patch applied (packages/base): FIX #2722: update RULES for the Category/Arrow split

[Don Stewart]

ross:
> Tue Nov  4 06:45:15 PST 2008  Ross Paterson <ross at soi.city.ac.uk>
>   * FIX #2722: update RULES for the Category/Arrow split
>   
>   The rule
>   
>   	arr id = id
>   
>   interacts unpleasantly with the advice to define
>   
>   	id = arr id
>   
>   in instances of Category that are also instances of Arrow (#2722).
>   
>   Also changed a couple of >>>'s to .'s in later rules.
> 
>     M ./Control/Arrow.hs -4 +2

should the new arrows library be on hackage ?