[Haskell-cafe] [Haskell] Defining Cg, HLSL style vectors in Haskell

[Krasimir Angelov]

Hi Slavomir,

On 11/28/06, Slavomir Kaslev <slavomir.kaslev at gmail.com> wrote:
> instance Num Float3 where
>    .....
>    signum a | a == Float3 0 0 0 = 0
>                  | otherwise = 1

signum has a natural generalization for vectors.

signum v = vector with the same direction as v but with |v| = 1

where |v| is the absolute length of v. The problematic function in Num
is abs. Ideally abs should be defined as:

abs v = |v|

but its type is Float3 -> Float while the Num class requires Float3 -> Float3.

Cheers,
   Krasimir