[GHC] #8100: Standalone deriving using template haskell

[GHC]

#8100: Standalone deriving using template haskell
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       Reporter:  acube             |             Owner:
           Type:  feature request   |            Status:  new
       Priority:  normal            |         Milestone:
      Component:  Template Haskell  |           Version:
       Keywords:                    |  Operating System:  Unknown/Multiple
   Architecture:  Unknown/Multiple  |   Type of failure:  None/Unknown
     Difficulty:  Unknown           |         Test Case:
     Blocked By:                    |          Blocking:
Related Tickets:                    |
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 Currently, there seems to be no support for standalone deriving in
 TemplateHaskell:

 {{{
 Prelude Data.Typeable Language.Haskell.TH> :set -XStandaloneDeriving
 Prelude Data.Typeable Language.Haskell.TH> data Weird a (b :: * -> * -> *)
 c = Weird
 Prelude Data.Typeable Language.Haskell.TH> runQ $ [d| deriving instance
 Typeable Weird |]
 []
 }}}

 ''Use case'':

 The library [http://hackage.haskell.org/package/typeable-th typeable-th]
 can already generate Typeable instances using TH for GHC 7.4 and 7.6. To
 add support for GHC 7.8 in a way that the user doesn't have to care about
 the version, there has to be a way to make Typeable instances via TH in
 GHC 7.8. This is currently impossible, but with StandaloneDeriving support
 for TH, it would be possible.

-- 
Ticket URL: <http://ghc.haskell.org/trac/ghc/ticket/8100>
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