[web-devel] (Yesod) PersistEntity Key types

I ran into another snag getting the tests running for MongoDB backend. The PersistEntity class, and, it appears, the TH is hardcoded to set the key type as Int64. This is a problem since the key type in MongoDB is a 12 byte blob. The other problem is that it looks like PersistBackends are pretty much hardcoded to that type as well. I guess the correct approach would be to allow the designation in mkPersist and then ensure that the PersistBackends can parametrically deal with differing Key types. Or, in the case of MongoDB, hardcode it to a 12 byte blob, because other key types (ObjectId's) rarely make sense. Thoughts?