On 02/21/2010 11:57 PM, haskell-cafe-request@haskell.org wrote:

Message: 2 Date: Sun, 21 Feb 2010 12:36:21 +0000 From: Magnus Therning Subject: [Haskell-cafe] Parsing of bytestrings with non-String errors? To: haskell-cafe Message-ID: <4B8128C5.6030105@therning.org> Content-Type: text/plain; charset="utf-8"

I've looked at polyparse and attoparsec and they seem to have in common that the error always is a String. My current ideas for a project would be a lot easier if I could just return some other type, something that I can pattern match on.

Is there a parser combinator library out there that works on bytestrings and allows using a custom error type?

Or maybe there's some very basic reason why String is so commonly used?

You can try to play with ParsecT / ErrorT