Overlapping instances vs. Haskell98 Report [was: How to disable warning for "export item 'module ...' exports nothing"?]

[Isaac Dupree]

Sean Leather wrote:
> That's interesting. So, maybe there should be some language extension or
> warning (with associated -fno-warn) for this in GHC.
> 
> Personally, I prefer the way it's done now. (I guess that's obvious,
> considering I'm developing a library that will take advantage of it. ;) )
> But it makes sense that instances are only looked up when needed, instead of
> globally tracked.

see: http://hackage.haskell.org/trac/ghc/ticket/2356