[GHC] #15453: Bug in opt_trans_rule in OptCoercion

[GHC]

#15453: Bug in opt_trans_rule in OptCoercion
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        Reporter:  ningning          |                Owner:  ningning
            Type:  bug               |               Status:  closed
        Priority:  normal            |            Milestone:  8.6.1
       Component:  Compiler          |              Version:  8.4.3
      Resolution:  fixed             |             Keywords:
Operating System:  Unknown/Multiple  |         Architecture:
                                     |  Unknown/Multiple
 Type of failure:  None/Unknown      |            Test Case:
      Blocked By:                    |             Blocking:
 Related Tickets:                    |  Differential Rev(s):  Phab:D5018
       Wiki Page:                    |
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Comment (by ningning):

 Replying to [comment:14 simonpj]:
 > A first step would be to include `GRefl` and anything else that isn't
 reflected in the paper.

 Questions:

 - In this paper, types and kinds are separated, coercions are between
 types, and they are homogeneous; while in GHC, types and kinds are merged,
 coercions can be between kinds. This is important because all GRefl is
 doing is casts between kinds. Do we want to merge types and kinds in the
 paper, make coercion heterogeneous and add kinds information?
 - Do we want to add roles?
 - If the answer is yes for both questions, I am actually wondering if it
 might be simpler to add coercion optimization rules in core-spec.

-- 
Ticket URL: <http://ghc.haskell.org/trac/ghc/ticket/15453#comment:16>
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