Re: [Haskell-cafe] partial inheritance

Tue, 19 Jul 2011 01:02:22 -0700 



On 19/07/2011, at 0:09, Patrick Browne <[email protected]> wrote:

> instance Bird Emperor where
> -- No fly method
>   walk x y = y
> 
> instance Penguin Emperor where
> -- How can I override the walk method in the instance Penguin?
> -- walk x y = x

Why would you want to override the walk method for Emperor?  It already has one 
due to being a Bird.  How could you possibly distinguish an Emperor walking as 
a Bird from an Emperor walking as a Penguin?  Why would it be desirable?

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