Build an environment containing Python packages

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1

I’m trying to build an environment to manage my packages declaratively. Following the instructions in the manual, I’ve put the following lines in config.nix file:

{
  packageOverrides = pkgs: with pkgs; {
    python3Env = python3.withPackages (ps: with ps;
      [
        matplotlib
        numpy
        scipy
      ]
    );
    myPackages = pkgs.buildEnv {
      name = "my-packages";
      paths = [
        coreutils
        emacs
        python3Env # this does not work, why?
      ];
    };
  };
}

When python3Env is included in the path list, I get the following error:

% nix-env -iA myPackages
replacing old 'my-packages'
installing 'my-packages'
error: undefined variable 'python3Env' at /Users/smaret/.config/nixpkgs/config.nix:17:9
(use '--show-trace' to show detailed location information)

How can I fix that?

2

Use the rec keyword when defining the attrset.

{
  packageOverrides = pkgs: with pkgs; rec { … };
}
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