Proposal #2560 again: add newtype Down/ReverseOrd to Data.Ord

[Sterling Clover]

FlipOrd { unFlipOrd :: a } ?

--S

On Jan 6, 2009, at 10:58 AM, Twan van Laarhoven wrote:

> kahl at cas.mcmaster.ca wrote:
>> Me neither...
>> How about:
>> -- intended for |qualified| import |as Ord|:
>> newtype Dual a = Dual { unDual :: a } deriving Eq
>
> In my opinion "dual" is even worse:
>
>  - "dual" is not a name that people think about when they want  
> something sorted in descending order or they want a different  
> priority queue, etc. I think of names like "reverse", "descending"  
> and "something to do with order".
>
>  - "dual" can mean many more things. First of all there are  
> different dualities in mathematics, I guess this refers to the  
> categorical dual. Then there are many ways to use that duality in  
> Haskell. The first thing that comes to mind, and which is a closer  
> fit, is  newtype Op t a b = Op (t b a), the dual of a  
> Control.Category style category.
>
> Twan
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