Copyright | Daan Leijen 1999-2001, Bryan O'Sullivan 2009-2010, Mario Blažević <blamario@yahoo.com> 2014 |
---|---|
License | BSD3 |
Maintainer | Mario Blažević |
Stability | experimental |
Portability | portable |
Safe Haskell | Safe-Inferred |
Language | Haskell2010 |
Useful parser combinators, similar to those provided by Parsec.
- try :: Parser t a -> Parser t a
- (<?>) :: Parser t a -> String -> Parser t a
- choice :: Alternative f => [f a] -> f a
- count :: Monad m => Int -> m a -> m [a]
- option :: Alternative f => a -> f a -> f a
- many' :: MonadPlus m => m a -> m [a]
- many1 :: Alternative f => f a -> f [a]
- many1' :: MonadPlus m => m a -> m [a]
- manyTill :: Alternative f => f a -> f b -> f [a]
- manyTill' :: MonadPlus m => m a -> m b -> m [a]
- sepBy :: Alternative f => f a -> f s -> f [a]
- sepBy' :: MonadPlus m => m a -> m s -> m [a]
- sepBy1 :: Alternative f => f a -> f s -> f [a]
- sepBy1' :: MonadPlus m => m a -> m s -> m [a]
- skipMany :: Alternative f => f a -> f ()
- skipMany1 :: Alternative f => f a -> f ()
- eitherP :: Alternative f => f a -> f b -> f (Either a b)
- endOfInput :: MonoidNull t => Parser t ()
- atEnd :: MonoidNull t => Parser t Bool
Combinators
try :: Parser t a -> Parser t a Source
Attempt a parse, and if it fails, rewind the input so that no input appears to have been consumed.
This combinator is provided for compatibility with Parsec. Picoparsec parsers always backtrack on failure.
Name the parser, in case failure occurs.
choice :: Alternative f => [f a] -> f a Source
choice ps
tries to apply the actions in the list ps
in order,
until one of them succeeds. Returns the value of the succeeding
action.
count :: Monad m => Int -> m a -> m [a] Source
Apply the given action repeatedly, returning every result.
option :: Alternative f => a -> f a -> f a Source
option x p
tries to apply action p
. If p
fails without
consuming input, it returns the value x
, otherwise the value
returned by p
.
priority = option 0 (digitToInt <$> digit)
many' :: MonadPlus m => m a -> m [a] Source
many' p
applies the action p
zero or more times. Returns a
list of the returned values of p
. The value returned by p
is
forced to WHNF.
word = many' letter
many1 :: Alternative f => f a -> f [a] Source
many1 p
applies the action p
one or more times. Returns a
list of the returned values of p
.
word = many1 letter
many1' :: MonadPlus m => m a -> m [a] Source
many1' p
applies the action p
one or more times. Returns a
list of the returned values of p
. The value returned by p
is
forced to WHNF.
word = many1' letter
manyTill :: Alternative f => f a -> f b -> f [a] Source
manyTill p end
applies action p
zero or more times until
action end
succeeds, and returns the list of values returned by
p
. This can be used to scan comments:
simpleComment = string "<!--" *> manyTill anyChar (string "-->")
(Note the overlapping parsers anyChar
and string "-->"
.
While this will work, it is not very efficient, as it will cause a
lot of backtracking.)
manyTill' :: MonadPlus m => m a -> m b -> m [a] Source
manyTill' p end
applies action p
zero or more times until
action end
succeeds, and returns the list of values returned by
p
. This can be used to scan comments:
simpleComment = string "<!--" *> manyTill' anyChar (string "-->")
(Note the overlapping parsers anyChar
and string "-->"
.
While this will work, it is not very efficient, as it will cause a
lot of backtracking.)
The value returned by p
is forced to WHNF.
sepBy :: Alternative f => f a -> f s -> f [a] Source
sepBy p sep
applies zero or more occurrences of p
, separated
by sep
. Returns a list of the values returned by p
.
commaSep p = p `sepBy` (symbol ",")
sepBy' :: MonadPlus m => m a -> m s -> m [a] Source
sepBy' p sep
applies zero or more occurrences of p
, separated
by sep
. Returns a list of the values returned by p
. The value
returned by p
is forced to WHNF.
commaSep p = p `sepBy'` (symbol ",")
sepBy1 :: Alternative f => f a -> f s -> f [a] Source
sepBy1 p sep
applies one or more occurrences of p
, separated
by sep
. Returns a list of the values returned by p
.
commaSep p = p `sepBy1` (symbol ",")
sepBy1' :: MonadPlus m => m a -> m s -> m [a] Source
sepBy1' p sep
applies one or more occurrences of p
, separated
by sep
. Returns a list of the values returned by p
. The value
returned by p
is forced to WHNF.
commaSep p = p `sepBy1'` (symbol ",")
skipMany :: Alternative f => f a -> f () Source
Skip zero or more instances of an action.
skipMany1 :: Alternative f => f a -> f () Source
Skip one or more instances of an action.
eitherP :: Alternative f => f a -> f b -> f (Either a b) Source
Combine two alternatives.
State observation and manipulation functions
endOfInput :: MonoidNull t => Parser t () Source
Match only if all input has been consumed.
atEnd :: MonoidNull t => Parser t Bool Source
Return an indication of whether the end of input has been reached.