#4807: Data instance for Data.Map is incomplete
---------------------------------+------------------------------------------
Reporter: sclv | Owner:
Type: bug | Status: new
Priority: normal | Component: libraries/base
Version: 7.0.1 | Keywords:
Testcase: | Blockedby:
Os: Unknown/Multiple | Blocking:
Architecture: Unknown/Multiple | Failure: Incorrect result at runtime
---------------------------------+------------------------------------------
There's no dataCast1 defined for Data.Map. This makes the `ext1` family
unusable with Maps, since `ext` is built on dataCast rather than gcast.
Observe:
{{{
Prelude Data.Data Data.Generics Data.Map> gcast1 (Just empty :: forall d.
(Data d) => Maybe (Map Int d)) :: Maybe (Maybe (Map Int Int))
Just (Just (fromList []))
Prelude Data.Data Data.Generics Data.Map> dataCast1 (Just empty :: forall
d. (Data d) => Maybe (Map Int d)) :: Maybe (Maybe (Map Int Int))
Nothing
}}}
--
Ticket URL: <http://hackage.haskell.org/trac/ghc/ticket/4807>
GHC <http://www.haskell.org/ghc/>
The Glasgow Haskell Compiler
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