Text.ParserCombinators.ReadPrec

This library defines parser combinators for precedence parsing.

Documentation

data ReadPrec a

Instances

Alternative ReadPrec

Monad ReadPrec

Functor ReadPrec

MonadPlus ReadPrec

Applicative 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