2.3 Nix syntax: the complete tour

The complete tour of Nix syntax in one focused sitting: strings and indented strings (with the tricky ${} escapes), numbers, lists, attribute sets and inherit, functions and currying, let/with scoping and their pitfalls, import, and how to merge sets with // versus lib.recursiveUpdate. After this, nixpkgs source stops looking like a foreign alphabet and becomes something you can actually read.