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GHC 9.10.3 · lts/ghc-9.10.x · c74966e · 2026-09-27

Moduletext-icu-0.8.0.5Haskell98

Data.Text.ICU

Commonly used functions for Unicode, implemented as bindings to the International Components for Unicode (ICU) libraries.

This module contains only the most commonly used types and functions. Other modules in this package expose richer interfaces.

  • 25 types
  • 1 class
  • 73 values
  • Packagetext-icu-0.8.0.5
  • Exports99
  • LanguageHaskell98
  • LicenceBSD-3-Clause
  • SourceICU.hs

Data representation

0 declarations

The Haskell Text type is implemented as an array in the Haskell heap. This means that its location is not pinned; it may be copied during a garbage collection pass. ICU, on the other hand, works with strings that are allocated in the normal system heap and have a fixed address.

To accommodate this need, these bindings use the functions from Data.Text.Foreign to copy data between the Haskell heap and the system heap. The copied strings are still managed automatically, but the need to duplicate data does add some performance and memory overhead.

Types

1 declaration
datadata LocaleName
#

The name of a locale.

Constructors

Instances6Eq, Ord, Read, Show, IsString, NFData

Locales

1 declaration
valueavailableLocales :: IO [String]
#

Get the available default locales, i.e. locales that return data when passed to ICU APIs, but not including legacy or alias locales.

Boundary analysis

14 declarations

Text boundary analysis is the process of locating linguistic boundaries while formatting and handling text. Examples of this process include:

  • Locating appropriate points to word-wrap text to fit within specific margins while displaying or printing.

  • Counting characters, words, sentences, or paragraphs.

  • Making a list of the unique words in a document.

  • Figuring out if a given range of text contains only whole words.

  • Capitalizing the first letter of each word.

  • Locating a particular unit of the text (For example, finding the third word in the document).

The Breaker type was designed to support these kinds of tasks.

For the impure boundary analysis API (which is richer, but less easy to use than the pure API), see the Data.Text.ICU.Break module. The impure API supports some uses that may be less efficient via the pure API, including:

  • Locating the beginning of a word that the user has selected.

  • Determining how far to move the text cursor when the user hits an arrow key (Some characters require more than one position in the text store and some characters in the text store do not display at all).

newtypenewtype Breaker a
#

A boundary analyser.

datadata Break a
#

A break in a string.

Instances3Eq, Show, NFData
  • Eq a => Eq (Break a)Defined in text-icu-0.8.0.5 · Data.Text.ICU.Break.Pure
  • Show a => Show (Break a)Defined in text-icu-0.8.0.5 · Data.Text.ICU.Break.Pure
  • NFData a => NFData (Break a)Defined in text-icu-0.8.0.5 · Data.Text.ICU.Break.Pure
datadata Line
#

Line break status.

Constructors

  • Soft

    A soft line break is a position at which a line break is acceptable, but not required.

  • Hard
Instances4Enum, Eq, Show, NFData
  • Enum LineDefined in text-icu-0.8.0.5 · Data.Text.ICU.Break
  • Eq LineDefined in text-icu-0.8.0.5 · Data.Text.ICU.Break
  • Show LineDefined in text-icu-0.8.0.5 · Data.Text.ICU.Break
  • NFData LineDefined in text-icu-0.8.0.5 · Data.Text.ICU.Break
datadata Word
#

Word break status.

Constructors

  • Uncategorized

    A "word" that does not fit into another category. Includes spaces and most punctuation.

  • Number

    A word that appears to be a number.

  • Letter

    A word containing letters, excluding hiragana, katakana or ideographic characters.

  • Kana

    A word containing kana characters.

  • Ideograph

    A word containing ideographic characters.

Instances4Enum, Eq, Show, NFData
  • Enum WordDefined in text-icu-0.8.0.5 · Data.Text.ICU.Break
  • Eq WordDefined in text-icu-0.8.0.5 · Data.Text.ICU.Break
  • Show WordDefined in text-icu-0.8.0.5 · Data.Text.ICU.Break
  • NFData WordDefined in text-icu-0.8.0.5 · Data.Text.ICU.Break
valuebreakCharacter :: LocaleName -> Breaker ()
#

Break a string on character boundaries.

Character boundary analysis identifies the boundaries of "Extended Grapheme Clusters", which are groupings of codepoints that should be treated as character-like units for many text operations. Please see Unicode Standard Annex #29, Unicode Text Segmentation, http://www.unicode.org/reports/tr29/ for additional information on grapheme clusters and guidelines on their use.

valuebreakLine :: LocaleName -> Breaker Line
#

Break a string on line boundaries.

Line boundary analysis determines where a text string can be broken when line wrapping. The mechanism correctly handles punctuation and hyphenated words.

valuebreakSentence :: LocaleName -> Breaker ()
#

Break a string on sentence boundaries.

Sentence boundary analysis allows selection with correct interpretation of periods within numbers and abbreviations, and trailing punctuation marks such as quotation marks and parentheses.

valuebreakWord :: LocaleName -> Breaker Word
#

Break a string on word boundaries.

Word boundary analysis is used by search and replace functions, as well as within text editing applications that allow the user to select words with a double click. Word selection provides correct interpretation of punctuation marks within and following words. Characters that are not part of a word, such as symbols or punctuation marks, have word breaks on both sides.

Case mapping

3 declarations
valuetoCaseFold
  1. :: Bool

    Whether to include or exclude mappings for dotted and dotless I and i that are marked with I in CaseFolding.txt.

  2. -> Text
  3. -> Text
#

Case-fold the characters in a string.

Case folding is locale independent and not context sensitive, but there is an option for treating the letter I specially for Turkic languages. The result may be longer or shorter than the original.

valuetoLower :: LocaleName -> Text -> Text
#

Lowercase the characters in a string.

Casing is locale dependent and context sensitive. The result may be longer or shorter than the original.

valuetoUpper :: LocaleName -> Text -> Text
#

Uppercase the characters in a string.

Casing is locale dependent and context sensitive. The result may be longer or shorter than the original.

Iteration

4 declarations
datadata CharIterator
#

A type that supports efficient iteration over Unicode characters.

As an example of where this may be useful, a function using this type may be able to iterate over a UTF-8 ByteString directly, rather than first copying and converting it to an intermediate form. This type also allows e.g. comparison between Text and ByteString, with minimal overhead.

Instances3Eq, Ord, Show
  • Eq CharIteratorDefined in text-icu-0.8.0.5 · Data.Text.ICU.Iterator · orphan
  • Ord CharIteratorDefined in text-icu-0.8.0.5 · Data.Text.ICU.Iterator · orphan
  • Show CharIteratorDefined in text-icu-0.8.0.5 · Data.Text.ICU.Internal

Normalization

5 declarations

See module Data.Text.ICU.Normalization2 for the full interface which provides some compatibility with the former API.

valuenfc :: Text -> Text
#

Create an NFC normalizer and apply this to the given text.

Let's have a look at a concrete example that contains the letter a with an acute accent twice. First as a combination of two codepoints and second as a canonical composite or precomposed character. Both look exactly the same but one character consists of two and one of only one codepoint. A bytewise comparison does not give equality of these.

Example4 expressions
import Data.Textlet t = pack "a\x301á"t"a\769\225"putStr táápack "a\x301" == pack "á"False

But now lets apply some normalization functions and see how these characters coincide afterwards in two different ways:

Example2 expressions
nfc t"\225\225"nfd t"a\769a\769"

That is exactly what compareUnicode' does:

Example1 expression
pack "a\x301" `compareUnicode'` pack "á"
valuenfd :: Text -> Text
#

Create an NFD normalizer and apply this to the given text.

valuenfkc :: Text -> Text
#

Create an NFKC normalizer and apply this to the given text.

valuenfkd :: Text -> Text
#

Create an NFC normalizer and apply this to the given text.

valuenfkcCasefold :: Text -> Text
#

Create an NFKCCasefold normalizer and apply this to the given text.

Checks for normalization

String comparison

0 declarations

Normalization-sensitive string comparison

datadata CompareOption
#

Options to compare.

Constructors

  • InputIsFCD

    The caller knows that both strings fulfill the FCD conditions. If not set, compare will quickCheck for FCD and normalize if necessary.

  • CompareIgnoreCase

    Compare strings case-insensitively using case folding, instead of case-sensitively. If set, then the following case folding options are used.

  • FoldCaseExcludeSpecialI

    When case folding, exclude the special I character. For use with Turkic (Turkish/Azerbaijani) text data.

Instances3Enum, Eq, Show
valuecompareUnicode :: [CompareOption] -> Text -> Text -> Ordering
#

Compare two strings for canonical equivalence. Further options include case-insensitive comparison and codepoint order (as opposed to code unit order).

Canonical equivalence between two strings is defined as their normalized forms (NFD or NFC) being identical. This function compares strings incrementally instead of normalizing (and optionally case-folding) both strings entirely, improving performance significantly.

Bulk normalization is only necessary if the strings do not fulfill the FCD conditions. Only in this case, and only if the strings are relatively long, is memory allocated temporarily. For FCD strings and short non-FCD strings there is no memory allocation.

Locale-sensitive string collation

For the impure collation API (which is richer, but less easy to use than the pure API), see the Data.Text.ICU.Collate module.

newtypenewtype Collator
#

String collator type.

Regular expressions

8 declarations
datadata MatchOption
#

Options for controlling matching behaviour.

Constructors

  • CaseInsensitive

    Enable case insensitive matching.

  • Comments

    Allow comments and white space within patterns.

  • DotAll

    If set, '.' matches line terminators. Otherwise '.' matching stops at line end.

  • Literal

    If set, treat the entire pattern as a literal string. Metacharacters or escape sequences in the input sequence will be given no special meaning.

    The option CaseInsensitive retains its meanings on matching when used in conjunction with this option. Other options become superfluous.

  • Multiline

    Control behaviour of '$' and '^'. If set, recognize line terminators within string, Otherwise, match only at start and end of input string.

  • HaskellLines

    Haskell-only line endings. When this mode is enabled, only '\n' is recognized as a line ending in the behavior of '.', '^', and '$'.

  • UnicodeWord

    Unicode word boundaries. If set, '\\b' uses the Unicode TR 29 definition of word boundaries.

    Warning: Unicode word boundaries are quite different from traditional regular expression word boundaries. See http://unicode.org/reports/tr29/#Word_Boundaries.

  • ErrorOnUnknownEscapes

    Throw an error on unrecognized backslash escapes. If set, fail with an error on patterns that contain backslash-escaped ASCII letters without a known special meaning. If this flag is not set, these escaped letters represent themselves.

  • WorkLimit Int

    Set a processing limit for match operations.

    Some patterns, when matching certain strings, can run in exponential time. For practical purposes, the match operation may appear to be in an infinite loop. When a limit is set a match operation will fail with an error if the limit is exceeded.

    The units of the limit are steps of the match engine. Correspondence with actual processor time will depend on the speed of the processor and the details of the specific pattern, but will typically be on the order of milliseconds.

    By default, the matching time is not limited.

  • StackLimit Int

    Set the amount of heap storage available for use by the match backtracking stack.

    ICU uses a backtracking regular expression engine, with the backtrack stack maintained on the heap. This function sets the limit to the amount of memory that can be used for this purpose. A backtracking stack overflow will result in an error from the match operation that caused it.

    A limit is desirable because a malicious or poorly designed pattern can use excessive memory, potentially crashing the process. A limit is enabled by default.

Instances2Eq, Show
  • Eq MatchOptionDefined in text-icu-0.8.0.5 · Data.Text.ICU.Regex.Internal
  • Show MatchOptionDefined in text-icu-0.8.0.5 · Data.Text.ICU.Regex.Internal
datadata ParseError
#

Detailed information about parsing errors. Used by ICU parsing engines that parse long rules, patterns, or programs, where the text being parsed is long enough that more information than an ICUError is needed to localize the error.

Instances3Show, Exception, NFData
valueerrLine :: ParseError -> Maybe Int
#

The line on which the error occured. If the parser uses this field, it sets it to the line number of the source text line on which the error appears, which will be be a positive value. If the parser does not support line numbers, the value will be Nothing.

valueerrOffset :: ParseError -> Maybe Int
#

The character offset to the error. If the errLine field is Just some value, then this field contains the offset from the beginning of the line that contains the error. Otherwise, it represents the offset from the start of the text. If the parser does not support this field, it will have a value of Nothing.

datadata Match
#

A match for a regular expression.

Instances2Show, Regular
  • Show MatchDefined in text-icu-0.8.0.5 · Data.Text.ICU.Regex.Pure
  • Regular MatchDefined in text-icu-0.8.0.5 · Data.Text.ICU.Regex.Pure
newtypenewtype Regex
#

A compiled regular expression.

Regex values are usually constructed using the regex or regex' functions. This type is also an instance of IsString, so if you have the OverloadedStrings language extension enabled, you can construct a Regex by simply writing the pattern in quotes (though this does not allow you to specify any Options).

Instances3Show, IsString, Regular
  • Show RegexDefined in text-icu-0.8.0.5 · Data.Text.ICU.Regex.Pure
  • IsString RegexDefined in text-icu-0.8.0.5 · Data.Text.ICU.Regex.Pure
  • Regular RegexDefined in text-icu-0.8.0.5 · Data.Text.ICU.Regex.Pure
classclass Regular r where
#

A typeclass for functions common to both Match and Regex types.

Instances2Regular
  • Regular MatchDefined in text-icu-0.8.0.5 · Data.Text.ICU.Regex.Pure
  • Regular RegexDefined in text-icu-0.8.0.5 · Data.Text.ICU.Regex.Pure

Construction

valueregex :: [MatchOption] -> Text -> Regex
#

Compile a regular expression with the given options. This function throws a ParseError if the pattern is invalid, so it is best for use when the pattern is statically known.

Inspection

valuepattern :: Regular r => r -> Text
#

Return the source form of the pattern used to construct this regular expression or match.

Searching

valuefindAll :: Regex -> Text -> [Match]
#

Lazily find all matches for the regular expression in the given text.

Match groups

Capturing groups are numbered starting from zero. Group zero is always the entire matching text. Groups greater than zero contain the text matching each capturing group in a regular expression.

valuegroupCount :: Regular r => r -> Int
#

Return the number of capturing groups in this regular expression or match's pattern.

valuespan :: Match -> Text
#

Return the span of text between the end of the previous match and the beginning of the current match.

valueprefix :: Int -> Match -> Maybe Text
#

Return the prefix of the nth capturing group in a match (the text from the start of the string to the start of the match), or Nothing if n is out of bounds.

valuesuffix :: Int -> Match -> Maybe Text
#

Return the suffix of the nth capturing group in a match (the text from the end of the match to the end of the string), or Nothing if n is out of bounds.

Spoof checking

5 declarations

The Spoof type performs security checks on visually confusable (spoof) strings. For the impure spoof checking API (which is richer, but less easy to use than the pure API), see the Data.Text.ICU.Spoof module.

See UTR #36 and UTS #39 for detailed information about the underlying algorithms and databases used by these functions.

newtypenewtype Spoof
#

Spoof checker type.

datadata SpoofParams
#

Constructors

Instances2Eq, Show
  • Eq SpoofParamsDefined in text-icu-0.8.0.5 · Data.Text.ICU.Spoof.Pure
  • Show SpoofParamsDefined in text-icu-0.8.0.5 · Data.Text.ICU.Spoof.Pure
datadata SpoofCheck
#

Constructors

  • SingleScriptConfusable

    Makes areConfusable report if both identifiers are both from the same script and are visually confusable. Does not affect spoofCheck.

  • MixedScriptConfusable

    Makes areConfusable report if both identifiers are visually confusable and at least one identifier contains characters from more than one script.

    Makes spoofCheck report if the identifier contains multiple scripts, and is confusable with some other identifier in a single script.

  • WholeScriptConfusable

    Makes areConfusable report if each identifier is of a different single script, and the identifiers are visually confusable.

  • AnyCase

    By default, spoof checks assume the strings have been processed through toCaseFold and only check lower-case identifiers. If this is set, spoof checks will check both upper and lower case identifiers.

  • RestrictionLevel

    Checks that identifiers are no looser than the specified level passed to setRestrictionLevel.

  • Invisible

    Checks the identifier for the presence of invisible characters, such as zero-width spaces, or character sequences that are likely not to display, such as multiple occurrences of the same non-spacing mark.

  • CharLimit

    Checks whether the identifier contains only characters from a specified set (for example, via setAllowedLocales).

  • MixedNumbers

    Checks that the identifier contains numbers from only a single script.

  • AllChecks

    Enables all checks.

  • AuxInfo

    Enables returning a RestrictionLevel in the SpoofCheckResult.

Instances5Bounded, Enum, Eq, Show, ToBitMask
datadata RestrictionLevel
#

Constructors

  • ASCII

    Checks that the string contains only Unicode values in the range ߝ inclusive.

  • SingleScriptRestrictive

    Checks that the string contains only characters from a single script.

  • HighlyRestrictive

    Checks that the string contains only characters from a single script, or from the combinations (Latin + Han + Hiragana + Katakana), (Latin + Han + Bopomofo), or (Latin + Han + Hangul).

  • ModeratelyRestrictive

    Checks that the string contains only characters from the combinations (Latin + Cyrillic + Greek + Cherokee), (Latin + Han + Hiragana + Katakana), (Latin + Han + Bopomofo), or (Latin + Han + Hangul).

  • MinimallyRestrictive

    Allows arbitrary mixtures of scripts.

  • Unrestrictive

    Allows any valid identifiers, including characters outside of the Identifier Profile.

Instances5Bounded, Enum, Eq, Show, ToBitMask
datadata SpoofCheckResult
#

Constructors

Instances2Eq, Show

Construction

String checking

valuegetSkeleton :: Spoof -> Maybe SkeletonTypeOverride -> Text -> Text
#

Generates re-usable "skeleton" strings which can be used (via Unicode equality) to check if an identifier is confusable with some large set of existing identifiers.

If you cache the returned strings in storage, you must invalidate your cache any time the underlying confusables database changes (i.e., on ICU upgrade).

By default, assumes all input strings have been passed through toCaseFold and are lower-case. To change this, pass SkeletonAnyCase.

By default, builds skeletons which catch visually confusable characters across multiple scripts. Pass SkeletonSingleScript to override that behavior and build skeletons which catch visually confusable characters across single scripts.

Configuration

valuegetAllowedLocales :: Spoof -> [String]
#

Gets the locales whose scripts are currently allowed by the spoof checker. (We don't use LocaleName since the root and default locales have no meaning here.)

Persistence

valueserialize :: Spoof -> ByteString
#

Serializes the rules in this spoof checker to a byte array, suitable for re-use by spoofFromSerialized.

Only includes any data provided to openFromSource. Does not include any other state or configuration.

Calendars

4 declarations
datadata CalendarField
#

All the fields that comprise a Calendar.

Constructors

  • Era

    Field indicating the era, e.g., AD or BC in the Gregorian (Julian) calendar. This is a calendar-specific value.

  • Year

    Field indicating the year. This is a calendar-specific value.

  • Month

    Field indicating the month. This is a calendar-specific value. The first month of the year is JANUARY; the last depends on the number of months in a year. Note: Calendar month is 0-based.

  • WeekOfYear

    Field indicating the week number within the current year. The first week of the year, as defined by UCAL_FIRST_DAY_OF_WEEK and UCAL_MINIMAL_DAYS_IN_FIRST_WEEK attributes, has value 1. Subclasses define the value of UCAL_WEEK_OF_YEAR for days before the first week of the year.

  • WeekOfMonth

    Field indicating the week number within the current month. The first week of the month, as defined by UCAL_FIRST_DAY_OF_WEEK and UCAL_MINIMAL_DAYS_IN_FIRST_WEEK attributes, has value 1. Subclasses define the value of WEEK_OF_MONTH for days before the first week of the month.

  • DayOfMonth

    Field indicating the day of the month. This is a synonym for DAY_OF_MONTH. The first day of the month has value 1.

  • DayOfYear

    Field indicating the day number within the current year. The first day of the year has value 1.

  • DayOfWeek

    Field indicating the day of the week. This field takes values SUNDAY, MONDAY, TUESDAY, WEDNESDAY, THURSDAY, FRIDAY, and SATURDAY. Note: Calendar day-of-week is 1-based. Clients who create locale resources for the field of first-day-of-week should be aware of this. For instance, in US locale, first-day-of-week is set to 1, i.e., UCAL_SUNDAY.

  • DayOfWeekInMonth

    Field indicating the ordinal number of the day of the week within the current month. Together with the DAY_OF_WEEK field, this uniquely specifies a day within a month. Unlike WEEK_OF_MONTH and WEEK_OF_YEAR, this field's value does not depend on getFirstDayOfWeek() or getMinimalDaysInFirstWeek(). DAY_OF_MONTH 1 through 7 always correspond to DAY_OF_WEEK_IN_MONTH 1; 8 through 15 correspond to DAY_OF_WEEK_IN_MONTH 2, and so on. DAY_OF_WEEK_IN_MONTH 0 indicates the week before DAY_OF_WEEK_IN_MONTH 1. Negative values count back from the end of the month, so the last Sunday of a month is specified as DAY_OF_WEEK = SUNDAY, DAY_OF_WEEK_IN_MONTH = -1. Because negative values count backward they will usually be aligned differently within the month than positive values. For example, if a month has 31 days, DAY_OF_WEEK_IN_MONTH -1 will overlap DAY_OF_WEEK_IN_MONTH 5 and the end of 4.

  • AmPm

    Field indicating whether the HOUR is before or after noon. E.g., at 10:04:15.250 PM the AM_PM is PM.

  • Hour

    Field indicating the hour of the morning or afternoon. HOUR is used for the 12-hour clock. E.g., at 10:04:15.250 PM the HOUR is 10.

  • HourOfDay

    Field indicating the hour of the day. HOUR_OF_DAY is used for the 24-hour clock. E.g., at 10:04:15.250 PM the HOUR_OF_DAY is 22.

  • Minute

    Field indicating the minute within the hour. E.g., at 10:04:15.250 PM the UCAL_MINUTE is 4.

  • Second

    Field indicating the second within the minute. E.g., at 10:04:15.250 PM the UCAL_SECOND is 15.

  • Millisecond

    Field indicating the millisecond within the second. E.g., at 10:04:15.250 PM the UCAL_MILLISECOND is 250.

  • ZoneOffset

    Field indicating the raw offset from GMT in milliseconds.

  • DstOffset

    Field indicating the daylight savings offset in milliseconds.

  • YearWoY

    Field indicating the extended year corresponding to the UCAL_WEEK_OF_YEAR field. This may be one greater or less than the value of UCAL_EXTENDED_YEAR.

  • DoWLocal

    Field indicating the localized day of week. This will be a value from 1 to 7 inclusive, with 1 being the localized first day of the week.

  • ExtendedYear

    Year of this calendar system, encompassing all supra-year fields. For example, in Gregorian/Julian calendars, positive Extended Year values indicate years AD, 1 BC = 0 extended, 2 BC = -1 extended, and so on.

  • JulianDay

    Field indicating the modified Julian day number. This is different from the conventional Julian day number in two regards. First, it demarcates days at local zone midnight, rather than noon GMT. Second, it is a local number; that is, it depends on the local time zone. It can be thought of as a single number that encompasses all the date-related fields.

  • MillisecondsInDay

    Ranges from 0 to 23:59:59.999 (regardless of DST). This field behaves exactly like a composite of all time-related fields, not including the zone fields. As such, it also reflects discontinuities of those fields on DST transition days. On a day of DST onset, it will jump forward. On a day of DST cessation, it will jump backward. This reflects the fact that it must be combined with the DST_OFFSET field to obtain a unique local time value.

  • IsLeapMonth

    Whether or not the current month is a leap month (0 or 1). See the Chinese calendar for an example of this.

Instances3Eq, Read, Show

Construction

valuecalendar :: Text -> LocaleName -> CalendarType -> IO Calendar
#

Open a Calendar.

A Calendar may be used to convert a millisecond value to a year, month, and day.

Note: When unknown TimeZone ID is specified or if the TimeZone ID specified is "Etc/Unknown", the Calendar returned by the function is initialized with GMT zone with TimeZone ID UCAL_UNKNOWN_ZONE_ID ("EtcUnknown") without any errorswarnings. If you want to check if a TimeZone ID is valid prior to this function, use ucal_getCanonicalTimeZoneID.

Example3 expressions
import qualified Data.Text as Tc <- calendar (T.pack "CET") (Locale "de_DE") TraditionalCalendarTypeshow c2021-10-12 17:37:43

Operations on calendars

valueroll
  1. :: Calendar
  2. -> [(CalendarField, Int)]

    The field and the signed amount to add to this field. If the amount causes the value to exceed to maximum or minimum values for that field, the field is pinned to a permissible value.

  3. -> Calendar
#

Add a specified signed amount to a particular field in a Calendar.

See rollField for further details.

Example9 expressions
import qualified Data.Text as Tc1 <- calendar (T.pack "CET") (Locale "de_DE") TraditionalCalendarTypeshow c12021-10-12 17:53:26let c2 = roll c1 [(Hour, 2)]show c22021-10-12 19:53:26let c3 = roll c1 [(Hour, 12)]show c32021-10-12 17:53:26let c4 = add c1 [(Hour, 12)]show c42021-10-13 5:53:26
valueadd
  1. :: Calendar

    The Calendar to which to add.

  2. -> [(CalendarField, Int)]

    Field type and the signed amount to add to field. If the amount causes the value to exceed to maximum or minimum values for that field, other fields are modified to preserve the magnitude of the change.

  3. -> Calendar
#

Add a specified signed amount to a particular field in a Calendar.

See addField for further details and see rollField for examples and differences compared to rolling.

Number formatting

6 declarations

Date formatting

7 declarations
datadata FormatStyle
#

The possible date/time format styles.

Constructors

  • FullFormatStyle

    Full style, such as Tuesday, April 12, 1952 AD or 3:30:42pm PST

  • LongFormatStyle

    Long style, such as January 12, 1952 or 3:30:32pm

  • MediumFormatStyle

    Medium style, such as Jan. 12, 1952

  • ShortFormatStyle

    Short style, such as 121352 or 3:30pm

  • DefaultFormatStyle

    Default style

  • RelativeFormatStyle

    Relative style: ICU currently provides limited support for formatting dates using a “relative” style, specified using RELATIVE_SHORT, RELATIVE_MEDIUM, RELATIVE_LONG or RELATIVE_FULL. As currently implemented, relative date formatting only affects the formatting of dates within a limited range of calendar days before or after the current date, based on the CLDR type="day"/relative data: For example, in English, “Yesterday”, “Today”, and “Tomorrow”. Within this range, the specific relative style currently makes no difference. Outside of this range, relative dates are formatted using the corresponding non-relative style (SHORT, MEDIUM, etc.). Relative time styles are not currently supported, and behave just like the corresponding non-relative style.

  • NoFormatStyle

    No style.

Instances3Enum, Eq, Show
  • Enum FormatStyleDefined in text-icu-0.8.0.5 · Data.Text.ICU.DateFormatter
  • Eq FormatStyleDefined in text-icu-0.8.0.5 · Data.Text.ICU.DateFormatter
  • Show FormatStyleDefined in text-icu-0.8.0.5 · Data.Text.ICU.DateFormatter
datadata DateFormatSymbolType
#

The possible types of date format symbols.

Constructors

  • Eras

    The era names, for example AD.

  • Months

    The month names, for example February.

  • ShortMonths

    The short month names, for example Feb.

  • Weekdays

    The CLDR-style format "wide" weekday names, for example Monday.

  • ShortWeekdays

    The CLDR-style format "abbreviated" (not "short") weekday names, for example "Mon." For the CLDR-style format "short" weekday names, use UDAT_SHORTER_WEEKDAYS.

  • AmPms

    The AM/PM names, for example AM.

  • LocalizedChars

    The localized characters.

  • EraNames

    The long era names, for example Anno Domini.

  • NarrowMonths

    The narrow month names, for example F.

  • NarrowWeekdays

    The CLDR-style format "narrow" weekday names, for example M.

  • StandaloneMonths

    Standalone context versions of months.

  • StandaloneWeekdays

    The CLDR-style stand-alone "wide" weekday names.

  • StandaoneShortWeekdays

    The CLDR-style stand-alone "abbreviated" (not "short") weekday names. For the CLDR-style stand-alone "short" weekday names, use UDAT_STANDALONE_SHORTER_WEEKDAYS.

  • StandaloneNarrowWeekdays

    The CLDR-style stand-alone "narrow" weekday names.

  • Quarters

    The quarters, for example 1st Quarter.

  • ShortQuarters

    The short quarter names, for example Q1.

  • StandaloneQuarters

    Standalone context versions of quarters.

  • ShorterWeekdays

    The CLDR-style short weekday names, e.g. Su, Mo", etc. These are named SHORTER to contrast with the constants using SHORT above, which actually get the CLDR-style abbreviated versions of the corresponding names.

  • StandaloneShorterWeekdays

    Standalone version of UDAT_SHORTER_WEEKDAYS.

  • CyclicYearsWide

    Cyclic year names (only supported for some calendars, and only for FORMAT usage; udat_setSymbols not supported for UDAT_CYCLIC_YEARS_WIDE)

  • CyclicYearsAbbreviated

    Cyclic year names (only supported for some calendars, and only for FORMAT usage)

  • CyclicYearsNarrow

    Cyclic year names (only supported for some calendars, and only for FORMAT usage; udat_setSymbols not supported for UDAT_CYCLIC_YEARS_NARROW)

  • ZodiacNamesWide

    Calendar zodiac names (only supported for some calendars, and only for FORMAT usage; udat_setSymbols not supported for UDAT_ZODIAC_NAMES_WIDE)

  • ZodiacNamesAbbreviated

    Calendar zodiac names (only supported for some calendars, and only for FORMAT usage)

  • ZodiacNamesNarrow

    Calendar zodiac names (only supported for some calendars, and only for FORMAT usage; udat_setSymbols not supported for UDAT_ZODIAC_NAMES_NARROW)

  • NarrowQuarters

    The narrow quarter names, for example 1.

  • StandaloneNarrowQuarters

    The narrow standalone quarter names, for example 1.

valuepatternDateFormatter :: Text -> LocaleName -> Text -> IO DateFormatter
#

Create a new DateFormatter using a custom pattern as described at https://unicode-org.github.io/icu/userguide/format_parse/datetime/#datetime-format-syntax. For examples the pattern "yyyy.MM.dd G at HH:mm:ss zzz" produces “1996.07.10 AD at 15:08:56 PDT” in English for the PDT time zone.

A date pattern is a string of characters, where specific strings of characters are replaced with date and time data from a calendar when formatting or used to generate data for a calendar when parsing.

The Date Field Symbol Table contains the characters used in patterns to show the appropriate formats for a given locale, such as yyyy for the year. Characters may be used multiple times. For example, if y is used for the year, "yy" might produce “99”, whereas "yyyy" produces “1999”. For most numerical fields, the number of characters specifies the field width. For example, if h is the hour, "h" might produce “5”, but "hh" produces “05”. For some characters, the count specifies whether an abbreviated or full form should be used, but may have other choices, as given below.

Two single quotes represents a literal single quote, either inside or outside single quotes. Text within single quotes is not interpreted in any way (except for two adjacent single quotes). Otherwise all ASCII letter from a to z and A to Z are reserved as syntax characters, and require quoting if they are to represent literal characters. In addition, certain ASCII punctuation characters may become variable in the future (eg : being interpreted as the time separator and / as a date separator, and replaced by respective locale-sensitive characters in display).

“Stand-alone” values refer to those designed to stand on their own independently, as opposed to being with other formatted values. “2nd quarter” would use the wide stand-alone format "qqqq", whereas “2nd quarter 2007” would use the regular format "QQQQ yyyy". For more information about format and stand-alone forms, see CLDR Calendar Elements.

The pattern characters used in the Date Field Symbol Table are defined by CLDR; for more information see CLDR Date Field Symbol Table.

👉 Note that the examples may not reflect current CLDR data.

valuedateSymbols :: DateFormatter -> DateFormatSymbolType -> [Text]
#

Get relevant date related symbols, e.g. month and weekday names.

Example5 expressions
import Data.TextdfDe <- standardDateFormatter LongFormatStyle LongFormatStyle (Locale "de_DE") (pack "CET")dateSymbols dfDe Months["Januar","Februar","M\228rz","April","Mai","Juni","Juli","August","September","Oktober","November","Dezember"]dfAt <- standardDateFormatter LongFormatStyle LongFormatStyle (Locale "de_AT") (pack "CET")dateSymbols dfAt Months["J\228nner","Februar","M\228rz","April","Mai","Juni","Juli","August","September","Oktober","November","Dezember"]
valueformatCalendar :: DateFormatter -> Calendar -> Text
#

Format a Calendar using a DateFormatter.

Example4 expressions
import Data.TextdfDe <- standardDateFormatter LongFormatStyle LongFormatStyle (Locale "de_DE") (pack "CET")c <- calendar (pack "CET") (Locale "de_DE") TraditionalCalendarTypeformatCalendar dfDe c"13. Oktober 2021 um 12:44:09 GMT+2"