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

[GHC]

#14170: 8.2.1 regression: GHC fails to simplify `natVal`
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        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:                    |
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Changes (by RyanGlScott):

 * cc: phadej (added)


Comment:

 We certainly wouldn't want to revert that commit in its entirety (if that
 is the route we decide to embark on)—besides changing the evidence type,
 that commit also reworked `base` a bit to export a different API in the
 form of the `GHC.TypeNats` module. We could conceivably change the
 evidence type and keep the new API, but it would take some care.

 To be honest, I'm inclined to just wait for Bodigrim's patch. After all,
 these changes are already in a released version of GHC—I'd rather wait
 slightly longer to get things right.

 (cc'ing phadej, who authored 1fcede43d2b30f33b7505e25eb6b1f321be0407f)

-- 
Ticket URL: <http://ghc.haskell.org/trac/ghc/ticket/14170#comment:10>
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