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Search found 4 results on 1 pages for 'attoparsec'.

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• Problem with incomplete input when using Attoparsec

  - by Dan Dyer

  I am converting some functioning Haskell code that uses Parsec to instead use Attoparsec in the hope of getting better performance. I have made the changes and everything compiles but my parser does not work correctly. I am parsing a file that consists of various record types, one per line. Each of my individual functions for parsing a record or comment works correctly but when I try to write a function to compile a sequence of records the parser always returns a partial result because it is expecting more input. These are the two main variations that I've tried. Both have the same problem. items :: Parser [Item] items = sepBy (comment <|> recordType1 <|> recordType2) endOfLine For this second one I changed the record/comment parsers to consume the end-of-line characters. items :: Parser [Item] items = manyTill (comment <|> recordType1 <|> recordType2) endOfInput Is there anything wrong with my approach? Is there some other way to achieve what I am attempting?

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• Examples of attoparsec in parsing binary file formats?

  - by me2

  Previously attoparsec was suggested to me for parsing complex binary file formats. While I can find examples of attoparsec parsing HTTP, which is essentially text based, I cannot find an example parsing actual binary, for example, a TCP packet, or image file, or mp3. Can someone post some code or pointer to some code which does this using attoparsec?

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• Generalized Bottom up Parser Combinators in Haskell

  - by Panini Sai

  I am wondered why there is no generalized parser combinators for Bottom-up parsing in Haskell like a Parsec combinators for top down parsing. ( I could find some research work went during 2004 but nothing after https://haskell-functional-parsing.googlecode.com/files/Ljunglof-2002a.pdf http://www.di.ubi.pt/~jpf/Site/Publications_files/technicalReport.pdf ) Is there any specific reason for not achieving it?

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• Haskell: Best tools to validate textual input?

  - by Ana

  In Haskell, there are a few different options to "parsing text". I know of Alex & Happy, Parsec and Attoparsec. Probably some others. I'd like to put together a library where the user can input pieces of a URL (scheme e.g. HTTP, hostname, username, port, path, query, etc.) I'd like to validate the pieces according to the ABNF specified in RFC 3986. In other words, I'd like to put together a set of functions such as: validateScheme :: String -> Bool validateUsername :: String -> Bool validatePassword :: String -> Bool validateAuthority :: String -> Bool validatePath :: String -> Bool validateQuery :: String -> Bool What is the most appropriate tool to use to write these functions? Alex's regexps is very concise, but it's a tokenizer and doesn't straightforwardly allow you to parse using specific rules, so it's not quite what I'm looking for, but perhaps it can be wrangled into doing this easily. I've written Parsec code that does some of the above, but it looks very different from the original ABNF and unnecessarily long. So, there must be an easier and/or more appropriate way. Recommendations?

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