Text.ParserCombinators.Parsec.Number

adjusted and portable number parsers stolen from Text.ParserCombinators.Parsec.Token

The basic top-level number parsers are decimal, nat, int, fractional, decimalFract, natFract, floating, decimalFloat, natFloat.

natFloat parses numeric literals as defined for Haskell. All numbers are unsigned, i.e. non-negative. Leading zeros are allowed. At least a single digit is required. A decimal point must be preceded and followed by at least one digit.

A result type (Either Integer Double) can be converted to a final Double using (either fromInteger id) as is done for the parsers fractional2 and floating2.

The parser nat, natFract and natFloat parse hexadecimal and octal integrals (beginning with 0x, 0X, 0o or 0O) that are disallowed when using decimal, decimalFract and decimalFloat.

The parsers decimalFract and natFract only allow a decimal point, whereas decimalFloat and natFloat also allow the exponent notation using e or E.

The parser fractional requires a decimal point between at least two digits and floating requires either a decimal point or the exponent notation using e or E. (Both parsers do not return integral values and do not support hexadecimal or octal values).

Signed numbers can be parsed using "ap sign" as is done for the int parser.

A couple of parsers have been added that take a Bool argument, where False does not require any digit following the decimal dot. The parsers fractional3 and floating3 allow even to start a number with the decimal dot. Also parsers hexFract, binFract, hexFloat and binFloat for hexadecimal or binary fractions and floats have been added.

Note that most top-level parsers succeed on a string like "1.0e-100", but only the floating point parsers consume the whole string. The fractional parsers stop before the exponent and the integral parsers before the decimal point. You may wish to check for the end of a string using eof, i.e. "liftM2 const nat eof".

The returned values may be inaccurate. Int may overflow. Fractional numbers should be accurate as only one division is performed. Floating point numbers with decimal exponents may be inaccurate due to using **. Rational numbers are needed for correct conversions, but large positive or negative exponents may be a problem and the class RealFloat is needed to check for minimal and maximal exponents.

floats

floating :: Floating f => CharParser st f

parse a decimal unsigned floating point number containing a dot, e or E

floating2 :: Floating f => Bool -> CharParser st f

parse a floating point number possibly containing a decimal dot, e or E

floating3 :: Floating f => Bool -> CharParser st f

parse a floating point number possibly starting with a decimal dot. Note, that a single decimal point or a number starting with .E is illegal.

decimalFloat :: (Integral i, Floating f) => CharParser st (Either i f)

same as floating but returns a non-negative integral wrapped by Left if a fractional part and exponent is missing

decFloat :: (Integral i, Floating f) => Bool -> CharParser st (Either i f)

same as floating but returns a non-negative integral wrapped by Left if a fractional part and exponent is missing

hexFloat :: (Integral i, Floating f) => Bool -> CharParser st (Either i f)

parse a hexadecimal floating point number

binFloat :: (Integral i, Floating f) => Bool -> CharParser st (Either i f)

parse a binary floating point number

natFloat :: (Integral i, Floating f) => CharParser st (Either i f)

parse hexadecimal, octal or decimal integrals or floating

float parts

zeroNumFloat :: (Integral i, Floating f) => CharParser st (Either i f)

parse any hexadecimal, octal, decimal or floating point number following a zero

fractExponent :: Floating f => Integer -> CharParser st f

parse a floating point number given the number before a dot, e or E

hexFractExp :: Floating f => Integer -> Bool -> CharParser st f

parse a hex floating point number given the number before a dot, p or P

binFractExp :: Floating f => Integer -> Bool -> CharParser st f

parse a binary floating point number given the number before a dot, p or P

fractExp :: Floating f => Integer -> Bool -> CharParser st f

parse a floating point number given the number before a dot, e or E

genFractExp :: Floating f => Integer -> CharParser st f -> CharParser st (f -> f) -> CharParser st f

parse a floating point number given the number before the fraction and exponent

genFractAndExp :: Floating f => f -> CharParser st f -> CharParser st (f -> f) -> CharParser st f

parse a floating point number given the number before the fraction and exponent that must follow the fraction

exponentFactor :: Floating f => CharParser st (f -> f)

parse a floating point exponent starting with e or E

hexExponentFactor :: Floating f => CharParser st (f -> f)

parse a hexadecimal floating point starting with p (IEEE 754)

extExponentFactor :: Floating f => Int -> CharParser st (f -> f)

parse a signed decimal and compute the exponent factor given a base. For hexadecimal exponential notation (IEEE 754) the base is 2 and the leading character a p.

exponentValue :: Floating f => Int -> Integer -> f

compute the factor given by the number following e or E. This implementation uses ** rather than ^ for more efficiency for large integers.

fractional numbers (with just a decimal point between digits)

fractional :: Fractional f => CharParser st f

parse a fractional number containing a decimal dot

fractional2 :: Fractional f => Bool -> CharParser st f

parse a fractional number possibly containing a decimal dot

fractional3 :: Fractional f => Bool -> CharParser st f

parse a fractional number possibly starting with a decimal dot

decFract :: (Integral i, Fractional f) => Bool -> CharParser st (Either i f)

a decimal fractional

hexFract :: (Integral i, Fractional f) => Bool -> CharParser st (Either i f)

a hexadecimal fractional

binFract :: (Integral i, Fractional f) => Bool -> CharParser st (Either i f)

a binary fractional

decimalFract :: (Integral i, Fractional f) => CharParser st (Either i f)

same as fractional but returns a non-negative integral wrapped by Left if a fractional part is missing

natFract :: (Integral i, Fractional f) => CharParser st (Either i f)

parse hexadecimal, octal or decimal integrals or fractional

zeroNumFract :: (Integral i, Fractional f) => CharParser st (Either i f)

parse any hexadecimal, octal, decimal or fractional number following a zero

fractional parts

fractFract :: Fractional f => Integer -> Bool -> CharParser st f

parse a fractional number given the number before the dot

genFractFract :: Fractional f => Integer -> CharParser st f -> CharParser st f

combine the given number before the dot with a parser for the fractional part

fraction :: Fractional f => Bool -> CharParser st f

parse a dot followed by decimal digits as fractional part

hexFraction :: Fractional f => Bool -> CharParser st f

parse a dot followed by hexadecimal digits as fractional part

binFraction :: Fractional f => Bool -> CharParser st f

parse a dot followed by binary digits as fractional part

baseFraction :: Fractional f => Bool -> Int -> CharParser st Char -> CharParser st f

parse a dot followed by base dependent digits as fractional part

fractionValue :: Fractional f => Int -> String -> f

compute the fraction given by a sequence of digits following the dot. Only one division is performed and trailing zeros are ignored.

integers and naturals

int :: Integral i => CharParser st i

parse an optional sign immediately followed by a nat. Note, that in Daan Leijen's code the sign was wrapped as lexeme in order to skip comments and spaces in between.

sign :: Num a => CharParser st (a -> a)

parse an optional plus or minus sign, returning negate or id

decimal :: Integral i => CharParser st i

parse plain non-negative decimal numbers given by a non-empty sequence of digits

binDigit :: CharParser st Char

parse 0 or 1

binary :: Integral i => CharParser st i

parse a binary number

nat :: Integral i => CharParser st i

parse non-negative hexadecimal, octal or decimal numbers

natural parts

zeroNumber :: Integral i => CharParser st i

parse a nat syntactically starting with a zero

hexOrOct :: Integral i => CharParser st i

hexadecimal or octal number

hexadecimal :: Integral i => CharParser st i

parse a hexadecimal number preceded by an x or X character

hexnum :: Integral i => CharParser st i

parse a hexadecimal number

octal :: Integral i => CharParser st i

parse an octal number preceded by an o or O character

number :: Integral i => Int -> GenParser tok st Char -> GenParser tok st i

parse a non-negative number given a base and a parser for the digits

numberValue :: Integral i => Int -> String -> i

compute the value from a string of digits using a base