[Haskell-cafe] Either as a Monad instance

[Ross Paterson]

On Tue, Oct 03, 2006 at 07:52:54AM -0400, Lennart Augustsson wrote:
> Yes, having fail in the Monad is a horrible wart.
> And like some other warts in Haskell it was added to cure the symptom  
> rather than the disease. :(

Switching metaphors, what do you see as the disease in this case?
(As far as I know, it's there for the translation of pattern match
failure in do-expressions.)