[Haskell] Re: compares :: Ord a => a -> a -> Ordering -> Ordering

Christian Maeder maeder at tzi.de
Wed Feb 15 06:53:24 EST 2006


Ben Rudiak-Gould wrote:
> I just realized that the class Ord should have an additional method:
> 
>   class Eq a => Ord a where
>     compares :: a -> a -> Ordering -> Ordering
>     compares x y d = case compare x y of { EQ -> d ; o -> o }
>     ...

How about:

instance (Ord a, Ord b, Ord c, Ord d) => Ord (a,b,c,d) where
	compare (a1,b1,c1,d1) (a2,b2,c2,d2) =
		compare ((a1,b1,c1),d1) ((a2,b2,c2),d2)

or another tuple nesting)

Christian


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