On Mon, Sep 05, 2005 at 11:31:00AM -0700, Scherrer, Chad wrote:
> I keep getting this error in GHCi:
>
> Illegal instance declaration for `PlusEq (a i e) (a i e) (m ())'
> (the instance types do not agree with the functional dependencies of the
> class)
> In the instance declaration for `
Hi,
I'm trying to use functionally dependent typeclasses to create an
overloaded (+=) function. A simplified example of a first bit of code
is...
class PlusEq a b c | a b -> c where
(+=) :: a -> b -> c
instance (MArray a e m, Num e, Ix i) =>
PlusEq (a i e) (a i e) (m ()) where
(+=)
