[Haskell] Empty instance declaration

Isaac Dupree isaacdupree at charter.net
Fri Dec 28 12:35:51 EST 2007

Neil Mitchell wrote:
> If the default
> methods form a cycle, and the user has not broken that cycle by
> inserting a real implementation, that's almost certainly a bug - I'd
> go as far as to say its an error rather than a warning.

I'd agree except that

"instance Num () where"

with no specified definitions

is already allowed in Haskell and can only generate warnings in GHC already.


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