Latest Template Haskell Breaks Package

[Dominic Steinitz]

I am on a Mac as you have cleverly deduced. I tried cabal install --with-gcc=gcc-4.9 but no luck.

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

On 23 Dec 2014, at 16:13, Erik Hesselink <hesselink at gmail.com> wrote:

> Are you on a Mac? OS X switched to clang, which caused all kinds of
> problems as GHC uses the C compiler as a C preprocessor, and clang
> behaves differently from gcc.
> 
> Erik
> 
> On Tue, Dec 23, 2014 at 4:06 PM, Dominic Steinitz <dominic at steinitz.org> wrote:
>> Hi Erik,
>> 
>> Thank you very much. With that clue the compilation now doesn’t fail at that particular point.
>> 
>> The bad news is it now fails to compile this module
>> 
>> https://hackage.haskell.org/package/yarr-1.3.2/docs/src/Data-Yarr-Utils-Primitive.html#clampM%27
>> 
>> with a parse error(!). Not only do I not have much experience with TH but this has now exposed my ignorance of CPP.
>> 
>>> Data/Yarr/Utils/Primitive.hs:119:126: Parse error in pattern: con
>> 
>> If I comment out the last four lines
>> 
>>> PRIM_COMP_INST(Int, I#, (<=#), (>=#))
>>> PRIM_COMP_INST(Char, C#, leChar#, geChar#)
>>> PRIM_COMP_INST(Word, W#, leWord#, geWord#)
>>> PRIM_COMP_INST(Double, D#, (<=##), (>=##))
>>> PRIM_COMP_INST(Float, F#, leFloat#, geFloat#)
>> 
>> then the module compiles but of course then the whole package does *not* compile.
>> 
>> Did something change in 7.8.3 with regard to CPP (this code has not been modified for at least two years)?
>> 
>> Thanks once again.
>> 
>> Dominic Steinitz
>> dominic at steinitz.org
>> http://idontgetoutmuch.wordpress.com
>> 
>> On 23 Dec 2014, at 13:42, Erik Hesselink <hesselink at gmail.com> wrote:
>> 
>>> Hi Dominic,
>>> 
>>> It looks like just a representation change: a TySynEqn is a data type
>>> containing a [Type] and a Type, and those were the original two
>>> arguments. So it looks like with a little bit of CPP, you could
>>> support both versions. Something like
>>> 
>>> #if MIN_VERSION_template_haskell(2,9,0)
>>> ...
>>> #else
>>> ...
>>> #endif
>>> 
>>> In general, I think each major release of template haskell has quite
>>> some breaking changes, but I don't know of any place where they're
>>> enumerated. The GHC changelog only has a couple of high level bullet
>>> points.
>>> 
>>> Regards,
>>> 
>>> Erik
>>> 
>>> On Tue, Dec 23, 2014 at 2:20 PM, Dominic Steinitz <dominic at steinitz.org> wrote:
>>>> 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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>>