Hi all, we have published the first version of Setoid in haskell. https://hackage.haskell.org/package/setoid-0.1.0.0 Setoid is a useful data structure when equivalence has to be chosen not to be equality. This makes membership of the elements in a setoid stricter and allows to do some computations. For more details and usage examples, please refer to the documentation on hackage. You can also contribute to it on github: https://github.com/ptek/setoid Regards, Pavlo.