Miguel Mitrofanov rebukes Sönke Hahn, who -:
wrote:
I used to implement fromInteger n = (r, r) where r = fromInteger n , but thinking about it, fromInteger n = (fromInteger n, 0) seems very reasonable, too.
Stop pretending something is a number when it's not.
Miguel Mitrofanov, please kindly stop pretending that you KNOW what is a number, and what is not. The numeric classes in standard Haskell are disgraceful, and the idea that if something can be added, it is a number is bad. Vectors are not numbers, but inventing "special" (+) for all kinds of Abelian additions is awkward. So, people call "numbers" what they wish, and it is *their* business. I needed to add functions (of course, without Eq nor Show membership), I had to fake... Pairs (a,b) may be "numbers" in various contexts, for example (value,derivative) in automatic differentiation. Or (mainTerm,otherOrders) in some infinitesimal calculus. Or pairs (scalar, 3vector) for quaternions. The idea of putting fromInteger in the same class, is a design bug (my personal opinion, of course). There are plenty of examples where conversions from integers are legitimate, but no addition or (*)seem natural. Or the other way round ; apparently Sönke Hahn is in that situation, so he fakes... Jerzy Karczmarczuk