Re: [GHC] #11719: Cannot use higher-rank kinds with type families

21 Mar 2016

      #11719: Cannot use higher-rank kinds with type families
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        Reporter:  ocharles          |                Owner:
            Type:  bug               |               Status:  new
        Priority:  normal            |            Milestone:
       Component:  Compiler (Type    |              Version:  8.0.1-rc2
  checker)                           |
      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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Comment (by Richard Eisenberg ):

 In [changeset:"1701255c06fed2aa2811f7f29f108d88fc4d6f26/ghc" 1701255/ghc]:
 {{{
 #!CommitTicketReference repository="ghc"
 revision="1701255c06fed2aa2811f7f29f108d88fc4d6f26"
 Fix #11635 / #11719.

 Instead of creating a new meta-tyvar and then unifying it with
 a known kind in a KindedTyVar in a LHsQTyVars, just use the known kind.

 Sadly, this still doesn't make #11719 usable, because while you can
 now define a higher-kinded type family, you can't write any equations
 for it, which is a larger problem.

 test cases: dependent/should_compile/T{11635,11719}
 }}}

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Ticket URL: http://ghc.haskell.org/trac/ghc/ticket/11719#comment:1
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