The problem Dual is taken by Data.Monoid. With Opposite it isn't clear what is being inverted as well. Perhaps Desc (or Descending)? That would permit nice descriptions when used with the extended list comprehension sugar. Sent from my iPad On Nov 19, 2011, at 7:28 AM, Herbert Valerio Riedel wrote:

On Sat, 2011-11-19 at 12:07 +0100, Sjoerd Visscher wrote:

...

I like the concept, but not the name. Inverse (or Inv) would be a better name imho.

btw, doesn't that "Down" transform the Ord relation into its "dual" (in the category sense)? If so, wouldn't a categorical term like "Dual" or "Opposite" (as in "Opposite Category") be more appropriate (given that Haskell libraries already recycles many categorical terms?)

Just saying... :-)

-- hvr.

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On 19 November 2011 20:12, Felipe Almeida Lessa wrote:

I like Desc, and it's better than Descending.

+1 (whatever the name is chosen)

<bikeshedding> I often use the name Desc in code as a shortening of Description... </bikeshedding>

On Sat, Nov 19, 2011 at 6:19 PM, Sjoerd Visscher wrote:

Desc has the same problem as Down: it doesn't make clear that it makes an already descending ordering ascending.

Desc reminds me of tables where you click the header and change between ascending and descending. Invert, Dual, Down and Opposite don't remind me of anything regarding orders at all. What are you inverting? Dual of what? Of couse, that's only my humble opinion. =) Cheers, -- Felipe.

Dual already has an Ord instance. Sent from my iPhone On Nov 19, 2011, at 4:46 PM, Ben Millwood wrote:

On Sat, Nov 19, 2011 at 8:32 PM, Felipe Almeida Lessa wrote:

...

On Sat, Nov 19, 2011 at 6:19 PM, Sjoerd Visscher wrote:

...

Desc has the same problem as Down: it doesn't make clear that it makes an already descending ordering ascending.

Desc reminds me of tables where you click the header and change between ascending and descending. Invert, Dual, Down and Opposite don't remind me of anything regarding orders at all. What are you inverting? Dual of what? Of couse, that's only my humble opinion. =)

Just to confuse and frustrate things further, I'm going to suggest Reverse. I think that's the normal word I'd use to describe a flipped ordering.

I don't see any harm in reusing the existing Dual newtype from Monoid, though.

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Because sometimes you put them in containers directly. I've done this, it isn't a theoretical situation. Sent from my iPhone On Nov 19, 2011, at 5:24 PM, Herbert Valerio Riedel wrote:

On Sat, 2011-11-19 at 17:03 -0500, Edward Kmett wrote:

...

Dual already has an Ord instance.

...btw, why does a monoid need an Ord instance anyway? :-)

Reverse is better indeed, but +1 on any name that ends with -verse. Sjoerd On Nov 20, 2011, at 11:56 PM, wren ng thornton wrote:

On 11/19/11 3:19 PM, Sjoerd Visscher wrote:

...

Desc has the same problem as Down: it doesn't make clear that it makes an already descending ordering ascending.

FWIW I call the newtype Reverse in my local libraries. Another option would be Converse. (Both of which are a bit less ambiguous than Inverse.)

-- Live well, ~wren

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On Sun, Nov 20, 2011 at 3:21 PM, wren ng thornton wrote:

On 11/20/11 6:11 PM, Sjoerd Visscher wrote:

...

Reverse is better indeed, but +1 on any name that ends with -verse.

So that's three votes for Reverse. Are there any complaints against this color for the bikeshed?

Reverse sounds good to me too, especially since it matches up with the reverse function so well. Michael

On 11/21/11 10:23 AM, Edward Kmett wrote:

I have to admit I don't like this color for the same reason as my dislike of the Opposite and Dual suggestions. It isn't entirely clear which operator is being reversed, so you can call me a -1.

Would Converse be any clearer? The ambiguity of what's being inverted is the reason why I'm not a fan of Inverse (e.g., we invert multiplication all the time, to the point where we abuse notation and say we're inverting the numbers themselves). But other than Reverse and Converse, I can't think of any name that would immediately invoke the idea that the ordering relation is what's being dualized. Unless we go the Java route and choose something verbose like ReverseOrdering (or decide to be really perverse and choose CoOrd). But really, what else can be reversed? Sorting and ordering functions can have their outputs reversed. Whereas relations in general are conversed, binary operators are commuted, arguments to functions are flipped, components of pairs are swapped,... -- Live well, ~wren

If yinz keep bikeshedding over what to call it, I'm gonna propose TheOtherWayRound. :) -- brandon s allbery allbery.b@gmail.com wandering unix systems administrator (available) (412) 475-9364 vm/sms

+1 for Reverse 2011/11/22 John Meacham :

I'd like to add 'Flip', 'Invert', and 'AntiOrd' to the mix. Actually. AntiOrd is sounding nice.

On Nov 22, 2011 12:53 AM, "Brandon Allbery" wrote:

...

If yinz keep bikeshedding over what to call it, I'm gonna propose TheOtherWayRound.  :)

-- brandon s allbery                                      allbery.b@gmail.com wandering unix systems administrator (available)     (412) 475-9364 vm/sms

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On 21 November 2011 12:57, Brent Yorgey wrote:

On Mon, Nov 21, 2011 at 12:11:27AM +0100, Sjoerd Visscher wrote:

...

Reverse is better indeed, but +1 on any name that ends with -verse.

In that case I propose Universe, Adverse, or Perverse. ;)

Wouldn't Perverse have some kind of random (via unsafePerformIO of course!) comparison functionality? ;-) -- Ivan Lazar Miljenovic Ivan.Miljenovic@gmail.com IvanMiljenovic.wordpress.com

On Sun, Nov 20, 2011 at 09:08:34PM -0500, Brandon Allbery wrote:

On Sun, Nov 20, 2011 at 21:06, Ivan Lazar Miljenovic < ivan.miljenovic@gmail.com> wrote:

...

Wouldn't Perverse have some kind of random (via unsafePerformIO of course!) comparison functionality? ;-)

sortBy (\_ _ = EQ) ?

Haha, yes, having everything compare as equal sounds much more perverse: it is technically valid but completely defeats the entire purpose. (Random comparison, in comparison, would just be evil.) -Brent

On 11/19/11 6:07 AM, Sjoerd Visscher wrote:

I like the concept, but not the name. Inverse (or Inv) would be a better name imho.

+1, on both counts. -- Live well, ~wren