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

Edward Kmett ekmett at gmail.com
Wed Jun 30 19:25:42 EDT 2010

On Wed, Jun 30, 2010 at 6:57 PM, Ross Paterson <ross at soi.city.ac.uk> 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
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