[Haskell-cafe] Binary and Serialize classes

[Jeremy Shaw]

Hello,

You might consider using safecopy, which explicitly supports the case
where the serialization format or the datastructure itself changes and
the data needs to be migrated to the new format?

http://acid-state.seize.it/safecopy

- jeremy

On Thu, Apr 28, 2011 at 10:00 AM, Evan Laforge <qdunkan at gmail.com> wrote:
> It's been remarked to me that relying on the Binary and Serialize
> classes is dangerous, because there's no guarantee they won't maintain
> a consistent format.  So if my app uses the Serialize instances that
> come with cereal, it could suddenly fail to read old saves after an
> upgrade to cereal.
>
> However, neither binary nor cereal expose the underlying serialization
> algorithms for various types except through the instances, so I would
> have to copy and paste the code over if I want control over it.  If I
> don't trust 'instance Serialize String' to not change behind my back,
> maybe I could at least trust 'Data.Serialize.stringToUtf8' to not
> change since if it did the name would now be wrong.
>
> Are these fears justified?  I imagine if the Int instance for
> Serialize changed there would be an uproar and it would probably have
> to be changed back.  I sent a bug to the maintainers of data-binary a
> long time ago about the Double instance not serializing -0, and they
> ignored it, probably because it would be bad to change the instance.
> So can I use the included instances without fear of them changing
> between releases?  Of course I still run the risk of an instance from
> some other package changing, but I'm less likely to be using those.