Text.ParserCombinators.ReadP (original) (raw)
The ReadP typePrimitive operations
Consumes and returns the next character. Fails if there is no input left.
(<++) :: ReadP a -> ReadP a -> ReadP a infixr 5 Source #
Local, exclusive, left-biased choice: If left parser locally produces any result at all, then right parser is not used.
gather :: ReadP a -> ReadP (String, a) Source #
Transforms a parser into one that does the same, but in addition returns the exact characters read. IMPORTANT NOTE: [gather](Text-ParserCombinators-ReadP.html#v:gather "Text.ParserCombinators.ReadP") gives a runtime error if its first argument is built using any occurrences of readS_to_P.
munch :: (Char -> Bool) -> ReadP String Source #
Parses the first zero or more characters satisfying the predicate. Always succeeds, exactly once having consumed all the characters Hence NOT the same as (many (satisfy p))
munch1 :: (Char -> Bool) -> ReadP String Source #
Parses the first one or more characters satisfying the predicate. Fails if none, else succeeds exactly once having consumed all the characters Hence NOT the same as (many1 (satisfy p))
count :: Int -> ReadP a -> ReadP [a] Source #
count n p parses n occurrences of p in sequence. A list of results is returned.
option :: a -> ReadP a -> ReadP a Source #
option x p will either parse p or return x without consuming any input.
sepBy :: ReadP a -> ReadP sep -> ReadP [a] Source #
sepBy p sep parses zero or more occurrences of p, separated by sep. Returns a list of values returned by p.
sepBy1 :: ReadP a -> ReadP sep -> ReadP [a] Source #
sepBy1 p sep parses one or more occurrences of p, separated by sep. Returns a list of values returned by p.
chainr :: ReadP a -> ReadP (a -> a -> a) -> a -> ReadP a Source #
chainr p op x parses zero or more occurrences of p, separated by op. Returns a value produced by a right associative application of all functions returned by op. If there are no occurrences of p, x is returned.
chainl :: ReadP a -> ReadP (a -> a -> a) -> a -> ReadP a Source #
chainl p op x parses zero or more occurrences of p, separated by op. Returns a value produced by a left associative application of all functions returned by op. If there are no occurrences of p, x is returned.
manyTill :: ReadP a -> ReadP end -> ReadP [a] Source #
manyTill p end parses zero or more occurrences of p, until end succeeds. Returns a list of values returned by p.
type ReadS a = String -> [(a, String)] Source #
A parser for a type a, represented as a function that takes a[String](Data-String.html#t:String "Data.String") and returns a list of possible parses as (a,`[String](Data-String.html#t:String "Data.String")`) pairs.
Note that this kind of backtracking parser is very inefficient; reading a large structure may be quite slow (cf [ReadP](Text-ParserCombinators-ReadP.html#t:ReadP "Text.ParserCombinators.ReadP")).
readP_to_S :: ReadP a -> ReadS a Source #
Converts a parser into a Haskell ReadS-style function. This is the main way in which you can "run" a [ReadP](Text-ParserCombinators-ReadP.html#t:ReadP "Text.ParserCombinators.ReadP") parser: the expanded type isreadP_to_S :: ReadP a -> String -> [(a,String)]
readS_to_P :: ReadS a -> ReadP a Source #
Converts a Haskell ReadS-style function into a parser. Warning: This introduces local backtracking in the resulting parser, and therefore a possible inefficiency.