[GHC] #9064: Support default class method signatures in Template Haskell

GHC ghc-devs at haskell.org
Fri May 2 18:02:58 UTC 2014


#9064: Support default class method signatures in Template Haskell
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       Reporter:  goldfire          |             Owner:  goldfire
           Type:  feature request   |            Status:  new
       Priority:  normal            |         Milestone:
      Component:  Template Haskell  |           Version:  7.8.2
       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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 If I say

 {{{
 blah = [d|
   class C a where
     foo :: a -> String
     default foo :: Show a => a -> String
     foo = show
   |]
 }}}

 I get

 {{{
     Illegal default signature for ‘[foo]’
     Default signatures are not supported by Template Haskell
 }}}

 I would like this feature. I will implement this in due course.

--
Ticket URL: <http://ghc.haskell.org/trac/ghc/ticket/9064>
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