#2856: GeneralizedNewtypeDeriving doesn't work with data families
-----------------------------+----------------------------------------------
Reporter: guest | Owner:
Type: bug | Status: new
Priority: normal | Component: Compiler
Version: 6.10.1 | Severity: normal
Keywords: | Testcase:
Os: Unknown/Multiple | Architecture: Unknown/Multiple
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Observe:
{{{
{-# LANGUAGE TypeFamilies, GeneralizedNewtypeDeriving #-}
module Bug9 where
class C a where
data D a
instance C Bool where
newtype D Bool = DInt Int deriving (Eq, Show, Num)
}}}
The deriving of Num fails, whereas the corresponding standalone newtype
works fine.
--
Ticket URL: <http://hackage.haskell.org/trac/ghc/ticket/2856>
GHC <http://www.haskell.org/ghc/>
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