Distribution.Compat.CharParsing

Parsers for character streams

Originally in parsers package.

Combinators

oneOf :: CharParsing m => [Char] -> m Char

oneOf cs succeeds if the current character is in the supplied list of characters cs. Returns the parsed character. See also satisfy.

  vowel  = oneOf "aeiou"

noneOf :: CharParsing m => [Char] -> m Char

As the dual of oneOf, noneOf cs succeeds if the current character is not in the supplied list of characters cs. Returns the parsed character.

 consonant = noneOf "aeiou"

spaces :: CharParsing m => m ()

Skips zero or more white space characters. See also skipMany.

space :: CharParsing m => m Char

Parses a white space character (any character which satisfies isSpace) Returns the parsed character.

newline :: CharParsing m => m Char

Parses a newline character ('\n'). Returns a newline character.

tab :: CharParsing m => m Char

Parses a tab character ('\t'). Returns a tab character.

upper :: CharParsing m => m Char

Parses an upper case letter. Returns the parsed character.

lower :: CharParsing m => m Char

Parses a lower case character. Returns the parsed character.

alphaNum :: CharParsing m => m Char

Parses a letter or digit. Returns the parsed character.

letter :: CharParsing m => m Char

Parses a letter (an upper case or lower case character). Returns the parsed character.

digit :: CharParsing m => m Char

Parses a digit. Returns the parsed character.

hexDigit :: CharParsing m => m Char

Parses a hexadecimal digit (a digit or a letter between 'a' and 'f' or 'A' and 'F'). Returns the parsed character.

octDigit :: CharParsing m => m Char

Parses an octal digit (a character between '0' and '7'). Returns the parsed character.

satisfyRange :: CharParsing m => Char -> Char -> m Char

Class

class Parsing m => CharParsing m where

Additional functionality needed to parse character streams.

Minimal complete definition

satisfy

Methods

satisfy :: (Char -> Bool) -> m Char

Parse a single character of the input, with UTF-8 decoding

char :: Char -> m Char

char c parses a single character c. Returns the parsed character (i.e. c).

e.g.

semiColon = char ';'

notChar :: Char -> m Char

notChar c parses any single character other than c. Returns the parsed character.

anyChar :: m Char

This parser succeeds for any character. Returns the parsed character.

string :: String -> m String

string s parses a sequence of characters given by s. Returns the parsed string (i.e. s).

 divOrMod    =   string "div"
             <|> string "mod"

text :: Text -> m Text

text t parses a sequence of characters determined by the text t Returns the parsed text fragment (i.e. t).

Using OverloadedStrings:

 divOrMod    =   text "div"
             <|> text "mod"

Instances

CharParsing ParsecParser

Defined in Distribution.Parsec

Methods

satisfy :: (Char -> Bool) -> ParsecParser Char

char :: Char -> ParsecParser Char

notChar :: Char -> ParsecParser Char

anyChar :: ParsecParser Char

string :: String -> ParsecParser String

text :: Text -> ParsecParser Text

(CharParsing m, MonadPlus m) => CharParsing (IdentityT m)

Defined in Distribution.Compat.CharParsing

Methods

satisfy :: (Char -> Bool) -> IdentityT m Char

char :: Char -> IdentityT m Char

notChar :: Char -> IdentityT m Char

anyChar :: IdentityT m Char

string :: String -> IdentityT m String

text :: Text -> IdentityT m Text

(CharParsing m, MonadPlus m) => CharParsing (ReaderT e m)

Defined in Distribution.Compat.CharParsing

Methods

satisfy :: (Char -> Bool) -> ReaderT e m Char

char :: Char -> ReaderT e m Char

notChar :: Char -> ReaderT e m Char

anyChar :: ReaderT e m Char

string :: String -> ReaderT e m String

text :: Text -> ReaderT e m Text

(CharParsing m, MonadPlus m) => CharParsing (StateT s m)

Defined in Distribution.Compat.CharParsing

Methods

satisfy :: (Char -> Bool) -> StateT s m Char

char :: Char -> StateT s m Char

notChar :: Char -> StateT s m Char

anyChar :: StateT s m Char

string :: String -> StateT s m String

text :: Text -> StateT s m Text

(CharParsing m, MonadPlus m) => CharParsing (StateT s m)

Defined in Distribution.Compat.CharParsing

Methods

satisfy :: (Char -> Bool) -> StateT s m Char

char :: Char -> StateT s m Char

notChar :: Char -> StateT s m Char

anyChar :: StateT s m Char

string :: String -> StateT s m String

text :: Text -> StateT s m Text

(CharParsing m, MonadPlus m, Monoid w) => CharParsing (WriterT w m)

Defined in Distribution.Compat.CharParsing

Methods

satisfy :: (Char -> Bool) -> WriterT w m Char

char :: Char -> WriterT w m Char

notChar :: Char -> WriterT w m Char

anyChar :: WriterT w m Char

string :: String -> WriterT w m String

text :: Text -> WriterT w m Text

(CharParsing m, MonadPlus m, Monoid w) => CharParsing (WriterT w m)

Defined in Distribution.Compat.CharParsing

Methods

satisfy :: (Char -> Bool) -> WriterT w m Char

char :: Char -> WriterT w m Char

notChar :: Char -> WriterT w m Char

anyChar :: WriterT w m Char

string :: String -> WriterT w m String

text :: Text -> WriterT w m Text

Stream s m Char => CharParsing (ParsecT s u m)

Defined in Distribution.Compat.CharParsing

Methods

satisfy :: (Char -> Bool) -> ParsecT s u m Char

char :: Char -> ParsecT s u m Char

notChar :: Char -> ParsecT s u m Char

anyChar :: ParsecT s u m Char

string :: String -> ParsecT s u m String

text :: Text -> ParsecT s u m Text

(CharParsing m, MonadPlus m, Monoid w) => CharParsing (RWST r w s m)

Defined in Distribution.Compat.CharParsing

Methods

satisfy :: (Char -> Bool) -> RWST r w s m Char

char :: Char -> RWST r w s m Char

notChar :: Char -> RWST r w s m Char

anyChar :: RWST r w s m Char

string :: String -> RWST r w s m String

text :: Text -> RWST r w s m Text

(CharParsing m, MonadPlus m, Monoid w) => CharParsing (RWST r w s m)

Defined in Distribution.Compat.CharParsing

Methods

satisfy :: (Char -> Bool) -> RWST r w s m Char

char :: Char -> RWST r w s m Char

notChar :: Char -> RWST r w s m Char

anyChar :: RWST r w s m Char

string :: String -> RWST r w s m String

text :: Text -> RWST r w s m Text

Cabal additions

integral :: (CharParsing m, Integral a) => m a

signedIntegral :: (CharParsing m, Integral a) => m a

Accepts negative (starting with -) and positive (without sign) integral numbers.

Since: 3.4.0.0

munch1 :: CharParsing m => (Char -> Bool) -> m String

Greedily munch characters while predicate holds. Require at least one character.

munch :: CharParsing m => (Char -> Bool) -> m String

Greedely munch characters while predicate holds. Always succeeds.

skipSpaces1 :: CharParsing m => m ()

Parsing Combinators

choice :: Alternative m => [m a] -> m a

choice ps tries to apply the parsers in the list ps in order, until one of them succeeds. Returns the value of the succeeding parser.

option :: Alternative m => a -> m a -> m a

option x p tries to apply parser p. If p fails without consuming input, it returns the value x, otherwise the value returned by p.

 priority = option 0 (digitToInt <$> digit)

optional :: Alternative f => f a -> f (Maybe a)

One or none.

skipOptional :: Alternative m => m a -> m ()

skipOptional p tries to apply parser p. It will parse p or nothing. It only fails if p fails after consuming input. It discards the result of p. (Plays the role of parsec's optional, which conflicts with Applicative's optional)

between :: Applicative m => m bra -> m ket -> m a -> m a

between open close p parses open, followed by p and close. Returns the value returned by p.

 braces  = between (symbol "{") (symbol "}")

some :: Alternative f => f a -> f [a]

One or more.

many :: Alternative f => f a -> f [a]

Zero or more.

sepBy :: Alternative m => m a -> m sep -> m [a]

sepBy p sep parses zero or more occurrences of p, separated by sep. Returns a list of values returned by p.

 commaSep p  = p `sepBy` (symbol ",")

sepByNonEmpty :: Alternative m => m a -> m sep -> m (NonEmpty a)

sepByNonEmpty p sep parses one or more occurrences of p, separated by sep. Returns a non-empty list of values returned by p.

sepEndByNonEmpty :: Alternative m => m a -> m sep -> m (NonEmpty a)

sepEndByNonEmpty p sep parses one or more occurrences of p, separated and optionally ended by sep. Returns a non-empty list of values returned by p.

sepEndBy :: Alternative m => m a -> m sep -> m [a]

sepEndBy p sep parses zero or more occurrences of p, separated and optionally ended by sep, ie. haskell style statements. Returns a list of values returned by p.

 haskellStatements  = haskellStatement `sepEndBy` semi

endByNonEmpty :: Alternative m => m a -> m sep -> m (NonEmpty a)

endByNonEmpty p sep parses one or more occurrences of p, separated and ended by sep. Returns a non-empty list of values returned by p.

endBy :: Alternative m => m a -> m sep -> m [a]

endBy p sep parses zero or more occurrences of p, separated and ended by sep. Returns a list of values returned by p.

  cStatements  = cStatement `endBy` semi

count :: Applicative m => Int -> m a -> m [a]

count n p parses n occurrences of p. If n is smaller or equal to zero, the parser equals to return []. Returns a list of n values returned by p.

chainl :: Alternative m => m a -> m (a -> a -> a) -> a -> m a

chainl p op x parses zero or more occurrences of p, separated by op. Returns a value obtained by a left associative application of all functions returned by op to the values returned by p. If there are zero occurrences of p, the value x is returned.

chainr :: Alternative m => m a -> m (a -> a -> a) -> a -> m a

chainr p op x parses zero or more occurrences of p, separated by op Returns a value obtained by a right associative application of all functions returned by op to the values returned by p. If there are no occurrences of p, the value x is returned.

chainl1 :: Alternative m => m a -> m (a -> a -> a) -> m a

chainl1 p op x parses one or more occurrences of p, separated by op Returns a value obtained by a left associative application of all functions returned by op to the values returned by p. . This parser can for example be used to eliminate left recursion which typically occurs in expression grammars.

 expr   = term   `chainl1` addop
 term   = factor `chainl1` mulop
 factor = parens expr <|> integer

 mulop  = (*) <$ symbol "*"
      <|> div <$ symbol "/"

 addop  = (+) <$ symbol "+"
      <|> (-) <$ symbol "-"

chainr1 :: Alternative m => m a -> m (a -> a -> a) -> m a

chainr1 p op x parses one or more occurrences of p, separated by op Returns a value obtained by a right associative application of all functions returned by op to the values returned by p.

manyTill :: Alternative m => m a -> m end -> m [a]

manyTill p end applies parser p zero or more times until parser end succeeds. Returns the list of values returned by p. This parser can be used to scan comments:

 simpleComment   = do{ string "<!--"
                     ; manyTill anyChar (try (string "-->"))
                     }

Note the overlapping parsers anyChar and string "-->", and therefore the use of the try combinator.

Parsing Class

class Alternative m => Parsing m where

Additional functionality needed to describe parsers independent of input type.

Minimal complete definition

try, (<?>), unexpected, eof, notFollowedBy

Methods

try :: m a -> m a

Take a parser that may consume input, and on failure, go back to where we started and fail as if we didn't consume input.

(<?>) :: m a -> String -> m a infixr 0

Give a parser a name

skipMany :: m a -> m ()

A version of many that discards its input. Specialized because it can often be implemented more cheaply.

skipSome :: m a -> m ()

skipSome p applies the parser p one or more times, skipping its result. (aka skipMany1 in parsec)

unexpected :: String -> m a

Used to emit an error on an unexpected token

eof :: m ()

This parser only succeeds at the end of the input. This is not a primitive parser but it is defined using notFollowedBy.

 eof  = notFollowedBy anyChar <?> "end of input"

notFollowedBy :: Show a => m a -> m ()

notFollowedBy p only succeeds when parser p fails. This parser does not consume any input. This parser can be used to implement the 'longest match' rule. For example, when recognizing keywords (for example let), we want to make sure that a keyword is not followed by a legal identifier character, in which case the keyword is actually an identifier (for example lets). We can program this behaviour as follows:

 keywordLet  = try $ string "let" <* notFollowedBy alphaNum

Instances

Parsing ParsecParser

Defined in Distribution.Parsec

Methods

try :: ParsecParser a -> ParsecParser a

(<?>) :: ParsecParser a -> String -> ParsecParser a

skipMany :: ParsecParser a -> ParsecParser ()

skipSome :: ParsecParser a -> ParsecParser ()

unexpected :: String -> ParsecParser a

eof :: ParsecParser ()

notFollowedBy :: Show a => ParsecParser a -> ParsecParser ()

(Parsing m, Monad m) => Parsing (IdentityT m)

Defined in Distribution.Compat.Parsing

Methods

try :: IdentityT m a -> IdentityT m a

(<?>) :: IdentityT m a -> String -> IdentityT m a

skipMany :: IdentityT m a -> IdentityT m ()

skipSome :: IdentityT m a -> IdentityT m ()

unexpected :: String -> IdentityT m a

eof :: IdentityT m ()

notFollowedBy :: Show a => IdentityT m a -> IdentityT m ()

(Parsing m, MonadPlus m) => Parsing (ReaderT e m)

Defined in Distribution.Compat.Parsing

Methods

try :: ReaderT e m a -> ReaderT e m a

(<?>) :: ReaderT e m a -> String -> ReaderT e m a

skipMany :: ReaderT e m a -> ReaderT e m ()

skipSome :: ReaderT e m a -> ReaderT e m ()

unexpected :: String -> ReaderT e m a

eof :: ReaderT e m ()

notFollowedBy :: Show a => ReaderT e m a -> ReaderT e m ()

(Parsing m, MonadPlus m) => Parsing (StateT s m)

Defined in Distribution.Compat.Parsing

Methods

try :: StateT s m a -> StateT s m a

(<?>) :: StateT s m a -> String -> StateT s m a

skipMany :: StateT s m a -> StateT s m ()

skipSome :: StateT s m a -> StateT s m ()

unexpected :: String -> StateT s m a

eof :: StateT s m ()

notFollowedBy :: Show a => StateT s m a -> StateT s m ()

(Parsing m, MonadPlus m) => Parsing (StateT s m)

Defined in Distribution.Compat.Parsing

Methods

try :: StateT s m a -> StateT s m a

(<?>) :: StateT s m a -> String -> StateT s m a

skipMany :: StateT s m a -> StateT s m ()

skipSome :: StateT s m a -> StateT s m ()

unexpected :: String -> StateT s m a

eof :: StateT s m ()

notFollowedBy :: Show a => StateT s m a -> StateT s m ()

(Parsing m, MonadPlus m, Monoid w) => Parsing (WriterT w m)

Defined in Distribution.Compat.Parsing

Methods

try :: WriterT w m a -> WriterT w m a

(<?>) :: WriterT w m a -> String -> WriterT w m a

skipMany :: WriterT w m a -> WriterT w m ()

skipSome :: WriterT w m a -> WriterT w m ()

unexpected :: String -> WriterT w m a

eof :: WriterT w m ()

notFollowedBy :: Show a => WriterT w m a -> WriterT w m ()

(Parsing m, MonadPlus m, Monoid w) => Parsing (WriterT w m)

Defined in Distribution.Compat.Parsing

Methods

try :: WriterT w m a -> WriterT w m a

(<?>) :: WriterT w m a -> String -> WriterT w m a

skipMany :: WriterT w m a -> WriterT w m ()

skipSome :: WriterT w m a -> WriterT w m ()

unexpected :: String -> WriterT w m a

eof :: WriterT w m ()

notFollowedBy :: Show a => WriterT w m a -> WriterT w m ()

(Stream s m t, Show t) => Parsing (ParsecT s u m)

Defined in Distribution.Compat.Parsing

Methods

try :: ParsecT s u m a -> ParsecT s u m a

(<?>) :: ParsecT s u m a -> String -> ParsecT s u m a

skipMany :: ParsecT s u m a -> ParsecT s u m ()

skipSome :: ParsecT s u m a -> ParsecT s u m ()

unexpected :: String -> ParsecT s u m a

eof :: ParsecT s u m ()

notFollowedBy :: Show a => ParsecT s u m a -> ParsecT s u m ()

(Parsing m, MonadPlus m, Monoid w) => Parsing (RWST r w s m)

Defined in Distribution.Compat.Parsing

Methods

try :: RWST r w s m a -> RWST r w s m a

(<?>) :: RWST r w s m a -> String -> RWST r w s m a

skipMany :: RWST r w s m a -> RWST r w s m ()

skipSome :: RWST r w s m a -> RWST r w s m ()

unexpected :: String -> RWST r w s m a

eof :: RWST r w s m ()

notFollowedBy :: Show a => RWST r w s m a -> RWST r w s m ()

(Parsing m, MonadPlus m, Monoid w) => Parsing (RWST r w s m)

Defined in Distribution.Compat.Parsing

Methods

try :: RWST r w s m a -> RWST r w s m a

(<?>) :: RWST r w s m a -> String -> RWST r w s m a

skipMany :: RWST r w s m a -> RWST r w s m ()

skipSome :: RWST r w s m a -> RWST r w s m ()

unexpected :: String -> RWST r w s m a

eof :: RWST r w s m ()

notFollowedBy :: Show a => RWST r w s m a -> RWST r w s m ()