-----BEGIN PGP SIGNED MESSAGE----- Hash: RIPEMD160 Hello, I defined an enumeration datatype like this data MyType = One | Two | Four | Eight and want to make it an instance of the class Enum. deriving Enum won't do what I want, as it labels the items 0,1,2,3. Is there a better way to do this than instance Enum MyType where fromEnum One = 1 fromEnum Two = 2 ... toEnum 8 = Eight Something like instance Enum MyType where fromEnum One = 1 fromEnum x = 2*pred x toEnum 1 = One toEnum x = succ (toEnum x `div` 2) Which doesn't work because succ and pred are not (properly?) defined. Is there a way to let deriving Enum do *some* of work (i.e. defining succ and pred) while manually defining the other functions? -----BEGIN PGP SIGNATURE----- Version: GnuPG v1.4.7 (MingW32) Comment: Using GnuPG with Mozilla - http://enigmail.mozdev.org iD8DBQFGCTRJ11V8mqIQMRsRA4GFAJwKaxQoKdEW91pHUskzJadDvh7lXgCeLg6P dmQKcjRZEg4fqoZfQ4jOuhg= =RWQ+ -----END PGP SIGNATURE-----