Merge pull request #267 from fricklerhandwerk/nix-language-tutorial

Nix language tutorial

source/anti-patterns/language.md

@@ -7,6 +7,7 @@ Nix syntax supports URLs as verbatim, so one can write `https://example.com` ins
 There's was an [RFC 45](https://github.com/NixOS/rfcs/pull/45) accepted to deprecate verbatim URLS and provides
 a number of arguments how this feature does more harm than good.
 
+(rec-expression)=
 ## `rec { ... }` expression
 
 `rec` allows you to reference variables within an attribute set.
@@ -87,6 +88,7 @@ buildInputs = builtins.attrValues {
 buildInputs = lib.attrVals ["curl" "jq"] pkgs
 ```
 
+(search-path)=
 ## `<...>` search path
 
 You will often see Nix language code samples that refer to `<nixpkgs>`.

source/conf.py

@@ -52,7 +52,7 @@ myst_enable_extensions = [
 ]
 
 # GitHub-style automatic anchors for headings
-myst_heading_anchors = 2
+myst_heading_anchors = 3
 
 
 copybutton_prompt_text = r"# |\$ "

source/tutorials/ad-hoc-developer-environments.md

@@ -153,6 +153,7 @@ All the subsequent `#! nix-shell` lines are used to build up the shell's configu
 
 We've only covered the bare essentials of Nix here. Once you're comfortable with these examples, take a look at:
 
+- {ref}`reading-nix-language` to learn about the Nix language, which is used to declare packages and configurations.
 - {ref}`pinning-nixpkgs` to see different ways to import Nixpkgs.
 - {ref}`declarative-reproducible-envs` to create reproducible shell environments given a declarative configuration file called a Nix expression.
 - [Garbage Collection](https://nixos.org/manual/nix/stable/package-management/garbage-collection.html)- as when using `nix-shell`, packages are downloaded into `/nix/store`, but never removed.

source/tutorials/index.md

@@ -5,6 +5,7 @@
 
 install-nix.rst
 ad-hoc-developer-environments.rst
+nix-language.rst
 towards-reproducibility-pinning-nixpkgs.rst
 declarative-and-reproducible-developer-environments.rst
 continuous-integration-github-actions.rst