configuration.nix

...
  environment.variables.EDITOR = "${pkgs.vim_configurable.out}/bin/vim";
  environment.systemPackages = with pkgs; [
    ...
    (import pkgs/vim.nix)
    ...
  ];
...

vim.nix

with import <nixpkgs> {};

vim_configurable.customize {
	# Specifies the vim binary name.
	# E.g. set this to "my-vim" and you need to type "my-vim" to open this vim
	# This allows to have multiple vim packages installed (e.g. with a different set of plugins)
	name = "vim";
	vimrcConfig.customRC = ''
		set nu ai tabstop=4
	'';
	vimrcConfig.vam.knownPlugins = pkgs.vimPlugins;
	vimrcConfig.vam.pluginDictionaries = [
		{ names = [
			# Here you can place all your vim plugins
			# They are installed managed by `vam` (a vim plugin manager)
			"Syntastic"
			"rust-vim"
			"vim-racer"
			"vim-addon-nix"
		]; }
	];
}