[GHC] #14170: 8.2.1 regression: GHC fails to simplify `natVal`

[GHC]

#14170: 8.2.1 regression: GHC fails to simplify `natVal`
-------------------------------------+-------------------------------------
        Reporter:  vagarenko         |                Owner:  Bodigrim
            Type:  bug               |               Status:  new
        Priority:  high              |            Milestone:  8.2.3
       Component:  Compiler          |              Version:  8.2.1
      Resolution:                    |             Keywords:
Operating System:  Unknown/Multiple  |         Architecture:
                                     |  Unknown/Multiple
 Type of failure:  None/Unknown      |            Test Case:
      Blocked By:                    |             Blocking:
 Related Tickets:                    |  Differential Rev(s):
       Wiki Page:                    |
-------------------------------------+-------------------------------------

Comment (by mpickering):

 Could we not fix this by reverting
 1fcede43d2b30f33b7505e25eb6b1f321be0407f ?

 Is there enough motivation to replace the evidence type?

-- 
Ticket URL: <http://ghc.haskell.org/trac/ghc/ticket/14170#comment:9>
GHC <http://www.haskell.org/ghc/>
The Glasgow Haskell Compiler