[Haskell-cafe] Help needed for converting IOArray to ByteString

Michael Snoyman michael at snoyman.com
Tue Feb 8 10:22:44 CET 2011

On Tue, Feb 8, 2011 at 11:13 AM, C K Kashyap <ckkashyap at gmail.com> wrote:
> On Tue, Feb 8, 2011 at 2:26 PM, Michael Snoyman <michael at snoyman.com> wrote:
>> Your array contains machine-sized Ints, which in practice are likely
>> either 32-bit or 64-bit, while a ByteString is the equivalent of an
>> array or 8-bit values. So you'll need to somehow convert the Ints to
>> Word8s. Do you know if you need big or little endian?
>> A basic approach would be:
>> * Use freeze to convert your IOArray into an IArray
>> * Use putIArrayOf and put (from cereal) to generate a Putter value
>> * Use runPut to generate a ByteString from that
> Thanks Michael,
> Actually, I need an array of 8-bit words - Is that available?
> Also, would be hard to do it without cereal?
> Regards,
> Kashyap

1) Just use Data.Word.Word8 instead of the second Int in your type sig
for IOArray
2) Use getElems to get a [Word8]
3) Data.ByteString.pack converts a [Word8] into a ByteString


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