[GHC] #8539: Data.Complex shouldn't use default implementation of (**)

[GHC]

#8539: Data.Complex shouldn't use default implementation of (**)
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        Reporter:  jjaredsimpson     |            Owner:
            Type:  bug               |           Status:  new
        Priority:  low               |        Milestone:
       Component:  Prelude           |          Version:  7.6.3
      Resolution:                    |         Keywords:
Operating System:  Unknown/Multiple  |     Architecture:  Unknown/Multiple
 Type of failure:  Incorrect result  |       Difficulty:  Easy (less than 1
  at runtime                         |  hour)
       Test Case:                    |       Blocked By:
        Blocking:                    |  Related Tickets:
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Comment (by isaacdupree):

 That solves `0**nonzero`.  `0**0` is controversial but often 1 (
 https://en.wikipedia.org/wiki/0^0 ) and in Double is 1:
 {{{
 > 0**0 :: Double
 1.0
 }}}
 We probably want `0**0` to be consistent between Double and Complex
 Double.

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Ticket URL: <http://ghc.haskell.org/trac/ghc/ticket/8539#comment:1>
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