On 5/23/05, [EMAIL PROTECTED] <[EMAIL PROTECTED]> wrote:
>
> Hi,
>
> I'm new to Haskell and even newer to this list. I have over 20 years of
> experience in C or C++.
>
> For fun, I decided to write a Fourier transform in Haskell. It would be
> convenient if I had a function that converts any real or complex number into
> a complex number. My attempt at doing this is below. Hugs produces errors
> when I try to load this code.
>
> Essentially, I'm trying to define a class called ConvertibleToComplex.
> There is a function in this class called toComplex. toComplex has the type:
>
> class ConvertibleToComplex a where
> toComplex :: RealFloat b => a -> Complex b
I don't think you want an arbitrary type 'b'. Try: (pass -98 to Hugs
or -fglasgow-exts to GHCi when loading this code)
import Complex
class ConvertibleToComplex a b | a -> b where
toComplex :: RealFloat b => a -> Complex b
instance ConvertibleToComplex Float Float where
toComplex f = f :+ 0
instance ConvertibleToComplex Double Double where
toComplex d = d :+ 0
instance ConvertibleToComplex (Complex a) a where
toComplex c = c
--
Friendly,
Lemmih
_______________________________________________
Haskell-Cafe mailing list
[email protected]
http://www.haskell.org/mailman/listinfo/haskell-cafe
