darcs patch: Adding isLeft, isRight, fromLeft, fromRight, splitEithers

[Ross Paterson]

On Tue, Oct 31, 2006 at 02:20:04PM +0300, Bulat Ziganshin wrote:
> nevertheless, we want to use them all :)   "don't teach me a life,
> just give some money :)"

Sure.  Meanwhile over at http://hackage.haskell.org/trac/ghc/ticket/960
we have yet another discussion of how to track down the runtime errors
that result from this style.