[GHC] #4259: Relax restrictions on type family instance overlap

[GHC]

#4259: Relax restrictions on type family instance overlap
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    Reporter:  lilac                    |       Owner:                  
        Type:  feature request          |      Status:  new             
    Priority:  normal                   |   Milestone:  7.6.1           
   Component:  Compiler (Type checker)  |     Version:  6.12.1          
    Keywords:                           |          Os:  Unknown/Multiple
Architecture:  Unknown/Multiple         |     Failure:  None/Unknown    
  Difficulty:                           |    Testcase:                  
   Blockedby:                           |    Blocking:                  
     Related:                           |  
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Comment(by goldfire):

 I ([http://www.cis.upenn.edu/~eir Richard]) am working on adding
 overlapping type family instances and have documented my work on the
 NewAxioms page. That work is somewhat orthogonal to the discussion here,
 but it touches on some of these issues. Of perhaps more direct interest is
 NewAxioms/CoincidentOverlap, which directly continues the discussion
 started here. Any comments and/or feedback welcome.

-- 
Ticket URL: <http://hackage.haskell.org/trac/ghc/ticket/4259#comment:21>
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