Michail Pevnev
Hello everyone!
For a library I write at the moment, I made a class for approximate geometric equality comparisons (and dubbed it `ApproxEq`). It's not a very lawful class, but there is one invariant that should hold absolutely always - if two entities coincide but have different representations, they should compare "equal".
The approximate-equality package (https://hackage.haskell.org/package/approximate-equality) provides a nicer way of doing that IMO. I've used that a few times when I needed an aprpimxate Floating type. Generally I think it is just better to use exact number types, like Rational, when implementing geometric algorithms though. That is what I tend to use in hgeometry as well ( that quite often a Fractional constraint is sufficient anyway). -- - Frank