[Haskell-cafe] Cabal failures...

[Greg Fitzgerald]

> cabal install -v cabal-install

Not sure if you're running into this one, but a configuration that
wasn't working for me:

1) Install Haskell Platform
2) Install GHC 7.6.1
3) cabal install cabal-install

As I recall, the error had something to do with a Cabal-generated
'Paths' file assuming the Prelude exported 'catch'.  It was affecting
a bunch of other packages too, which forced me to upgrade
cabal-install.

To get things working, I had to boot GHC 7.6 from my system PATH,
upgrade cabal-install using GHC 7.4, and then put 7.6 back in the
system path.  After doing that, everything has worked well with GHC
7.6.

-Greg


On Mon, Nov 19, 2012 at 1:38 PM, Johan Tibell <johan.tibell at gmail.com> wrote:
> Hi Greg,
>
> On Mon, Nov 19, 2012 at 1:25 PM, Gregory Guthrie <guthrie at mum.edu> wrote:
>>
>> I follow the Cabal-messes threads with some interest, since that is the
>> hardest area for me since starting to use Haskell. Probably 40-60% of all
>> package install fail for some mysterious reason, with threats that trying
>> to fix them will break more things, which generally is true. :-)
>
>
> We're working on it. Be brave, things are going to get better!
>
>>
>> I am not exert in the area, but I wonder how /why/ this is different than
>> other package managers, like apt in Linux, I have never had any problems
>> with it, and I would think that their dependencies are of at least similar
>> complexities.
>
>
> The Linux package managers solve a different problems. They let you install
> a set of packages that have been manually curated and are know to work
> together (i.e. all version dependencies are fixed) while cabal does version
> resolution on packages that might not ever have been tried together. If you
> install Haskell packages via your distro's package manager I assume they
> will always install cleanly. The problem is that people want the latest
> bleeding edge of packages, which haven't made it into the distros yet, and
> hence they get to experience some of the pains associated with being on the
> bleeding edge. Being on Windows also makes things harder, as most developers
> don't have a Windows box to test their stuff on.
>
>>
>> In any case; Trying to do a cabal update" I was told to try to update
>> "cabal-install", which I think means actually updating cabal (since I
>> actually run installs via cabal install...), but that fails with this
>> message below, and I don't know how to proceed.
>
>
> cabal-install is the package that includes the "cabal" executable. Cabal
> (with a capital C) is the library that cabal-install uses. The naming is
> unfortunate but hard to change at this point. To update cabal-install you
> do:
>
> $ cabal update && cabal install cabal-install
>
> Make sure that the place that the "cabal" binary gets installed into (which
> is printed at the end of the install) is on your PATH.
>
>>
>> Linking
>> C:\Users\guthrie\AppData\Local\Temp\Cabal-1.16.0.3-13880\Cabal-1.16.0.3\dist\setup\setup.exe
>> ...
>> Configuring Cabal-1.16.0.3...
>> Warning: This package indirectly depends on multiple versions of the same
>> package. This is highly likely to cause a compile failure.
>
>
> This is a sure sign that things are not going to work well. Could you
> include the output of
>
> cabal install -v cabal-install
>
> please. The output here is not enough to tell me what's going on. Please
> also include the output of
>
> cabal --version
> ghc --version
>
> Are you using the Haskell Platform, if so, which version?
>
> -- Johan
>
>
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