[Nix-dev] Nix expressions for channel nixpkgs-unstable

[Konrad Hinsen]

Eelco Dolstra writes:

 > Thanks, I've fixed this.  The problem was that Nixpkgs also contains packages
 > for Python 2.6 (the python26Packages attribute in all-packages.nix).  So if you

OK, that explains everything.

 > It's always possible to disambiguate by using the -A flag to select a package by
 > attribute name, e.g.:
 > 
 >   $ nix-env -iA pythonPackages.numpy

$ nix-env --dry-run  -iA pythonPackages.numpy
(dry run; not doing anything)
error: attribute `pythonPackages' in selection path `pythonPackages' not found

 > You can do a checkout of the Subversion repository of Nixpkgs.  However, the
 > Nixpkgs channel is *also* a "source code version"; it's just a copy of some
 > revision of the Nixpkgs repository, along with a pointer to pre-built binaries.

I think I found it:

  $HOME/.nix-defexpr/channels/nixpkgs_unstable/pkgs/

Still something seems to be missing. In
$HOME/.nix-defexpr/channels/nixpkgs_unstable/pkgs//top-level/all-packages.nix
I see definitions for various versions of gfortran, but I can't install them:

   $ nix-env --dry-run -i gfortran42
   (dry run; not doing anything)
   error: selector `gfortran42' matches no derivations


To make it even weirder:

   $ nix-env -i --dry-run python-numpy
   (dry run; not doing anything)
   warning: there are multiple derivations named `python-numpy-1.6.1'; using the first one
   installing `python-numpy-1.6.1'
   these derivations will be built:
     /nix/store/1amh5wlzx8gv1b1qfm8jbfgkwl4q223a-gfortran-4.6.3.drv
     /nix/store/45a1synjmzvx3hp8svk8h504z02mcwkb-hook.drv
     ...

which suggests there is a derivation called gfortran-4.6.3, but if I
ask for it it's not there:

   $ nix-env --dry-run -i gfortran-4.6.3
   (dry run; not doing anything)
   error: selector `gfortran-4.6.3' matches no derivations

Konrad.