Re: [Haskell-cafe] Unit and pair

On 09/05/12 03:49, MigMit wrote:

On 8 May 2012, at 21:42, Felipe Almeida Lessa wrote:

...

On Tue, May 8, 2012 at 2:36 PM, MigMit wrote:

...

Hi café, a quick question.

Is there a somewhat standard class like this:

class Something c where unit :: c () () pair :: c x y -> c u v -> c (x, u) (y, v)

?

I'm using it heavily in my current project, but I don't want to repeat somebody else's work, and it seems general enough to be defined somewhere; but my quick search on Hackage didn't reveal anything.

I know about arrows; this, however, is something more general, and it's instances aren't always arrows. Are you aware of generalized arrows [1]? It's still a lot more than your Something, though. I've heard of them, but some instances of my Something class aren't categories either, which rules out GArrows too.

---

Haskell-Cafe mailing list Haskell-Cafe@haskell.org http://www.haskell.org/mailman/listinfo/haskell-cafe data-lens has something similar (Tensor):

http://hackage.haskell.org/packages/archive/data-lens/2.10.0/doc/html/Contro... -- Tony Morris http://tmorris.net/