[GHC] #8356: Strangeness with FunDeps

[GHC]

#8356: Strangeness with FunDeps
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        Reporter:  ksf                        |            Owner:
            Type:  bug                        |           Status:  new
        Priority:  normal                     |        Milestone:
       Component:  Compiler                   |          Version:  7.7
      Resolution:                             |         Keywords:
Operating System:  Unknown/Multiple           |     Architecture:
 Type of failure:  GHC rejects valid program  |  Unknown/Multiple
       Test Case:                             |       Difficulty:  Unknown
        Blocking:                             |       Blocked By:
                                              |  Related Tickets:
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Comment (by ksf):

 For reference, here's the whole code:

 http://lpaste.net/93383

 ...trying to minimise the inferred type for {{{foo}}}, both with and
 without {{{li}}} fixed. With the added {{{sy ys -> b}}} constraint, the
 {{{ElemTy sy ys ~ b}}} constraint on {{{mapKey}}} could be elided.

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Ticket URL: <http://ghc.haskell.org/trac/ghc/ticket/8356#comment:3>
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