Haddock generated documentation for Control.Monad.Error

[Sean Seefried]

Hi,

When I look in the Haddock generated code at:  
http://www.haskell.org/ghc/docs/latest/html/libraries/base/ 
Control.Monad.html#t%3AMonadPlus, I don't seem to find any reference to  
the IO monad being an instance of the MonadPlus class.

But when I look at the source code in  
libraries/mtl/Control/Monad/Error.hs it clearly is.  Why is this  
happening?

Cheers,

Sean