congruence-relation

Decidable congruence relations for Haskell: up to you whether this is a joke.

The laws of Eq only require that you have a decidable equivalence relation defined on a type; they do not force you to guarantee abstraction with respect to the relation, i.e. you can write anti-extensional operations without violating the laws. This package provides an alternative for when functionality with respect to an equivalence relation is desired.