[Haskell-cafe] Why does this work: 'instance Num (Show a) where'

Richard Eisenberg eir at cis.upenn.edu
Tue Nov 4 15:18:04 UTC 2014

That's a bug. As you surmise, the code is meaningless. It seems to be fixed in 7.8.

On Nov 4, 2014, at 3:30 AM, Tom Ellis <tom-lists-haskell-cafe-2013 at jaguarpaw.co.uk> wrote:

> This is accepted by GHC 7.6.3.  Is this a bug?  What does it mean?
>    instance Num (Show a) where
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