[GHC] #9588: Add `MonadPlus {IO, Either e}` and `Alternative (Either e)` instances

[GHC]

#9588: Add `MonadPlus {IO,Either e}` and `Alternative (Either e)` instances
-------------------------------------+-------------------------------------
       Reporter:  hvr                |                   Owner:  hvr
           Type:  task               |                  Status:  new
       Priority:  normal             |               Milestone:  7.10.1
      Component:  libraries/base     |                 Version:
       Keywords:                     |        Operating System:
   Architecture:  Unknown/Multiple   |  Unknown/Multiple
     Difficulty:  Unknown            |         Type of failure:
     Blocked By:                     |  None/Unknown
Related Tickets:                     |               Test Case:
                                     |                Blocking:
                                     |  Differential Revisions:
-------------------------------------+-------------------------------------
 The following 3 instances are currently Orphans in `transformers` but
 shall be defined in `base` instead:

 {{{#!hs
 instance MonadPlus IO
 instance MonadPlus (Either e)
 instance Alterantive (Either e)
 }}}

 This proposal by SPJ already passed the CLC back in April and only needs
 implementing. I'll submit a patch shortly to Phab

--
Ticket URL: <http://ghc.haskell.org/trac/ghc/ticket/9588>
GHC <http://www.haskell.org/ghc/>
The Glasgow Haskell Compiler