Is aeson working out for you? It looks like a more flexible json generator was just released [1], including support for generating converters in both directions. Yesod will definitely still be sticking with aeson, but we aim to make the usage of alternatives convenient.

Greg Weber

[1] http://martijn.van.steenbergen.nl/journal/2011/05/08/introducing-jsongrammar/

On Sun, Mar 20, 2011 at 12:54 AM, Michael Snoyman <michael@snoyman.com> wrote:
On Fri, Mar 18, 2011 at 9:55 AM, Max Cantor <mxcantor@gmail.com> wrote:
>>
>> Yeah, I think this would make sense for *some* kind of DSL. I'm not
>> sure what exactly it should look like yet, but this is definitely
>> worth a discussion.
>
> This is nice:
> http://hackage.haskell.org/packages/archive/text-json-qq/0.2.0/doc/html/Text-JSON-QQ.html

If I'm not mistaken, text-json-qq is only for generating output, not
for parsing JSON back into Haskell. I think if we go the route of a
DSL, we should make sure to support both.

Michael