Thanks for the reference. Sounds like a neat idea so I'll definitely check it out! Right now, there are lots of complications in designing this library, at least if I want a nice API. I have lots and lots of type definitions to encode the various constructs of the protocol I'm working with. New versions could make arbitrary changes: add or remove a field to a record, change the type of a record field, add or remove one of several possible cases (which I encode with sum types), and so on. It's not at all clear to me yet how I should factor my type definitions, and/or use other features such as polymorphic types, type classes, etc. But I guess this is a different thread. On Wed, May 12, 2010 at 4:35 PM, Stephen Blackheath [to Haskell-Beginners] < mutilating.cauliflowers.stephen@blacksapphire.com> wrote:
Ashish,
I've been using XML picklers for serialization, which you might want to consider if you can handle a little extra CPU/data cost. I'm the author of hexpat-pickle, so this is a plug for my package. I lifted the idea wholesale from the HXT package.
Handling changes in protocol version is really easy. I've been doing a lot of
xpSomething = new `xpTryCatch` old where new = ... old = ...
If the new encoding fails to parse, it tries the old one, and on transmission it uses the new one. I find it very quick and convenient to bang out a new pickler now that I'm familiar with it. You write your pickler and your unpickler with the same code - it works well.
I am also working on hexpat-iteratee which is a lot more socket friendly since it doesn't use Haskell's lazy I/O. The learning curve increases a little bit with doing it that way, though.
Steve
On 13/05/10 05:15, Ashish Agarwal wrote:
Thanks for all the advice. It seems I should avoid making my types instances of Binary. In fact, this relates to another design issue I've been grappling with, supporting multiple versions of the protocol. Probably I'll need something like, putProtVersion1, putProtVersion2, etc. Or something along this line.
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