[GHC] #15895: Unable to match instance signatures

[GHC]

#15895: Unable to match instance signatures
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        Reporter:  Iceland_jack      |                Owner:  (none)
            Type:  bug               |               Status:  new
        Priority:  normal            |            Milestone:  8.6.3
       Component:  Compiler          |              Version:  8.6.2
      Resolution:                    |             Keywords:  InstanceSigs
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 goldfire):

 At issue here is whether the instance signature `id :: Arr a a` (excuse my
 Latin letters) stands alone, or should be considered in the context of the
 instance it's written in. Alone, there's no way to know that `a`'s kind is
 `Type`. But, in context, it's obvious. I think we should check an instance
 signature in light of this information.

-- 
Ticket URL: <http://ghc.haskell.org/trac/ghc/ticket/15895#comment:1>
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