3 Nov
2014
3 Nov
'14
3:18 p.m.
On Mon, 3 Nov 2014, Edward Kmett wrote:
To be honest I don't think omitting an instance because you don't believe the type should be used at all is a useful strategy.
Explicitly forbidding Storable (Ratio a) has the advantage that we can explain the reasons in the documentation of the blocking instance. In contrast, a missing instance just looks like someone has forgotten it. It would be simple to turn a blocked instance into a useful one in future, once one is found. It is also easier to do so if no orphan instances of Storable (Ratio a) lie around.