[Haskell-cafe] Why not some subclass of Floating to model NaNs as some handleable bottom?

[Olaf Klinke]

> * libraries assume a naive equality works for all types. Holds in a world
> of infinte precision and lossless operations, but never holds for
> approximations.
> 
> * our propagation of universal error values is incomplete, and usually
> missing from complex algorithms. In other words `Either String` Monad does
> not work: we want collections of error values just like we have collections
> of inputs.
> 
> Personally I will be overjoyed when our community finally gets the better
> type class library for approximated types.
> 
> Would You agree to review a teaser if I post it here?

Yes, please. 

I'm curious whether there is a single abstraction that can describe
both finite precision with variable errors as well as potentially
infinite precision with known errors. 

Olaf