I'm trying to define a Quaternion, which is sort of a four-element vector with special rules for multiplication. ----- Quaternion.hs ----- data Quaternion = Quaternion Double Double Double Double deriving (Show) (*) :: (Quaternion a) => a -> a -> a (*) (Quaternion w1 x1 y1 z1) (Quaternion w2 x2 y2 z2) = Quaternion w x y z where w = w1*w2 - x1*x2 - y1*y2 - z1*z2 x = x1*w2 + w1*x2 + y1*z2 - z1*y2 y = w1*y2 - x1*z2 + y1*w2 + z1*x2 z = w1*z2 + x1*y2 - y1*x2 + z1*w2 ----- end code ----- When I try to load this into ghci, I get: Quaternion.hs:6:13: Ambiguous occurrence `*' It could refer to either `Main.*', defined at Quaternion.hs:5:0 or `Prelude.*', imported from Prelude ... and lots more messages like that. I understand roughly what the message means, but I don't know how to tell it that when I use "*" within the definition, I just want ordinary multiplication. Thanks in advance for any help! Amy