[Haskell-cafe] [SOLVED] Writing and testing a Storable instance for a record wrapping ForeignPtrs

[Hécate]

Thanks for the knowledge regarding the size of the ByteString!

Eventually the outside serialisation isn't up to me, but rather the 
consumers. I have one potential user who told me they need the signature 
and the message to be separate for the protocol they are implementing.

I guess if I defer to ByteString early on it'll be easier for the 
library to be adapted to whatever use case comes after.

Thanks a lot Viktor, I believe I'll go to bed less ignorant tonight. :)

Le 28/11/2022 à 20:34, Viktor Dukhovni a écrit :
> On Mon, Nov 28, 2022 at 08:14:15PM +0100, Hécate wrote:
>> Ah sorry, I misunderstood your question.
>>
>> I am writing a high-level interface to my libsodium bindings, and I'm
>> trying to provide implementations of helpful typeclasses.
>>
>> I actually don't need Storable to do the FFI stuff, thankfully, but the
>> main case of using this library would involve sending the result of the
>> signing operation to the network (as ByteStrings), with authorization
>> tokens like Biscuit¹ in mind.
>>
>> ¹ https://www.biscuitsec.org
> For serialisation to external standard formats, like JSON, or binary
> JSON, ... you're definitely not looking for `Storable`.  Simply
> returning the message as two octet-strings (ByteStrings), one for the
> raw data and another for the signature is all you need.  From there,
> various higher-level formats are possible.
>
> The main thing to be mindful of is that ByteStrings are limited to 2^31
> bytes on 32-bit machines, so very large messages don't fit in a
> ByteString on some (increasingly less common) architectures.
>
> Or am I missing some reason why you'd want to create a single binary
> blob <length,<$length bytes>,<signature>>?
>
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