -> Char) -> SizedLazyText s -> SizedLazyText s

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 -> SizedLazyText s -> SizedLazyText s

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 :: IsNotEmpty s => (Char -> Char -> Char) -> SizedLazyText s -> SizedLazyText s

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

Accumulating maps

mapAccumL :: forall a s. (a -> Char -> (a, Char)) -> a -> SizedLazyText s -> (a, SizedLazyText s)

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

mapAccumR :: forall a s. (a -> Char -> (a, Char)) -> a -> SizedLazyText s -> (a, SizedLazyText s)

The mapAccumR function behaves like a combination of map and a strict foldr; it applies a function to each element of a SizedLazyText, passing an accumulating parameter from right to left, and returning a final value of this accumulator together with the new SizedLazyText. Performs replacement on invalid scalar values.

Generation and unfolding

replicate :: KnownNat n => Proxy n -> SizedLazyText s -> SizedLazyText (s <*> Exactly n)

O(n*m) replicate n t is a SizedLazyText consisting of the input t repeated n times, n should be strictly positive.

cycle :: SizedLazyText s -> SizedLazyText (AtLeast 0)

cycle ties a finite, SizedLazyText into a circular one, or equivalently, the infinite repetition of the original SizedLazyText.

iterate :: (Char -> Char) -> Char -> SizedLazyText (AtLeast 0)

iterate f x returns an infinite SizedLazyText of repeated applications of f to x:

iterate f x == [x, f x, f (f x), ...]

Substrings

Breaking strings

take :: (KnownNat n, Includes s n) => Proxy n -> SizedLazyText s -> SizedLazyText (AtMost n)

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

takeEnd :: (KnownNat n, Includes s n) => Proxy n -> SizedLazyText s -> SizedLazyText (AtMost n)

O(n) takeEnd n t returns the suffix remaining after taking n characters from the end of t.

Examples:

>>> takeEnd 3 "foobar"
"bar"

drop :: (KnownNat n, Includes s n) => Proxy n -> SizedLazyText s -> SizedLazyText (s <-> Exactly n)

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

dropEnd :: (KnownNat n, Includes s n) => Proxy n -> SizedLazyText s -> SizedLazyText (s <-> Exactly n)

O(n) dropEnd n t returns the prefix remaining after dropping n characters from the end of t.

Examples:

>>> dropEnd 3 "foobar"
"foo"

takeWhile :: (Char -> Bool) -> SizedLazyText s -> SizedLazyText (RestrictAtMost s)

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

takeWhileEnd :: (Char -> Bool) -> SizedLazyText s -> SizedLazyText (RestrictAtMost s)

O(n) takeWhileEnd, applied to a predicate p and a SizedLazyText, returns the longest suffix (possibly empty) of elements that satisfy p. Examples:

>>> takeWhileEnd (=='o') "foo"
"oo"

dropWhile :: (Char -> Bool) -> SizedLazyText s -> SizedLazyText (RestrictAtMost s)

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

dropWhileEnd :: (Char -> Bool) -> SizedLazyText s -> SizedLazyText (RestrictAtMost s)

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) -> SizedLazyText s -> SizedLazyText (RestrictAtMost s)

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 :: SizedLazyText s -> SizedLazyText (RestrictAtMost s)

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

dropAround isSpace

stripStart :: SizedLazyText s -> SizedLazyText (RestrictAtMost s)

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

dropWhile isSpace

stripEnd :: SizedLazyText s -> SizedLazyText (RestrictAtMost s)

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

dropWhileEnd isSpace

splitAt :: (KnownNat n, Includes s n) => Proxy n -> SizedLazyText s -> (SizedLazyText (RestrictAtMost s), SizedLazyText (RestrictAtMost s))

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).

breakOn :: SizedLazyText s -> SizedLazyText s' -> (SizedLazyText (RestrictAtMost s), SizedLazyText (RestrictAtMost s))

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 :: SizedLazyText s -> SizedLazyText s' -> (SizedLazyText (RestrictAtMost s), SizedLazyText (RestrictAtMost s))

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")

break :: (Char -> Bool) -> SizedLazyText s -> (SizedLazyText (RestrictAtMost s), SizedLazyText (RestrictAtMost s))

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) -> SizedLazyText s -> (SizedLazyText (RestrictAtMost s), SizedLazyText (RestrictAtMost s))

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 :: SizedLazyText s -> Sized (RestrictAtMost s) [SizedLazyText (RestrictAtMost s)]

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

groupBy :: (Char -> Char -> Bool) -> SizedLazyText s -> Sized (RestrictAtMost s) [SizedLazyText (RestrictAtMost s)]

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

inits :: SizedLazyText s -> Sized (s <+> Exactly 1) [SizedLazyText (RestrictAtMost s)]

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

tails :: SizedLazyText s -> Sized (s <+> Exactly 1) [SizedLazyText (RestrictAtMost s)]

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

Breaking into many substrings

Splitting functions in this library do not perform character-wise copies to create substrings; they just construct new Texts that are slices of the original.

splitOn

Arguments

:: SizedLazyText s

String to split on. If this string is empty, an error will occur.

-> SizedLazyText s'

Input text.

-> Sized (RestrictAtMost s') [SizedLazyText (RestrictAtMost s')]

O(m+n) Break a SizedLazyText 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) -> SizedLazyText s -> Sized (RestrictAtMost s) [SizedLazyText (RestrictAtMost s)]

O(n) Splits a SizedLazyText 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 :: (KnownNat n, Includes s n) => Proxy n -> SizedLazyText s -> Sized (AtMost d) [SizedLazyText (RestrictAtMost s)]

O(n) Splits a SizedLazyText 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 :: SizedLazyText s -> Sized (RestrictAtMost s) [SizedLazyText (RestrictAtMost s)]

O(n) Breaks a SizedLazyText up into a list of SizedLazyTexts 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.

words :: SizedLazyText s -> Sized (RestrictAtMost s) [SizedLazyText (RestrictAtMost s)]

O(n) Breaks a SizedLazyText up into a list of words, delimited by Chars representing white space.

unlines :: Sized s [SizedLazyText s'] -> SizedLazyText (s <*> (s' <+> Exactly 1))

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

unwords :: Sized s [SizedLazyText s'] -> SizedLazyText (s <*> (s' <+> Exactly 1))

O(n) Joins words using single space characters.

Predicates

isPrefixOf :: IsMoreGeneral s' s => SizedLazyText s -> SizedLazyText s' -> Bool

O(n) The isPrefixOf function takes two SizedLazyTexts and returns True if and only if the first is a prefix of the second.

isSuffixOf :: IsMoreGeneral s' s => SizedLazyText s -> SizedLazyText s' -> Bool

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

isInfixOf :: (IsMoreGeneral s' s, HasCallStack) => SizedLazyText s -> SizedLazyText s' -> Bool

O(n+m) The isInfixOf function takes two SizedLazyTexts 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 :: SizedLazyText s -> SizedLazyText s' -> Maybe (SizedLazyText (s <-> s'))

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.Sized as T

fnordLength :: SizedLazyText -> Int
fnordLength (stripPrefix "fnord" -> Just suf) = T.length suf
fnordLength _                                 = -1

stripSuffix :: SizedLazyText s -> SizedLazyText s' -> Maybe (SizedLazyText (s <-> s'))

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.Sized as T

quuxLength :: SizedLazyText -> Int
quuxLength (stripSuffix "quux" -> Just pre) = T.length pre
quuxLength _                                = -1

commonPrefixes :: SizedLazyText s -> SizedLazyText s' -> 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

filter :: (Char -> Bool) -> SizedLazyText s -> SizedLazyText (RestrictAtMost s)

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

breakOnAll

Arguments

:: SizedLazyText s

needle to search for

-> SizedLazyText s'

haystack in which to search

-> Sized (RestrictAtMost s) [(SizedLazyText (RestrictAtMost s), SizedLazyText (RestrictAtMost s))]

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.

find :: (Char -> Bool) -> SizedLazyText s -> Maybe Char

O(n) The elem function takes a character and a SizedLazyText, and returns True if the element is found in the given SizedLazyText, or False otherwise.

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

partition :: (Char -> Bool) -> SizedLazyText s -> (SizedLazyText (RestrictAtMost s), SizedLazyText (RestrictAtMost s))

O(n) The partition function takes a predicate and a SizedLazyText, and returns the pair of Texts 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 :: (KnownNat n, Includes s n, HasCallStack) => SizedLazyText s -> Proxy n -> Char

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

count :: SizedLazyText s -> SizedLazyText s' -> Int64

O(n+m) The count function returns the number of times the query string appears in the given SizedLazyText. An empty query string is invalid, and will cause an error to be raised.

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

Zipping

zip :: SizedLazyText s -> SizedLazyText s -> Sized s [(Char, Char)]

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

zipWith :: (Char -> Char -> Char) -> SizedLazyText s -> SizedLazyText s -> SizedLazyText s

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.

Orphan instances

SizedSingleton Text

Associated Types

type SizedSingletonElement Text

Methods

sizedSingleton :: Proxy Text -> SizedSingletonElement Text -> Text

SizedFromContainer Text

Methods

calculateSize :: Text -> Int

isAtLeast :: Int -> Text -> Bool

isAtMost :: Int -> Text -> Bool

isExactly :: Int -> Text -> Bool

isBetween :: Int -> Int -> Text -> Bool