[GHC] #16009: Deprecate `optional` from Text.ParserCombinators.ReadP

[GHC]

#16009: Deprecate `optional` from Text.ParserCombinators.ReadP
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        Reporter:  dbaynard          |                Owner:  (none)
            Type:  feature request   |               Status:  new
        Priority:  normal            |            Milestone:  8.10.1
       Component:  libraries/base    |              Version:  8.6.2
      Resolution:                    |             Keywords:  Applicative,
                                     |  Parsers, ReadP
Operating System:  Unknown/Multiple  |         Architecture:
                                     |  Unknown/Multiple
 Type of failure:  Other             |            Test Case:
      Blocked By:                    |             Blocking:
 Related Tickets:                    |  Differential Rev(s):
       Wiki Page:                    |
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Comment (by mpickering):

 It isn't really clear what the advantage here is to deprecating this
 function. There is the clear disadvantage that it will break people's
 programs which use it. Does anyone feel the pain of this inconsistency?

-- 
Ticket URL: <http://ghc.haskell.org/trac/ghc/ticket/16009#comment:4>
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