[Haskell-cafe] [Haskell] JustHub 'Sherkin' Release

[Chris Dornan]

Hi Peter and Andres,

> > Where is this functionality provided by Nix?
>
> simply run these commands
>
> ...
>
> # Haskell Platform 2012.2.0.0'
> nix-env -p ~/ghc-7.4.1 -iA haskellPackages_ghc741.haskellPlatform
>
> and you'll have profiles that contain the appropriate binaries and
libraries
> defined by the corresponding platform. 

What you have here is a mechanism for setting up a user-environment for an
appropriate platform. Unfortunately I cannot see how it can address any of
the
user-level Haskell package database management and sandboxing mechanisms
that
I mentioned in the announcement and subsequent emails.  

Also it requires that the user load up a special environment before going to
work on a work tree rather than the drivers detecting from the context
the correct toolchain and invoking it automatically. It might not
sound like much but imagine how it would be if you had to set up a special
environment before you could work with a git work tree -- there is quite
a difference between the two approaches in practice.

Finally the Nix method is of course fundamentally dependent upon Nix.
I can appreciate why you may believe that everybody should just get Haskell
through Nix but I think there is merit to developing a mechanism that allows
Haskell to be better packaged regardless of its distribution channel. If
I thought there was any chance at all that Haskell could be universally
provided through Nix then it might be different, but I don't.  

None of which detracts from general excellence of Nix and the Nix Haskell
distribution. And I still think the mechanism I am proposing would work well
with the Nix distribution. Indeed it may be best placed to make full use of
it.

Chris