On Tue, Jun 29, 2010 at 09:16:03PM +0200, Claus Reinke wrote:
-1, because the default definition of fail is error, which would render the Monad instance useless (unless I'm missing something?).
I don't see this as a problem, the either monad provides a generic monad with a short-circuit return, there is no particular reason to associate a short circuit return with failure. There can be many reasons you want a short circuit return rather than just a concept of 'failure'. The original mistake was thinking that 'Left' had to be associated with failure or errors for some reason. Like any other monad without a sensible definition for 'fail', the default of 'error' is just fine. John -- John Meacham - ⑆repetae.net⑆john⑈ - http://notanumber.net/