[Haskell-cafe] How to define an operation in terms of itself (but of different type)?

[Olex P]

Well if telepaths on vacation...

class Vector v where
    (^+^)       :: v -> v -> v

data Vector3 = V3 !Double !Double !Double

instance Vector Vector3 where
    (V3 x1 y1 z1) ^+^ (V3 x2 y2 z2) = V3 (x1 + x2) (y1 + y2) (z1 + z2)

class Matrix m where
    (^+^)     :: m -> m -> m

data Matrix3 = M3 !Vector3 !Vector3 !Vector3

instance Matrix Matrix3 where
    (M3 r11 r12 r13) ^+^ (M3 r21 r22 r23) = M3 (r11 ^+^ r21)
                                                                  (r12 ^+^
r22)
                                                                  (r13 ^+^
r23)

Hope this is better :)
So yeah... r11 ^+^ r21 just doesn't work.
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