Add Ord Laws to next Haskell Report

[Henning Thielemann]

On Thu, 7 Feb 2019, Merijn Verstraaten wrote:

> I think the default behaviour for Float/Double should use a trapping 
> NaN. The current value NaN is as if every Double value has an implicit 
> "fromJust"

I like to think of it like all operations are lifted to (Maybe Float).

> Trapping NaN would also eliminate the brokenness of Ord. If some people 
> are really attached to value NaNs (why?!? What's wrong with you?) we 
> could allow disabling trapping at compile or runtime so they get the old 
> behaviour.

What about calling into foreign code? If I call a BLAS routine and one 
element of the result vector is NaN, shall this be trapped? Or shall it be 
trapped once I access the NaN element?