Hello All, I'm trying to create a generic function (*) using classes. I've been playing with ghc extensions but haven't found what I need yet. class HasTimes a b c where (*) :: a -> b -> c This doesn't work because it can't figure out what the return types are for a general expression a*(b*c). This kinda makes sense since someone could overload HasTimes Float Float Int and HasTimes Float Float Float. What about: class HasTimes a b where (*) :: a -> b -> c This would sort of imply that c is the only possible result of a (*) for types a and b. But I'm pretty sure this functionality hasn't been implemented. Why is this important? I'm trying to reduce ugliness of code using the following library: data Matrix = Matrix ((Float,Float),(Float,Float)) data HVec = HVec Float Float data VVec = VVec Float Float idMatrix = Matrix ((1.0,0.0),(0.0,1.0)) vhVecMult (VVec a b) (HVec c d) = Matrix ((a*c,a*d),(b*c,b*d)) matMult (Matrix ((a,b),(c,d))) (Matrix ((e,f),(g,h))) = Matrix (((a*e+b*g),(a*f+b*h)),((c*e+d*g),(c*f+d*h))) matVVecMult (Matrix ((c,d),(e,f))) (VVec a b) = VVec (a*c + b*d) (a*e + b*f) hVecMatMult (HVec a b) (Matrix ((c,d),(e,f))) = HVec (c*c+b*e) (a*d+b*f) vVecMinus (VVec a b) (VVec c d) = VVec (a-c) (b-d) vVecPlus (VVec a b) (VVec c d) = VVec (a+c) (b+d) matMinus (Matrix ((a,b),(c,d))) (Matrix ((e,f),(g,h))) = Matrix ((a-e,b-f),(c-g,d-h)) hvVecMult (HVec a b) (VVec c d) = a*c + b*d scalHVecMult :: Float -> HVec -> HVec scalHVecMult i (HVec a b ) = HVec (i*a) (i*b) Thanks, David J. Sankel