Hello Ian, Monday, January 16, 2006, 12:52:42 AM, you wrote: IL> OK, I have one library which provides IL> inflate :: [Word8] -- The input IL> -> ([Word8], -- A prefix of the input inflated (uncompressed) IL> [Word8]) -- The remainder of the input you can use strict state monad for this task. "strictness" here designate that it evaluates higher level of state, but it don't fully evaluates the state (which itslef is impossible without using DeepSeq class technique). so, for example, when you perform something like "state = tail state" the lazy state monad may store call to tail function in the state field and not evaluate it before needed, while strict state monad will evaluate this higher-level expression and store exactly the lazy expression that represents remainder of list it's interesting that your work has a lot of common with my Binary/Streams library. i'm used the same monadic types to define char enocding/decoding routines (see DataCharEncoding.hs), i've defined universal "mutable references" interface to transparently work with variables in IO/ST monads, i've extended John's StringReader/StringBuffer types to work in any monad. hust now i'm working on extending my "ByteStream->BitStream" transformer to also support any monads although i'm not sure that Haskell implementation of inflate/deflate algorithms will be a useful (just because it will be 100-1000 times slower than existing C routines), nevertheless i glad to offer my help, especially in optimizing code and making it monad-neutral in particular, looking at your code in MissingH 0.13, i recommend you try to use DiffUArray instead of Array IL> while (some input left) read header call inflate read IL> footer return (concat all the inflate results) IL> Reading headers is a fiddly enough task that passing the input around by IL> hand is undesirable. btw, "reading headers" is an perfect task for my Binary library. the ony difference is what in your library "getBits" is an built-in operation of special InfM monad, while in my library "getBits" operation is applied to the Stream objects, but nevertheless work in any monad (to be exact, it works in the monad, to which this Stream obect belongs): getBits :: (Monad m, Stream m h) => Int -> h -> m Int "getBits bits h" returns 'bits' bits read from stream 'h' most of types supporting Stream interface, works only in IO monad (including Handle and MemoryBuffer), but at least StringReader & StringBuffer types can be specialized to IO and ST monads and, in general, to any monad, which is able to support readRef/writeRef operations if you want, you can try to implement the whole inflate process on top of my Binary/Streams library, using these `getBits` operations. something like these: -- 's' is String containing your input data runST (do h <- openBitAlignedLE =<< newStringReader s ... -- here you can use `getBits bits h` to read `s` as bits sequence return ...) ps: http://freearc.narod.ru/Binary.tar.gz -- Best regards, Bulat mailto:bulatz@HotPOP.com