[Haskell-cafe] Re: Numeric type classes

[Aaron Denney]

On 2006-09-12, Bryan Burgers <bryan.burgers at gmail.com> wrote:
> And another problem I can see is that, for example, the Integers are a
> group over addition, and also a group over multiplication;

Not over multiplication, no, because there is no inverse.

I know of no good way to express that a given data type obeys the
same interface two (or more) ways.  Some OO languages try to handle the
case of of an abstract base class being inherited twice through two
different intermediate classes, but none of them do it well.

-- 
Aaron Denney
-><-