[Haskell-cafe] Problems with type family in a class

[Niklas Haas]

On Mon, 21 Jul 2014 15:39:08 -0400, adam vogt <vogt.adam at gmail.com> wrote:
> Also, the "ComplexSignal csx" constraint is redundant, since the
> Complexable superclass constraint includes it. In other words, you can
> write:
> 
> class (Complexable s) ⇒ FourierTransformable s where
>         fft  :: (csx ~ ComplexSignalType s) ⇒ csx → csx

In fact, this type should now even be equivalent to:

class Complexable s => FourierTransformable s where
  fft :: ComplexSignalType s -> ComplexSignalType s