base-4.3.1.0: Basic libraries

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

Text.ParserCombinators.ReadPrec

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 Source

Instances

Functor ReadPrec

MonadPlus ReadPrec

Precedences

type Prec = Int Source

minPrec :: Prec Source

Precedence operations

lift :: ReadP a -> ReadPrec aSource

Lift a precedence-insensitive ReadP to a ReadPrec .

prec :: Prec -> ReadPrec a -> ReadPrec aSource

(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 aSource

Increases the precedence context by one.

reset :: ReadPrec a -> ReadPrec aSource

Resets the precedence context to zero.

Other operations

All are based directly on their similarly-named ReadP counterparts.

get :: ReadPrec Char Source

Consumes and returns the next character. Fails if there is no input left.

look :: ReadPrec String Source

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

(+++) :: ReadPrec a -> ReadPrec a -> ReadPrec aSource

Symmetric choice.

(<++) :: ReadPrec a -> ReadPrec a -> ReadPrec aSource

Local, exclusive, left-biased choice: If left parser locally produces any result at all, then right parser is not used.

pfail :: ReadPrec aSource

Always fails.

choice :: [ReadPrec a] -> ReadPrec aSource

Combines all parsers in the specified list.

Converters

readPrec_to_P :: ReadPrec a -> Int -> ReadP aSource

readP_to_Prec :: (Int -> ReadP a) -> ReadPrec aSource

readPrec_to_S :: ReadPrec a -> Int -> ReadS aSource

readS_to_Prec :: (Int -> ReadS a) -> ReadPrec aSource