[GHC] #7459: deriving Generic does not work with TypeLits

[GHC]

#7459: deriving Generic does not work with TypeLits
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Reporter:  maxtaldykin       |          Owner:  dreixel         
    Type:  feature request   |         Status:  new             
Priority:  normal            |      Component:  Compiler        
 Version:  7.6.1             |       Keywords:                  
      Os:  Unknown/Multiple  |   Architecture:  Unknown/Multiple
 Failure:  Other             |      Blockedby:                  
Blocking:                    |        Related:                  
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Changes (by dreixel):

  * owner:  => dreixel
  * failure:  GHC rejects valid program => Other
  * type:  bug => feature request


Comment:

 Thanks for the report, although I don't think this is a bug. We have not
 intended `Generic` to be used with `TypeLits` (or any `DataKinds` stuff);
 the error message is not entirely accurate, but that's not what you are
 reporting.

 Changing `isTauTy` might have deep implications throughout the compiler; I
 don't think that's the right "fix" here. I would be more inclined to
 change `bad_arg_type` in `TcGenGenerics`. But first we should think
 exactly of what generic programming with arguments of kind `Symbol`
 implies. Can you tell me what kind of generic functionality you want on
 datatypes such as `F` and `X`? Just some example values and the functions
 you would want to use on them would be clarifying.

-- 
Ticket URL: <http://hackage.haskell.org/trac/ghc/ticket/7459#comment:1>
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