[Haskell-cafe] Potential problem with AC-Vector-Fancy package

Andrew Coppin andrewcoppin at btinternet.com
Thu Aug 11 19:45:08 CEST 2011

On 10/08/2011 11:04 PM, Dave Tapley wrote:
> Is anyone maintaining the AC-Vector-Fancy package?
> I haven't had a reply from the latest maintainer (Andrew Coppin) on
> Hackage, so I thought I'd open it up to cafe:

Oh, right. I haven't checked my mailbox recently...

> I think I have found a problem with the union function:
> If you look here: http://hpaste.org/49889
> You will see that line 4 gives a different result to lines 6, 8, 10;
> this shouldn't be the case because union is commutative.

AC-Vector-Fancy is merely a "fancy" facard over AC-Vector. So the bug is 
actually with AC-Vector.

Looking at my source code, the true bug is in Data.BoundingBox.Range 
[which provides the engine that all the other bounding box types use). 
The actual bug turns out to by face-slappingly stupid: it's a typo in 
one of the variable names.

I'll go get that fixed... and then maybe write some QuickCheck properties.

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