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Language	Haskell98

Text.ParserCombinators.Poly.Plain

Contents

The Parser datatype
- Basic parsers
- Re-parsing
Re-export all more general combinators

Synopsis

The Parser datatype

newtype Parser t a #

This Parser datatype is a fairly generic parsing monad with error reporting. It can be used for arbitrary token types, not just String input. (If you require a running state, use module Poly.State instead)

Constructors

P ([t] -> Result [t] a)

Instances

Monad (Parser t) #
Methods (>>=) :: Parser t a -> (a -> Parser t b) -> Parser t b # (>>) :: Parser t a -> Parser t b -> Parser t b # return :: a -> Parser t a # fail :: String -> Parser t a #
Functor (Parser t) #
Methods fmap :: (a -> b) -> Parser t a -> Parser t b # (<$) :: a -> Parser t b -> Parser t a #
Applicative (Parser t) #
Methods pure :: a -> Parser t a # (<>) :: Parser t (a -> b) -> Parser t a -> Parser t b # (>) :: Parser t a -> Parser t b -> Parser t b # (<*) :: Parser t a -> Parser t b -> Parser t a #
Alternative (Parser t) #
Methods empty :: Parser t a # (<\|>) :: Parser t a -> Parser t a -> Parser t a # some :: Parser t a -> Parser t [a] # many :: Parser t a -> Parser t [a] #
PolyParse (Parser t) #

Commitment (Parser t) #
Methods commit :: Parser t a -> Parser t a # adjustErr :: Parser t a -> (String -> String) -> Parser t a # oneOf' :: [(String, Parser t a)] -> Parser t a #

data Result z a #

A return type like Either, that distinguishes not only between right and wrong answers, but also has commitment, so that a failure cannot be undone. This should only be used for writing very primitive parsers - really it is an internal detail of the library. The z type is the remaining unconsumed input.

Constructors

Success z a
Failure z String
Committed (Result z a)

Instances

Functor (Result z) #
Methods fmap :: (a -> b) -> Result z a -> Result z b # (<$) :: a -> Result z b -> Result z a #

runParser :: Parser t a -> [t] -> (Either String a, [t]) #

Apply a parser to an input token sequence.

Basic parsers

next :: Parser t t #

Simply return the next token in the input tokenstream.

eof :: Parser t () #

Succeed if the end of file/input has been reached, fail otherwise.

satisfy :: (t -> Bool) -> Parser t t #

Return the next token if it satisfies the given predicate.

satisfyMsg :: Show t => (t -> Bool) -> String -> Parser t t #

Return the next token if it satisfies the given predicate. The String argument describes the function, for better error messages.

onFail :: Parser t a -> Parser t a -> Parser t a infixl 6 #

p onFail q means parse p, unless p fails, in which case parse q instead. Can be chained together to give multiple attempts to parse something. (Note that q could itself be a failing parser, e.g. to change the error message from that defined in p to something different.) However, a severe failure in p cannot be ignored.

Re-parsing

reparse :: [t] -> Parser t () #

Push some tokens back onto the front of the input stream and reparse. This is useful e.g. for recursively expanding macros. When the user-parser recognises a macro use, it can lookup the macro expansion from the parse state, lex it, and then stuff the lexed expansion back down into the parser.

Re-export all more general combinators

module Text.ParserCombinators.Poly.Base

module Control.Applicative