[Haskell-cafe] Re: cabal install HaXml installs wrong version unless I specify the version number

Duncan Coutts duncan.coutts at worc.ox.ac.uk
Sat Nov 15 08:39:18 EST 2008

On Sat, 2008-11-15 at 13:31 +0100, Thomas Hartman wrote:
> This is all news to me, and un-googleable to boot:
> http://www.google.pl/search?hl=en&sa=X&oi=spell&resnum=0&ct=result&cd=1&q=cabal+referred-versions&spell=1
> (no results)

It finds something for me (with the right spelling of preferred), eg
this thread from the libraries list:


> So yes, I think this referred-versions machinery should at least be
> made more transparent for situations when it does the wrong thing,
> like with xml-parsec.

Sure, though it is worth remembering that doing the right thing for
xml-parsec is completely a guessing game since the package does not say
which version it needs and yet works with some versions and not others.
That is the root of this problem. We should be thinking about ways to
persuade package authors (or others) to supply the correct information.

That's where the package versioning policy comes in.

> I think your last suggestion is good
> > cabal install haxml
> > Downloading HaXml-1.13.3...
> > Note: the recommended version is HaXml-1.13.3 but latest version is
> > HaXml-1.19, use cabal install haxml-1.19 if you want that version.
> I would have this message pop up for both cabal install and cabal
> upgrade -- especiallly since with cabal upgrade the result was for me
> completely bafflling.

Ok, so that we do not forget this, would you mind filing a ticket to
explain the confusion and the suggested solution. Linking to this thread
would also help.



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