deriving...

[Keean Schupke]

Okay so that does the deriving...  How are you deriving the constraints? 
(in the ghc code there is
some equaion expansion, where it finds the fixed point).

Still the main point was that it would be nice to seamlessly integrate 
this... Surely it wouldn't take much
to get the compiler to look for a template-haskell splice $(derivingX)  
when the compiler encounters a "deriving X" statement that is not built-in?

Ulf Norell wrote:

>>Keean Schupke <k.schupke at imperial.ac.uk> writes:
>>
>>    
>>
>>>Yes, I could quite easily write the generator in TemplateHaskell (have
>>>played with it before)
>>>_but_ I don't like the $(xxx) syntax... Perhaps if Simon could be
>>>persuaded to allow deriving
>>>clauses to be defined in TH?
>>>
>>>data X x = X x
>>>$(deriveMyClass (reify X))
>>>
>>>could perhaps be defined from
>>>
>>>data X x = X x deriving MyClass
>>>
>>>
>>>I saw the same suggestion earlier today on the Haskell list...
>>>      
>>>
>>Check out Ulf Norell's IOHCC submission, his DeriveData.hs module does
>>this,
>>though I can't tell if it will work for parameterized types.
>>    
>>
>
>It doesn't. A version that does can be downloaded from
>
>http://www.cs.chalmers.se/~ulfn/th/DeriveData.hs
>
>/ Ulf
>
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