[Haskell-cafe] Can subclass override its super-class' default implementation of a function?

[siki]

The actual problem is quite similar to the one that I provided or to the one
in the description of the proposed extension that you linked. 

Someone on another forum suggested record functions but I'm not sure I
understood correctly how that would work around this problem. Any suggestion
is greatly appreciated!

Thanks,

-Gabor



Martijn van Steenbergen-2 wrote:
> 
> siki wrote:
>> I'm not sure if this is possible at all. I'd like to do something like
>> this:
>> 
>> class A a where
>>     foo :: a -> Double
>>     
>>     foo a = 5.0
>> 
>> 
>> class (A a) => B a where
>>     foo a = 7.0
> 
> This is currently not possible in Haskell. It's been proposed, though:
> 
> http://haskell.org/haskellwiki/Class_system_extension_proposal
> 
> If you have an actual example we might be able to come up with a 
> different way of modelling it so that it does what you want, though.
> 
> Martijn.
> 
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> Haskell-Cafe at haskell.org
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> 
> 

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