Visual Studio Code
Installing Microsoft's Visual Studio Code
Because it is NixOS, you don't have to be root in order to be able to install stuff. As a normal user, do:
$ nix-env -iA nixos.vscode
And to open or launch the IDE, do:
$ code
As a normal user, you might be curious what stuff you have installed. To find out, do:
$ nix-env -q
Also, if you want to uninstall stuff that you installed there as a normal user, do:
$ nix-env --uninstall package-name-here
Replace the package-name-here with whatever package returned by 'nix-env -q'.