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Text.ParserCombinators.ReadPrec |

Portability | non-portable (uses Text.ParserCombinators.ReadP)
Stability | provisional
Maintainer | libraries@haskell.org

Contents

Precedences
Precedence operations
Other operations
Converters

Description
This library defines parser combinators for precedence parsing.
Synopsis

data ReadPrec a
type Prec = Int
minPrec :: Prec
lift :: ReadP a -> ReadPrec a
prec :: Prec -> ReadPrec a -> ReadPrec a
step :: ReadPrec a -> ReadPrec a
reset :: ReadPrec a -> ReadPrec a
get :: ReadPrec Char
look :: ReadPrec String
(+++) :: ReadPrec a -> ReadPrec a -> ReadPrec a
(<++) :: ReadPrec a -> ReadPrec a -> ReadPrec a
pfail :: ReadPrec a
choice :: [ReadPrec a] -> ReadPrec a
readPrec_to_P :: ReadPrec a -> Int -> ReadP a
readP_to_Prec :: (Int -> ReadP a) -> ReadPrec a
readPrec_to_S :: ReadPrec a -> Int -> ReadS a
readS_to_Prec :: (Int -> ReadS a) -> ReadPrec a

Documentation
data ReadPrec a

Instances

Functor ReadPrec
Monad ReadPrec
MonadPlus ReadPrec

Precedences
type Prec = Int
minPrec :: Prec
Precedence operations
lift :: ReadP a -> ReadPrec a
Lift a precedence-insensitive `ReadP` to a `ReadPrec`.
prec :: Prec -> ReadPrec a -> ReadPrec a
`(prec n p)` checks whether the precedence context is less than or equal to `n`, and

- if not, fails
- if so, parses `p` in context `n`.

step :: ReadPrec a -> ReadPrec a
Increases the precedence context by one.
reset :: ReadPrec a -> ReadPrec a
Resets the precedence context to zero.
Other operations
All are based directly on their similarly-named `ReadP` counterparts.
get :: ReadPrec Char
Consumes and returns the next character. Fails if there is no input left.
look :: ReadPrec String
Look-ahead: returns the part of the input that is left, without consuming it.
(+++) :: ReadPrec a -> ReadPrec a -> ReadPrec a
Symmetric choice.
(<++) :: ReadPrec a -> ReadPrec a -> ReadPrec a
Local, exclusive, left-biased choice: If left parser locally produces any result at all, then right parser is not used.
pfail :: ReadPrec a
Always fails.
choice :: [ReadPrec a] -> ReadPrec a
Combines all parsers in the specified list.
Converters
readPrec_to_P :: ReadPrec a -> Int -> ReadP a
readP_to_Prec :: (Int -> ReadP a) -> ReadPrec a
readPrec_to_S :: ReadPrec a -> Int -> ReadS a
readS_to_Prec :: (Int -> ReadS a) -> ReadPrec a
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