Streamly.Unicode.Parser

To parse a text input, use the decode routines from Streamly.Unicode.Stream module to convert an input byte stream to a Unicode Char stream and then use these parsers on the Char stream.

Setup

To execute the code examples provided in this module in ghci, please run the following commands first.

>>> :m
>>> import qualified Streamly.Data.Stream as Stream
>>> import qualified Streamly.Unicode.Parser as Unicode

For APIs that have not been released yet.

>>> import qualified Streamly.Internal.Unicode.Parser as Unicode (number, mkDouble)

Single Chars

char :: Monad m => Char -> Parser Char m Char

Match a specific character.

charIgnoreCase :: Monad m => Char -> Parser Char m Char

Match a specific character ignoring case.

alpha :: Monad m => Parser Char m Char

Match any character that satisfies isAlpha

alphaNum :: Monad m => Parser Char m Char

Match any character that satisfies isAlphaNum

letter :: Monad m => Parser Char m Char

Match any character that satisfies isLetter

ascii :: Monad m => Parser Char m Char

Match any character that satisfies isAscii

asciiLower :: Monad m => Parser Char m Char

Match any character that satisfies isAsciiLower

asciiUpper :: Monad m => Parser Char m Char

Match any character that satisfies isAsciiUpper

latin1 :: Monad m => Parser Char m Char

Match any character that satisfies isLatin1

lower :: Monad m => Parser Char m Char

Match any character that satisfies isLower

upper :: Monad m => Parser Char m Char

Match any character that satisfies isUpper

mark :: Monad m => Parser Char m Char

Match any character that satisfies isMark

printable :: Monad m => Parser Char m Char

Match any character that satisfies isPrint

punctuation :: Monad m => Parser Char m Char

Match any character that satisfies isPunctuation

separator :: Monad m => Parser Char m Char

Match any character that satisfies isSeparator

space :: Monad m => Parser Char m Char

Match any character that satisfies isSpace

symbol :: Monad m => Parser Char m Char

Match any character that satisfies isSymbol

digit :: Monad m => Parser Char m Char

Match any character that satisfies isDigit

octDigit :: Monad m => Parser Char m Char

Match any character that satisfies isOctDigit

hexDigit :: Monad m => Parser Char m Char

Match any character that satisfies isHexDigit

numeric :: Monad m => Parser Char m Char

Match any character that satisfies isNumber

Char Sequences

string :: Monad m => String -> Parser Char m String

Match the input with the supplied string and return it if successful.

stringIgnoreCase :: Monad m => String -> Parser Char m String

Match the input with the supplied string and return it if successful.

dropSpace :: Monad m => Parser Char m ()

Drop zero or more white space characters.

dropSpace1 :: Monad m => Parser Char m ()

Drop one or more white space characters.

Digit Sequences (Numbers)

decimal :: (Monad m, Integral a) => Parser Char m a

Parse and decode an unsigned integral decimal number.

hexadecimal :: (Monad m, Integral a, Bits a) => Parser Char m a

Parse and decode an unsigned integral hexadecimal number. The hex digits 'a' through 'f' may be upper or lower case.

Note: This parser does not accept a leading "0x" string.

double :: Monad m => Parser Char m Double

Parse a decimal Double value. This parser accepts an optional sign (+ or -) followed by at least one decimal digit. Decimal digits are optionally followed by a decimal point and at least one decimal digit after the point. This parser accepts the maximal valid input as long as it gives a valid number. Specifcally a trailing decimal point is allowed but not consumed. This function does not accept "NaN" or "Infinity" string representations of double values.

Definition:

>>> double = uncurry Unicode.mkDouble <$> Unicode.number

Examples:

>>> p = Stream.parse Unicode.double . Stream.fromList

>>> p "-1.23e-123"
Right (-1.23e-123)

Trailing input examples:

>>> p "1."
Right 1.0

>>> p "1.2.3"
Right 1.2

>>> p "1e"
Right 1.0

>>> p "1e2.3"
Right 100.0

>>> p "1+2"
Right 1.0

Error cases:

>>> p ""
Left (ParseError "number: expecting sign or decimal digit, got end of input")

>>> p ".1"
Left (ParseError "number: expecting sign or decimal digit, got '.'")

>>> p "+"
Left (ParseError "number: expecting decimal digit, got end of input")

Modifiers

signed :: (Num a, Monad m) => Parser Char m a -> Parser Char m a

Allow an optional leading '+' or '-' sign character before any parser.