[Haskell-cafe] Unit and pair

Felipe Almeida Lessa felipe.lessa at gmail.com
Tue May 8 19:42:40 CEST 2012

On Tue, May 8, 2012 at 2:36 PM, MigMit <miguelimo38 at yandex.ru> 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.

[1] http://www.cs.berkeley.edu/~megacz/garrows/


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