Hi, Simon. You should look at the Data.Derive module to see how to create your own instances.
Cheers, David ____________________ David Place Owner, Panpipes Ho! LLC http://panpipesho.com d@vidplace.com On Jun 14, 2011, at 8:07 AM, Haisheng Wu wrote:
Hi guys, What I understanding `deriving` is Haskell automatically make a type to be a instance of a particular typeclass. If that's the case, the question is How does Haskell do that underline?
Take code below as sample, the type Day is now an instance of Bounded.
data Day = Monday | Tuesday | Wednesday | Thursday | Friday | Saturday | Sunday deriving (Bounded, Enum)
Therefore, minBound :: Day will produce Monday.
Just be curious how it is being implemented.
Thanks. Simon _______________________________________________ Beginners mailing list Beginners@haskell.org http://www.haskell.org/mailman/listinfo/beginners