[GHC] #3787: GHC 6.12.1 panic

[GHC]

#3787: GHC 6.12.1 panic
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    Reporter:  blamario                 |        Owner:  simonpj                           
        Type:  bug                      |       Status:  infoneeded                        
    Priority:  normal                   |    Milestone:  7.0.1                             
   Component:  Compiler (Type checker)  |      Version:  6.12.1                            
    Keywords:  panic                    |     Testcase:  indexed-types/should_compile/T3787
   Blockedby:  4232                     |   Difficulty:                                    
          Os:  Linux                    |     Blocking:                                    
Architecture:  x86_64 (amd64)           |      Failure:  Compile-time crash                
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Comment(by simonpj):

 For reasons described in "Let should not be generalised" GHC doesn't
 generalise local let bindings, at least not when you are using GADTs.
 That can give rise to skolem escape checks like you see.

 The fix is to add a type signature for your local definition; in this case
 you probably want a type signature for 'repeat'.  Does that fix it?

 Simon

-- 
Ticket URL: <http://hackage.haskell.org/trac/ghc/ticket/3787#comment:12>
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