[Haskell-cafe] Re: problem with cabal for syb-with-class

Andrew U. Frank frank at geoinfo.tuwien.ac.at
Tue Aug 26 11:43:50 EDT 2008

thank you very much for the explanation!
i take that in this case, the error is in the cabal, which does not list
the required package.


On Tue, 2008-08-26 at 15:09 +0100, Duncan Coutts wrote:
> On Tue, 2008-08-26 at 14:30 +0100, Dougal Stanton wrote:
> > On Tue, Aug 26, 2008 at 2:22 PM, Duncan Coutts
> > <duncan.coutts at worc.ox.ac.uk> wrote:
> > 
> > > So when ghc finds that one of your modules needs to import something
> > > that is not in one of the given packages it says that it's in another
> > > package that is 'hidden'. Of course it's only hidden because Cabal told
> > > ghc to hide them.
> > 
> > Yes, it is one of those unfortunate error messages that says "I know
> > what the problem is *and* how to fix it, but I'm not going to". ;-)
> Actually it's more like: "I know what the problem is but I cannot fix
> it. He knows how to fix it, but doesn't know there's a problem!" :-)
> GHC knows what the problem is but it's just following orders. Cabal gave
> the orders but doesn't know there is a problem.
> That's why it'll be fixed when Cabal does the dep chasing rather than
> delegating that to ghc --make. Cabal will then be able to either just
> pull in the (probably) right packages, or report the problem using the
> language of the problem domain and not the implementation.
> Duncan

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