At 2002-04-13 21:22, Benny wrote: >type Poly = [Float] > >addPoly::Poly->Poly->Poly >addPoly x y = zipWith (+) x y > >instance (Float a) => Num (Poly a) where > (+) = addPoly > > >I got the error message "Cannot use type synonym in instance head" when I >was trying to compile the codes above. Can anyone tell me why and how to >solve it?
There are at least two errors here. Firstly the context of your instance "(Float a) =>" is wrong. "Float" is not a class. Secondly, "(Poly a)" is meaningless, since Poly is a type and does not take any parameter. -- Ashley Yakeley, Seattle WA _______________________________________________ Haskell-Cafe mailing list [EMAIL PROTECTED] http://www.haskell.org/mailman/listinfo/haskell-cafe