$ nix-repl
Welcome to Nix version 1.10. Type :? for help.

nix-repl> :l <nixpkgs>
Added 6640 variables.

nix-repl> idea.
idea.clion                  idea.idea14-community       idea.phpstorm               idea.recurseForDerivations
idea.idea-community         idea.idea14-ultimate        idea.pycharm-community      idea.ruby-mine
idea.idea-ultimate          idea.idea15-ultimate        idea.pycharm-professional   idea.webstorm