On Tue, Jan 27, 2009 at 4:51 AM, <o...@okmij.org> wrote: > Doug McIlroy wrote: >> A fragment of an attempt to make pairs serve as complex numbers, >> using ghc/hugs extensions: >> >> instance Num a => Num (a,a) where >> (x,y) * (u,v) = (x*u-y*v, x*v+y*u) > The recent versions of GHC have a nifty equality constraint, so the > code can be written simply
I'm confused on why instance Num a => Num (a, a) where is not equivalent to instance (Num a, Num b, a ~ b) => Num (a, b) where I don't know the details of the type inference algorithm. What am I missing to understand why they are not the same? Cheers, Corey O'Connor _______________________________________________ Haskell mailing list Haskell@haskell.org http://www.haskell.org/mailman/listinfo/haskell
