On Mar 12, 2013, at 12:44 AM, "Richard A. O'Keefe" <o...@cs.otago.ac.nz> wrote: > > Prelude> :type (+) > (+) :: Num a => a -> a -> a > > The predefined (+) in Haskell requires its arguments and its result > to be precisely the same type. > > I think you had better justify the claim that Date+Period -> Date and > Date+Period -> Period are possible at the same time by showing us > actual code.
Ehm... import Prelude hiding (Num) class SumDP a where (+) :: Date -> Period -> a instance SumDP Date where date + period = <your_implementation_here> instance SumDP Period where date + period = <and_here> _______________________________________________ Haskell-Cafe mailing list Haskell-Cafe@haskell.org http://www.haskell.org/mailman/listinfo/haskell-cafe
