Proposal: Num instance for tuples
Edward Kmett
ekmett at gmail.com
Thu Oct 18 13:34:45 CEST 2012
Unlike the rest of the comments so far, I am
+1
to this proposal.
It has the only reasonable semantics.
Sent from my iPad
On Oct 18, 2012, at 5:58 AM, Twan van Laarhoven <twanvl at gmail.com> wrote:
> Dear list,
>
>
> 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.
>
>
> Discussion period: 2 weeks, ends 2012-11-01.
>
>
> Twan
>
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