/Haskell 8


Copyright (c) Daan Leijen 1999-2001 (c) Paolo Martini 2007
License BSD-style (see the LICENSE file)
Maintainer [email protected]
Stability provisional
Portability portable
Safe Haskell Safe
Language Haskell2010


Parse errors

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.

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 and Eq classes.

Eq ParseError
Instance details

Defined in Text.Parsec.Error

Show ParseError
Instance details

Defined in Text.Parsec.Error

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

© The University of Glasgow and others
Licensed under a BSD-style license (see top of the page).