[Haskell-cafe] How best to make GHC 6.6 and 6.8 co-exist on one server/account

Duncan Coutts duncan.coutts at worc.ox.ac.uk
Sat Jan 19 11:12:27 EST 2008

On Sat, 2008-01-19 at 10:47 -0500, Steve Lihn wrote:
> Hi,
> It appears some of the latest hackages are moving towards 6.8 to take
> advantage of the new features, while quite a few remains at 6.6. The
> compatibility between the two versions has been problematic. I only
> have 6.6 installed, but now thinking to add 6.8 to my account (so I
> can switch between them, depending what works where).

It should all work. I've got 3 ghc versions installed.

> What is the best practice to make 6.8 co-exist with 6.6 ? Specific
> questions are:
> 1) I installed 6.6 under prefix=$HOME/ghc. If I install 6.8 to the
> same prefix, it will overwrite 6.6. Correct? How do I get around it?

That could be ok. Check what the layout if $HOME/ghc is. If it looks

then that's fine and you'll be able to install another ghc to the same
prefix, since the sub-dirs are versioned. You'll end up with
$HOME/bin/ghc being the latest ghc, and the older version available as

> 2) I installed additional tools and packages under $HOME/htools using
> 6.6. (Which I begin to wonder if that is necessary.) Do I have to use
> a different directory for 6.8? I noticed that, for each package, the
> path is $HOME/htools/lib/<package-ver>/ghc-6.6.1/ etc etc. It seems
> that 6.8 will create subdirectories, so they can co-exist peacefully.
> Correct?


The aim is to be able to have multiple haskell implementations, multiple
versions of each haskell implementations and multiple versions of each
library built for any/all haskell implementation/version and to have
them all co-exist peacefully.


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