Safe Haskell | None |
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- newtype Parser s t a = P (Parser s t a)
- data Result z a
- runParser :: Parser s t a -> s -> [t] -> (a, s, [t])
- next :: Parser s t t
- eof :: Parser s t ()
- satisfy :: (t -> Bool) -> Parser s t t
- onFail :: Parser s t a -> Parser s t a -> Parser s t a
- manyFinally :: Parser s t a -> Parser s t z -> Parser s t [a]
- stUpdate :: (s -> s) -> Parser s t ()
- stQuery :: (s -> a) -> Parser s t a
- stGet :: Parser s t s
- reparse :: [t] -> Parser s t ()
- module Text.ParserCombinators.Poly.Base
- module Control.Applicative

# The Parser datatype

The only differences between a State and a StateLazy parser are the
instance of Applicative, and the type (and implementation) of runParser.
We therefore need to *newtype* the original Parser type, to allow it
to have a different instance.

Monad (Parser s t) | |

Functor (Parser s t) | |

Applicative (Parser s t) | |

Alternative (Parser s t) | |

PolyParse (Parser s t) | |

Commitment (Parser s t) |

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.

runParser :: Parser s t a -> s -> [t] -> (a, s, [t])Source

Apply a parser to an input token sequence.

## Basic parsers

satisfy :: (t -> Bool) -> Parser s t tSource

Return the next token if it satisfies the given predicate.

onFail :: Parser s t a -> Parser s t a -> Parser s t aSource

`p `

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.
`onFail`

q

manyFinally :: Parser s t a -> Parser s t z -> Parser s t [a]Source

## State-handling

## Re-parsing

reparse :: [t] -> Parser s t ()Source

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 Control.Applicative