[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 dbaynard):

 I can certainly give a reason to deprecate (I wouldn't underestimate the
 confusion caused by this inconsistency; error messages for functions of
 the same name are often difficult to process) but I'm not well placed to
 describe it as an advantage.

-- 
Ticket URL: <http://ghc.haskell.org/trac/ghc/ticket/16009#comment:5>
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