[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:  GHCi              |              Version:  8.0.1
      Resolution:                    |             Keywords:
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 nomeata):

 What I observe in bash (and miss in ghci as well) is that
 {{{
 $ ls
 $ ls
 $ history |tail -n 3
  4992  man bash
  4993  ls
  4994  history |tail -n 3
 }}}
 i.e. there are no *successive* duplicated entries.

 But
 {{{
 $ ls
 $ echo hi
 $ ls
 $ history |tail -n 4
  4995  ls
  4996  echo hi
  4997  ls
  4998  history |tail -n 4
 }}}
 so there is no duplication of everything. I believe the OP asks for the
 former (and I support this.)
 }}}

--
Ticket URL: <http://ghc.haskell.org/trac/ghc/ticket/13697#comment:4>
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