Thanks for your detailed input -- I appreciate seeing these rather abstract techniques being applied to specific problems.
Tom Nielsen pointed me in the direction of the solution you've supplied, so I should have replied to the list that my question had been addressed. Anyhow, I now have code that looks a little like: > class DummySolidObject flag o > class SolidObject o > > instance FiniteSolidObject o => DummySolidObject Dummy1 o > instance InfiniteSolidObject o => DummySolidObject Dummy2 o > instance DummySolidObject d o => SolidObject o > > data Dummy1 > data Dummy2 Thanks, Eric _______________________________________________ Haskell-Cafe mailing list Haskell-Cafe@haskell.org http://www.haskell.org/mailman/listinfo/haskell-cafe
