[Haskell-beginners] Expressing the idea of a group in Haskell

[Stephen Tetley]

Pragmatically you might want two classes - AdditiveGroup and
MultiplicativeGroup.

There is a lot of work in this area such as the NumericPrelude on
Hackage and Jerzy Karczmarczuk's paper "Functional Programming and
Mathematical Objects" [link below]. Numeric hierarchies expose
problems for Haskell's class system, hence everyone complains about
the Num classes but no-one has been able to fix them.


http://citeseerx.ist.psu.edu/viewdoc/summary?doi=10.1.1.32.3328