[Haskell-cafe] Ord for partially ordered sets

[Tom Ellis]

On Fri, Apr 24, 2015 at 11:06:07PM +1000, Ivan Lazar Miljenovic wrote:
> What is the validity of defining an Ord instance for types for which
> mathematically the `compare` function is partially ordered?

I'm confused.  What is supposed to be the result of `g1 <= g2` when `g1` and
`g2` are not comparable according to the partial order?