[GHC] #10097: GHC 7.11 errors on dictionary casting tricks

[GHC]

#10097: GHC 7.11 errors on dictionary casting tricks
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        Reporter:  heisenbug         |                   Owner:
            Type:  bug               |                  Status:  new
        Priority:  normal            |               Milestone:
       Component:  Compiler          |                 Version:  7.11
      Resolution:                    |                Keywords:
Operating System:  Unknown/Multiple  |            Architecture:
 Type of failure:  None/Unknown      |  Unknown/Multiple
      Blocked By:                    |               Test Case:
 Related Tickets:                    |                Blocking:
                                     |  Differential Revisions:
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Comment (by simonpj):

 A recent (somewhat obscure) change is that GHC actually does eta-expansion
 to make higher-rank types match up.  That is often useful (i.e. makes more
 programs typecheck).  And really it is confusing if eta-expansion can make
 a difference to type checking.

 So I'm disinclined to "fix" this.  Or at least I'd require more
 motivation!

 Simon

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Ticket URL: <http://ghc.haskell.org/trac/ghc/ticket/10097#comment:2>
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