diff --git a/flake.nix b/flake.nix
index a289545..4faf3e9 100644
--- a/flake.nix
+++ b/flake.nix
@@ -24,6 +24,7 @@
       formatter = nixpkgs.legacyPackages.${system}.alejandra;
       checks = {
         inherit (self.packages.${system}) default;
+        # TODO: clippy
       };
       devShell = with pkgs;
         mkShell {
diff --git a/readme.md b/readme.md
index 91a3f7d..e245992 100644
--- a/readme.md
+++ b/readme.md
@@ -1,7 +1,10 @@
 # Learn Rust in a Month of Lunches
 
 Bought [this book][book] and this code contains my musings and other stuff that
-I write as I work through it.
+I write as I work through it. I'm already familiar with a few aspects of Rust
+and maintain a widely-deployed Rust project at work, so will be focusing on
+stuff new and/or interesting to me and mostly ignoring anything that I believe
+I'm familiar with -- correctly or not.
 
 Enjoy!
 
diff --git a/src/main.rs b/src/main.rs
index 1621a54..45ba317 100644
--- a/src/main.rs
+++ b/src/main.rs
@@ -1,11 +1,43 @@
+#![warn(
+    clippy::all,
+    clippy::style,
+    clippy::absolute_paths,
+    clippy::pedantic,
+    clippy::nursery,
+    // clippy::cargo
+)]
+
+//! my code and notes from the book "Learn Rust in a Month of Lunches"
+
 /// a doc comment - use `cargo doc --open` to see it?
 fn main() {
+    // ch 1
     let c: char = '\u{D1EA}';
-    let bytes = b"yoyoyo";
-    let me = "meeeeeeeeeeeeeeeeeeeeeeeeeee";
     println!("Hello, world! {c}");
+
+    // ch 2
+    let bytes = b"yoyoyo";
     println!("Hello, bytes! {bytes:?}");
+
+    let me = "meeeeeeeeeeeeeeeeeeeeeeeeeee";
     println!("Hello, {me: <4.12}, meet the real {me}.");
+
+    // ch 3
+    let children = 5;
+    let married = true;
+
+    // match guards
+    match (children, married) {
+        (children, married) if !married => {
+            println!("Not married with {children} kids");
+        }
+        (children, married) if children == 0 && married => {
+            println!("Married but no children");
+        }
+        _ => {
+            println!("Married? {married}. Number of children: {children}.");
+        }
+    }
 }
 
 // if I were to write a webapp, I would like to avoid postgres