Documentation

Version of Unicode standard used by base: 15.1.0.

@since base-4.15.0.0

Unicode General Categories (column 2 of the UnicodeData table) in the order they are listed in the Unicode standard (the Unicode Character Database, in particular).

Examples

>>> :t OtherLetter
OtherLetter :: GeneralCategory

>>> UppercaseLetter == UppercaseLetter
True
>>> UppercaseLetter == LowercaseLetter
False

>>> NonSpacingMark <= MathSymbol
True

>>> enumFromTo ModifierLetter SpacingCombiningMark
[ModifierLetter,OtherLetter,NonSpacingMark,SpacingCombiningMark]

>>> read "DashPunctuation" :: GeneralCategory
DashPunctuation
>>> read "17" :: GeneralCategory
*** Exception: Prelude.read: no parse

>>> show EnclosingMark
"EnclosingMark"

>>> minBound :: GeneralCategory
UppercaseLetter
>>> maxBound :: GeneralCategory
NotAssigned

>>> import GHC.Internal.Data.Ix ( index )
>>> index (OtherLetter,Control) FinalQuote
12
>>> index (OtherLetter,Control) Format
*** Exception: Error in array index

The Unicode general category of the character. This relies on the Enum instance of GeneralCategory, which must remain in the same order as the categories are presented in the Unicode standard.

Examples

>>> generalCategory 'a'
LowercaseLetter
>>> generalCategory 'A'
UppercaseLetter
>>> generalCategory '0'
DecimalNumber
>>> generalCategory '%'
OtherPunctuation
>>> generalCategory '♥'
OtherSymbol
>>> generalCategory '\31'
Control
>>> generalCategory ' '
Space

Selects the first 128 characters of the Unicode character set, corresponding to the ASCII character set.

Selects the first 256 characters of the Unicode character set, corresponding to the ISO 8859-1 (Latin-1) character set.

Selects control characters, which are the non-printing characters of the Latin-1 subset of Unicode.

Selects ASCII upper-case letters, i.e. characters satisfying both isAscii and isUpper.

Selects ASCII lower-case letters, i.e. characters satisfying both isAscii and isLower.

Selects printable Unicode characters (letters, numbers, marks, punctuation, symbols and spaces).

This function returns False if its argument has one of the following GeneralCategorys, or True otherwise:

• LineSeparator
• ParagraphSeparator
• Control
• Format
• Surrogate
• PrivateUse
• NotAssigned

Returns True for any Unicode space character, and the control characters \t, \n, \r, \f, \v.

Selects upper-case or title-case alphabetic Unicode characters (letters). Title case is used by a small number of letter ligatures like the single-character form of Lj.

Note: this predicate does not work for letter-like characters such as: 'Ⓐ' (U+24B6 circled Latin capital letter A) and 'Ⅳ' (U+2163 Roman numeral four). This is due to selecting only characters with the GeneralCategory UppercaseLetter or TitlecaseLetter.

See isUpperCase for a more intuitive predicate. Note that unlike isUpperCase, isUpper does select title-case characters such as 'Dž' (U+01C5 Latin capital letter d with small letter z with caron) or 'ᾯ' (U+1FAF Greek capital letter omega with dasia and perispomeni and prosgegrammeni).

Selects upper-case Unicode letter-like characters.

Note: this predicate selects characters with the Unicode property Uppercase, which include letter-like characters such as: 'Ⓐ' (U+24B6 circled Latin capital letter A) and 'Ⅳ' (U+2163 Roman numeral four).

See isUpper for the legacy predicate. Note that unlike isUpperCase, isUpper does select title-case characters such as 'Dž' (U+01C5 Latin capital letter d with small letter z with caron) or 'ᾯ' (U+1FAF Greek capital letter omega with dasia and perispomeni and prosgegrammeni).

@since base-4.18.0.0

Selects lower-case alphabetic Unicode characters (letters).

Note: this predicate does not work for letter-like characters such as: 'ⓐ' (U+24D0 circled Latin small letter a) and 'ⅳ' (U+2173 small Roman numeral four). This is due to selecting only characters with the GeneralCategory LowercaseLetter.

See isLowerCase for a more intuitive predicate.

Selects lower-case Unicode letter-like characters.

Note: this predicate selects characters with the Unicode property Lowercase, which includes letter-like characters such as: 'ⓐ' (U+24D0 circled Latin small letter a) and 'ⅳ' (U+2173 small Roman numeral four).

See isLower for the legacy predicate.

@since base-4.18.0.0

Selects alphabetic Unicode characters (lower-case, upper-case and title-case letters, plus letters of caseless scripts and modifiers letters). This function is equivalent to isLetter.

This function returns True if its argument has one of the following GeneralCategorys, or False otherwise:

• UppercaseLetter
• LowercaseLetter
• TitlecaseLetter
• ModifierLetter
• OtherLetter

These classes are defined in the Unicode Character Database, part of the Unicode standard. The same document defines what is and is not a "Letter".

Selects ASCII digits, i.e. '0'..'9'.

Selects ASCII octal digits, i.e. '0'..'7'.

Selects ASCII hexadecimal digits, i.e. '0'..'9', 'a'..'f', 'A'..'F'.

Selects alphabetic or numeric Unicode characters.

Note that numeric digits outside the ASCII range, as well as numeric characters which aren't digits, are selected by this function but not by isDigit. Such characters may be part of identifiers but are not used by the printer and reader to represent numbers, e.g., Roman numerals like V, full-width digits like '１' (aka '65297').

This function returns True if its argument has one of the following GeneralCategorys, or False otherwise:

• UppercaseLetter
• LowercaseLetter
• TitlecaseLetter
• ModifierLetter
• OtherLetter
• DecimalNumber
• LetterNumber
• OtherNumber

Selects Unicode punctuation characters, including various kinds of connectors, brackets and quotes.

This function returns True if its argument has one of the following GeneralCategorys, or False otherwise:

• ConnectorPunctuation
• DashPunctuation
• OpenPunctuation
• ClosePunctuation
• InitialQuote
• FinalQuote
• OtherPunctuation

These classes are defined in the Unicode Character Database, part of the Unicode standard. The same document defines what is and is not a "Punctuation".

Examples

>>> isPunctuation 'a'
False
>>> isPunctuation '7'
False
>>> isPunctuation '♥'
False
>>> isPunctuation '"'
True
>>> isPunctuation '?'
True
>>> isPunctuation '—'
True

Selects Unicode symbol characters, including mathematical and currency symbols.

This function returns True if its argument has one of the following GeneralCategorys, or False otherwise:

• MathSymbol
• CurrencySymbol
• ModifierSymbol
• OtherSymbol

These classes are defined in the Unicode Character Database, part of the Unicode standard. The same document defines what is and is not a "Symbol".

Examples

>>> isSymbol 'a'
False
>>> isSymbol '6'
False
>>> isSymbol '='
True

>>> isSymbol '+'
True
>>> isSymbol '-'
False

Convert a letter to the corresponding upper-case letter, if any. Any other character is returned unchanged.

Convert a letter to the corresponding lower-case letter, if any. Any other character is returned unchanged.

Convert a letter to the corresponding title-case or upper-case letter, if any. (Title case differs from upper case only for a small number of ligature letters.) Any other character is returned unchanged.