[GHC] #8095: TypeFamilies painfully slow

[GHC]

#8095: TypeFamilies painfully slow
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        Reporter:  MikeIzbicki       |                Owner:  goldfire
            Type:  bug               |               Status:  new
        Priority:  high              |            Milestone:  8.4.1
       Component:  Compiler (Type    |              Version:  7.6.3
  checker)                           |
      Resolution:                    |             Keywords:  TypeFamilies
Operating System:  Unknown/Multiple  |         Architecture:
 Type of failure:  Compile-time      |  Unknown/Multiple
  performance bug                    |            Test Case:
      Blocked By:                    |             Blocking:
 Related Tickets:  #5321, #11598,    |  Differential Rev(s):  Phab:D3752
  #12506                             |
       Wiki Page:                    |
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Comment (by simonpj):

 As Richard says this is a direction we've been wanting to move for some
 time.

 But do read comment:15 above carefully.   It's ''crucial'' to keep track
 of the free coercion variables of a coercion, otherwise GHC may (after
 discarding coercions) "optimise" a correct program into one that seg-
 faults.  We don't wan that.

-- 
Ticket URL: <http://ghc.haskell.org/trac/ghc/ticket/8095#comment:41>
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