[Haskell-cafe] Is there a type class for boring types?

[Tom Ellis]

On Tue, Feb 02, 2016 at 12:41:34PM -0500, David Feuer wrote:
> Or, alternatively, some common class that lets me express that a type is
> boring (i.e., inhabited by precisely one fully-defined value)?

FWIW it's the dual of Empty:

    https://hackage.haskell.org/package/total-1.0.4/docs/Lens-Family-Total.html