[GHC] #13697: Teach GHCi to deduplicate history

[GHC]

#13697: Teach GHCi to deduplicate history
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           Reporter:  bgamari        |             Owner:  (none)
               Type:  bug            |            Status:  new
           Priority:  normal         |         Milestone:
          Component:  Compiler       |           Version:  8.0.1
           Keywords:                 |  Operating System:  Unknown/Multiple
       Architecture:                 |   Type of failure:  None/Unknown
  Unknown/Multiple                   |
          Test Case:                 |        Blocked By:
           Blocking:                 |   Related Tickets:
Differential Rev(s):                 |         Wiki Page:
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 GHCi's (or rather, Haskeline's) history functionality tends to duplicate
 entries, even when the user used history to enter an entry. This is quite
 annoying and an issue I've not noticed in other command line libraries.

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Ticket URL: <http://ghc.haskell.org/trac/ghc/ticket/13697>
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