[Haskell-cafe] Unable to install packages

[Albert Y. C. Lai]

On 10-11-30 05:19 AM, Ketil Malde wrote:
> 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?

GHC is glad to take more databases, using -package-conf and 
GHC_PACKAGE_PATH.
http://www.haskell.org/ghc/docs/latest/html/users_guide/packages.html#package-databases

However, all tricks of installing a million instances of binary-0.5.0.2 
are in vain — GHC will still pick one instance by a priority rule and 
ignore the rest.