patch applied (packages/mtl): use Control.Monad.Instances from base

[Donald Bruce Stewart]

ross:
> Mon Apr 10 04:25:33 PDT 2006  Ross Paterson <ross at soi.city.ac.uk>
>   * use Control.Monad.Instances from base
> 
>     M ./Control/Monad/Error.hs -4 +1
>     M ./Control/Monad/Reader.hs -10 +1

Oh, that reminds me. Something we've often talked about on #haskell.
Should the (a -> ) monad in Control.Monad.Reader be moved into the base
package, since its such a fundamental structure?

Its quite hard to find, which is annoying since lambdabot's refactoring
tools use the (a ->) monad all over the place.

This guy:
    instance Functor ((->) r) where
        fmap = (.)

    instance Monad ((->) r) where
        return  = const
        m >>= k = \r -> k (m r) r

Anyone agree? Seems very "foundational"

-- Don