Unicode.Char.Numeric

Numeric character property related functions.

Since: 0.3.0

Predicates

isNumeric :: Char -> Bool Source #

Selects Unicode character with a numeric value.

Note: a character may have a numeric value but return False with the predicate isNumber, because isNumber only tests GeneralCategory: some CJK characters are OtherLetter and do have a numeric value.

isNumeric c == isJust (numericValue c)

Since: 0.3.1

Numeric values

numericValue :: Char -> Maybe Rational Source #

Numeric value of a character, if relevant.

Note: a character may have a numeric value but return False with the predicate isNumber, because isNumber only tests GeneralCategory: some CJK characters are OtherLetter and do have a numeric value.

Since: 0.3.1

integerValue :: Integral a => Char -> Maybe a Source #

Integer value of a character, if relevant.

This is a special case of numericValue.

Warning: There is a risk of integer overflow depending of the chosen concrete return type. As of Unicode 15.1 the results range from 0 to 1e16.

>>> minimum [v | v@Just{} <- integerValue <$> [minBound..]] :: Maybe Integer
Just 0
>>> maximum (integerValue <$> [minBound..]) :: Maybe Integer
Just 10000000000000000
>>> integerValue '\x4EAC' :: Maybe Int64 -- OK
Just 10000000000000000
>>> integerValue '\x4EAC' :: Maybe Int32 -- Will overflow!
Just 1874919424

Therefore it is advised to use: integerValue @Int64.

Note: A character may have a numeric value but return False with the predicate isNumber, because isNumber only tests GeneralCategory: some CJK characters are OtherLetter and do have a numeric value.

Since: 0.3.1

Single digit characters

intToDigiT :: Int -> Char Source #

Same a intToDigit, but with upper case.

>>> intToDigiT <$> [0..15]
"0123456789ABCDEF"

Since: 0.6.0

Re-export from base

isDigit :: Char -> Bool Source #

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

isOctDigit :: Char -> Bool Source #

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

isHexDigit :: Char -> Bool Source #

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

digitToInt :: Char -> Int Source #

Convert a single digit Char to the corresponding Int. This function fails unless its argument satisfies isHexDigit, but recognises both upper- and lower-case hexadecimal digits (that is, '0'..'9', 'a'..'f', 'A'..'F').

Examples
Expand

Characters '0' through '9' are converted properly to 0..9:

>>> map digitToInt ['0'..'9']
[0,1,2,3,4,5,6,7,8,9]

Both upper- and lower-case 'A' through 'F' are converted as well, to 10..15.

>>> map digitToInt ['a'..'f']
[10,11,12,13,14,15]
>>> map digitToInt ['A'..'F']
[10,11,12,13,14,15]

Anything else throws an exception:

>>> digitToInt 'G'
*** Exception: Char.digitToInt: not a digit 'G'
>>> digitToInt '♥'
*** Exception: Char.digitToInt: not a digit '\9829'

intToDigit :: Int -> Char Source #

Convert an Int in the range 0..15 to the corresponding single digit Char. This function fails on other inputs, and generates lower-case hexadecimal digits.