simultaneous ghc versions

Erik de Castro Lopo mle+hs at
Fri Jul 31 22:20:54 UTC 2015

Wolfram Kahl wrote:

> I use essentially the same setup,
> but found that cabal-install does not play nicely with this:
> No matter under which prefix I install cabal-install,
> it always assumes the same global path for its configuration file.

I install cabal-install from debian which just puts it in /usr/bin/
which works fine, with and without sandboxes.

> This is a nuisance in particular when for some reason different versions
> of GHC need different versions of cabal-install --- apparently older GHCs
> don't work with newer versions of cabal-install?

I have not run into this problem with ghc-7.6.3, ghc-7.8.4 and ghc-7.10.2

> I did experiment with cabal-install's -w and sandboxes,
> and agree with what was previously mentioned:
> It only helps if you never use GHC without cabal-install.

With a recent version of cabal, run 'cabal user-config diff' to 
display what if different between your ~/.cabal/config and what
cabal would install if it didn't exist. Sometimes an older
~/.cabal/config file can cause troubles.


PS: Please reply to the list and do not CC me.
Erik de Castro Lopo

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