Instances for UUID

[ploeh]

The current support for SQL Server's UNIQUEIDENTIFIER treats database values as ByteString values. Would you consider also supporting UUID from the uuid package?

I do realise that this means taking on another dependency, so this is meant as a completely open question. If you don't want to do that, then that's the end of that story 😄

It turns out that it isn't as trivial as I first thought to convert back and forth between odbc's ByteString representation, and UUID values: haskell-hvr/uuid#48

I do, however, have a working solution, and I'll be happy to contribute a pull request, if this is something that you want to move forward with.

[chrisdone]

I don't mind depending on uuid. I think that you may want to use the Binary type as a testbed.

The ByteString type will treat the content as a kind of SQL Server string which has a more ambiguous meaning about whether it's raw binary or some kind of interpreted string.