#1769: Deriving Typeable for data families
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Reporter: chak | Owner: chak
Type: task | Status: closed
Priority: low | Milestone: 7.0.1
Component: Compiler (Type checker) | Version: 6.9
Resolution: fixed | Keywords:
Testcase: indexed-types/should_compile/T1769 | Blockedby:
Difficulty: Unknown | Os:
Unknown/Multiple
Blocking: | Architecture:
Unknown/Multiple
Failure: None/Unknown |
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Comment(by heatsink):
Replying to [comment:10 mitar]:
As a workaround, you can derive from Typeable without this feature by
writing your own instance.
{{{
data family T a
instance Typeable a => Typeable (T a) where
typeOf x = mkTyConApp (mkTyCon "T") [typeOf (unT x)]
where
unT :: T a -> a
unT = undefined
}}}
--
Ticket URL: <http://hackage.haskell.org/trac/ghc/ticket/1769#comment:11>
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