[Haskell-cafe] Colour tutorial (Was: AC-Vector, AC-Colour and
derek.a.elkins at gmail.com
Sat Jul 11 14:12:33 EDT 2009
On Sat, Jul 11, 2009 at 12:54 PM, Derek Elkins<derek.a.elkins at gmail.com> wrote:
> On Fri, Jul 10, 2009 at 12:42 AM, <roconnor at theorem.ca> wrote:
>> On Thu, 9 Jul 2009, roconnor at theorem.ca wrote:
>>> You can use by lib without worrying about the CIE. You can use my library
>>> without ever importing or using the word CIE. However, the CIE stuff is
>>> there for those who need it.
>>> Perhaps I (maybe with some help) need to make a tutorial on the haskell
>>> wiki to try to make it less intimidating.
>> Okay, I threw together a quick introduction at
>> <http://www.haskell.org/haskellwiki/Colour>. Any changes, comments,
>> corrections, and addtions are welcome. It's a wiki!
>> The word CIE does occur at all in the document.
> I read this and it irks me that opaque is not a monoid homomorphism
> despite being the natural injection of non-transparent colours into
> semi-transparent colours with pureColour being the projection back.
> [Incidentally, you have a typo in pureColour, ac `over` mempty should
> be ac `over` black or opaque black presumably, or even opaque mempty,
> which I think was what you were going for, illustrating my point.]
> It's like defining mappend on Integers as (+) and on Reals as (*);
> actually, I think this is very close to what is actually happening.
I'm mistaken about the typo in pureColour, but luckily the mistake
just further illustrates my point.
More information about the Haskell-Cafe