[GHC] #13337: GHC doesn't think a type is of kind *, despite having evidence for it

[GHC]

#13337: GHC doesn't think a type is of kind *, despite having evidence for it
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        Reporter:  RyanGlScott       |                Owner:  (none)
            Type:  bug               |               Status:  new
        Priority:  normal            |            Milestone:
       Component:  Compiler (Type    |              Version:  8.0.2
  checker)                           |
      Resolution:                    |             Keywords:
Operating System:  Unknown/Multiple  |         Architecture:
 Type of failure:  GHC rejects       |  Unknown/Multiple
  valid program                      |            Test Case:
      Blocked By:                    |             Blocking:
 Related Tickets:                    |  Differential Rev(s):
       Wiki Page:                    |
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Comment (by RyanGlScott):

 Ah, I completely overlooked bottoming equalities. Thanks for the
 reference.

 In light of this, my "equivalent" program in comment:3 is not equivalent
 at all, since the `k ~ Type` evidence in `go_on` isn't known //a priori//
 to terminate, whereas in the original program, the equality is known not
 to bottom out by pattern matching on `Refl`.

 So I suppose a better title for this bug would be "GHC doesn't think a
 type is of kind *, despite having Typeable-induced evidence for it", and
 the first program would be related to Dependent Haskell, which is, erm, in
 progress :)

--
Ticket URL: <http://ghc.haskell.org/trac/ghc/ticket/13337#comment:5>
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