Yep, That's what I had in mind. Thanks for the link. On Sun, 2010-03-14 at 19:09 +0000, Stephen Tetley wrote:
Hi David
Ah ha - this form of binary file layout is quite common (e.g. PECOFF object files and OpenType / TrueType fonts).
Parsec and other parsing libraries are perhaps not ideal for the task, as they consume input as they parse. I have my own alternative to Parsec - Kangaroo [1] - for parsing binary files. It moves a cursor around inside the file (strictly speaking an array in memory from reading the file), so you can parse within a sub-region of the file and jump back out again.
Although its on Hackage, I wouldn't really recommend its use - its now fairly well documented but the API is not stable and I only work on it sporadically. Because I didn't want any dependencies, the package is quite a bit larger than it need be - if someone were interested in technique they might be better off using it as a start point. The most important bits are the 'intraparse' function and the monadic machinery inside the Kangaroo.ParseMonad module.
Even when a binary format has a published standard, unfortunately the standard might not be detailed enough to actually produce a parser. This is the case for True Type and PECOFF which I wrote Kangaroo for, and as I don't have much enthusiasm for deriving a parser from another open-source implementation, its rather stalling any continued development of Kangaroo.
[1] http://hackage.haskell.org/package/kangaroo
Best wishes
Stephen _______________________________________________ Haskell-Cafe mailing list Haskell-Cafe@haskell.org http://www.haskell.org/mailman/listinfo/haskell-cafe