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GHC 9.10.3 · lts/ghc-9.10.x · 248f8f0 · 2026-10-05

Modulererebase-1.21.2Haskell2010

Text.ParserCombinators.ReadP

  • 2 types
  • 33 values
newtypenewtype ReadP a
#
Instances7Monad, Functor, MonadFail, Applicative, Alternative, MonadPlus, …
  • Monad ReadPDefined in ghc-internal-9.1003.0 · GHC.Internal.Text.ParserCombinators.ReadP
  • Functor ReadPDefined in ghc-internal-9.1003.0 · GHC.Internal.Text.ParserCombinators.ReadP
  • MonadFail ReadPDefined in ghc-internal-9.1003.0 · GHC.Internal.Text.ParserCombinators.ReadP
  • Applicative ReadPDefined in ghc-internal-9.1003.0 · GHC.Internal.Text.ParserCombinators.ReadP
  • Alternative ReadPDefined in ghc-internal-9.1003.0 · GHC.Internal.Text.ParserCombinators.ReadP
  • MonadPlus ReadPDefined in ghc-internal-9.1003.0 · GHC.Internal.Text.ParserCombinators.ReadP
  • Invariant ReadPDefined in invariant-0.6.4 · Data.Functor.Invariant
valueoptional :: ReadP a -> ReadP ()
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optional p optionally parses p and always returns ().

valuemany :: ReadP a -> ReadP [a]
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Parses zero or more occurrences of the given parser.

typetype ReadS a = String -> [(a, String)]
#

A parser for a type a, represented as a function that takes a String and returns a list of possible parses as (a,String) pairs.

Note that this kind of backtracking parser is very inefficient; reading a large structure may be quite slow (cf ReadP).

valueget :: ReadP Char
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Consumes and returns the next character. Fails if there is no input left.

valuecount :: Int -> ReadP a -> ReadP [a]
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count n p parses n occurrences of p in sequence. A list of results is returned.

valuemunch1 :: (Char -> Bool) -> ReadP String
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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))

valuesepBy1 :: ReadP a -> ReadP sep -> ReadP [a]
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sepBy1 p sep parses one or more occurrences of p, separated by sep. Returns a list of values returned by p.

valuereadP_to_S :: ReadP a -> ReadS a
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Converts a parser into a Haskell ReadS-style function. This is the main way in which you can "run" a ReadP parser: the expanded type is readP_to_S :: ReadP a -> String -> [(a,String)]

valuegather :: ReadP a -> ReadP (String, a)
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Transforms a parser into one that does the same, but in addition returns the exact characters read. IMPORTANT NOTE: gather gives a runtime error if its first argument is built using any occurrences of readS_to_P.

valuelook :: ReadP String
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Look-ahead: returns the part of the input that is left, without consuming it.

value(<++) :: ReadP a -> ReadP a -> ReadP a
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Local, exclusive, left-biased choice: If left parser locally produces any result at all, then right parser is not used.

valuebetween :: ReadP open -> ReadP close -> ReadP a -> ReadP a
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between open close p parses open, followed by p and finally close. Only the value of p is returned.

valuechainl :: ReadP a -> ReadP (a -> a -> a) -> a -> ReadP a
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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.

valuechainr :: ReadP a -> ReadP (a -> a -> a) -> a -> ReadP a
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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.

valueendBy :: ReadP a -> ReadP sep -> ReadP [a]
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endBy p sep parses zero or more occurrences of p, separated and ended by sep.

valueendBy1 :: ReadP a -> ReadP sep -> ReadP [a]
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endBy p sep parses one or more occurrences of p, separated and ended by sep.

valueeof :: ReadP ()
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Succeeds iff we are at the end of input

valuemany1 :: ReadP a -> ReadP [a]
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Parses one or more occurrences of the given parser.

valuemanyTill :: ReadP a -> ReadP end -> ReadP [a]
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manyTill p end parses zero or more occurrences of p, until end succeeds. Returns a list of values returned by p.

valuemunch :: (Char -> Bool) -> ReadP String
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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))

valueoption :: a -> ReadP a -> ReadP a
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option x p will either parse p or return x without consuming any input.

valuereadS_to_P :: ReadS a -> ReadP a
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Converts a Haskell ReadS-style function into a parser. Warning: This introduces local backtracking in the resulting parser, and therefore a possible inefficiency.

valuesatisfy :: (Char -> Bool) -> ReadP Char
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Consumes and returns the next character, if it satisfies the specified predicate.

valuesepBy :: ReadP a -> ReadP sep -> ReadP [a]
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sepBy p sep parses zero or more occurrences of p, separated by sep. Returns a list of values returned by p.