[GHC] #14203: GHC-inferred type signature doesn't actually typecheck

[GHC]

#14203: GHC-inferred type signature doesn't actually typecheck
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        Reporter:  RyanGlScott       |                Owner:  (none)
            Type:  bug               |               Status:  new
        Priority:  normal            |            Milestone:
       Component:  Compiler (Type    |              Version:  8.2.1
  checker)                           |             Keywords:  TypeInType,
      Resolution:                    |  TypeFamilies
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):

 I'm well aware of the fact that this is an ambiguous definition. But the
 point that I'm making (that no one has addressed yet) is that
 `AllowAmbiguousTypes` should allow GHC to accept such a definition!

 Replying to [comment:7 simonpj]:
 > But alas we do not check for ambiguous kinds.

 If we don't do this currently, then we should! There are many programs
 that I can't write because of this restriction.

-- 
Ticket URL: <http://ghc.haskell.org/trac/ghc/ticket/14203#comment:8>
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