haskellbytestring

How to convert a Integer to a ByteString in Haskell

We'd like to serialize data in a specific binary format. We use Data.ByteStrings internally.

So, the question is: How to convert the different data types we use to a ByteString. For String we have no problem, we can use encodeLazyByteString UTF8 "string". But we'd also like to convert Integers to ByteStrings (big-endian).

Does anyone know how to do that and/or has any good tips using Haskell and binary formats?

Thanks!

Solution

  • A perfect job for Data.Binary:

    Prelude> :m + Data.Binary
Prelude Data.Binary> encode (pi :: Double)
Chunk "\SOH\SOH\NUL\NUL\NUL\NUL\NUL\NUL\NUL\a\CAN-DT\251!\EM\255\255\255\255\255\255\255\205" Empty

Prelude Data.Binary> encode (42 :: Integer)
Chunk "\NUL\NUL\NUL\NUL*" Empty

    to yield lazy bytestrings, which can of course be converted to strict ones. The cereal package provides much the same interface, but yields strict bytestrings only (so no infinite streaming of encodings).