No instance for (Fractional Int32)

Gabor Greif ggreif at
Fri Feb 8 20:37:38 CET 2013

On 2/8/13, Stephen Paul Weber <singpolyma at> wrote:
> Somebody claiming to be Christopher Vollick wrote:
>>On Fri, Feb 08, 2013 at 01:20:53PM +0100, Gabor Greif wrote:
>>> libraries/base/Foreign/C/Types.hs:162:72:
>>>     No instance for (Fractional Int32)
>>>       arising from the 'deriving' clause of a data type declaration
>>>     Possible fix:
>>>       use a standalone 'deriving instance' declaration,
>>>         so you can specify the instance context yourself
>>>     When deriving the instance for (Fractional CFloat)
>>> Has anybody seen this with HEAD?
> This may be a side effect of the fix for
> <>

Yeah, something with the test that contains the literal double 1.4
When configure runs, it does not succeed to set HTYPE_IS_INTEGRAL
to "" and this leads it down the signed/unsigned road.

Will check tomorrow what is going on here.
Possibly we need to change the test to C++,
where compile-time detection of these things
is a breeze (because of overloading).

Cheers and thanks,


> --
> Stephen Paul Weber, @singpolyma
> See <> for how I prefer to be contacted
> edition right joseph
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