parsec-3.1.3: Monadic parser combinators

Portability | portable
Stability | provisional
Maintainer | derek.a.elkins@gmail.com
Safe Haskell | Safe-Inferred

Text.Parsec.Error

Description

Parse errors

Synopsis

- data Message
  - = SysUnExpect !String
  - | UnExpect !String
  - | Expect !String
  - | Message !String
- messageString :: Message -> String
- data ParseError
- errorPos :: ParseError -> SourcePos
- errorMessages :: ParseError -> [Message]
- errorIsUnknown :: ParseError -> Bool
- showErrorMessages :: String -> String -> String -> String -> String -> [Message] -> String
- newErrorMessage :: Message -> SourcePos -> ParseError
- newErrorUnknown :: SourcePos -> ParseError
- addErrorMessage :: Message -> ParseError -> ParseError
- setErrorPos :: SourcePos -> ParseError -> ParseError
- setErrorMessage :: Message -> ParseError -> ParseError
- mergeError :: ParseError -> ParseError -> ParseError

# Documentation

data Message Source

This abstract data type represents parse error messages. There are four kinds of messages:

      data Message = SysUnExpect String
                   | UnExpect String
                   | Expect String
                   | Message String

The fine distinction between different kinds of parse errors allows the system to generate quite good error messages for the user. It also allows error messages that are formatted in different languages. Each kind of message is generated by different combinators:

- A `SysUnExpect` message is automatically generated by the `satisfy` combinator. The argument is the unexpected input.
- A `UnExpect` message is generated by the `unexpected` combinator. The argument describes the unexpected item.
- A `Expect` message is generated by the `<?>` combinator. The argument describes the expected item.
- A `Message` message is generated by the `fail` combinator. The argument is some general parser message.

Constructors

SysUnExpect !String |
UnExpect !String |
Expect !String |
Message !String |

Instances

Enum Message |
Eq Message |
Ord Message |

messageString :: Message -> String Source

Extract the message string from an error message

data ParseError Source

The abstract data type `ParseError` represents parse errors. It provides the source position (`SourcePos`) of the error and a list of error messages (`Message`). A `ParseError` can be returned by the function `parse`. `ParseError` is an instance of the `Show` class.

Instances

Show ParseError |

errorPos :: ParseError -> SourcePos Source

Extracts the source position from the parse error

errorMessages :: ParseError -> [Message]Source

Extracts the list of error messages from the parse error

errorIsUnknown :: ParseError -> Bool Source

showErrorMessages :: String -> String -> String -> String -> String -> [Message] -> String Source

newErrorMessage :: Message -> SourcePos -> ParseError Source

newErrorUnknown :: SourcePos -> ParseError Source

addErrorMessage :: Message -> ParseError -> ParseError Source

setErrorPos :: SourcePos -> ParseError -> ParseError Source

setErrorMessage :: Message -> ParseError -> ParseError Source

mergeError :: ParseError -> ParseError -> ParseError Source