On Sat, Jul 10 2010, wren ng thornton wrote:
[...] > > Yes, you can add multiple dependencies. The syntax is to use , after > the first |. > > While having eight parameters is surely a desperate need for > refactoring, there are times when you'd want multiple dependencies. > For example, you can say > > class F a b | a -> b, b -> a where... > > to express a bijective function on types (that is, for every pair of A > and B, if you know one of them then you know what the other must be > uniquely). I know i should read the relevant articles, but how would one express such a bijection using type families? TIA, jao -- You err by thinking simplicity and elegance are mostly cosmetic. Simplicity and elegance are overwhelmingly practical virtues. - William D Clinger, comp.lang.scheme _______________________________________________ Haskell-Cafe mailing list Haskell-Cafe@haskell.org http://www.haskell.org/mailman/listinfo/haskell-cafe
