[GHC] #7102: Type family instance overlap accepted in ghci

[GHC]

#7102: Type family instance overlap accepted in ghci
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  Reporter:  exbb2                        |          Owner:                  
      Type:  bug                          |         Status:  closed          
  Priority:  normal                       |      Milestone:                  
 Component:  GHCi                         |        Version:  7.4.1           
Resolution:  wontfix                      |       Keywords:                  
        Os:  Unknown/Multiple             |   Architecture:  Unknown/Multiple
   Failure:  GHC accepts invalid program  |     Difficulty:  Unknown         
  Testcase:                               |      Blockedby:                  
  Blocking:                               |        Related:                  
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Comment(by simonpj):

 It turns out that, as Ian says, this is by design.  A new type instance
 declaration in GHCi ''replaces'' any earlier one with the same LHS.

 But it was not documented, so I have added a note to the user manual to
 say so.

 Simon

-- 
Ticket URL: <http://hackage.haskell.org/trac/ghc/ticket/7102#comment:2>
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