[GHC] #9627: Type error with functional dependencies

[GHC]

#9627: Type error with functional dependencies
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        Reporter:  augustss          |                Owner:  (none)
            Type:  bug               |               Status:  new
        Priority:  normal            |            Milestone:
       Component:  Compiler (Type    |              Version:  7.8.3
  checker)                           |
      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 simonpj):

 > Does that "inability" date to before the FDs via CHRs 2006 paper?

 I think that
 [https://people.cs.kuleuven.be/~tom.schrijvers/portfolio/haskell2017a.html
 Elaboration on functional dependencies] (Karachalias and Schrijvers, 2017)
 does he job nicely.  Indeed they use the above example in their motivation
 section.  It describes how to translate fundeps into type families -- so
 the intermediate language is exactly System FC, as today.

 I never implemented this, but if someone did then fundeps would acquire
 the same expressive power as type families.

-- 
Ticket URL: <http://ghc.haskell.org/trac/ghc/ticket/9627#comment:4>
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