The Parser type is a monad.

The result of a parse.

Run a parser.

If a parser has returned a Partial result, supply it with more input.

Run a parser that cannot be resupplied via a Partial result.

Run a parser and print its result to standard output.

Run a parser with an initial input string, and a monadic action that can supply more input if needed.

Convert a Result value to a Maybe value. A Partial result is treated as failure.

Convert a Result value to an Either value. A Partial result is treated as failure.

Attempt a parse, and if it fails, rewind the input so that no input appears to have been consumed.

This combinator is useful in cases where a parser might consume some input before failing, i.e. the parser needs arbitrary lookahead. The downside to using this combinator is that it can retain input for longer than is desirable.

Match a specific character.

Match a specific character, but return its Word8 value.

Match any character.

Match any character except the given one.

The parser satisfy p succeeds for any byte for which the predicate p returns True. Returns the byte that is actually parsed.

digit = satisfy isDigit
    where isDigit c = c >= '0' && c <= '9'

Parse a single digit.

Match a letter, in the ISO-8859-15 encoding.

Match a letter, in the ASCII encoding.

Parse a space character.

Note: This parser only gives correct answers for the ASCII encoding. For instance, it does not recognise U+00A0 (non-breaking space) as a space character, even though it is a valid ISO-8859-15 byte.

A fast digit predicate.

A fast digit predicate.

A fast alphabetic predicate for the ISO-8859-15 encoding

Note: For all character encodings other than ISO-8859-15, and almost all Unicode code points above U+00A3, this predicate gives wrong answers.

A fast alphabetic predicate for the ASCII encoding

Note: For all character encodings other than ASCII, and almost all Unicode code points above U+007F, this predicate gives wrong answers.

Fast predicate for matching ASCII space characters.

Note: This predicate only gives correct answers for the ASCII encoding. For instance, it does not recognise U+00A0 (non-breaking space) as a space character, even though it is a valid ISO-8859-15 byte. For a Unicode-aware and only slightly slower predicate, use Data.Char.isSpace

Fast Word8 predicate for matching ASCII space characters.

Match any character in a set.

vowel = inClass "aeiou"

Range notation is supported.

halfAlphabet = inClass "a-nA-N"

To add a literal '-' to a set, place it at the beginning or end of the string.

Match any character not in a set.

string s parses a sequence of bytes that identically match s. Returns the parsed string (i.e. s). This parser consumes no input if it fails (even if a partial match).

Note: The behaviour of this parser is different to that of the similarly-named parser in Parsec, as this one is all-or-nothing. To illustrate the difference, the following parser will fail under Parsec given an input of for:

string "foo" <|> string "for"

The reason for its failure is that that the first branch is a partial match, and will consume the letters 'f' and 'o' before failing. In Attoparsec, the above parser will succeed on that input, because the failed first branch will consume nothing.

Satisfy a literal string, ignoring case.

Skip over white space.

Skip past input for as long as the predicate returns True.

Consume exactly n bytes of input.

A stateful scanner. The predicate consumes and transforms a state argument, and each transformed state is passed to successive invocations of the predicate on each byte of the input until one returns Nothing or the input ends.

This parser does not fail. It will return an empty string if the predicate returns Nothing on the first byte of input.

Note: Because this parser does not fail, do not use it with combinators such as many, because such parsers loop until a failure occurs. Careless use will thus result in an infinite loop.

Consume input as long as the predicate returns True, and return the consumed input.

This parser does not fail. It will return an empty string if the predicate returns False on the first byte of input.

Note: Because this parser does not fail, do not use it with combinators such as many, because such parsers loop until a failure occurs. Careless use will thus result in an infinite loop.

Consume input as long as the predicate returns True, and return the consumed input.

This parser requires the predicate to succeed on at least one byte of input: it will fail if the predicate never returns True or if there is no input left.

Consume input as long as the predicate returns False (i.e. until it returns True), and return the consumed input.

This parser does not fail. It will return an empty string if the predicate returns True on the first byte of input.

Note: Because this parser does not fail, do not use it with combinators such as many, because such parsers loop until a failure occurs. Careless use will thus result in an infinite loop.

Consume all remaining input and return it as a single string.

Consume all remaining input and return it as a single string.

Match either a single newline character '\n', or a carriage return followed by a newline character "\r\n".

A predicate that matches either a carriage return '\r' or newline '\n' character.

A predicate that matches either a space ' ' or horizontal tab '\t' character.

Parse and decode an unsigned decimal number.

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

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

Parse a number with an optional leading '+' or '-' sign character.

Parse a rational number.

The syntax accepted by this parser is the same as for rational.

Note: This function is almost ten times faster than rational, but is slightly less accurate.

The Double type supports about 16 decimal places of accuracy. For 94.2% of numbers, this function and rational give identical results, but for the remaining 5.8%, this function loses precision around the 15th decimal place. For 0.001% of numbers, this function will lose precision at the 13th or 14th decimal place.

This function does not accept string representations of "NaN" or "Infinity".

A numeric type that can represent integers accurately, and floating point numbers to the precision of a Double.

Parse a number, attempting to preserve both speed and precision.

The syntax accepted by this parser is the same as for rational.

Note: This function is almost ten times faster than rational. On integral inputs, it gives perfectly accurate answers, and on floating point inputs, it is slightly less accurate than rational.

This function does not accept string representations of "NaN" or "Infinity".

Parse a rational number.

This parser accepts an optional leading sign character, followed by at least one decimal digit. The syntax similar to that accepted by the read function, with the exception that a trailing '.' or 'e' not followed by a number is not consumed.

Examples with behaviour identical to read, if you feed an empty continuation to the first result:

rational "3"     == Done 3.0 ""
rational "3.1"   == Done 3.1 ""
rational "3e4"   == Done 30000.0 ""
rational "3.1e4" == Done 31000.0, ""

Match only if all input has been consumed.

Return an indication of whether the end of input has been reached.