[Haskell-cafe] Re: Unable to install packages

[Ketil Malde]

Thanks for the clarification, the SICP article was something I feel I
should have known, but did not.

It seems to me that while there are *three* ways to install stuff: apt-get
install, cabal install --global, and cabal install --user, there are
just *two* ways things get installed, globally and user(ly?).

The "obvious" solution would be to have three package.confs as well, say
"system" (/var/lib), "global" (/usr/lib?), and "user" (~/.ghc).
Is there a fundamental limitation of GHC or something that makes it
impossible to work with three package configuration files?  Or would
this not solve anything after all?  

-k

"Albert Y. C. Lai" <trebla at vex.net> writes:

> On 10-11-29 03:15 PM, Albert Y. C. Lai wrote:
>> cabal install --global binary
>> apt-get install libghc6-binary-dev
>>
>> They are the same version (at the time of writing, and assume Ubuntu
>> 10.10) and they will fight for the unique throne of "binary-0.5.0.2" in
>> the metadata.
>
> Oh bother, Debian/Ubuntu's packages are even more treacherous. They
> circumvent the uniqueness checks of ghc-pkg register. They just
> smuggle records into /var/lib/ghc-6.12.1/package.conf.d and call
> ghc-pkg recache. This procedure allows both binary-0.5.0.2 instances
> to be recorded, both as global. Ironically, ghc-pkg check does not see
> a problem.
>
> But this is more corruption, not less:
>
>> cabal install --global maccatcher
>> (this brings in binary)
>> apt-get install libghc6-agda-dev
>> (this brings in libghc6-binary-dev)
>
> The same problem remains. When you finally try to use binary, GHC
> still picks one instance only. Depend on luck, one of maccatcher and
> agda is hosed.
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