[Nix-dev] Using several versions of GHC at once

[Vladimír Čunát]

On 06/12/2013 01:19 AM, Nikita Karetnikov wrote:
> I'm trying to install several versions of GHC.  There are two
> problems:
>
> 1. According to this page [1], it should be possible to use multiple
>     versions at once.  But 'nix-env -iA' always replaces the previous
>     version.  For example, if I run the following commands:
>
>     # nix-env -iA nixpkgs.haskellPackages_ghc6104.ghc
>     # nix-env -iA nixpkgs.haskellPackages_ghc762.ghc
>
>     my profile will only contain 'ghc-7.6.2', not both.  I can "switch"
>     to 6.10.4 if I execute the first command again.  But the mentioned
>     page says that it's only necessary "to invoke the versioned binaries
>     [...] in order to get the correct instance."

Installing multiple versions at once does *not* imply installing them 
into one profile. What would "ghc" command do?? However, any user can 
use any number of profiles, e.g. people do that they create a profile 
for every project they're working on... because you might want a 
different GHC there than you're using as normal user.


Vlada


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