Re: #4159: move Monad and MonadFix instances for Either from mtl to base

I can't decide if I like the fail s = error s or fail s = Left (error s) behaviour better, and I'd prefer if we could put whatever we decide upon in the Prelude, but +1 for the proposal overall. I'd also like the function instances of Functor and Monad in the Prelude, for that matter. - Cale On 30 June 2010 19:25, Edward Kmett wrote:

On Wed, Jun 30, 2010 at 6:57 PM, Ross Paterson wrote:

...

On Thu, Jul 01, 2010 at 12:29:57AM +0200, Claus Reinke wrote:

...

As I said, even if you just want to drop 'Error', you could define 'fail s = Left (error s)'. That would still be less defined than the current instance, but more defined than the proposed instance.

That didn't occur to me -- it seems harmless enough, but it wouldn't be enough to support pattern binding with the Either monad, would it?

I think it would be. -Edward Kmett _______________________________________________ Libraries mailing list Libraries@haskell.org http://www.haskell.org/mailman/listinfo/libraries