[Haskell-beginners] "Trinary" version of Either

[Antoine Latter]

On Thu, Jun 9, 2011 at 3:58 PM, Christopher Howard
<christopher.howard at frigidcode.com> wrote:
> My preference would be: just like a regular Monad either instance from mtl,
> except that the Middle value also bypasses the bound function. My semantics
> would be: left value represents error, right reprents normal results, and
> middle represents results that are not erroneous but that prevent further
> calculations. I have some idea of how this could be used to chain together
> actions and avoid messy branching in code.
>