Fwd: Latest Template Haskell Breaks Package

[Dominic Steinitz]

I realise I should have sent this to the libraries list.

Dominic Steinitz
dominic at steinitz.org
http://idontgetoutmuch.wordpress.com

Begin forwarded message:

> From: Dominic Steinitz <dominic at steinitz.org>
> Subject: Latest Template Haskell Breaks Package
> Date: 23 December 2014 13:14:26 GMT
> To: Haskell-Cafe <haskell-cafe at haskell.org>
> 
> Hello Fellow Haskellers,
> 
> I have become a maintainer for yarr (https://hackage.haskell.org/package/yarr). This no longer compiles with ghc-7.8.3 because it specifies base == 4.6. Relaxing this to base >=4.6 && <4.8 tells me I need a newer version of Template Haskell
> 
>> rejecting: template-haskell-2.7.0.0, 2.6.0.0, 2.5.0.0, 2.4.0.1, 2.4.0.0,
>> 2.3.0.1, 2.3.0.0, 2.2.0.0 (conflict: yarr => template-haskell>=2.8 && <2.9)
> 
> If I now relax the constraint for Template Haskell I get a compiler error as there has been a breaking change from Template Haskell 2.9 to 2.10.
> 
>> Data/Yarr/Utils/FixedVector/VecTuple.hs:45:16:
>>     Couldn't match expected type ‘TypeQ -> Q Dec’
>>                 with actual type ‘Q Dec’
>>     The function ‘tySynInstD’ is applied to three arguments,
>>     but its type ‘Name -> TySynEqnQ -> DecQ’ has only two
> 
> And indeed looking at the changes in http://git.haskell.org/packages/template-haskell.git/commitdiff/ccd7891c536b29b8bea96eb92520f46e21390e39 I can see that the function in question has changed.
> 
>> -tySynInstD :: Name -> [TypeQ] -> TypeQ -> DecQ
>> -tySynInstD tc tys rhs = 
>> +tySynInstD :: Name -> [TySynEqnQ] -> DecQ
>> +tySynInstD tc eqns = 
> 
> Did I miss some announcement of this breaking change and the advice on what to do about it?
> 
> If I did can someone please point me at the relevant document. If not then I feel sad and would be very grateful if someone could help me as I know very little about Template Haskell.
> 
> Many thanks
> 
> Dominic Steinitz
> dominic at steinitz.org
> http://idontgetoutmuch.wordpress.com
> 

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