Old code broken by new Typeable class
2014-08-05 16:41:05 GMT
I've been working with GHC-4.6.3, and updating to GHC-4.8.3 breaks my code,
because the Typeable class has been changed. The compiler produces this
‘typeOf’ is not a (visible) method of class ‘Typeable’
I want to define System.Posix.Process.ProcessStatus to be an instance of
Typeable, so I can throw and catch it as an exception. ProcessStatus isn't
typeable by default.
Is it still possible to make ProcessStatus a member of Typeable? How?
Obviously, you can't accomplish it by deriving Typeable, because the definition
can't be changed any longer.
This is the spot in question:
data ProcessStatus = Exited ExitCode
| Terminated Signal
| Stopped Signal
deriving (Eq, Ord, Show)
instance Typeable ProcessStatus where
typeOf = const tyCon_ProcessStatus
tyCon_ProcessStatus = mkTyConApp (mkTyCon3 "hsshellscript"
instance Exception ProcessStatus
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