A few correction on the otherwise good article:

* Nix 2.0 includes the repl. Just run `nix repl`

* The URL literal returns a string

* It would be good to explain how the `<...>` notation resolves paths from the NIX_PATH. For example `<nixpkgs>` looks for the `nixpkgs` key in `NIX_PATH=nixpkgs=/path/to/channel`