On Fri, Oct 22, 2010 at 9:11 PM, wren ng thornton
<wren@freegeek.org> wrote:
On 10/22/10 8:46 AM, Alexey Khudyakov wrote:
Hello everyone!
It's well known that Num & Co type classes are not adequate for vectors
(I don't mean arrays). I have an idea how to address this problem.
Conal Elliott wrote very nice set of type classes for vectors.
(Definition below). I used them for some time and quite pleased. Code is
concise and readable.
> class AdditiveGroup v where
> zeroV :: v
> (^+^) :: v -> v -> v
> negateV :: v -> v
[...]
I'd like to know opinion of haskellers on this and specifically opinion
of Conal Eliott as author and maintainer (I CC'ed him)
Just my standard complaint: lack of support for semirings, modules, and other simple/general structures. How come everyone's in such a hurry to run off towards Euclidean spaces et al.?
I'd rather see,
class Additive v where -- or AdditiveMonoid, if preferred
zeroV :: v
(^+^) :: v -> v -> v
class Additive v => AdditiveGroup v where
negateV :: v -> v
type family Scalar :: * -> *
class Additive v => LeftModule v where
(*^) :: Scalar v -> v -> v
class Additive v => RightModule v where
(^*) :: v -> Scalar v -> v
...
Though I don't know how much that'd affect the niceness properties you mentioned.
--
Live well,
~wren