patch applied (packages/base): Must import ExitCode for its
instance to be re-exported.
Malcolm.Wallace at cs.york.ac.uk
Wed Aug 13 10:09:44 EDT 2008
Ross Paterson <ross at soi.city.ac.uk> wrote:
> > Wed Aug 13 05:57:10 PDT 2008 Malcolm.Wallace at cs.york.ac.uk
> > * Must import ExitCode for its instance to be re-exported.
> > The Cabal library depends on "instance Exception ExitCode", and
> > expects to import it from Control.Exception, not
> > Control.Exception.Base.
> But Control.Exception imports Control.Exception.Base.
> Is this another nhc98 thing?
I don't know whether it is H'98 behaviour, or something more quirky.
* C.E imports C.E.B, but does not import System.ExitCode.
* Hence, the instance for Exception ExitCode is not imported, since it
won't be needed.
* When C.E exports the class Exception, it only exports instances of
it for any types that are in scope.
* Hence, the instance for ExitCode is not exported.
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