[Haskell-cafe] why doesn't ghc give you a type signature that works ?

[KC]

If you're importing the module as

import qualified Math.FFT as FFT

Shouldn't "Math.FFT" become "FFT"?  :)


On Tue, May 17, 2011 at 8:44 PM,  <briand at aracnet.com> wrote:
> for example:
>
> I will ask the glorious compiler, and it says:
>
> *Main> :t calcFFT
> calcFFT
>  :: (Math.FFT.Base.FFTWReal r) =>
>     V.Vector (Complex r) -> V.Vector (Complex r)
>
> I then put the signature in my code, reload it, and:
>
>  Not in scope: type constructor or class `Math.FFT.Base.FFTWReal'
>
>
> It seems very strange to me that the fully qualified module name doesn't work, nor does any combination thereof, e.g. FFT.FFTWReal, FFT.Base.FFTWReal, etc...
>
> I'm importing FFT as:
>
>  import qualified Math.FFT as FFT
>
> I'm not sure if that causes the problem.
>
> Generally speaking this happens to me quite a lot, and I've never tried to understand what's going on, because the signature is not required.  I've decided to try now :-)
>
> Obviously I'll need some help.
>
> Thanks,
>
> Brian
>
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-- 
--
Regards,
KC