NixOS: write about NixOS

spotlight_courses/HS24_NixOS/main.typ

@@ -39,7 +39,8 @@
 // FIXME: this TOC is only for us to have an overvview while writing the talk
 #outline(depth: 1)
 
-== Today's goals
+
+== Today's topics
 - What sets *`NixOS`* apart from other distros? 
 
 - benefits of *`nix`* and *`NixOS`*
@@ -312,8 +313,33 @@ in
 
 
 = NixOS
+== What is NixOS?
+
+#quote(attribution: link("https://nixos.org/manual/nixos/stable/#preface")[NixOS Manual])[
+  a Linux distribution based on the purely functional package management system *Nix*, that is composed using modules and packages defined in the *Nixpkgs* project 
+]
+
+- *nixpkgs*: NixOS's package repository
+
+  $==>$ gigantic collection of nix code
+
+== `nixpkgs` - Exampe of package
+
+
+== nixpkgs - `cache.nixos.org`
+
+- We do not want build every package ourselves...
+
+- Built packages are cached at #link("https://cache.nixos.org")[`cache.nixos.org`]
+
+*Reminder*: If nothing changes, a derivation will have the same hash!
+
+$==>$ If your change ('override') a package, it will automatically be built locally.
+
+
+
 
-= Flakes
+= Fakes
 
 = `nixos-rebuild`
 - uses `Nix` to manage almost *everything* about your system