On 19 October 2010 03:28, Antoine Latter
The cereal[2] library also supports the Alternative operations in the Control.Applicative, and is written for decoding low-level binary streams, so it presumably also support some form of backtracking. It doesn't ship with a "manyTill' function, which is what I would want to use for your data, but it doesn't look hard to write. I have no idea how well it would perform, though.
Well thought out "serialization" formats shouldn't need a backtracking parser, as backtracking introduces a substantial performance penalty. Where binary data formats have alternatives the choice to take is typically flagged with a tag byte first. I haven't looked much at recent textual serialization formats like JSON - if they need backtracking it would be my opinion that they're not very well designed. If you want speed for deserializing with a combinator parser avoiding backtracking choice (i.e. Alternative) is the way to go.