Re: [Haskell-beginners] Enum for natural numbers

2009/12/17 :

Hi, I have data Nat = Z | S Nat deriving (Eq,Ord,Show)

toEnum should return Z for negative numbers. I did something like this but the problem is I don't know how to set "less than". I tried > and lt:

instance Enum Nat where    toEnum (gt 0) = S Z    toEnum (lt 1) = Z -- GRATIS für alle GMX-Mitglieder: Die maxdome Movie-FLAT! Jetzt freischalten unter http://portal.gmx.net/de/go/maxdome01 _______________________________________________ Beginners mailing list Beginners@haskell.org http://www.haskell.org/mailman/listinfo/beginners

Fill in the gaps: instance Enum Nat where toEnum x | x <= 0 = ... | otherwise = ... -- Deniz Dogan