[GHC] #10751: Implement Phase 1 of MonadFail Proposal (MFP)

[GHC]

#10751: Implement Phase 1 of MonadFail Proposal (MFP)
-------------------------------------+-------------------------------------
        Reporter:  hvr               |                Owner:  quchen
            Type:  task              |               Status:  patch
        Priority:  highest           |            Milestone:  8.0.1
       Component:  Compiler          |              Version:  7.10.2
      Resolution:                    |             Keywords:  report-impact
Operating System:  Unknown/Multiple  |         Architecture:
                                     |  Unknown/Multiple
 Type of failure:  None/Unknown      |            Test Case:
      Blocked By:                    |             Blocking:
 Related Tickets:                    |  Differential Rev(s):  Phab:D1248
-------------------------------------+-------------------------------------

Comment (by spl):

 I worked a bit on the wiki proposal.

 I think it would be good to indicate (1) which {{{MonadFail}}} instances
 will be created and (2) which types with {{{Monad}}} instances will not
 have {{{MonadFail}}} instances. Since this change affects a number of
 important packages, those packages should probably be included.

 Also, I'm not clear on the conclusion for having {{{Monad}}} vs.
 {{{Applicative}}} as the superclass constraint on {{{MonadFail}}}. I tried
 to develop the discussion text on this a bit. Since we're getting
 {{{ApplicativeDo}}} soon, I think it would be useful to work out whether
 and how these two features are related. I didn't see anything on
 ApplicativeDo referring to the desugaring of pattern matching.

--
Ticket URL: <http://ghc.haskell.org/trac/ghc/ticket/10751#comment:16>
GHC <http://www.haskell.org/ghc/>
The Glasgow Haskell Compiler