[Haskell-cafe] [Ann] group-theory

[Mario]

On 2020-12-05 7:04 p.m., Jack Kelly via Haskell-Cafe wrote:
> Dunno what the answer is, but I wanted to flag it while your package is young and breaking changes are easy. I've been meaning to have a crack at moving the reflex patch-verse over to monoid-subclasses ( https://hackage.haskell.org/package/monoid-subclasses ), which I provides some the necessary tools with different names (patch reinvents MonoidNull, and I'm hoping that a subtraction-that-removes keys could be lawful for one of the Reductive/Cancellative classes).


I'm the author and maintainer of monoid-subclasses, and I'd accept a PR 
that adds InverseSemigroup without overly disturbing the existing 
classes. The whole purpose of the package, after all, is to support 
mathematical abstractions that are richer than semigroups but are not 
proper groups.