RFC for a change in EmptyDataDecls instance deriving

Herbert Valerio Riedel hvr at gnu.org
Thu Jul 16 11:14:38 UTC 2015

On 2015-07-16 at 05:28:03 +0200, David Feuer wrote:
> It's all a bit weird. I think the Proxy instance is lazy too. I would tend
> to think that empty types shouldn't have these instances, and that if they
> do that should be strict (empty case), but I can't prove that's the right
> way.

Btw, something similiar came up for deepseq, regarding NFData instances
for types only inhabited by ⊥ (and the issue of H2010 forbidding
instance auto-derivation for constructor-less types was mentioned too):


-- hvr

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