[Haskell] Re: [Haskell-cafe] Strafunski

Christopher Brown cmb21 at kent.ac.uk
Mon Apr 3 20:14:32 EDT 2006


Thanks very much - this solved my problem!



On 3 Apr 2006, at 17:03, Joost Visser wrote:

> Hi Chris,
> Changes in the libraries of GHC have broken Strafunski  
> compatibility in the past. I have not upgraded to GHC 6.5 myself so  
> I'm not sure if this is the case again. Which versions of DrIFT and  
> Strafunski are you using?
> Based on what you write, it seems new instances for Typeable have  
> been added to the libs (possibly using deriving), which means some  
> of your own instances are now redundant. You'll have to remove them  
> (which will then break compatibility of your code with 6.4.1, sigh).
> Alternatively, you may consider to switch from the "drift-default"  
> mode of Strafunski to the "deriving" mode. This means that you will  
> be relying on the Typeable+Data classes rather than on the Typeable 
> +Term classes. You make the switch simply by changing the search  
> path, all your strategic functions should work like before. I guess  
> GHC 6.5 supports deriving both for Typeable and Data (personally, I  
> prefer to use DriFT rather than the deriving clause, because it  
> gives me a bit more control over visibility of instances). For  
> details, see the section "Supported models of functional  
> strategies" in the README file of StrategyLib.
> Regards,
> Joost
> --
> Dr. ir. Joost Visser   | Departamento de Informática
> phone  +351-253-604461 | Universidade do Minho
> fax    +351-253-604471 | mailto:Joost.Visser at di.uminho.pt
> mobile +351-91-6253618 | http://www.di.uminho.pt/~joost.visser
> On Apr 3, 2006, at 3:41 PM, Christopher Brown wrote:
>> Hi,
>> I am trying to use Strafunski with GHC 6.5 and was wondering if  
>> someone could help me. I have all the instances for Term and  
>> Typeable defined for my data types, but when I try to compile with  
>> GHC 6.5 I get lots of "overlapping instance" errors. In  
>> particular, it seems the instances I am using (generated by DrIFT)  
>> are clashing with the ones in Data.Typeable. Is there a way I can  
>> fix this?
>> Also I have heard that it is possible to add "deriving Typeable"  
>> to each data type and I don't need to use the instances I have  
>> created. However, now it complains that it can't find instances  
>> for Term - but I can't derive from Term. Does anyone have any  
>> ideas how I can get Strafunski working with GHC 6.5?
>> Thanks.
>> Chris.
>> Christopher Brown
>> PhD Student, University of Kent.
>> http://www.cs.kent.ac.uk/people/rpg/cmb21/
>> cmb21 at kent.ac.uk
>> _______________________________________________
>> Haskell-Cafe mailing list
>> Haskell-Cafe at haskell.org
>> http://www.haskell.org/mailman/listinfo/haskell-cafe

Christopher Brown
PhD Student, University of Kent.
cmb21 at kent.ac.uk

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