[Haskell-cafe] Parsing of bytestrings with non-String errors?

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? /M -- Magnus Therning (OpenPGP: 0xAB4DFBA4) magnus＠therning．org Jabber: magnus＠therning．org http://therning.org/magnus identi.ca|twitter: magthe