Hi Jeremy Is this really a problem practically rather than hypothetically? Data.Text and Syb-with-class - both are general, neither uses the other for their implementation, adding a dependency to one sounds like a bad idea - so making a separate 'instance' package seems most sensible. Unless you believe otherwise, Data.Text appears more 'general' than happstack-data, so Data.Text shouldn't provide happstack-data instances. Then its a choice between adding a direct dependency on Data.Text to happstack-data and defining the instance there or making a separate instance package again. A category on Hackage for 'instance' packages would seem to make sense as would a naming convention for the packages, hopefully stopping any proliferation of identical packages. Best wishes Stephen