I'm still confused about this point: On 4/16/08, Dan Weston <[EMAIL PROTECTED]> wrote: > > > class C a b c | c -> a b > > > > > > Notice that there are multiple (two) parameters in the range of the FD. > > > > > > It's tempting to convert the above to > > > > > > class C a b c | c -> a, c -> b > > > > > > but this yields a weaker (in terms of type improvement) system.
In both cases the statement is that given a type x, the instance C x y z for some y,z and the constraint C x a b, we unambiguously have a ~ y, b ~ z (where ~ is type equality) How does the order in (c -> a b) matter? -- ryan _______________________________________________ Haskell-Cafe mailing list [email protected] http://www.haskell.org/mailman/listinfo/haskell-cafe
