One piece of utility code that I find myself writing over and over again is the pointwise Num instance for tuples, i.e.
instance (Num a, Num b) => Num (a,b) where fromInteger x = (fromInteger x, fromInteger x) (a,b) + (a',b') = (a + a', b + b') (a,b) - (a',b') = (a - a', b - b') (a,b) * (a',b') = (a * a', b * b') negate (a,b) = (negate a, negate b) abs (a,b) = (abs a, abs b) signum (a,b) = (signum a, signum b)
I therefore propose that this instance be added to the base library. If we do that, the equivalent instances for (,,) (,,,) etc. should perhaps also be added, as well as instances for other numeric classes such as Fractional and Floating.
-1 from me. While this is a sensible instance, it has the potential to cause great confusion. It will make bug hunting that much harder when you accidentally put a numeric literal where a tuple of distinct numbers is supposed to be. Put the instance in its own package, and those that want it can just install the package. -- Dan Burton