pandora-0.2.5: Pandora/Pattern/Object/Group.hs

module Pandora.Pattern.Object.Group (Group (..)) where

import Pandora.Pattern.Object.Quasiring (Quasiring)

{- |
> When providing a new instance, you should ensure it satisfies the two laws:
> * Right absorption: x * invert x ≡ zero
> * Left absorption: invert x * x ≡ zero
-}

class Quasiring a => Group a where
	{-# MINIMAL invert #-}
	invert :: a -> a