Field labels must be globally unique?

[Marc Ziegert]

--------------------It would be nice to be able to overload class-functions like classes:

instance (+), (-) -> Vector where
    (+) v1 v2 = ...
    (-) v1 v2 = ...

--------------------instead of overloading parts of a class... (because of runtime-errors!)

instance Num Vector where
    (+) v1 v2 = ...
    (-) v1 v2 = ...
    (*) _ _ = undefined
    (/) _ _ = undefined

--------------------or BETTER just to split classes:

class HalfBody a => (Num a =>(+), (-)) where

instance HalfBody Vector where
    (+) v1 v2 = ...
    (-) v1 v2 = ...

--------------------instead of defining new operators...

class HalfBody a where
    (+§) :: a -> a -> a
    (-§) :: a -> a -> a

instance (Num a) => HalfBody a where
    (+§) = (+)
    (-§) = (-)

instance HalfBody Vector where
    (+§) v1 v2 = ...
    (-§) v1 v2 = ...

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> > One is to allow function overloading.  This is probably not desirable
> > because it turns type checking into an NP-hard problem.