NixOS: selection path ‘haskellPackages.styx’ not found

[Skyfold]

I'm a bit new to NixOS so I might be missing something very simple, but when I run:

nix-env -f "<nixpkgs>" -iA haskellPackages.styx

I get:

error: attribute ‘styx’ in selection path ‘haskellPackages.styx’ not found

I already have cabal-install and cabal2nix installed.

[jyp]

Do you have NixOS installed, or just the nix package manager?

[Skyfold]

I have NixOS installed.

[jyp]

Alright, I am not using nixos myself, so this may require a couple of tries. As per the wiki (https://nixos.org/wiki/Install/remove_software#Root_user_installation) it seems that you should do

nix-env -iA nixos.haskellPackages.styx

However Styx has not made it to the stable channel yet, so check your version of nixos:

nixos-version