ANNOUNCE: yap-0.0 - yet another prelude

[Henning Thielemann]

On Fri, 12 Aug 2011, Paterson, Ross wrote:

> wren ng thornton [wren at freegeek.org] writes:
>> On 8/10/11 9:53 AM, Paterson, Ross wrote:
>>> Yet another restructuring of the Prelude numeric classes on algebraic lines, proposed for a revision of the Haskell Prelude:
>>>
>>> http://hackage.haskell.org/package/yap-0.0
>>
>> Very nice in its simplicity, but it suffers from the same problem as all
>> the other attempts I've seen. Namely it ignores the importance of
>> semirings and runs headlong towards fields and beyond. The {(-), abs,
>> signum, negate} methods really must be broken out from (+).
>
> abs and signum are already split off, but it could be further split, with
> Monoid and Semiring subclasses of AbelianGroup and Ring, and that
> would fit nicely with a Natural type.  I wasn't sure it was worth it
> (having + operate on lists might be confusing for beginners).

Having a (+) is possible for both Additive Group or more fine-grained 
classes, isn't it? There is still the question, whether (+) lists shortens 
like zipWith (+) or expands to the longer list. Or do you even mean to 
define (+) as being (++) on lists? (Which would be also non-commutative, 
that is, non-Abelian.)