In article
This is what I want. For a given set of vectors, the associated scalars are unique, otherwise I would have problems with norm. But I have problems anyway...
instance Vspace a a where
This says, for any vector type "a", the associated scalar is "a". That pretty much rules out any other instance. It's the same as writing "instance Vspace v v" of course.
instance (Num a)=>Vspace a (c->a) where instance (Vspace a v) => Vspace a (c->v) where
These are also incompatible. The first says that if the vector type is "p -> q", then the scalar type is "q". The second says that if the vector type is "p -> q", then the scalar type is some other type "r" fulfilling "Vspace r q". Which do you want, "q", or "(Vspace r q) => r"? -- Ashley Yakeley, Seattle WA