Hello, I've been following the list optimization thread with great interest, as it pertains to something I'm working on at the moment. I'm working with moderate-sized files (tens to hundreds of MBs) that have some ascii header data followed by a bunch of 32-bit ints. I can read the files into a lazy ByteString (and parse the header), but I'd like some advice as to the best data type to convert the ints into. Ideally, I'd have some functions like this: decode :: ByteString -> (FileFormat, [Int32]) encode :: FileFormat -> [Int32] -> ByteString but I don't know if Int32 is actually the best choice. It seems to me that something like a lazy list of strict arrays (analogous to a lazy bytestring) would be better. Is there a library like this already? Or is this a case of premature optimization, and I should just try the list and see if it's good enough? Any suggestions would be appreciated. Also, I'd like to let the maintainers and implementors know that I really appreciate the work that's been done on optimizing Haskell. I haven't used Haskell much yet, but I've fallen in love with the language and it's great to see that performance even for heavy I/O tasks can be comparable to or exceed C. Thank you, John Lato