[GHC] #7776: Can't make operator called ~#

[GHC]

#7776: Can't make operator called ~#
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  Reporter:  adrianmay                  |          Owner:                           
      Type:  bug                        |         Status:  closed                   
  Priority:  normal                     |      Milestone:                           
 Component:  Compiler (Parser)          |        Version:  7.6.1                    
Resolution:  fixed                      |       Keywords:  tilde hash sharp operator
        Os:  Linux                      |   Architecture:  x86_64 (amd64)           
   Failure:  GHC rejects valid program  |     Difficulty:  Unknown                  
  Testcase:                             |      Blockedby:                           
  Blocking:                             |        Related:                           
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Comment(by goldfire):

 I would argue that {{{~#}}} should never be user-visible syntax, as there
 is no use case for it. In source Haskell, {{{~#}}} is a type constructor
 of kind {{{k -> k -> #}}} but this type has no values. This certainly
 isn't blocking anything, but I was quite surprised that {{{~#}}} was
 available at all in source Haskell.

 For those of you unfamiliar with {{{~#}}}, that's the type constructor for
 GHC's internal notion of type equality --- it's an unlifted form of
 {{{~}}}.

-- 
Ticket URL: <http://hackage.haskell.org/trac/ghc/ticket/7776#comment:4>
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