[Haskell-cafe] Re: [Haskell] specification of sum

On 2005-11-02, ajb@spamcop.net wrote:

(Moving this to the cafe.)

G'day all.

Quoting Cale Gibbard :

...

We already do rely on them in most cases. Of course, not every property can be proved by the compiler, but many pieces of code are going to assume quite a lot.

Agreed.

...

I think that the assumption that (+) and (*) in Num define something like a ring on the given type is a sensible one.

I'm not so certain. Octonian multiplication, to pick one example, is not associative, but I'd like to be able to use (*) nonetheless.

(*) is already defined as being left-associative in H98. I'm actually working with non-associative structures at the moment where the operation is usually considerd "multiplication", but I still wouldn't want to use (*) for it. Too much hassle for normal uses. -- Aaron Denney -><-