[GHC] #5978: Type error in one function causes wrong type error report in another function in the presence of functionally dependent types

[GHC]

#5978: Type error in one function causes wrong type error report in another
function in the presence of functionally dependent types
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    Reporter:  Lemming                  |       Owner:                           
        Type:  bug                      |      Status:  new                      
    Priority:  normal                   |   Milestone:                           
   Component:  Compiler (Type checker)  |     Version:  7.4.1                    
    Keywords:                           |          Os:  Unknown/Multiple         
Architecture:  Unknown/Multiple         |     Failure:  GHC rejects valid program
  Difficulty:  Unknown                  |    Testcase:                           
   Blockedby:                           |    Blocking:                           
     Related:                           |  
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Comment(by Lemming):

 At first I thought that the type checker is wrong, since it reports a type
 error where no type error is. If I understand you correctly, then GHC
 still correctly identifies type correct and type incorrect programs, only
 the error message is misleading. If so, then this bug has no high priority
 for me.
 You may simply add "if this type error message confuses you, then better
 switch to type families" to every type error message concerning functional
 dependencies. :-)

-- 
Ticket URL: <http://hackage.haskell.org/trac/ghc/ticket/5978#comment:8>
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