Hi, Im trying to overload a multiplication operator for scalars and vectors, but keep running into the error message "Functional dependencies conflict". What I think is going on is that the dependency check doesn't work with incoherent (or overlapping) instances. In the example below, the two instances of Mult are overlapping. What I want is the vector version to be used for vectors and the scalar version used for numbers, even if a vector-type is an instance of the Num-class (I believe -fallow-incoherent-instances would make that kind of choise for me, right?). Im using the Visual Studio plugin Visual Haskell, and thus GHC version 6.6. Otherwise I think associated types might have worked better for this... Regards Tobias Bexelius {-# OPTIONS_GHC -fglasgow-exts -fallow-undecidable-instances -fallow-incoherent-instances #-} data V2 a = V2 a a class Vec v a where dot :: v a -> v a -> a instance Num a => Vec V2 a where V2 a1 a2 `dot` V2 b1 b2 = a1*b1+a2*b2 class Mult a b c | a b -> c where (*.) :: a -> b -> c instance (Num x) => Mult x x x where (*.) = (*) instance (Vec a x) => Mult (a x) (a x) x where (*.) = dot