[core libraries] Data.Display - Textual representation of Haskell values (was Re: PROPOSAL: Add displayException to Exception typeclass)

[Simon Hengel]

> *  I think usage of MINIMAL pragmas could help a lot for your concerns
> about which of `display` or `displayBuilder` the user implements.

I'm not sure this will work.  We would need to specify something like

    {} | {displayBuilder}

as minimal complete definition (where {} denotes the empty set), but I'm
not aware of a way to specify the empty set with MINIMAL.

Unless somebody knows a solution, I would probably open a GHC ticket and
propose to extend the MINIMAL pragma to allow for empty sets.

Cheers,
Simon